Relieve Effect of Rewatering on Morphology and Yield of Cotton at Flower and Boll Stage during Mild Drought Stress
Abstrac The lack of water resources is one of the main factors of limiting the sustainable development of cotton.It is necessary to clarify the amount of rewatering irrigation,rewatering time and the degree of influence on growth and development of cotton after drought.It can provide scientific basis for the effective drought relief and loss reduction measures.Using precision water simulation test,the effects of different degrees of r basis for the effective drought relief and loss reduction measures,ewatering(50%,75%,100%irrigation)on the mild drought stress(50%-60%)in cotton at flower and boll stage were analyzed under membrane drip irrigation.The results showed that,the cotton buds and bolls dry matter,the total dry matter above ground of cotton of 100%and 75%rewatering treatments,were significantly higher than that control after drought rewatering,and the increase of dry matter was proportional to the degree of rewatering.The dry matter of 50%rewatering treatments was lower than that control,and the effect of rewatering on relieving drought was not significant.In the process of rewatering,the trend of soil moisture and water content of plant leaf reached the highest in the 4th day after rewatering,and then decreased.The water content of plant leaf of 50%rewatering treatment was significantly lower than that control,and the soil had developed into severe drought.There was no significance of water content of plant leaf between 100%and 75%rewatering treatment and control,and the soil was no drought.The two indexes could quickly monitor the drought condition of cotton field.After rewatering,the number of bud bells,single bell weight and cotton fiber length were lower than that control,the bud bell shedding rate increased,and the final yield was lower than that control.The difference of yield was not significant between treatments of 75%and 100%reclaimed water and the control.The treatment of 50%reclaimed water could not relieve the effect of mild drought stress on the growth and development of cotton.The effect of mild drought stress could be discharged in the treatments of 75%and 100%reclaimed water respectively.There was a vigorous period of recovery and growth of cotton within the 19th days after rewatering.The degree and time difference of rewatering should be considered for rewatering irrigation after drought.
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