THE EFFECT OF HOST NUTRITION ON CONCENTRATION OF TOBACCO-MOSAIC VIRUS

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Abstract
The influence of N nutrition on virus production in Turkish tobacco plants was studied by supplying them with nutrient solns. containing either a low, medium, or high level of N, inoculating them with tobacco-mosaic virus, and measuring the virus activity in juice from frozen plants harvested at 3 different intervals following inoculation. The virus activity of expressed juice was directly correlated with the amt. of N supplied to the plants. The virus conc. of juice from plants receiving an ample N supply was over 80 times that of juice from N-deficient plants. Moreover, the virus content of expressed juice from plants in sand receiving the medium-N soln. was more than double that found in juice from plants grown in composted soil. It is probable that the low virus activity of expressed juice from N-deficient plants is brought about by the limitation in N supply. With insufficient N, the total virus content in extracted juice decreased following the initial systemic spread of the virus through the plant. With an overabundance of N, the virus content increased at a faster rate than that at which the plants grew. The increase in virus content showed no apparent correlation with the growth of the plants. Although the soil-grown plants were much larger than those in sand that received the high-N soln., they had only about 2/3 as much total virus in their expressed juice. The total-N and protein-N contents in the expressed juice varied directly with the N level of the nutrient soln. These amts. were much larger in juice from diseased plants than in juice from healthy plants on corresponding treatments. Virus activity was directly correlated with the N content in juice of diseased plants. The juice with the highest total- and protein-N contents had the highest virus activity.