药液在作物叶片的流失点和最大稳定持留量研究

用微量称重法可以方便地测定作物叶片的流失点 (POR)和最大稳定持留量(Rm) ,用浸渍法和喷雾法测定的 Rm 结果不同。引用润湿方程的概念来分析影响 Rm 的规律 ,浸渍法测定的 Rm 与粘附张力有关 ,当接触角大于 90°,叶片表面不粘附液体 ,Rm 趋于零。用喷雾法测定作物叶片 Rm,结果显示与药液的粘附功 [γ× (COSθ+1) ]有关 ,即使接触角大于 90°时 ,由于粘附功大于零 ,Rm 值也大于零。对于水稻这样难润湿的作物叶片 ,清水中添加表面活性剂可以提高 Rm;反之 ,对于棉花、黄瓜这样的作物叶片 ,添加表面活性剂反而会降低 Rm。

Study on the Point of Run-off and the Maximum Retention of Spray Liquid on Crop Leaves

Micro weighing method was used to determine the point of run off ( POR ) of spray liquid and the maximum retention ability ( Rm) on plant leaves concerned. Both immersion method and spray method were used to study the Rm on plant leaves. Based on Young's equation, relationship Rm and adhesion force was revealed by immersion method. Relationship between Rm and adhesion work, γ ×(COS θ +1) was also revealed by spray method. The Rm could be increased on difficult to wet leaves, like rice, if surfactants were added, but decreased on easy to wet leaves too, like cotton.