喷施敌草快对紫云英含水率、荚果性状的影响及其应用安全性评价

Effects of Diquat on Moisture Content and Pod Traits of Astragalus sinicus and Evaluation on Application Safety

为解决紫云英(Astragalus sinicus)收获期茎秆贪青晚熟影响机械化收获的问题,本试验研究了不同浓度的敌草快催枯及其对紫云英种子产量的影响,并对其施用安全性进行了评价。研究发现:敌草快施用6 d后紫云英含水率显著降低,中部和顶部茎秆含水率下降至30%~40%,底部茎秆下降至54%~61%,显著低于喷施清水处理(P<0.05),但不同浓度的敌草快处理间无显著差异;20 g·L^(-1)敌草快处理显著降低紫云英总花荚数、荚果总重和种子产量,对千粒重无显著影响;5 g·L^(-1)敌草快处理荚果性状和产量与喷施清水处理无显著差异;20 g·L^(-1)敌草快处理下荚果中敌草快残留量达2.34μg·g^(-1),茎残留0.42μg·g^(-1),显著高于10 g·L^(-1)处理(0.70μg·g^(-1)和0.16μg·g^(-1))和5 g·L^(-1)处理(0.05μg·g^(-1)和0.01μg·g^(-1));水稻(Oryza sativa)和紫云英种子萌发及生长的敌草快安全阈值分别为0.01 mg·L^(-1)和1 mg·L^(-1)。综合考虑脱水效果、荚果性状、种子产量、敌草快残留及其对受体的毒性等情况,紫云英种子生产中适宜施用5 g·L^(-1)敌草快进行催枯,残留不影响水稻接茬。

In order to solve the problem that the late-ripening of Astragalus sinicus in the harvest period hinders mechanical harvest,the dehydration effect and the seed yield of Astragalus sinicus were studied in the periods after diquat application,and the application safety was evaluated.The results showed that the moisture content of the middle and upper stems decreased to 30%~40%and the bottom to 54%~61%under diquat treatments,which were significantly lower than those of the control(75%~83%),but there was no significant difference among the diquat treatments.Diquat at 20 g·L^(-1) significantly reduced the inflorescence number,total pod weight and seed yield of Astragalus sinicus,but had no significant effect on the 1000-seed weight.There was no difference in pod character and yield between low concentration treatment(5 g·L^(-1))and control.Diquat residues were 2.34μg·g^(-1) in pods and 0.42μg·g^(-1) in stems under 20 g·L^(-1) diquat treatment,which were significantly higher than that under 10 g·L^(-1) diquat treatment(0.70μg·g^(-1) and 0.16μg·g^(-1))and 5 g·L^(-1) diquat treatment(0.05μg·g^(-1) and 0.01μg·g^(-1)).The safety thresholds of residue concentration for seed germination and growth of Oryza sativa and Astragalus sinicus were 0.01 mg·L^(-1) and 1 mg·L^(-1),respectively.In consideration of dehydration effect,pod character,seed yield and toxicity of residues,diquat at 5 g·L^(-1) was suitable for Astragalus sinicus seed production,and the residue did not hinder rice cropping.