Study on Yield Formation Mechanism of Salinity and Alkalinity Stress in Japonica Rice of Cold Region

In order to make clear the effect of salinity-alkalinity stress on yield formation mechanism in japonica rice of cold region, three kinds of rice with soil of different levels salinity-alkalinity stress were studied by pot test. The results showed as follows: with the increasing of development on salinity- alkalinity stress, there existed differences among varieties, the growth stage was delayed, tiller number was decreased, as well as effective panicles per hole, and panicle setting rate and grain weight were reduced significantly. Analysis of variance results showed that panicles per hole, panicle setting rate and grain weight being reduced determined yield decreased of salinity-alkalinity stress in rice. It had no significant differences in yield between Ji Yujing and Sui Jing 5 which were saline- alkali tolerant varieties with control treatment in low saline-alkali soil, while extremely remarkable differences were examined in high and medium saline- alkali soil. There was extremely remarkable difference in yield between Song Jing 6 which was saline- alkali resistance variety with check treatment under different levels salinity- alkalinity stress. It is very important to enhance panicles, panicle setting rate and thousand panicles weight of more saline- alkali tolerant varieties in suitable salinealkali condition for rice production in saline-alkali soil.