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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. ©Verlag Ferdinand Berger & Söhne Ges.m.b.H., Horn, Austria, download unter www.biologiezentrum.at 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