实践证明,棉花花铃期喷施农药的最佳时间是在下午5时左右至天黑前这段时间。 若在早晨喷药,由于露水的影响,药液易从叶片滚落流失而降低药效;若在上午8～10时喷药,由于此时正是花朵开放、授精的时候,所喷药液会使具有高渗透压的花粉粒吸水膨胀而破裂,丧失授精能力,造成脱落花多;若在上午10时至下午4时喷药,由于 Practice has proved that the best time to spray pesticides in the cotton flower boll cycle is about 5 pm until dark before this period of time. If spraying in the morning, due to the dew, the liquid is easy to reduce the effect of rolling down from the leaves; if at 8 am to 10 pm spraying, because this time is the flower open, insemination when the liquid sprayed Pollen grains with high osmotic pressure will swell and rupture, losing their ability to inseminate, resulting in shedding of flowers; if the spraying is carried out between 10 a.m. and 4 p.m. due to