| Corn is an important grain and forage crop,because of its high stalk,net pHotosynthetic efficiency and other characteristics.In recent years,corn become the China's largest food crops.Huang Huaihai area as an important summer corn planting area,during the corn growing season,often affected by drought,seriously affecting the summer maize yield.S-ABA(ABA)is an important source of plant growth and regulation of substances,not only can improve plant resistance to drought and other adversity,but also can regulate plant growth.However,the effect of S-ABA on the drought resistance of maize has less reported.In this study,we selected the appropriate dosage of S-ABA for corn spraying and seed dressing,studied the changes of pHysiological and biochemical indexes of maize seed germination and seedling growth under different drought stress.On the p Hotosynthetic characteristics,pHotosynthetic enzymes,protective enzyme activities and the content of stress-resistant substances in maize seedlings,and the effects of S-ABA on maize growth and yield were studied.The effects of different concentrations of S-ABA on seed activity and seedling growth of maize were studied under sand culture.The germination potential,germination rate,germination index and vigor index of maize seed were increased respectively by 25.41%,20.53%,22.44% and 44.18% compared with those without seed dressing.High root length,root number,fresh weight per plant,root shoot ratio increased by 2.21 cm,2.30 cm,0.26,0.15 g,0.55 respectively.The germination rate,germination percentage,germination index and vigor index of maize were increased by 36.51%,34.38%,37.14% and 103.53% respectively under the condition of severe drought stress in the concentration of 1.0 mg/10 kg seed,in addition,corn stem height,the main root lenth,the number of roots,fresh weight per plant,root shoot ratio increased by 2.32 cm,1.35 cm,1.09,0.14 g,0.56 respectively.The use of S-ABA seeding in two different drought levels could increase the chloropHyll content and soluble sugar content of maize seedling,furthermore,improve root activity.The effects of different concentrations of S-ABA seed dressing on seed activity and seedling growth of maize were studied by greenhouse condition.Compared with the untreated seeds,at the concentration of 1.2 mg/kg seed,the plant height,root length,the length of the sheath,the third leaf area,the fresh weight upon ground and the fresh weight underground were increased respectively by 8.9 cm,7.34 cm,0.14 cm,8.52 cm~2,0.49 g,0.33 g.The activities of CAT,POD,SOD,PEP carboxylase and RuBP were increased by 43.34%,34.65%,34.43%,72.12% and 52.48% respectively.The MDA content decreased by 44.24%,the root activity increased by 28.14%,the chlorop Hyll content was 27.71 %.Under the severe drought stress,in the 1.2 mg/kg seed concentration,the plant height,main root length,coleoptile length,third leaf area,fresh weight of aboveground and underground increased by 8.3 cm,1.66 cm,0.28 cm,8.02 cm~2,0.34 g,0.11 g.The activities of CAT,POD,SOD,PEP carboxylase and Ru BP were increased by 50.55%,47.23%,55.18%,71.68% and 50.89% respectively.The MDA content decreased by 42.94%,the root activity increased by 44.86% and the chloropHyll content was 21.12 %.The effects of S-ABA spraying treatment on pHysiological and biochemical indexes of maize were studied in two levels(moderate and severe)drought stress.The results showed that the biological characters such as plant height,root length,the fresh weight upon ground and the fresh weight underground were higher than those of catalase(CAT),peroxidase(POD),superoxide dismutase(SOD)activity and other pHysiological and biochemical indicators were improved compared with the control,which from 2 mg/kg to 3 mg/kg concentration of the most obvious effect.It is possible to promote the seedlings growth and increase the activities of protective enzymes(CAT,POD,SOD)moreover,also can increase the chloropHyll content and the root activity at the third leaf stage of maize.The effects of S-ABA spray treatment on the growth and yield of maize were studied in the field condition.The results showed that,sprayed with the concentration of 3 mg/kg S-ABA during 4 to 5 leaf stage(treatment A)of corn,the cluster length,ear length,panicle number,grain number,1000-grain weight and plot yield of maize were increased by 9.05%,9.14%,9.21%,9.94%,13.26% and 11.73%,the cluster barren ear tip decreased by 8.24%,significantly better than those of control(P <0.05).Sprayed at the concentration of 2 to 3mg/kg of S-ABA at 7-8 foliar stage(treatment B),the ear length and yield of maize were higher than those of the control.The barren ear tip of thecluster was obviously decreased.At the 4-5 and 7-8 leaf stage(treatment C),sprayed with the concentration of 3 mg/kg,the yield of ear length,ear perimeter,ear row number,row grain number,1000-grain weight and plot yield were increased by 10.73%,10.76% and 14.09%,14.09%,6.38% and 15.43% respectively,and the cluster barren ear tip decreased by 18.82%,better than the treatment of A and B. |
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