Effects Of Salt Stress On Agronomic Characters Of Japonica Rice And Selection Of Salt Tolerant Varieties

The total area of saline alkali land in China is close to 550 million mu,of which 83.6% has not been developed and utilized.In order to improve the saline alkali land,guarantee the increase of grain yield and the area of cultivated land,it is of great significance to select and cultivate rice varieties with strong salt tolerance.In this study,118 new rice lines bred in Liaoning Province were used as experimental materials,and the rice lines with strong salt tolerance were screened through the treatment of Na Cl solution with different concentrations at seedling and growth stages.At the same time,two japonica hybrid rice and two conventional japonica rice were used as test materials to identify the growth period under different concentrations of Na Cl solution,to compare the effects of salt stress on the agronomic characters of Japonica rice,and to analyze the differences in salt tolerance.The results show that:1.In the experiment of salt tolerance identification in seedling stage,through the comprehensive analysis of seedling quality under different concentrations of salt stress,it was found that germination rate and root weight were the most important factors affecting the salt tolerance of rice in seedling stage.Further using the principal component analysis method to evaluate,five lines with the strongest salt tolerance were selected,namely Yangeng 352,Huageng 1520,Yangeng 172,Shenxing rice 28 and Huageng 1505.2.In the identification test of salt tolerance in growing period,the analysis of salt tolerance showed that the strain with strong salt tolerance was stronger than the sensitive strain in tillering,plant height and other physiological indexes.Through the analysis of agricultural salt tolerance,only 1000 grain weight of lines with strong salt tolerance decreased significantly,but all yield indexes of lines with salt sensitivity decreased significantly to a very significant degree.Finally,five rice lines with strong agricultural salt tolerance were selected by sorting the relative yield,namely Yangeng 277,Shenxing 79,Huageng 1505,Huageng 1520 and Yangeng 352.3.With the increase of salt concentration,tiller and plant height decreased.The tiller number of Liao16You06 was significantly higher than other varieties at low concentration,and there was no significant difference between plant height and control.The dry matter accumulation of stem and sheath was significantly lower than that of control except Liaoyou 9906 at low concentration(0.3%),and that of leaf and ear was significantly lower than that of control at different salt concentrations.The physiological index of japonica hybrid rice is also higher than that of conventional rice.The effect of salt stress on the yield and taste quality of japonica rice was significantly different.The effective panicle number of japonica hybrid rice decreased significantly,but the seed setting rate and 1000 grain weight of conventional japonica rice were seriously affected.There was no significant difference in nutritional quality between the two,but conventional japonica rice was less affected in food taste.In general,the salt tolerance of japonica hybrid rice is stronger than that of conventional rice,and the yield index is less affected under stress;however,in terms of food taste,conventional rice has certain advantages and still can maintain high quality.The above results can provide variety support for the development and utilization of saline alkali land,and provide important germplasm resources and theoretical basis for the future development of new rice varieties with salt tolerance in the north and the south.