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ABSTRACT
ECOLOGICAL STUDIES OF WEEDS FROM RICE
FIELDS FROM BHOR AND VELHE TALUKA OF
PUNE DISTRICT, MAHARASHTRA STATE
A THESIS SUBMITTED TO
THE UNIVERSITY OF PUNE
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY
IN
ENVIRONMENTAL SCIENCES
BY
MRS. SAVITA ANAND GAIKWAD
M. Sc.
UNDER THE GUIDANCE OF
DR. D. K. KULKARNI
RESEARCH GUIDE
DR. (MRS.) A.S. UPADHYE
CO-GUIDE
DEPARTMENT OF ENVIRONMENTAL SCIENCES
UNIVERSITY OF PUNE
FEBRUARY 2013
INTRODUCTION:
Ecological aspects of the rice field are different than other ecology of animal
species, region specific, wildlife sanctuaries and national parks. Rice cultivation is a
single cycle of rice production in traditional method. A rice plant undergoes several
phenological stages, which can be combined into three main growth stages: vegetative
(germination-panicle initiation), reproductive (panicle development - flowering) and
ripening (milk grain - mature grain). The duration of the vegetative stage differs
according to the rice cultivar, while the other two stages remain the same irrespective of
the cultivar. The aquatic phase of the rice field represents the vegetative and the
reproductive stages of the rice plant, while the semi-aquatic and terrestrial dry phases
correspond to the grain ripening stage of the rice crop. Being a monoculture agroecosystem, rice fields at a specific time constitute a spatially homogeneous environment.
Therefore, as a whole, the ecology of rice fields is dominated by rapid physical, chemical
and biological changes.
Rice field ecosystems are diverse in nature and attracted attention of scientists for
evolving suitable methods for ecological investigations. Due to occurrence of different
types of organisms in soils, water and other habitats, different methods of sampling,
collection, enumeration, identification, preservation are to make sure that information
generated on their ecology are reliable.
It is worth while to mention that ecological methods to study rice field ecology
pertaining to soil, weeds, blue green algae, bryophytes, pteridophytes, fungi, microbes,
insects and other factors which are responsible for production of rice crop. Such type
of ecological studies is major concern in present attempt.
Ecology of weeds is always considered as unwanted plants growing in rice fields.
Some weeds are used as medicine, food, fodder etc.
Farmers from the area are growing traditional rice varieties. The yield of rice is
very low due to different factors. It is estimated that weeds cause an annual loss of about
Rs. 1980 crores to Indian agriculture, which is more than the combined losses caused by
insect, pests and diseases (Gupta 1998). It indicates that weed flora is an important aspect
and need to be studied on ecological point of view.
Bhor and Velhe talukas in Pune district are known for rice growing belt in
Maharashtra state. Documentation of rice varieties and associated weeds in pre-harvest
and post harvest period was not recorded earlier. In this respect, ecological aspect of rice
ecosystem has been investigated from western ghat region of Maharashtra.
Following objectives are considered for investigation:
Objectives:
•
To collect and record weed diversity in rice field from both the talukas.
•
To prepare systematic account of weeds, seed viability, growth rate, etc.
•
To study ecological parameters of weed flora in pre and post harvest fields.
•
Collection and analysis of soils in relation to weed flora.
•
To study exotic, medicinal, invasive weeds and their impact.
On these objectives present work is formulated in following chapters:
I: Introduction: This chapter gives information about ecological study of rice field and
its importance in rice field ecosystem.
II: Review of Literature: This chapter gives detailed information on weed flora, fauna,
blue green algae, fungi , bryophytes, pteridophytes and other factors in rice field
ecosystems from International, National and Regional studies.
III: Material and Methods: This chapter reveals the description of the study area,
climatic conditions, population, geology, collection of pre and post harvest weeds,
method of quantification of weeds, collection of information from farmers for their
medicinal use, herbarium preparation, and deposition of herbarium at AHMA and ATC.
Collection of soil sample and its analysis, preliminary chemical analysis, microbial
studies of soil samples, collection of associated weeds like bryophytes, algae, fungi and
pteridophytes. Method used for chemical analysis of husk and seeds of rice. Yield data
from weed control and weeded rice crop.
IV: Ecology of weeds: Rice fields from Bhor and Velhe taluka were visited in different
stages of growing rice. Bryophyte and pteriodophyte species were observed in rice field
as well as on vertical walls of rice fields. Collection and identification was done with
routine taxonomical observations. The algae were observed in different stages of growing
rice, collected and identification of algal flora. Fungi, microbes and insects were also
observed during growth of rice. Collected soil samples from 10 sites were analyzed for
physiochemical parameters such as pH, EC, organic carbon, N, P and K. Angiosperm
weeds of pre and post harvest season were collected and findings of quantitative analysis
were presented. Standard method of herbarium preparation and listing of weeds with their
categorization has been given. Experimental studies on viability of weed seeds was
carried out in laboratory. Preliminary chemical analysis of ash obtained from husk and
seeds were recorded. Impact of weeds on production of rice was investigated in each plot
having weeds and weed control. Some exotic medicinal invasive weeds were collected,
identified and recorded their effect on human ailments by local farmers.
V: Results and discussion – Findings from present work on ecology of rice field in all
aspects are compared with other relevant literature search and discussed. Some
noteworthy results are highlighted in this chapter.
VI: Summary and conclusion – The importance of this ecological study of rice field
weeds with respect to Bhor and Velhe taluka are discussed in this chapter.
References – The relevant literature is cited in this chapter.
Summary and conclusion of the thesis:
Previous studies on the biodiversity of rice fields were carried out mainly with
agronomic aspects, where the rice pests, their natural enemies and weeds have been
surveyed extensively. Comprehensive studies on the ecology and biodiversity of rice
fields are scanty. In this respect present study of Ecological study of weeds in rice fields
from Bhor and Velhe encompasses on soils, microbes, raab cultivation practices for rice
seed saplings, land races in the region, bund weeds, pre and post harvest weeds in rice
field, analysis of weeds, viability of weed seeds, effect of weed control and with weeds
on yield of rice and straw, ash values of rice grain and husk. Some exotic invasive weeds
were established in rice field and local people use them as medicines. Other associates
like algae, fungi, bryophytes, pteridophytes, fauna, invertebrates are part of rice field
ecosystem were studied.
Bhor and Velhe regions are situated in Western Ghat region. Rice is major
crop grown in the region. Local people growing local land races as well as improved
varieties. In this respect 35 farmers from Bhor region and 25 farmers from Velhe
residence of 10 villages were interviewed for rice cultivation practices, weed control in
rice field, medicinal uses of exotic invasive weeds. Ecology of rice field ecosystem and
weeds is carried out for the first time. 232 weed species observed in rice field and 208
weeds along the bunds. Some exotic invasive weeds are well established in the region.
Exotic invasive weeds are 44 occurred in the regions. They belong to 17 families, 38
genera, 44 species. All are herbs native to Brazil, Central and South America and few
from Africa, East Indies and Asia. Maximum weeds are from Asteraceae,
Amaranthaceae, Euphrobiaceae, Poaceae, Cyperaceae, Fabaceae families. Local people
use 19 weeds having properties like anthelmintic, anti-inflammatory, anti-tumour activity
diuretic, astringent, tonic, some plant parts for kidney stone, jaundice, skin diseases,
cough and cold, piles, fever, burns, urinary disorders etc.
Weed survey carried out by using 1 x 1 meter quadrate method and 100 quadrates
were laid down. Pre-harvest and post harvest weed data was analyzed. Impatiens
balsamina, Ammania baccifera, Cynodon dactylon, Cyperus rotundus, Eriocaulon
cinereum, Setaria pumila, Cyperus difformis, Smitha bigemina, Eragrostis uniolodes,
Brachiaria eruciformis are dominant species in pre-harvest season. In post harvest season
species like Parthenium hysterophorus, Cynodon dactylon, Cyperus deformis, Caesulia
axillaris, Ecilipta prostrata, Alternanthera sessilis, Cyperus rotundus Sphaeranthus
indicus are dominant species. Those species which have lower values are present in preharvest and post-harvest season like Zornia gibbosa, Tridax procumbens, Boerhavia
erecta, Cleome feline, Indigofera cordifolia. Ageratum conyzoids, Cassia obtusifolia,
Datura quercifolia, Solanum anguivi, Acalypha ciliata, Alternanthera pungens,
Arthraxon lanceolatus Exacum pedunculatum, etc. These weeds present in post harvest
season may be due to moisture content in soil for longer period and weed seed germinate
in these soils.
Soils from Bhor and Velhe were analyzed for pH, Electric conductivity,
Nitrogen, Phosphrous, Potash and micro-elements like Zn, Mn, Cu and Fe. pH values of
Karanje was 7.18 it is alkaline in nature and Nigudhghar has 5.19 in acidic in nature.
Higher levels of Nitrogen 0.54%, Zinc 2.45 ppm and Copper 10.60 ppm, Iron 54.00 ppm
in Nigudhghar. Salekarvasti has maximum level of EC 0.21, Phosphorous 0.011%,
Potash 0.084 and Iron 1.00 ppm and Manganese 32.40 ppm. Soil samples from Pabe has
5.56 pH is acidic and Vinzar is 7.34 in alkaline nature. Electric conductive 0.22
maximum in Ambavane, Gunjavane has 0.08 EC., Nitrogen 0.13%, Potash 0.13%, Zn
0.70 ppm, Cu 4.90 ppm minimum level, Pabe has 0.09% minimum level of Potash and
maximum level of Fe 55.00 ppm and minimum level of 28.70 ppm Mn while village
Wanjale has maximum level of nitrogen 1.34 %, Cu 11.60 and 34.60 Mn in ppm. Micro
element minimum level of Zn 2.31, Cu 12.34 in Karnawad, Fe 17.38 in Karanje and Mn
17.58 in Nigudhghar. Higher level of Zn 4.73 and Mn 77.36 in Salekarvasti, Fe 66.38 in
Nighudhgar and 40.43 Cu in Kiwat in Bhor region. Village Pabe has 1.28 Zn, 31.34 Mn,
7.32 Cu and 27.24 Fe in village Vinzar in low level. Fe level 60.06 in Pabe, Mn 56.03 in
Gunjavane, 6.73 Zn and 15.06 Cu in village Vinzar in higher concentration. All these soil
samples results showing variations in their analysis profile. Microbial analyses results of
soil samples shows that starch hydrolysis indicate that Salekarvasti and Wanjale shows
positive activity of bacteria and no hydrolysis in Kiwat and Pabe soil bacteria. The results
obtained from colony characters and biochemical findings and referring standard
Bergey’s Manual of determinative bacteriology. Bacteria like Alcaligenes, Halomonas,
Rhizobacterium, Meriisculus may be present in the soil samples.
These soils are burned by using leaf litter, twigs of trees, farm yard manure and
other material during raab method. Farmers opinion that due to raab practice it controls
weeds, eradicate diseases spores and disease resistant seedlings, vigorous growth of
seedlings, for easy to uproot seedlings, sturdy seedlings are obtained. Raab is also
effective in sterilize soil, burn the grass seeds and high rice seed germination. Soil
samples are weed seed bank and after one year germination of weed seeds observed in
laboratory. It indicates that soil samples in Wanjale, maximum growth of weeds i.e. 109
out of which 107 are monocots, Kiwat shows minimum weeds 16, out of which 11 are
dicot and 5 monocot and Vinzar out of 16, 6 dicot and 10 monocot weeds. Pabe and
Karanje soils have no germination of dicot weed flora.
The information on soil and weed indicator species is poorly documented, much
of it residing only in the minds of observant farmers. However, some species of weeds
occurred in saline soils like Cyperus difformis and Echinochloa colona in the region.
Details survey in relation to soil and weed flora needs special emphasis.
Yield of rice crop is dependent on varietal characters in local land race or hybrid
types and duration of crop, fertilizer application, pest and disease control and
environmental factor as well as weed population. The local land races like Taka,
Varangal, Jeera and Ekakadi drought resistant and suitable in coarse sand. Kalbhat and
Basamati are scented type. Some improved rice varieties like Indrayani, Komal, Poonum,
Rashipunam, Ratnagiri-24, Shan, Anupum, Indum, are cultivated in this region and
maturity variation from 90 days to 120 days. This factor is also affect weed population in
the rice field in contrast with pre and post harvest weeds. The yield component and rice
straw in weeded and weed control rice plot were investigated. Weed index is low as
22.86 in village Karnawad, rice yield 270 gram with weeds and 350 gram without weeds.
Wanjale has 530 and 890 gram rice yield with weeds and without weeds respectively and
weed index is 40.45.
Straw yield in without weed and with weed plot were recorded. Kiwat has 680
gram straw with weeds and Pabe village has minimum yield 90 gram straw in with
weeds and 260 gram without weeds. Similarly, 890 gram and 980 maximum yield of
straw in with and without weeds plot in village Wanjale. This indicate that weed and
without weeds in rice field decreases yield of grain and straw.
Kiwat and Pabe show highest ash value as compared to other different localities.
The comparative ash analysis shows that as the variation in environment and weeding
practices show positive correlation with ash values.
Ecologically algae, fungi, bryophytes, pteriodyphtes, birds, insects, invertebrates,
amphibians, etc organisms are the most adaptive in nature and are part of rice ecosystem.
Nine algal forms are playing major role in rice field ecosystem of present study area are
Chroococcus minutus (Kuetz) Naeg, Gloeocapsa rupestris Kuetz, Aphanocapsa roseana
de Bary, Oscillatoria princeps Vaaucher ex Gomont , Nostoc punctiforme (Kuetz) Hariot.
Anabaena variabilis Kuetzing ex Born et Flas, Aulosira firtschii Bharadwaja, Scytonema
chiastum Geitler, Gloeotrichia intermedia (Lemm.) Geitler. Fungi occurred in rice crop
are Nigrospora sphaerica (Sacc.) Mason, Cladosporium oxysporum Berk. & Curt.,
Cladosporium tenuissimum Cooke, Ephelis sp., Sporisorium sp. Alternaria longissima
Deighton & Mc Garvie, Volutella sp. Drechslera sp. The observations from this region
revealed that presence of 7 bryophytes which contributes towards water retention
phenomenon like Riccia cruciata Kash, Riccia melanospora Kash, Riccia gangetica
Ahmad, Riccia billardieri Mont. & Nees ex Gottsche, Riccia crystallina L, Cyathodium
tuberosum Kash, Anthoceros erectus Kash. Pteridophytes support in maintaining
moisture for long time in rice field. Their association in study area is an important aspect.
These are Adiantum lunulatum Burm. f., Marselia quadrifolia Linn, Selaginella
miniatospora (Dalz.) Bak.; Adiantum capillus – veneris L., Actinopteris dichotoma Kuhn.
Rice fields are a preferred habitat of amphibians and insectivorous vertebrates function as
important vertebrate natural enemies of pest insects. On this background some insects,
amphibians, fishes, etc. are long horned grass hopper, Robber flies, Meloid bettle, Apis
cerana (honey bees), Wasp, Cockroches, Earwia, Chrysomelidae beetle (leaf eating
bettle), Homopteran bugs, Fruit fly, Earthworms (Eukerria saltensis), Aquatic snails,
Rodents, Crabs and Frogs.
NOTABLE FINDINGS
Ecological studies of weeds in rice field from Bhor and Velhe region has following
significance:
1. Soils from Bhor and Velhe were analysed for pH, Electric conductivity, Nitrogen,
Phosphorous, Potash and micro-elements like Zn, Mn, Cu and Fe from rice fields.
Microbial analysis of soil samples were carried out.
2. It is observed that 232 weed species observed in rice field and 208 weeds along
the bunds. Rice field weeds are classified into in pre-harvest and post-harvest.
Such type studies are not carried out elsewhere in western ghat region so far.
3. Soil samples are weed seed bank and after one year germination of weed seeds
observed in laboratory.
4. Kiwat and Pabe show highest ash value as compared to other localities. The
comparative ash analysis shows that as the variation in environment and weeding
practices show positive correlation with ash values.
5. The yield component of rice and rice straw in weeded and weed control rice plot
were investigated.
6. 44 invasive alien weed species have been recorded out of which 19 species have
medicinal importance.
7. 7 species of bryophytes belonging to three genera & three families. Out of these
family Ricciaceae includes one genus & 5 species, Targioniaceae &
Anthocerotaceae includes 1 genus & 1 species each.
8. 5 Pteridophytes are recorded on wet soil, trenches & vertical walls along the rice
fields.
9. Nine algal forms are playing major role in rice field ecosystem of present study
area and 8 fungi were recorded from rice crop.
10. Rice fields are a preferred habitat of amphibians and insectivorous vertebrates
function as important vertebrate natural enemies of pest insects. On this
background some insects, amphibians, fishes, etc were recorded.
(Dr. D.K. Kulkarni)
Research guide
(Mrs. S. A. Gaikwad)
Research student
(Dr. (Mrs.) A.S. Upadhye)
Research co-guide