Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Plant physiology wikipedia , lookup
Ornamental bulbous plant wikipedia , lookup
Plant breeding wikipedia , lookup
Plant morphology wikipedia , lookup
Plant ecology wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Plant reproduction wikipedia , lookup
OBJECTIVES The student will be able to… • Explain differences between vegetative reproduction and sexual reproduction and the advantages of each. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 OBJECTIVES The student will be able to… • Design a seed germination setup for growing seeds indoors for later planting outdoors. • Draw how a seed with damping off would look and explain the cause. • Describe the processes for hardening off and transplanting for seedlings. • Take a hardwood, semihardwood, and softwood cutting from an outdoor plant. • Take a tip, stem section, leaf bud, and leaf cutting from an indoor plant. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 OBJECTIVES The student will be able to… • Identify suitable and unsuitable rooting media and say why each one is such. • Describe each of the parts of a commercial mist system and the functioning of the system. • Assemble the materials for air-layering an overgrown foliage plant. • Draw the processes of budding and grafting and explain why each process is useful in horticulture. • List five plant species that have been genetically engineered and explain why they were altered. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION • Plants are reproduced, or propagated, either sexually or vegetatively. – Sexual propagation involves seeds that result from the union of sperm and egg cells. • Possible in almost all cultivated plants & used extensively. – Vegetative propagation is based on using parts of existing plants to generate new plants. • These daughter plants will have traits identical to those of the plants from which they were derived. • Often faster than seed propagation. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION • Vegetative propagation results in clones, exact duplicates of the parent plants. – Essential for preservation of desirable characteristics that could be lost in sexual reproduction. • Such as fast growth or high yield. • Seedlings may resemble the parent plant, but will seldom be exactly like it. – A result of genetic recombination of male/female genes. • Gene mixing will result in offspring with a variety of traits. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION • Whether a plant is reproduced sexually or vegetatively depends on many factors: – Ease of germinating the seed. – The number of plants to be grown. – Importance of preserving a trait possessed by a parent plant. Sometimes plants are reproduced vegetatively to obtain a diseasefree offspring. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Seed Formation • Seeds can be formed as a result of a plant… – Fertilizing itself (self-pollination). – Being fertilized by another plant (cross-pollination). • Offspring resulting from cross-pollination are called hybrids and carry traits of both parents. – A seed package bearing the word hybrid indicates the seeds are the result of special breeding. • Selected hybrid seeds produce healthier, faster-growing plants, a phenomenon called hybrid vigor. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Seed Formation • Hybrid seed results from controlled crossing of two groups of plants, of known genetic makeup. – One designated the female line, the other the male line. • Crossing two genetically pure lines can produce seed with the best traits of both parents. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Seed Formation • Seed saved from hybrid plants will not grow good plants the following year. – Only the original hybrid seed bears the desirable traits. • Seeds included in fruit produced from hybrid seed result from random cross- or self-pollination, and will not produce the same superior plants – In some cases they may have low viability or be completely dead. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • Knowledge of genetics comes originally from work done in the 1800s by Czech monk Gregor Mendel. – He noted plant & animal offspring resemble their parents. • His experiments lasted for many years, studying many different plant traits, key among them… – – – – Plant height. Flower color and position on the plant. Seed color and seed shape, Pod color and shape. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • Mendel suspected that offspring characteristics are dependent upon contributions from both parents. – And specific characteristics from each parent are passed on directly rather than being blended together. • An offspring may look exactly like the female parent, even though it is a product of both parents. • This manifesting of the traits in a visible way is called the phenotype of the offspring. – As opposed to actual hereditary content of the offspring, which is the genotype. • These traits are in pairs in each parent, and later came to be called genes Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • Genes were classified initially as “recessive” or “dominant” depending on their ability to physically manifest themselves (phenotype) in the offspring. – It is now known relationships can exist between genes. – Partial dominance exists in some genes • Meaning it is not a winner-loser situation when they combine. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • Shown is an example of the most basic type of plant breeding done by Mendel. – Crossing a pea with a shrunken-shaped seed with one with a full round seed. Figure 5-1 Homozygous parents produce heterozygous offspring in the next generation (F1) Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • In each case, the s represents the recessive gene for seed shape (shrunken-shaped seeds). – And S for the dominant gene (full seeds). It is customary to write recessive genes as a lowercase letter and dominant genes as a capital letter. Figure 5-1 Homozygous parents produce heterozygous offspring in the next generation (F1) Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • The basic cross involves a pea parent homozygous for the gene of shrunken-seed shape. – Meaning both of its genes are recessive “s,” expressed as ss because each parent has the genes in pairs. Figure 5-1 Homozygous parents produce heterozygous offspring in the next generation (F1) Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • When combined, these would potentially yield, in a pool of four offspring, in the first generation (the F1), all “heterozygous” (Ss) offspring. – That contain one gene from each parent. Figure 5-1 Homozygous parents produce heterozygous offspring in the next generation (F1) Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • All of the offspring will all have full seeds (the phenotype). – Though they contain the gene for shrunken seeds. Figure 5-1 Homozygous parents produce heterozygous offspring in the next generation (F1) Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • Shown here is what most likely would happen in regard to seed shape if two of the first-generation offspring were crossed. – Yielding a second generation (F2) of four more offspring. Figure 5-2 Crossing heterozygous offspring from the F1 generation yields both heterozygous and homozygous offspring in the next generation (F2). Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • The genes recombine to give… – Two heterozygous offspring (Ss and sS) – Two homozygous offspring (SS and ss). Figure 5-2 Crossing heterozygous offspring from the F1 generation yields both heterozygous and homozygous offspring in the next generation (F2). Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Mendelian Genetics • In regard to the phenotype (visual expression of the genes), three offspring would have full seeds because the S is dominant. – One would have shrunken seeds. Figure 5-2 Crossing heterozygous offspring from the F1 generation yields both heterozygous and homozygous offspring in the next generation (F2). Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Techniques of Plant Breeding • Amateur plant breeding is an interesting activity, but it seldom yields very spectacular plants. – Desirable characteristics are usually the result of luck. • A few basic rules of genetics when breeding plants will help ensure success. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Techniques of Plant Breeding • The two plants to be crossed nearly must always belong to the same genus & often the same species. – Cultivars within a species will usually cross-pollinate. • Only in rare instances do plants cross between genera. • In nature, seeds from cross-pollination make up only 4% of all seeds produced. – Because pollen-bearing anthers within a flower are close to the female style, self-pollination is most likely. • Plants that never self-pollinate are species that produce male &female flowers on separate plants – Holly and bittersweet, for example. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Techniques of Plant Breeding • Self-pollination can be achieved by sealing a flower in a paper bag just before it opens. – The flower will open within the bag and, having no other source of pollen, will self-pollinate. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Techniques of Plant Breeding • For cross-pollination, flowers that are ready to open should be selected from two parent plants. – Petals & anthers of the female parent should be removed with scissors, and the blossom enclosed in a paper bag. – On the male parent, the flower should be opened by hand & a small paintbrush inserted to pick up some of the pollen. The pollen should then be taken to the female parent, brushed lightly over the style & the bag replaced. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. Figure 5-3 Hand pollinating a vanilla orchid, the source of natural vanilla. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Techniques of Plant Breeding • In several days the pollen will germinate and grow down through the style to the ovary where it will fertilize the eggs, and the style will shrivel and fall. – The bag can be removed and the flower tagged with the names of the parents. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Techniques of Plant Breeding • When seed is mature & ready for harvest, usually the seed pod splits, or the fruit drops to the ground. – The color of the mature seeds will darken as they ripen. • Cleaning removes the ovary tissues that surround the seed. – Dry fruits such as the pods of beans or fruits of many trees usually split open when mature • The seeds can be shelled out with the fingers. – With fleshy fruits such as peach or squash, cut the fruit apart, extract the seeds & dry several days on a paper towel. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Techniques of Plant Breeding • For general storage of vegetable & flower seeds, a sealed container kept in the refrigerator is sufficient. – Glass jars, plastic containers, and freezer bags are all suitable, as they maintain constant humidity. • The life span of seeds in storage varies from days to years among species. – Excess vegetable seeds are commonly stored for use the following year. • Even under ideal storage conditions, the longer the seeds are stored, the fewer seeds will germinate. – Seedlings that do emerge will be weaker. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Techniques of Plant Breeding • When planting seed that has been stored, it is advisable to do a germination test. – Planting a specific number of seeds & counting resulting seedlings to calculate the germination percentage. • This will allow the grower to sow the seed more thickly to compensate for a decreased germination rate. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SEXUAL AND VEGATATIVE PROPOGATION Commercial Seed Production • Many flowers and vegetables are grown from seed because it is the cheapest source of plant material. – Vegetable seed varieties are chosen for shipability, disease & herbicide resistance, ability to withstand mechanical harvesting, size, color, taste. – Flowers are selected for growth habit, size, flower color, disease resistance, and other qualities. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Growing Outdoors • Sowing seed outdoors is called direct seeding. – Used for commercially grown vegetables, flowers & herbs. • As well as in home gardening. • It is important to choose the site carefully. – Providing the correct amount of light for the species. – It should also be well drained. – Soil must be loose and crumble easily. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Growing Outdoors • Seeds should be sown at the depth and spacing recommended on the package. – The general rule is that seeds should be planted one and one-half times as deep as their diameter. – Spacing between seeds can be estimated from the mature size of the plant. • Thicker sowing is permissible/recommended, with weaker seedlings will be pulled out to achieve proper spacing. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Growing Outdoors • Soil used to cover seeds should be free of even small clods to enable the emerging shoots to reach the soil surface easily. – Rub the soil between the palms to pulverize it. • Timing is important when planting seeds outdoors. – If planted too early in spring, seeds will fail to germinate or germinate slowly because of cold weather. – If planted too late, they may not mature within the growing season. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Growing Outdoors • Adequate soil moisture during the germination and establishment parts of a plant’s life is essential. – Drying of the soil at these times will be fatal to seedlings. • Seeds in moist soil don’t need immediate watering. – They absorb moisture from the soil to start germination. • In dry soil, watering will supply moisture, and settle soil around the seed. – So the emerging root will have immediate contact with water & nutrients. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Growing Outdoors • A liquid fertilizer starter solution can be applied to seedlings after germination is complete. – While not essential, research has shown starter fertilizer will increase the growth rate of seedlings substantially. • Seedlings are considered established after true leaves appear, indicating the root system is absorbing water and nutrients from the soil. – And the plant no longer is dependent on carbohydrate stored in the seed. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Growing Outdoors • Timing is important when planting seeds outdoors. – If planted too early in spring, seeds will fail to germinate or germinate slowly because of cold weather. – If planted too late, they may not mature within the growing season. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Natural Reseeding of Outdoor Plants • A number of cultivated plants produce seed that germinates naturally the following season. – Such as tomatoes, corn, and petunias. • Seedlings that grow untended are called volunteers. – Generally do not produce plants of the same quality as the parents. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Seed Growing Indoors for Home Horticulture • Vegetable, flowers & herb seedlings can be started 6 to 8 weeks ahead of when required for the garden. – A container for raising seedlings need not be elaborate. • With adequate drainage for excess water. – For large numbers of seedlings, plastic, Styrofoam®, or wood nursery flats can be purchased. Compressed peat moss disks that swell with water and form a plantable container for one seedling are also available in garden centers. Figure 5-4 Compressed peat pots. Courtesy of Pinetree Garden Seeds, Gloucester, Me. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Seed Growing Indoors for Home Horticulture • The seeds are planted in a growing medium. – It must be fast-draining and not prone to packing. • Commercial potting soils sold for houseplants fit these requirements & are convenient for seedlings. – Pure garden soil should not be used because it packs when restricted in a container, making it unsuitable for growth. Figure 5-5 A commercially produced seed-starting system for homeowners. Courtesy A. M. Leonard Co. A home seed-starting unit can also be used. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Seed Growing Indoors for Home Horticulture • Sterilization of growing medium is an important precaution if outdoor soil is a part of the medium. – It kills fungi in the medium that cause plant diseases. • To sterilize the medium, dampen, place in a covered baking dish, in an 160 - 180 deg F oven for 1 hour. – After cooling, medium can be poured into a clean seeding container and seeds planted immediately – Keep excess medium in a sealed plastic bag to prevent recontamination. • Houseplant potting soil seldom requires any further preparation. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Seed Growing Indoors for Home Horticulture • Spacing between seeds can be close provided the plants will be transplanted soon after they emerge. • Water can be supplied by sprinkling or misting whenever the growing medium begins to dry. – An easy way is to water seeds after planting and enclose the seed container in a clear plastic bag. • The plastic prevents moisture from evaporating. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Seed Growing Indoors for Home Horticulture • For most rapid germination, seeded containers should be placed at a temperature of 70 - 80 deg F. • A sunny area is not required for germination, and should not be used for plastic covered/enclosed containers. – Heat from sunlight will build up and kill the seeds. • Not essential for germination, bright light or direct sunlight is needed after seedling emergence. – Limited light entering a window is often not sufficient to raise healthy transplants. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Seed Growing Indoors for Home Horticulture • For raising most transplants, artificial light, a greenhouse, or a greenhouse window is advisable. If the seedlings become pale and stringy instead of compact, poor garden plants will result. Figure 5-6 Stringy tomato seedlings raised in insufficient light. Photo by Kirk Zirion. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Commercial Greenhouse Production of Seedlings • Bedding plants are a commercial classification of plants sold in spring, and in some climates in fall. – Usually seedlings of annual flowers, vegetables, or perennials. • As a business they are worth $1.2 billion (wholesale) annually in the United States. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Commercial Greenhouse Production of Seedlings • Seedlings are sold in several container types. Four- or six-plant pony packs or 4-inch diameter pots are standard for retail sale. Figure 5-7 A pony pack of geraniums. Courtesy of National Garden Bureau. For commercial growers selling to commercial producers, plastic flats or plug flats (also known as thermoform flats) composed of 100 to 800 small cells, each with one plant, are common. Figure 5-8 A thermoform plug flat of seedlings. Courtesy of Blackmore Co., Belleville, Mich. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Commercial Greenhouse Production of Seedlings • The commercial system of production is highly mechanized, and sometimes automated. The trays are seeded mechanically using a commercial seeder, & germinated in growth rooms that precisely control temperature. Figure 5-9 A small-scale commercial seeder for plug production. Courtesy of Blackmore Co., Belleville, Mich. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Commercial Greenhouse Production of Seedlings • After germination, seedlings are moved to a greenhouse, or outdoors for several weeks. – During which time they are irrigated and fertilized with overhead irrigation systems. • The seedlings are sold to commercial growers, who transplant them directly to the field. – Or commercial flower growers who transplant them into containers such as pony or cell packs for further growing and eventual retail sale. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Damping Off • From emergence until several true leaves form, seedlings are susceptible to damping-off disease. – If a fungus is present in unsterilized growing media, the organism rots the seedling stem. Within a few days, the plant collapses and dies. Figure 5-10 A damping-off infection in seedlings. Courtesy of Dr. R. E. Partyka, Columbus, Ohio. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Damping Off • Once damping-off disease is detected, it can spread rapidly and kill the majority of the seedlings. – Fungicidal soil drenches are moderately effective in stopping the spread. • The best prevention is sterilizing the growing medium before planting. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Transplanting Seedlings at Home • It is advisable to transplant seedlings to larger containers as they begin to crowd each other. – As leaves of plants overlap, less light will be available to each seedling, and growth will slow accordingly. • Competition of crowded roots for nutrients also causes stunting. • Seedlings are very delicate, and transplanting must be done carefully to avoid injury. – Seedlings always should be picked up by a leaf rather than by the stem, as injury to the stem will kill the seedling. • Each plant should be watered to ensure contact between the growing medium and the roots. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Transplanting Seedlings at Home • Seedlings should be kept in a shaded location for 2 to 3 days to minimize transpiration water loss while the roots damaged during transplanting resume water absorption. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Hardening Off • Seedlings raised in a controlled environment should be subjected to a hardening-off period to acclimatize them to outdoor conditions before transplanting. – In suitable weather is suitable, the transplants should be moved outdoors for several hours each day. • After about a week, the transplants will be hardened and will appear less succulent. – Hardened plants are less likely to wilt or shock at transplanting. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SEED Transplanting Outdoors • If possible, an overcast day should be chosen for transplanting outdoors to minimize wilting. – If this is not possible, transplanting should be done late in the afternoon to allow roots to recuperate overnight. – Roots should be disturbed as little as possible and the plant watered afterward. • Some wilting should be expected, but if it is severe or lasts more than 1 to 2 days, the plant will need protection during reestablishment. • The soil should be moist at all times so the roots easily can replace water lost through transpiration. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SPORES • Of all the commonly cultivated plants, only one type, ferns, bears spores. In ferns, a spore drops on the ground & grows into a flat plant called a prothallus. The prothallus then develops the sperm and egg, which unite and form the new plant. Figure 5-11 Fern prothalli. From Wilson, Botany, 5/e. ©1971 Brooks/Cole, a part of Cengage Learning, Inc. By permission. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SPORES • Mature, healthy ferns develop hundreds of organs called spore cases on the undersides of their fronds. The spore cases resemble small brown dots or lines, and the cases protect and release the spores. Several months are required for a fern to develop & ripen spores. When the spores are mature, the spore cases open and release the spores into the air. Figure 5-12 Spore cases on the underside of a holly fern leaf. Photo by Rick Smith. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SPORES • To capture spores before they are released, test the maturity of the spore cases by lightly tapping the frond over a piece of white paper. – When specks appear on the paper, the frond should be cut off and enclosed in an envelope for several days. • The spore cases then will open in the envelope, yielding a tiny amount of spores in the bottom. • Spores have the same growing requirements as seeds: warmth, moisture, air & a growing medium. • As they grow, prothalli should be misted daily, as the egg and sperm they form can unite only in water. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GROWING PLANTS FROM SPORES • Eventually fronds will grow through the center of the prothalli, which will die slowly. – Young ferns then can be transplanted to individual pots as soon as they are large enough to handle. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION • Propagating plants vegetatively involves use of nonsexual plant organs such as leaves, stems & roots. – Vegetatively propagated plants almost always develop identically to its parent. • Preserves the work of plant breeders and natural mutations. • Another reason to propagate vegetatively is to reproduce plants that seldom flower or produce only sterile flowers. – Foliage plants and navel oranges fall into this group. • A third reason is the relatively short time required by vegetative propagation to produce a mature plant. – A cutting can be rooted in as little as 2 weeks. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Cuttings are the most widespread vegetative propagation method. – Vegetative plant parts such as leaves, stems & roots that regenerate missing parts to form new plants. • They are cut from parent plants called stock plants. • The environment required for growing cuttings is the same as for germinating seeds: warmth, moisture, and a growing medium. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Most parts used for vegetative propagation are taken from above-ground portions of the plant, and must regenerate roots. – The growing medium will determine whether roots will form, and their quality. • The main requirement is to drain quickly to admit air to the rooting area, yet retain some moisture. – There is not one superior rooting medium. • Many combinations of materials are used: – Sand and part peat moss, part perlite, part vermiculite. – Pure vermiculite, pure perlite, and pure sand. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Shrubs, vines, herbs, groundcovers, and a few perennial flowers are propagated by cuttings taken at different times of the year. • Cuttings from woody outdoor plants are classified by the degree of woodiness of the cutting. – Hardwood, semihardwood, or softwood. • A fourth classification, herbaceous, includes cuttings from nonwoody plants such as many groundcovers. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Hardwood cuttings should be taken in late fall through early spring from the matured wood of the past season’s growth. They are generally about 6 to 10 inches (15 to 25 centimeters) long and may come from either deciduous or evergreen plants such as juniper, viburnum, and apple. Figure 5-13 Hardwood cuttings of juniper (left), sycamore (middle), boxwood (right). Photo by Kirk Zirion. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • The specific procedures for rooting cuttings vary. – Cuttings are generally cuttings are wrapped in plastic and stored over winter in the refrigerator. • Cuttings should be enclosed in a plastic bag to prevent moisture loss & placed in a 70 - 80 deg F location – Roots should form in less than 6 weeks, and dormant buds should begin growing shortly thereafter. • Cuttings can be hardened off and transplanted several weeks later. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Semihardwood cuttings are taken in summer from the partially matured new growth of woody plants. – Cuttings are made 3 to 6 inches long. • Because they lose water through their leaves very rapidly, cuttings should be placed in a pre-moistened plastic bag as they are cut. • The procedure for rooting is the same as for hardwood cuttings. – But rooting is often more rapid. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Softwood cuttings are taken in late spring from succulent new growth produced that season. – They generally root more consistently and quickly than either hardwood or semihardwood cuttings. • Picking the cuttings at the right stage of maturity is crucial to success. – Rapidly growing shoots are too tender & prone to rotting. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Ideally, the shoots should be slightly flexible but should snap when bent to a 90 degree angle. – They should be harvested into wet plastic bags and rooted using the same directions as for hard- and softwood cuttings. • Because the younger parts of plants generally root more easily than more mature parts, softwood cuttings are the most reliable way to vegetatively propagate most woody outdoor plants. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Herbaceous cuttings are equivalent of softwood cuttings, but taken from herbaceous plants. – Such as coleus and impatiens, that never become woody. • Herbaceous cuttings can be taken and rooted at any time during the growing season. – Generally 2 to 4 inches long, taken from the tip of a stem. • As with all the types of cuttings, bases should be planted in damp rooting medium and the cuttings enclosed in a plastic bag to increase humidity. – Keeping cuttings wet from the time they are cut until they are stuck in the medium will reduce wilting. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Root cuttings are sections of thickened roots without leaves or stems attached. – Only a few outdoor plants will grow from root cuttings. • These species have the ability to generate an adventitious bud. • Root cuttings of most outdoor plants are best taken in early spring, just before new growth begins. – Carbohydrate reserves are at a maximum, and the plants are ready to emerge from dormancy. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Root cuttings should be protected from drying, and can be harvested by digging out medium-sized roots from around the base of an established plant. – The sections can be cut into 3-inch (8-centimeter) lengths and planted horizontally 1/2 inch deep in rooting medium. Figure 5-15 Rooting stem tip (left), stem section (middle) & leaf bud (right) cuttings. Photo by Rick Smith. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Cuttings of indoor plants can be of four types, depending on the part of the plant from which they are taken. – – – – Stem tip cuttings. Leaf Bud Cuttings. Stem Section. Leaf Cuttings. Figure 5-14 A typical dicot plant, showing where stem tip, leaf bud, and stem section cuttings would be found. Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Stem tip cuttings are the most common type and consist of the top 2 to 4 inches of a growing stem. The procedure for rooting the cuttings is the same as for cuttings of outdoor plants. Figure 5-14 A typical dicot plant, showing where stem tip, leaf bud, and stem section cuttings would be found. Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Leaf bud cuttings are taken after the stem tip has been used. – Any plant propagated by stem tip cuttings can be propagated by leaf bud cuttings. Each cutting includes a short section of stem, one leaf & its corresponding axillary bud. When the base of the cutting roots, the axillary bud breaks dormancy & forms the new stem of the plant. Figure 5-14 A typical dicot plant, showing where stem tip, leaf bud, and stem section cuttings would be found. Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Stem section or cane cuttings are short pieces of thickened, leafless stem. After the top of the plant is removed for a stem tip cutting, the remaining stem is cut into pieces containing two to three nodes each. The sections are laid horizontally half-buried in the rooting medium. A plastic covering is not essential provided the medium remains moist. Figure 5-14 A typical dicot plant, showing where stem tip, leaf bud, and stem section cuttings would be found. Drawing by Bethany Layport. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Leaf cuttings contain a single leaf & sometimes its petiole—propagation procedures vary by genera. Most indoor plants cannot be propagated using only a leaf. Only certain species generate buds where the leaf blade joins the petiole or along leaf veins or margins. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Leaves of African violet & peperomia are picked with the petiole attached. The leaf is buried in the rooting medium up to the blade, and new plants form at the soil line. Figure 5-16a African violet leaf cutting. Image copyright © 2008. Paul Postuma Ars Informatica. By permission. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Leaves of Bryophyllum and succulents such as jade plant, burro tail & echeveria, are picked directly off the plant & laid on the surface of the medium. A medium largely composed of sand is best; enclosing in a plastic bag is not advisable. Up to twenty new Bryophyllum plants will form around the leaf margin. With others, single plants will appear where the leaf was broken from the plant. Figure 5-16b Jade plant. Courtesy of Jim Mercer. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Fibrous-rooted begonias like rex begonia produce new plants along the veins of mature leaves. – And also where the petiole connects to the leaf blade. • Whole leaves or pieces of leaves should be laid on a damp rooting medium so veins make contact. • Cutting veins with a knife stimulates bud formation, and three to five cuts can be made on each leaf. – A mature leaf can be cut crosswise in 1” long sections and the base of each stuck in rooting medium. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Orientation of the cuttings is critical. – The end of the section on top originally must be up, and the part that was lower is planted in the rooting medium. • Sections inserted upside down do not root. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • After the leaf section roots, a new plant will be produced at the base & grow up beside the leaf section. Figure 5-16 Leaf cuttings. (a) African violet. (b) Jade plant. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Propagation from leaf cuttings is slow. – Generation of an adventitious bud and roots is an energy-consuming process. • Several months will be required before the young plants are large enough to be transplanted. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Select cuttings from shoots without flowers or flower buds, or if this is not possible, pick off the flowers. – A cutting with blossoms will channel energy into the reproductive parts, and be less likely or slower to root. • Note positions of nodes on the stem of the cutting. – Roots are often generated first at these sites, so cuttings should be made with at least one node near the base. • Leafy cuttings wilt easily and once severely wilted are less likely to root. – Cuttings should be kept moist after cutting & before being stuck in the medium to slow water loss. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • A humid chamber to minimize transpiration can be made easily with a light translucent storage box. Leafy cuttings wilt easily and once severely wilted are less likely to root. Cuttings should be kept moist after cutting & before being stuck in the medium to slow water loss. Figure 5-17 A rooting chamber made from a translucent storage box. Idea supplied by Janie Varley, Vanderbilt, Tex. Photo by Jennifer Finney Janssen, M.Ed., Jackson County Extension Agent—Family and Consumer Sciences, Texas AgriLife Extension Service. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Any leaves that will be covered after the cutting is stuck into the rooting medium should be removed. – Left on, they rot & provide a breeding ground for disease organisms. • Leaves that die and drop from the cuttings should be removed, with whole cuttings that appear dead. • A heat source at the bottom of the rooting chamber where the roots will be forming will increase the speed and success of rooting cuttings. • Use of a rooting hormone can increase rooting speed and success. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • Gently tug the rooting cuttings about once per week to determine whether rooting has occurred. – If it slips out easily, no anchoring roots have formed. • The cutting should be inspected for signs of rotting and, if still healthy, can be reinserted in the medium. – If the cutting does not pull out with gentle tugging, it has roots already. • The plastic lid can be opened partially to accustom the plants to normal humidity, and removed entirely after several days. – After 1 week, cuttings can be transplanted to pots. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Cuttings • A few outdoor plants, such as willow & pussy willow, and many tropical indoor plants can be rooted and grown in water. Stem tip cuttings are usually used, with lower leaves removed & the cutting absorbing water through the cut end until roots are formed. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Commercial Rooting of Cuttings • A greenhouse generally has one or more benches exclusively used for propagation and equipped with an intermittent mist system. This system is designed to keep transpiration at a minimum until the cuttings regenerate roots and can take up water & nutrients. Figure 5-18 A mist nozzle. Photo courtesy of CEV Multimedia, Ltd., Lubbock, Tex. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Commercial Rooting of Cuttings • The interval of time between mistings will depend on the rate of evaporation in the greenhouse. – The goal is to remist just before the leaves are fully dry. • But not to wet them excessively, as excessive wetting leaches nutrients from the leaves and increase occurrence of disease infection. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Commercial Rooting of Cuttings • The intermittent mist system consists of a time clock that times the interval of misting, an electric solenoid valve that turns the mist on and off, and piping and mist nozzles over the plants. In some cases an electronic leaf can be substituted for a time clock. This is a small metal sensing plate attached to an unit that controls the solenoid valve. Figure 5-19 A Mist-A-Matic to control a mist system. Photo courtesy of Griffin Greenhouse & Nursery Supplies. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Commercial Rooting of Cuttings • A root-zone heating system is often also used to warm only the bases of the cuttings to encourage faster and more reliable rooting of cuttings. Figure 5-20 A Heat-A-Matic suitable for use with pots or flats. Courtesy of Griffin Greenhouse & Nursery Supplies. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Crown Division • Crown division is probably the most common and reliable home propagation method. Used for herbaceous perennials, shrubs, & houseplants such as ferns, asparagus ferns, African violets, and spider plants. One plant is separated into two or more pieces, each with a portion of roots & crown. Figure 5-21 Division of a plantain lily into several smaller crowns. Photo by George Taloumis. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Crown Division • Shrubs to be divided must be multi-stemmed. • Division can be done any time in the growing season. – Plants in active growth must be treated carefully to minimize water loss through the leaves. • They should be divided when dormant if possible. – By cutting through the crown with a spade so that it is broken down into several sections. • A part of the parent crown can be left to rejuvenate the shrub. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Crown Division • With herbaceous perennials, the entire plant is dug up and cut apart. – The sections are then replanted and watered. • When dividing houseplants, the parent is removed from its pot, cut or pulled apart & sections repotted. – Pruning is normally unnecessary. • If wilting occurs, the newly potted sections can be left in plastic bags under indirect or filtered light for several weeks until the roots are reestablished. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Layering • Layering is another home method for propagating vines and shrubs with a trailing growth habit or flexible branches. – A low, flexible shoot is bent to the ground when the plant is in active growth. • It is held in place by a bent wire or heavy stone, and mounded with soil a short distance back from the tip. – Within a few months, roots should have formed on the covered portion of stem, and the layer can be cut from the parent plant and transplanted. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Air Layering • Air layering is a technique used primarily on large houseplants such as rubber plants. – It involves inducing stem rooting of a plant that still has its own root system. Used to obtain new plants from a large branched specimen, to shorten a plant that has grown too tall, or make a plant which has become tall and leafless short and bushy again. Figure 5-22 Air layer. Photo by the author. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Air Layering • Choose where the new root system is desired… – A 1” wide strip of bark should be cut around the stem & the bark pulled off. Girdling removes the phloem & cambium but not the xylem, which still translocates water to the top of the plant. – Place a handful or two of damp sphagnum moss over the girdled area & wrap with plastic. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. Figure 5-22 Air layer. Photo by the author. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Air Layering – Use twist-ties or tape to secure both ends and seal in moisture. – Place foil over the plastic if the air layer area will be exposed to direct sunlight. • To prevent overheating. – In 2 to 3 months, when several roots with lengths of 2” to 3” have formed, the air layer can be cut and transplanted to its own pot. Figure 5-22 Air layer. Photo by the author. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Runners, Rhizomes, and Stolons • Runners, Rhizomes, and Stolons are horizontal stems produced as a natural means of vegetative reproduction. – Runners grow above-ground. • Strawberries, ferns, spider plants, and strawberry begonias. – Rhizomes & stolons grow at ground level or below-ground. • Typically found on bamboo, grasses, and some irises. • There are subtle botanical differences among them, but they are handled much the same in propagation. – As modified stems, these organs have buds, nodes, and internodes. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Runners, Rhizomes, and Stolons • Runners are found on such plants as strawberries, ferns, spider plants, and strawberry begonias. Figure 5-23 Rooting a runner of a spider plant. Photo by Kirk Zirion. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Runners, Rhizomes, and Stolons • A runner will have only one bud at the tip, whereas stolons and rhizomes may have several. – The nodes are the sites where new plants will form. • With a runner on an outdoor plant, the stem can be positioned as it begins to form the new plant. – The runner will root without additional attention and can be severed from the parent and moved after rooting. • As houseplants are grown in pots, runner plants may never make contact with a rooting medium without help and can live attached to the parent indefinitely. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Runners, Rhizomes, and Stolons • When a new plant is wanted, a small pot of growing medium can be placed under the runner plant. – Roots will form in less than a month & the runner detached. • When this method is impractical, the runner can be detached & treated as an unrooted stem tip cutting. • Propagating plants from rhizomes and stolons is done much the same way. – The stem connecting the young plant to its parent is cut after a moderate amount of roots has formed. • The young plant is then transplanted to the new location. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Suckers and Offsets • Suckers and offsets are young shoots that grow from the roots or stems of mature plants. Functionally similar to rhizomes and stolons, and found in many shrubs & houseplants such as bromeliads, succulents, and cacti. Figure 5-24 A snake plant with two young offsets. Photo by Kirk Zirion. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Suckers and Offsets • Offsets on cacti are frequently produced on top of the plant and can be broken off and rooted without difficulty. • Suckers from the bases of plants may or may not have developed root systems independent from the parent. – If so, they can be transplanted directly. – If not, they are treated as cuttings. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. Figure 5-25 A pincushion cactus with offsets. Photo by Rick Smith. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Storage Organs: Bulbs, Corms, and Tubers • Underground storage organs are produced by some herbaceous perennials. – A repository of stored carbohydrate, botanically, these are modified stems with nodes, buds & modified leaves. • Lilies, gladiolas, and amaryllis. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Storage Organs: Bulbs, Corms, and Tubers • Their natural means of vegetative reproduction is the formation of clones of themselves (called bulbils, cormels, or tubers) around the base of the parent. – These can be broken off and planted in new locations. • Preferably while the plant is dormant. Blooming of storage organs may take 2 to 3 years after the year they are produced because a minimum size must be reached before flowering will occur. Figure 5-26 Removing a daughter bulb from the mother. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Grafting and Budding • Grafting and budding are fairly complex methods of propagation used for reproducing valuable fruit and ornamental cultivars in nurseries. – Budding & grafting unite genetically different plants so they heal together & function as a single plant. • An amateur who wishes to try should plan ahead and consult reference books for more in-depth information. • Budding transfers a bud of one plant to another plant that will function as the root system, whereas grafting attaches a small branch to another plant. – Most frequently combining two cultivars of a species into one plant that exhibits the best features of each. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Grafting and Budding • Grafting can also serve other purposes: – Repair of girdled trees that would otherwise die. – Creation of unusual plant forms such as tree roses or trees with weeping heads atop strong, straight trunks. – Changeover of old orchard fruit trees to a new cultivar. • Grafting & budding rely on activity of cambium cells. – Must be done when the cells are dividing actively and will heal the grafted area quickly. • To determine the correct stage for grafting, bark is examined for slippage. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Grafting and Budding • Rootstock diameter must be equal to or larger than that of the scion. – Scion wood is usually a pencil thickness or slightly larger. • Cambium of the stock & scion must be in contact, preferably over as great an area as possible. – If contact isn’t made, the graft won’t heal & the scion dies. • The stock and scion must fit tightly together, and the joint must be protected from drying. – A tight graft union is achieved by wrapping the area with special rubber ties or waxed string. • Drying is prevented by a coating of wax. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Grafting and Budding • Basic steps involved in a style called whip grafting. Stock & scion cut to equal size and ready for grafting. Figure 5-27a Steps in performing a whip graft. Courtesy CEV Multimedia, Ltd., Lubbock, Tx. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Grafting and Budding • Basic steps involved in a style called whip grafting. Stock & scion joined and held together with a rubber strip. Figure 5-27b Steps in performing a whip graft. Courtesy CEV Multimedia, Ltd., Lubbock, Tx. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Grafting and Budding • Budding involves removing a patch of bark with a bud from a scion and laying it directly against the cambium of the stock. – Less risky than grafting because the stock is damaged only slightly if the union doesn’t heal. As with grafting, the area of the union must be protected from drying with rubber ties. Figure 5-28 Bud patches to be used in budding (upper) and a bud patch in place on a branch (lower). Photo courtesy of Dr. Robert F. Carlson. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Tissue Culture • Tissue culture, also called micropropagation, is the propagation of plants from nearly microscopic portions of parent plants. Importance of propagation from virus- free parent stock has come to be appreciated recently as the detrimental effects of unrecognized virus infection have become known. Figure 5-29 Tissue-cultured strawberries. Photo courtesy of Barbara M. Reed, National Clonal Germplasm Repository, Corvallis, Ore. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Tissue Culture • The technique has two distinct advantages over traditional propagation: – It enables mass production of a cultivar from an extremely limited amount of parent stock, in a relatively small area. – It enables the propagator to eliminate disease-causing viruses from the parent material, unattainable through the use of pesticides. • And to propagate numerous virus-free offspring that are healthy and vigorous. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 VEGETATIVE PROPAGATION Tissue Culture • Tissue culture is not an amateur activity, because it is nearly impossible to achieve the sterile conditions necessary. • Tissue-cultured plants still in test tubes are sold in nurseries occasionally as novelty items. – Particularly orchids, which were the main plants tissue cultured for many years. • The test tube is left sealed and treated as a miniature terrarium. • When the plant outgrows the tube it sometimes can be transplanted to a pot, though the process is not always successful. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 GENETIC ENGINEERING • Genetic engineering can harness the biological machinery of bacteria and viruses to… – – – – Manufacture otherwise hard-to-obtain plant products. Combat genetically caused diseases. Improve tolerance of plants to adverses. Attain other similar commendable goals. • For plant improvement, it changes the genetic makeup of plants, without breeding or selection. • Its main advantage is that it makes possible the transfer of genes between completely unrelated plants or bacteria. – In rare cases, even from animals to plants. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 COMMERCIAL APPLICATION OF GENETIC ENGINEERING • In commercial horticultural production, research has centered mainly on vegetable and fruit crop genetic engineering. – With a limited amount on flowers and other crops. • Although genetically engineered crops are in widespread cultivation, most are not horticultural. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 COMMERCIAL APPLICATION OF GENETIC ENGINEERING • Generally, genetic engineering of horticultural crops has focused on – Imparting disease and pest resistance. – Imparting resistance to herbicides. – Extending the length of product shelf life. – Altering color. • In flowers. – Imparting cold-temperature resistance. • In strawberries and eucalyptus trees. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 COMMERCIAL APPLICATION OF GENETIC ENGINEERING • One of the best known genetically engineered horticultural crops is the ‘Flavr Savr’ tomato. – Engineered to retain a firm texture longer than normal. • Tomatoes destined for fresh eating must be handharvested to prevent bruising. – Unlike canning tomatoes that can be harvested mechanically—a less expensive process. • Fresh tomatoes must also be transported quickly and with careful packaging. – To ensure that they arrive at the supermarket in an attractive condition, appealing to the buyer. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 COMMERCIAL APPLICATION OF GENETIC ENGINEERING • The ‘Flavr Savr’ inhibits expression of the genetic material that causes fruit to soften when it ripens. – The softening part of ripening is slowed, although the flavor continues to develop. • This allows mechanical harvesting, increased transport time, and longer fresh shelf life in the supermarket. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 COMMERCIAL APPLICATION OF GENETIC ENGINEERING • A second genetically engineered crop receiving widespread attention is a Thompson Seedless grape variety engineered to be virus resistant. – One of the most commonly cultivated table grapes. • Also a component of blended wines. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 COMMERCIAL APPLICATION OF GENETIC ENGINEERING • Scientists hope that genetically engineered virus resistance will reduce the expense of chemicals, and their entry into the environment. – Because it will no longer be necessary to spray to prevent the disease. At present, only papaya & squash have been engineered successfully for virus resistance and put into field production. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 COMMERCIAL APPLICATION OF GENETIC ENGINEERING • Some opponents of genetic engineering fear it could upset the ecosystem in unknown ways. – They feel that the accelerated pace of genetic change could inundate the environment with bizarre plants, causing an unstable ecological situation. • Some organic farmers fear a biological pesticide, which they use to control infestations of worms, will no longer be effective due to insect resistance as a result of widespread incorporation in many crops. – Bacillus thuringiensis, is the source of genetic material put into plants to cause their cells to produce an insect poison. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 COMMERCIAL APPLICATION OF GENETIC ENGINEERING • The Environmental Protection Agency (EPA) has approved a number of genetically engineered plants. – Over 3 million acres of genetically engineered corn, cotton, and potatoes were planted in the U.S. in 1997. • A class-action suit has been filed against the EPA by thirty-one groups who charge that the EPA has been negligent in its approval of genetically engineered crops. Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 END OF CHAPTER Practical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458