Effect of soil moisture on panicle traits and yield of rice in cold region

Controlling water treatments(CWT) for two rice varieties(Shangyu 397 and Suijing 3) at(-0.030) to-0.035MPa and-0.060 to-0.065 MPa of soil water potential were carried out during tillering stage,panicle initiation stage,1～10 days after heading,and 11～20 days after heading,respectively.CWT during tillering stage reduced the panicles per hill and grains per panicle.CWT during panicle formation stage decreased distinctly the panicle length,panicle node number,branches on the neck-panicle,and grains per panicle,filled grain rate and 1 000-grain weight.CWT during 1～10 days after heading stage enabled grains per panicle and 1 000-grain weight to decrease.The effect of CWT on secondary branch number per panicle,total grains,filled grain rate and 1 000-grain on secondary branch weight were greater than that on primary branch.The order of yield reduction in two varieties under the same water stress condition was treated during panicle formation stagetreated during tillering stagetreated during 1～10 days after headingother treatments.The sequence of yield components affected by CWT was: panicle grains,filled grain rate,panicles per hill,(1 000)-grain weight.Increase of branch number of different positions,grains and filled grain rate on secondary branch will be more beneficial to improve rice yield.