CARBOHYDRATE AND NITROGEN RELATIONS IN WHEAT PLANTS WITH REFERENCE TO TYPE OF GROWTH UNDER DIFFERENT ENVIRONMENTAL CONDITIONS

Publisher Website
Google Scholar
Abstract
The leaves of young plants, sampled at the same age in the tillering stage, had the highest carbohydrate and lowest N % at the long day, which accelerated culm elongation and flowering in both vars. investigated (Hard Federation, a spring wheat, and Turkey, the winter var.). The lowest carbohydrate and highest N % were found at the short day, which retarded heading in both varieties and resulted in large vegetative plants, with reduced yield of grain in Hard Federation and complete sterility in Turkey. Supplementary light of relatively high intensity (100 foot-candles) resulted in higher % of acid-hydrolyzable material, and consequently of total carbohydrates, and lower of N, than the weaker light (15 to 50 ft.-candles). This difference in light intensity had no effects on the external appearance or rate of development of the plants.[long dash]The sugar content of the young plants of the limed plots with a soil reaction of pH 8.1 was generally much reduced, and the acid-hydrolyzable material somewhat increased, compared with that of plants of the neutral soil. The % of N was generally highest in the plants whose sugar content was reduced. The difference in soil reaction produced no visible effects on the appearance or rate of development.[long dash]The young plants of Turkey contained much more sugar, largely sucrose, at the low temp. where growth was normal than at the high temp. where the plants failed to head. In the case of Hard Federation, which headed and yielded fairly well at both temps., there was no significant difference in any of the carbohydrate fractions due to temp.[long dash]The N % of the young plants were higher at the low than at the high temp., except in 2 groups, but these also showed the higher % at the lower temp. when calculated on the residual or fresh-weight basis.[long dash]pH values of the juice of the young plants were generally highest at the short day and at the low temp. and lowest at the long day and the high temp.[long dash]The leaves of Turkey at the high temp., where culm elongation was largely inhibited in this variety, had total carbohydrate and N values of the same order of magnitude as were found in the leaves of the normal heading plants of the low temp. The only peculiarity noted in the leaves of these non-heading plants was their unusually high glucose-sucrose ratios.[long dash]Such correlations as were found between carbohydrate and N values and fruitfulness occurred in the culm analyses only, and had no counterparts in the leaf analyses. The culms of the natural-day plants of Hard Federation, which at both temps. produced relatively high yields of grain compared with those of the short and long days, were consistently characterized by the highest glucose contents and lowest N %, and the highest carbohydrate/N ratios. Both the natural- and long-day plants of Turkey at the low temp. gave high yields of grain, and their culms were likewise characterized by high carbohydrate/N ratios as compared with those of the sterile short-day plants.