Effects of Before-heading Water Supply on Quality of Rice in Cold Regions

With Kenjiandao 5 and Kendao 12 as experiment materials,the effects of before-heading water supply on the quality of rice in cold region were studied through pot planting in a rainproof chamber.The soil water potential(SWP) was monitored with negative pressure soil moisture tensiometers.The results show that with intermittent water control at SWP ranged from-10 to-8 kPa during the before heading stage,the whole rice rate was significantly improved for Kenjiandao 5 rather than Kendao 12,and the ratios of length to width decreased for the grains of both varieties.With the before-heading water control,the chalkiness rate and chalkiness degree were improved for the dominant grains and were reduced for the middle grains,implying possible reductions of amylose content for both varieties.Protein contents of all the grains of both varieties were enhanced,while the dominant grains received higher grades in regard to the taste and the middle grains had lower grades.With water controls at SWP of-18~-20 kPa and-28~-30 kPa before heading,the plants of the two varieties performed similar to those with the first treatment,except the chalkiness rate,chalkiness degree and taste grades were reduced for all the grains of both varieties.