Effects of elevated night temperature by far-infrared radiation at grain filling on grain quality of rice.

To determine the effects of elevated temperature during grain filling on grain quality of rice,Wuyujing 3(japonica rice) was planted in pots under elevated night temperature(ENT) and elevated daytime temperature(EDT) at the grain filling stage by using far-infrared heaters.The two treatments both decreased brown rice rate,milled rice rate and head rice rate,while increased chalky rice rate and chalkiness.The effect of EDT was more significant.ENT decreased amylose content,whereas EDT increased it.Under ENT,starch granules were compact in arrangement with larger granule and clearer edge,by contrast,under EDT the starch granules were smaller and spheric-shaped with few gaps.X-ray diffraction patterns revealed larger relative crystallinity under both temperature treatments as compared to control with a less increase under ENT.The results show that compared with EDT,ENT exerted similar but less effects on milling quality,appearance quality and nutritional quality.However,effects of both treatments on starch structure,eating and cooking quality were different.