关键词: 钾营养, 杂交稻, 光合作用, 暗呼吸, 蒸腾速率, 产量形成

Abstract: Pot experiment was carried out on semihydrogenic soil of low potassium content. Each pot filled with 15 kg soil with 2.25 g N as urea, 1.50 g P₂O₅ as superphosphate and three levels of K as potassium chloride: K₀(O), K₁(1.5g K/pot) and K₂(3.0gK/pot). All fertilizers were used as basal dressing. The results are summerized as follows:1) Deficiency of K decreased net photosynthetic rate and increased dark respiratory rate of the leaf in whole developmental course, photosynthetic area and duration of photosynthetic function were also reduced, with poor growth of hybrid rice plants. It was evident that net photosynthetic rate increased, duration of photosynthetic function prolonged and dark respiratory rate maintained a lower level in K treatment. 2) The chloroplast of K₀ treatment was developed slowly but destructed quickly, while it was changed to converse state by K treatment. 3) In the filling stage, the net photosynthetic rate of K₀ treatment showed significant midday depression, while K₁ and K₂ treatment showed in steady state. The midday depression of photosynthesis, causing a decrease of net photosynthetic rate was related to the high rate of transpiration with a peak at 9 AM, and 'the higher loss of water. 4) K content in leaves of K₀ treatment showed a clear gradient from top downward. The data of lower leaves contained only 30.08% of flag Ieaves at filling stage. Due to the lower K content in leaves, the rice plants showed senescence and poor growth of roots. K content in leaves of K₁ and K₂ showed no clear gradient from top downward. 5) Potassium nutrition increased photosynthetic area, photosynthetic duration, number of grains and grain yield.

Key words: Potassium nutrition, Hybrid rice, Photosynthesis, Dark respiration, Transpiration rate, Yield formation