UPTAKE OF P32 BY SOME CEREALS

Abstract

When wheat grains were germinated individually in test tubes containing 0.1 ml. solution in which initially 6.5-10 mrd. P32 in the form of phosphate were included, over 90% of the activity was absorbed by the grain and seedling within 13 days. At five days over 80% of the absorbed activity was in the embryo with less than 20% in the grain coats and endosperm. When plants were grown in washed sand of high quartz content about 5% of the activity added in solution to the sand at 31 days or at 40 days was absorbed by the plants. Activity added to soil in which barley plants were growing resulted in activity absorptions ranging from 0.97 to 10.4% of the amounts supplied. More P32 was absorbed when carrier P was provided than when carrier-free solutions were used. A method permitting uptake measurements to be made at intervals with the same plants was also tried. Initially, 1.66 mrd. P32 were available to each plant. At intervals, determinations of uptake were made. Then P32 was added to the solution to bring the level up to 1.66 mrd. per plant. The total energy received by individual vulgare wheat plants from decay of absorbed P32 was calculated to be 54.6 gram-roentgens.