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©Verlag Ferdinand Berger & Söhne Ges.m.b.H., Horn, Austria, download unter www.biologiezentrum.at
Phyton (Austria)
Vol. 14 Fasc. 1 — 2
37-39
16. XII. 1970
Influence of Nitrogen Supply on Host Susceptibility
to Tobacco mosaic virus Infection
By
Rajendra SINGH *)
Department of Botany, University of Gorakhpur, Gorakhpur, U. P., India
Received February 28, 1970
Introduction
The literature indicates that the susceptibility of plants to virus infection varies with varying nutrients (SPENCER 1935, BAWDEN & KASSANIS
1950). Since Chenopodium amamnticolor COSTE & REYN is useful test-plant
for viruses (HOLLINGS 1956) work on its physiology in relation to susceptibility to viruses seems to be necessary. The study of effects of nitrogen
nutrition on the susceptibility of this plant to tobacco mosaic virus, made
in the present paper contributes to the understanding of host virus relationship.
Materials and Methods
All the experiments were conducted in insect-proof chamber under
natural sunlight with a minimum night temperature of 19° C and a maximum day temperature of 32° C and the relative humidity 65—80%. The
culture of the virus was maintained on Nicotiana tabacum var. 'WhiteBurly'. Virus inoculum was prepared by crushing the infected tobacco
leaves in a mortar and squeezing the sap with the help of muslin cloth.
The infective sap, thus obtained was diluted 1:10 with distilled water
before inoculation. Seedlings were raised in 22.50 cm earthenware pots,
filled with compost soil. After three weeks, uniformly grown seedlings having
four leaves were transplanted in 10 cm paraffin coated earthenware pots filled
with pure quartz sand. One plant per pot was transplanted. Three groups
of 10 plants for each treatment were taken. The nutrient solutions containing different levels of nitrogen (0, 21, 70, 210, 420, 630 and 1050 p. p. m.)
were prepared as described by CHEO & al. 1952. Boron and manganese
*) Dr. Rajendra
pur, U. P., India.
SINGH,
Department of Botany, The University, Gorakh-
©Verlag Ferdinand Berger & Söhne Ges.m.b.H., Horn, Austria, download unter www.biologiezentrum.at
38
were added to all levels of nitrogen as H 3 BO 3 and MnSO4.2H2O at a concentration of 0.5 p. p. m. All the levels of nutrient solutions were adjusted
to pH 6.O.
Nutrient treatments were started after three days of transplantation
and each plant received 50 ml of specific nutrient solution thrice a week.
Distilled water was added to the pots, if necessary between feedings. Vegetative growth was measured in terms of height and green weight of plants.
Inoculations were made with tobacco mosaic virus after four weeks of
nutrient treatment. At this stage growth response to different levels of
nitrogen supplied was evident. A batch of 60 leaves of comparable size
Table 1
Effect of nitrogen supply on the susceptibility of C. amaranticolor plants to
infection
Nitrogen Cone.
(p. p. m.)
0
21
70
210
420
630
1050
cm
Fresh wt. in
gram
üSTo. of lesion produced per leaf *)
4.00
8.00
12.50
15.00
18.00
23.00
20.00
0.10
0.72
1.00
2.10
6.50
10.50
9.50
4.20
37.00
42.00
51.40
59.02
64.00
80.00
Height in
*) Average of 60 leaves
were inoculated and the height and fresh weight was recorded. After four
days of inoculations the lesion produced were noted. The inoculations were
made by gently rubbing the leaves of healthy plants with fore-finger dipped
in inoculum. Carborundum powder of 400 mesh was used as abrasive.
E x p e r i m e n t a l Results
Plants were grown separately in nutrient solutions containing 0, 21, 70,
210, 420, 630 and 1050 p. p. m. of nitrogen for four weeks. It was seen that
plants at 0 and 21 p. p. m. level were stunted, flowered earlier and showed
chlorosis of the leaves. The growth of the plants increased upto 630 p. p. m.
and the further increase in nitrogen level did not effect much. The results
are given in table 1.
It was evident from the Table 1 that the maximum growth of plants
occured at 630 p. p. m. and the lowest at 0 p. p. m. of nitrogen. The number
of lesions recorded was lowest at 0 p. p. m. and the maximum at 1050 p. p, m.
of nitrogen. This indicates a positive correlation between the nitrogen
supplied and number of lesions produced.
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39
Discussion
The results in the present experiment have shown that the growth of
C. amaranticolor increased with increase in nitrogen supply upto 630 p. p. m.
and further increase (1050 p. p. m.) retarded the growth. The number of
local lesions produced was highest in plants grown at 1050 p. p. m. and
lowest at 0 p. p. m. nitrogen level. The results indicate that the number of
lesions produced is directly proportional to the supply of nitrogen, irrespective of host growth. These finding are similar to those reported by SPENCER
1935, BAWDEN & KASSANIS 1950, PENZER 1957 and SASTRY 1962.
SIEGEL & ZAITLIN 1964 discussed factors affecting the phases
of virus
infection. The formation and function of infectible sites, the conversion of
sites to infective centers and spread of infection from the primary center
may be affected by conditions such as light, photosynthesis and temperature.
In the experiments described here, the affects of host nutrition on the
individual phases of infection were not measured. Possibly, nitrogen
nutrition induces some such changes in the host physiology which makes
it more susceptible to virus infection.
Acknowledgements
The author wishes to record his indebtedness to Prof. K. S. BHARGAVA,
Head of Botany Department for providing the necessary facilities.
Summary
Effect of nitrogen nutrition on Chenopodium amaranticolor COSTE &
REYN susceptibility to tobacco mosaic virus infection was measured by
number of local lesions produced, which increased with the increase in
nitrogen, even at higher level when the growth was retarded.
References
F. C. & KASSANIS B. 1950. Some effects of host nutrition on the
susceptibility of plants to infection by certain plant viruses. — Ann.
appl. Biol. 37: 46-57.
CHEO P. C, POUND G. S. & WEATHERS L. G. 1952. The relation of host nutrition
to the concentration of cucumber virus 1 in spinach. — Phytopathology
42: 377-381.
HOLLINGS M. 1956. Chenopodium amaranticolor as a test plant for plant viruses. - PI. Path. 5: 57-60.
PENZEB J. S. 1957. The effect of mineral salts on local lesion formation by
Phaseolus vulgaris inoculated with tobacco mosaic virus. — Phytopathology 17: 448 — 751.
SASTRY K. S. M. 1962. Effect of mineral nutrition on local lesion formation by
svmn-hemp mosaic virus in guar. — Indian Phytopath. 15: 254 — 258.
SPENCER E. L. 1935. Effect of nitrogen supply on host susceptibility to virus
infection. — Phytopathology 25: 174—191.
SIEGEL A. & ZAITLIN M. 1964. Infection process in plant viruses. — Ann.
Rev. Phytopathology 1: 179-202.
BAWDEN