Testing research on effects of top layer rice fog drop interception on pesticide spraying distribution in rice fields

The evaluation of precise pesticide spraying depends on the effective deposit of the liquid onto the crop. Research on fog drop interception by top layer rice plant during pesticide spraying provides technical data for the optimum design, performance improvements, and correct use of the sprayer. Research also has a wide significance in reasonably spraying pesticide, increasing the pesticide-applying efficiency, reducing pesticide residue and contamination, and ensuring foodstuff safety. A solution of Rhodamine-B mixed with water in 0.1% concentration was used instead of a pesticide to spray rice fields. Rice plant leaves were collected along the altitude direction of rice growth in three layers using a sampling frame. The deposit of spraying fog drop on rice plant in every layer was measured by means of a fluorescence spectrophotometer. The method of quantatively analyzing the effect of fog drop interception by top layer rice leaves on the deposit of spraying fog drop was first put forward in this paper. Tests were conducted in early season and late season rice fields. Results showed that when the rice plant was bedded in three layers, above 40 cm, between 20～40 cm and between 5～20 cm above the ground, the proportional factors of top layer rice aroplets interception to mid layer rice fog drop deposit, bottom layer rice aroplets deposit and to ground fog drop loss were -0.6615(and -0.7493 for early season rice), -0.3386(and -0.2511 for early season rice) and -1.1441, respectively. The nonuniformity coefficient of fog drop deposit was defined and studied. A conclusion was reached that top layer rice fog drop interception could not improve the uniformity of aroplets deposition of the mid layer or bottom layer.