| With Diantu502 (medium-maturing indica rice) and Hexi39 (medium-maturing japonica rice) as experiment materials. On purpose of revealing the substance basal of yield and quality formation of rice, the effect of resource-sink state on grain-filling, yield and rice quality, and relationship between grain-filling process and rice quality were studied in high altitude region by methods of sunshine-shading, leaf-cutting and spikelete-thinning. The results were as follows.(1) In the control of light intensity and CO2 concentration, the treatment of leaf-cutting had feedback improvement effects on rice flag leaf, including increase of net photosynthesis rate, apparent quantum yield and carboxylation efficiency. Different source-sink model of rice showed different responses to spikelet-thinning. Feedback effects of net photosynthesis rate of rice flag leaf on source limit yield were weaker, while the source-sink relation model or sink limit yield stronger.(2) Effects of source-sink adjustment on grain-filling and yield significantly. Sunshine-shading and leaf-cutting decreased the maximum grain filling rate and average grain filling rate, delayed days of reaching the maximum grain filling rate and decreased the highest grain weight. However the effect of spikelet-thinning was reversely, it increased grain filling rate and advanced days of reaching the maximum grain filling rate. Because superior grain lay in superiority situation than inferior grain, which filling rate increased for more matter of photosynthesis supply, its grain weight enhanced. Sunshine-shading and Leaf-cutting made source poor, the matter of photosynthesis reduced so that seed-setting rate, filling degree of grain and yield obviously reduced. Larger source and smaller sink after spikelet-thinning, the matter of photosynthesis abundant so that seed-setting rate, filling degree of grain increased, but yield reduced for the amount of spikelet reduced.(3) Effects of grain-filling process on rice quality significantly. The grain-filling rate, amount of ratio at early filling stage (in 15 days after full heading)mostly influenced ricequality, while those at late filling stage (30 days latter after full heading)secondly and those at middle filling stage (15-30 days after full heading)less influenced rice quality . While the grain-filling rate, amount and ratio at early filling stage increased, the chalkiness area and degree decreased and the peak and breakdown viscosity of rice starch increased, the chalkiness area and degree decreased and the peak and breakdown viscosity of rice starch increased. While the grain-filling rate, amount and ratio at late filling stage increased, the chalkiness area and degree increased and the peak and breakdown viscosity of rice starch decreased.(4) Effects of source-sink adjustment on rice quality in high altitude region. Sunshine shading increased the head milled rice rate, especially of superior grains. Under condition of sunshine shading, the chalkiness degree varied with the variety and grain position. Sunshine-shading decreased amylose content, the value of peak and breakdown viscosity of rice starch, elongated gel consistency of the experimental varieties. Leaf-cutting increased chalkiness degree and the effect of leaf-cutting on the value of peak and breakdown viscosity of rice starch were different among varieties. Spikelet-thinning decreased chalkiness degree and it had the tendency of decreasing breakdown viscosity of rice starch while effect of it on final viscosity was not obvious.The result of these studies suggested that the effect of sunshine-shading, leaf-cutting and spikelet-thinning not only on relatively supply amount of grain-filling dry matter but also on grain-filling process. There was consanguineous relationship between grain-filling dry matter, grain-filling process and rice quality. The effect of source-sink adjustment on rice quality was difference in high altitude region and low altitude region.
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