钾营养对水稻光合器功能的效应与谷粒产量的影响

水稻广陆矮四号和威优35盆栽试验的结果表明,施钾使叶绿体内基粒增多,Hill反应及光合磷酸化活力增强。分蘖末期在叶绿体反应液中添加KCl也可提高非环式光合磷酸化活力。适量施钾降低量子需要量可能与上述效应有关。钾使叶片超微结构改善:乳突大而多;硅化程度明显增加,故叶片更直立。叶水势及净光合率提高,两者呈直线正相关。灌桨期剑叶净光合率与谷粒产量呈直线正相关。

Effect of Potassium on the Function of Photosynthetic Apparatus and Grain Yield of Rice

Pot experiment was carried on semihydroge-nic soil to study the effect of potassium on the fun-ction of photosynthetic apparatus of rice (oryzasativa L). The available N, P and K in the soil were17.3 ppm, 23.8 ppm and 25 ppm, respectively,and the total N, P and K were 0. 13%,0.07% and0.42%, respectively. Each pot was filled with15 kg soil with 2.25 g N as urea, 1.5g P_2O_5 as su-perphosphate and different doses of K_2O as potas-sium chloride. All fertilizers were used as basaldressing. Measurements were made at differentdevelopmental stages with the 1st, 2nd and 3rdfully expanded leaves, counting from top down-ward. Electron micrographs showed that the ch-loroplasts were oblate and with more grana afterK treatment, while those of K-deficient plantswere shorter and wider with fewer grana. Potas-sium decreased quantum requirement which wasassociated with high activities of Hill reaction andphotophosphorylation of chloroplasts. Treat-ment with K in reaction mixture produced thesame effects. Photographs with scanning mi-croscope of K treatment showed more large pa-pillas on leaf surface than K-deficient treatment.Besides, K treatment increased silicified cells,which were shown very clearly on the vein andformed opal phytoliths which made the leavesmore erect and improved the light environmentof rice plants, and the development of plastidsand the activity of photosynthetic apparatus wereaccelerated. At booting stage, K increased the water po-tential of leaves which was positively correlatedwith net photosynthetic rate. The net photosyn-thetic rate of leaf at filling stage was positivelycorrelated with grain yield of rice.