抄録
Field exp. of three fertilizer elements treatments of wheat plants (Norin No. 52) were carried (out 1953-56, and N, P, K, Ca & Mg were analysed for leaf analysis. For the diagnosis of the nutritional status of wheat plants it was found suitable to use the leaf blade. Seasonal changes of N, P, K contents in L.B., 1953-55, were shown in Fig 1. The results of the 3 rd year, 1955-56, were omitted because of their similarity to the 2 nd year's results. From all of the 3 years' results 4 of each fertilizer treatments, Fig. 2 was obtained. Comparing the N contents of the four N supplied plots to those of the four non N plots, Fig.3 was gained. There was significant difference of N concentration in L.B. between N supplied plots and non N ones during the whole vegetative growth periods, and despite any combination of NPK fertilizer. Therefore, when the points of M+σ of the non N plots were combined, the critical N concentration curve showing N deficiency was obtained. It may be said that if the N concentration of the L.B. is lower than this curve, the plants are in danger of N deficiency. With P and K, critical concentration curves could be drawn, too (Figs. 4, 5, 6, 7). Ca content of L.B. was recognized to negatively correlate with the K content of L.B., but Mg content had no relation to the fertilizer treatments. By means of critical concentration of each of N, P, K during the whole vegetative growth periods, it may be possible to diagnose whether the plants are deficient in N, P, K or not.
