HIGH TRANSPLANT DENSITY CAUSE LOSS YIELD AND QUALITY DECREMENT BY AFFECTING PHOTOSYNTHESIS, DRY MATTER ACCUMULATION AND TRANSPORTATION IN SUPER RICE

Abstract

Transplant density is an important factor which has impacts on rice growth and development in transplanted rice production system. Present study used three transplant densities in paddy field experiment and set as D1 (transplant spacing of 20 cm × 24 cm, about 2.085 hundred thousand hills for each hectare), D2 (transplant spacing of 20 cm × 20 cm, about 2.603 hundred thousand hills for each hectare) and D3 (transplant spacing of 20 cm × 16 cm, about 3.120 hundred thousand hills for each hectare). The results showed that high density (D3) not only reduced the net photosynthetic rate and LAI values at heading stage, but also decreased dry matter accumulation and transportation compared to D1 density. The highest yield was recorded in D1 density and the lowest yield was recorded in D3 density. Study also revealed that high density caused yield loss by decreasing the grain number and seed-setting rate. Furthermore, high density also increased chalk rice rate and chalkiness while reducing the amylose content. The activity of sucrose synthase (SS) in D3 was significantly lower than D1 and it might relate to the reduction of grain quality. Keyword: rice, density, yield, quality, net photosynthetic rate, dry matter accumulation and transportation