21%氯氨吡啶酸水剂对不同生育期黄花棘豆的防控效果及对草地植被的影响

在黄花棘豆的不同生育期(返青期、现蕾期和初花期)以不同浓度的21%氯氨吡啶酸水剂对天然草地进行喷施,探讨其对黄花棘豆的防控效果和对草地植被的影响。结果表明,21%氯氨吡啶酸水剂对于黄花棘豆有很强的灭除效果:喷施后15d,85%的植株表现出明显药害症状;喷施后35d,92.5%的植株药害等级达到4级。喷施后75d,125.0mL/hm2处理的株防效可达85%以上;187.5mL/hm2处理的株防效可达95%。在鲜重防效方面,高浓度和低浓度处理都可达95%以上的防控效果。不同喷施时期和喷施浓度对于草地其他植物和草产量的影响存在明显差异。对于双子叶植物,高浓度和低浓度喷施水平下其草产量都明显降低,分别降低52.5%和40.3%,降低趋势为返青期现蕾期初花期。单子叶植物受21%氯氨吡啶酸水剂的影响不同于双子叶植物:高浓度喷施,所有处理组草产量都显著降低,平均降低18.7%;低浓度喷施时,返青期草产量降低26.3%,现蕾期和初花期草产量增加,分别增加1.0%和10.6%。对草地植被的调查表明,21%氯氨吡啶酸水剂喷施后草地单位面积植物种数、盖度和植物多样性都有明显的降低。

Control effect of 21% aminopyralid AS on Oxytropis ochrocephala and grassland vegetation at different growth periods

At different growth periods of yellow-hair crazyweed,herbicide spraying experiment was conducted to investigate the influence of aminopyralid 21% AS on the poisonous weed and natural grasslands under two concen-tration treatments.The results showed that aminopyralid 21%AS had a good inhibition to yellow-hair crazyweed and 85% of O .ochrocephala presented phytotoxicity symptoms 15 days after herbicide spraying,and 92.5% of O .ochrocephala were damage after 35 days.The plant control efficacy reached 85.0% at the dose of 125.0 mL/hm2 ,and 95.0% at the dose of 187.5 mL/hm2 after 75 days.Aminopyralid 21%AS at the above two doses could reduce by 95% of the fresh weight on yellow-hair crazyweed.However,spraying of aminopyralid 21%AS made different effects on dicotyledonous and monocotyledons plants.For dicotyledonous plants,aminopyralid 21%AS at the above two doses significantly reduced the fresh weight,with the reduction ratio of 52.5% and 40.3%,re-spectively,presenting the tendency as follows:turning green period>budding period>early flowering period. The effect of aminopyralid 21%AS on monocotyledons was different from that on dicotyledonous.Under high spraying concentrations,the grass yield was dropped by 18.7%,while at the low concentration,it decreased by 26.3% at the stage of turning green period,but increased by 1.0% in the budding period and 10.6% in the early flowering period.Further more,the results showed that plant species density,coverage and plant diversity re-duced significantly after spraying with aminopyralid 21% AS.