By selecting two cultivars of Kenjiandao 5(K5) and Kendao 12(K12) as materials and measuring soil water potential(SWP) by soil moisture tensiometer

the effects of water supply on rice growth

development and yield before heading stage were studied using the potted planting method within a rainproof chamber. The primary results indicated that in the intermittent irrigation treatment with the SWP of-8～-10kPa before heading stage

the economic yield for K5 was increased and for K12

decreased. The Leaf-age courses for the two varieties were brought forward slightly and the plant heights were increased

while the stem numbers were decreased. The yields for K5 and K12 were decreased by unremitting irrigation under SWP of -18～-20kPa and -28～-30kPa before heading stage. The leaf-age courses for K5were lagged at begin-ning and then developed fast

while for K12

lagged during the whole growing stage. The plant height

s tem number

dry matter content and leaf area index for K5and K10were all decreased significantly. The intermit-tent irrigation treatment with the SWP of -8～-10kPa before heading stage can be used as irrigation index to harvest high yield and high quality rice in cold region

but it is not suitable to keep unremitting irrigation treatment with the SWP of-18～-20kPa during the stage before heading.