Effect of potassium fertilization on the photosynthetic characteristics of the leaf of winter wheat population during its grain-filling stage
钾肥对灌桨期冬小麦群体内叶片光合特性的影响

Six years field trials with or without potassium application showed that under potassium application, the maximum photosynthetic rate (Pmax), light saturation point (LSP) and light compensation point (LCP) of the flag leaf of winter wheat during its grain-filling stage increased, the apparent photon utilization efficiency (alpha) decreased, and the dark respiration rate (Rd) increased slightly. For the daily variation of net photosynthetic rate (Pn) of winter wheat with and without potassium application, it appears a single peak curve, whether the weather condition was sunny or cloudy. "Stomatal factor" was the main cause of the decrease of net photosynthetic rate (Pn) in the before noon and afternoon of sunny days and in the whole day of cloudy days, while "non-stomatal factor" was the main cause for the decrease of Pn around midday in sunny days.