Study On The Effects Of Drought Stress And Potassium Application On Soybean Compensation Effec

According to the theory of compensation effect of water deficit,after rehydration under appropriate drought stress,crops have the ability to compensate and overcompensate in the subsequent growth process.Potassium fertilizer can improve the stress resistance of crops,promote the absorption and utilization of water in soybeans,help absorb and store water,improve the quality of soybeans,improve drought resistance and increase production.In this paper,Heihe 35,a super-early maturing and high-quality soybean,was used as the material to do pot experiments under three different levels of drought stress and potassium application,to find out the effects and limitations of two factors on soybean leaf area index,leaf area growth rate,aboveground and underground dry matter,root-shoot ratio,plant height,water consumption,water use efficiency,yield and related factors,and to systematically analyze the drought stress intensity and potassium application amount to find suitable irrigation methods and achieve compensatory and overcompensated soybean growth after drought.The results of this paper show that:(1)The synergistic effect of drought stress and potassium application significantly increased the compensatory growth of soybean leaf area index and leaf area growth rate,but did not produce effective compensatory growth for soybean plant height.Moderate drought stress can effectively inhibit the extravagant growth of soybean plants and the growth of leaves.Potassium application can promote the production of chlorophyll in soybean leaves,improve the transpiration rate and photosynthetic efficiency of leaves,and then weaken or offset some of the damage to plants caused by drought stress.The compensatory growth of soybean leaves is the result of the combined effect of drought stress and potassium application.(2)Under the synergistic effect of drought stress and potassium application,the underground dry matter quality and root-shoot ratio of soybean were significantly improved,but the improvement degree was different.When the available water is reduced,it will promote the root development of crops to go deeper,while the growth of stems and leaves will be inhibited,thus changing the growth rate of root caps and improving the root-shoot ratio.Although increasing the application of potassium fertilizer can promote the growth of roots,stems and leaves,it will only affect the peak growth of roots and stems,and has little effect on the root-shoot ratio.(3)Under the synergistic effect of drought stress and potassium application,the water use efficiency of soybean was significantly improved and the water consumption was reduced.Drought stress will reduce the total water consumption of soybean in the early stage.When the available water is reduced,its roots will go deeper into the soil and make the roots develop better.Root system will provide a lot of water and nutrients to crops in the middle and late stage,reduce the ineffective consumption of water and improve the water use efficiency.Under drought conditions,potassium application will increase stomatal resistance,reduce transpiration efficiency,reduce transpiration and increase net photosynthetic rate to fight drought.The combined action of the two will reduce water evaporation,improve water utilization and realize water saving and high yield.(4)Under the synergistic effect of drought stress and potassium application,soybean yield and related factors were significantly affected.Potassium application will promote the number of large pods,grains,100-grain weight and yield,and drought stress will inhibit the positive effect of grain number compensation per plant of soybean and promote the compensation of 100-grain weight of soybean.(5)Regression fitting was carried out on the yield results obtained from this experiment,and the threshold range of potassium application amount to produce yield compensation effect was: 150-300kg/hm2,when the relative water content of soil was30%-55%.The amount of potassium applied is 220kg/hm2;When the relative water content of soil is 38%,the yield reaches the maximum.