Ontogenetic changes of N, P, and K contents in individual leaves of field crops
1995
Osaki, M. (Hokkaido Univ., Sapporo (Japan). Faculty of Agriculture)
The ontogenetic changes of N, P, and K contents in leaves of rice, maize, soybean, adzuki bean, potato, and sugar beet were studied as the following results were obtained. 1) N content of rice and maize drastically changed at the primordia formation stage, while that of other crops did not show clear changes depending on the stage of growth. 2) P content of rice and maize was higher in upper leaves than lower leaves, but did not change appreciably in other crops. 3) K content of potato and sugar beet remained constant for a long period of time compared to other crops. 4) P-N relationship in rice and maize distinctly differed between upper and lower leaves; ratio of P content toN content of upper leaves was higher than that of lower leaves. 5) K-N relationship in potato and sugar beet was very different from that in other crops; K content remained constant regardless of the decrease in N content except for the lower leaves. Thus, as the P-N balance of rice and maize (Gramineae crops) and K-N balance of potato and sugar beet (root crops) showed distinctive characteristics compared to other crops, the physiological significance of the mineral balance must be further investigated
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