Effect of irrigation water depth on rice growth and yield in a saline-sodic soil in Songnen plain, China

It was hypothesized that reductions in rice yield under salinity stress can be ameliorated by adjusting the water depth. However, the effect of different irrigation water depths on rice growth and yield in a saline-sodic soil dominated by carbonate and bicarbonate salts is not yet well understood. A field experiment consisting of three levels of 1,4 and 7 cm irrigation water depth was conducted in an unameliorated saline-sodic soil in western of Songnen plain. The trends were found that tiller number per bill and LAI increased as the irrigation water depth increased. The yields of 1, 4 and 7 cm irrigation water depth treatments were 0.62, 1.38 and 2.62 t ha(-1), respectively. Panicle density (PD) of 1 cm and 4 cm irrigation water depth treatments both contributed more to yield compared to seed weight per panicle (SWP) while SWP at the 7 cm irrigation water depth treatment contributed over PD. Spikelets per panicle (SP) was maximum in 7 cm irrigation water depth treatment. Percent filled spikelet accounted for the most variation for SWP at each treatment probably owing to low air temperature and salinity and sodicity. We conclude that increasing water depth up to 7 cm increased rice grain yield mainly by increasing rice SP and PFS and alleviating the tillering inhibition.