Studies on Leaf Analysis. : VI. Critical leaf concentrations indicating N, P and K deficiencies of rice plants. : VII. N-P-K equilibrium in leaves and culms of rice plants.

[摘要] For the purpose of diagnosing nutritional status leaf analysis of rice plant, var. Norin No. 37, was carried out 1952∼54 by field experiment of N, P & K fertilizer treatments. The previous report showed that N, P & K concentrations of the particular parts of plants responded well to the N, P & K fertilizers respectively, and that the N status of the crop reflected good in the top L. B., and that the P & K status did in the 3 rd L. S. from the top leaf. This report, while confirming the above-stated results, is concluded as follows: Part VI, 1. The response of N fertilizer was detected properly in the N concentrations of the top L. B. during the vegetative growth period, and in those of the 3 rd L. B. as well. 2. The differences of the N concentrations of L. B. between N applied plots and non-N ones were remarkable under any combination of N, P & K during the vegetative growth period, and the values of N concentrations in the L. B. of non-N plots were determined to be the critical N concentration indicating N deficiency. 3. The critical N concentration of the 3 rd L. B. was also gained in the same way as in the top L. B. 4. Though in the top L. B. the P status was found, it was of little use. On thd other hand the differences of the P concentrations in the 3 rd L. S. between P applied plots and non-P ones were noticeable. The P values of the part were decided to be the critical P concentration indicating P deficiency. 5. The K status was assessed in the 3 rd L. S. and the critical K concentration was also obtained in the same manner as in the P status. 6. As the L. B. and L. S. did not always respond to the effect of fertilizer after heading stage, the part could not be used for this purpose, while the 14 th I. N. responded considerably to the effects of N & K supplies even at this stage. Therefore it seemed that this part could be used for the diagnosing of N & K status at heading time. 7. The nutritional status as to whether the rice plants are deficient in N, P & K or not on all fertilizer treatments is to be diagnosed by means of the critical N, P & K concentrations respectively during the vegetative growth period. Part VII. 1. N-P-K equilibrium, namely N, P & K composition percentage of NPK-unit, varied greatly in the parts of rice plant; L. B. had highest N and lowest P & K composition percentage, L. S. had higher P & K and lower N than those of L. B., and culms had lowest N. 2. N-P-K equilibrium of the top L. B. fluctuated according to the fertilizer treatments and the seasonal stages. As to the seasonal change of N-P-K balance, N composition percentage was highest at early tillering stage, then, as the growth progressed, it decreased, which caused K to increase (P changed little), and it reached min. value at young ear formating stage, and backed again a little at heading. 3. Effects of fertilizers were striking during early growth stage, that is, N, P & K composition percentages increased by the supplies of N, P & K fertilizers respectively, but the effects diminished after young ear formation. At heading stage N-P-K balance was nearly constant under any treatment of N, P & K; it is an interesting fact that the plants maintain constant balanced nutrient status. 4. N-P-K equilibrium in the 3 rd L. S. was greatly affected by the fertilizer treatments, and it responded the N, P & K supplies, while the L. B. did mainly in the N composition percentage. 5. In the case of N-P-K equilibrium in the 3 rd L. S., as the growth proceeded, N composition percentage decreased. On the other hand, P composition percentage increased and K composition percentage also increased except in the plots of the excess K supplied condition such as PK, K & Nil plots. 6. N-P-K balance in the 14 th I. N. of culm responded to the fertilizer treatments at heading time. 7. [the rest omitted]

[学科分类] 农业科学（综合）