Study On Effects Of Rice Growth Traits Under Salt Stress

Taking rice under salt stress as the research object,the experiment began on July 4,2019 at the experimental station of agricultural water conservation research center in Binhai area.The whole growth period of rice is divided into seedling stage,rejuvenation stage,tillering stage,jointing stage,booting stage,heading stage,filling stage,milk stage and yellow stage.Six field irrigation experiments with different salinity(2g / L,3g / L,4g / L,5g / L,6g / L,7g/ L)and fresh water(CK)were arranged in the experiment.Jindao 919 was selected as the rice variety to analyze the growth characteristics of rice under different salt stress conditions.The specific indexes measured include plant height,leaf area,tiller number,tiller ear number,grain number per ear,SPAD value,1000 grain weight and yield.The results can provide theoretical guidance for rice planting and irrigation system in saline alkali land of Tianjin.The main conclusions are as follows:(1)In general,plant height,leaf area,tiller number,tiller ear number and yield decreased with the increase of salt concentration.Among them,under the condition of salt stress in the whole growth period,the effect of 5g / L-7g / L brackish water on the growth characteristics of rice was significant.Plant height and leaf area decreased in different degrees,among which 7g / L brackish water had the most significant effect on rice.There was no significant inhibitory effect on plant height and leaf area of rice by 2g / L-3g / L brackish water.When the rice was irrigated with 3 g / L brackish water in single seedling stage and tillering stage,the growth rate of rice plant was the highest,which was 2.79cm/d.Under the irrigation of brackish water with different salinity,1g / L-2g / L low concentration of brackish water increased the soil osmotic potential,further promoted the absorption of water by rice roots,and there was no significant difference between the rise of plant height and leaf area and CK treatment group(P > 0.05).When the salt concentration of irrigation water was higher than 4g / L,the curve of plant height and leaf area decreased significantly.(2)Under different salt stress conditions,the SPAD values of rice in the whole growth period were different,among which the SPAD values of rice in heading period were the largest,while the SPAD values of rice in filling period,booting period,milk maturity period,tillering period,yellow maturity period,jointing period,rejuvenated period and Seedling period decreased in turn.Under salt stress during the whole growth period of rice,S6 and S7 treatment made the SPAD value of rice decrease in advance,and the high concentration of brackish water inhibited the absorption of nitrogen content of rice.Under the irrigation of brackish water at seedling stage and tillering stage,there was no significant effect on SPAD value at heading stage,but 6g / L-7g / L brackish water irrigation made the leaves turn yellow at tillering stage,and the SPAD value of rice decreased in advance.With the increase of salt tolerance in booting stage and milk stage,the inhibition effect of brackish water irrigation on nitrogen absorption and water capacity of rice roots was not significant,and the SPAD value of rice would not decline in advance.However,under the single-stage brackish water irrigation at booting stage,the nitrogen uptake was different,resulting in the stratification of SPAD value.(3)Under the whole growth period salt stress,the rice yield decreased with the increase of salt concentration.Among them,under the condition of 5g / L-7g / L salt concentration irrigation,the effect on rice was the most serious,the rice yield decreased by 45.48% and44.97% under the treatment of S6 and S7,and the color of rice appeared different.Under the salt stress of single seedling stage and tillering stage,the index of rice character decreased with different degrees,but the salt ion did not poison the booting and heading process,and the yield was slightly higher than that under the salt stress of the whole growth stage.However,under the treatment of 6g / L-7g / L in single seedling stage and tillering stage,the color of rice still appears yellowish.Under single stage salt stress at booting stage and milk maturity stage,with the increase of salt tolerance,the differences between different treatments of rice gradually decreased.There was no significant difference in rice yield between CK group and CK group under single stage salt stress at milk stage.