Effects of water stress on development of superior and inferior grains in different drought tolerant maize varieties
To investigate the physiological response mechanism of different degrees of water stress on develop-ment of superior and inferior grains in maize,a 2-year continuous pond planting maize experiment was conducted under controlled conditions.Two maize varieties with differences in drought tolerance were selected as experimental materials,and a total of six treatments were set up,including drought tolerant variety+no stress(T1),drought tol-erant variety+moderate water stress(T2),drought tolerant variety+severe water stress(T3),drought sensitive va-riety+no stress(T4),drought sensitive variety+moderate water stress(T5),and drought sensitive variety+severe water stress(T6).The study explored the changes in grain filling characteristics,starch synthesis,hormone con-tent,and yield of superior and inferior grains of maize under different degrees of water stress.The results indicated that water stress significantly affected the filling process of superior and inferior grains in maize.The filling rate of inferior grains in drought sensitive maize varieties during the late filling stage(45 d,55 d)and the decrease in 100-grain weight during each sampling period were higher than those in drought resistant maize varieties.The filling rate under moderate and severe water stress decreased by an average of 30.73％and 35.36％,respectively.The de-crease in maximum grain filling rate and average grain filling rate of inferior grains was higher than that of drought resistant maize varieties.Among them,under moderate and severe water stress,the maximum grain filling rate de-creased by an average of 24.97％and 39.68％,and the average grain filling rate decreased by 23.54％and 36.70％,respectively.Water stress significantly affected the starch content,acid sucrose invertase,starch synthase,sucrose synthase,and ADPG pyrophosphorylase activities,as well as the content of auxin,cytokinin,and abscisic acid in superior and inferior grains of maize.The drought sensitive maize variety had the highest degree of change in inferior grains.Compared with untreated maize varieties,drought sensitive maize varieties showed a higher decrease in yield,ear length,ear diameter,and number of grains per ear.Among them,maize yield de-creased by an average of 9.83％and 18.57％under moderate and severe water stress,and the decrease in 100-grain weight of inferior grains during maturity was higher.Under moderate and severe water stress,the average de-crease was 23.51％and 36.34％.In summary,water stress significantly impacted the final yield of maize by affect-ing starch synthesis and the filling of inferior grains,with severe water stress having an even greater effect.
maizewater stresssuperior and inferior grainsstarch synthesisplant hormone
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