Pressure deficit of water vapor in the air in liquid dispensing using a hydropneumatic sprayer

Abstract

The spraying of pesticides requires knowledge of the weather conditions before, during and after operations in the field . Thus , the aim of this work was to evaluate the influence of water vapor pressure deficit in the air , the parameters of the spray produced by the tip of hollow cone JA - 2 in the orange crop . The spraying was performed using a hydropneumatic sprayer. The analysis of the drops was performed using a laser particle analyzer and hidrossenssíveis labels. To determine the volume of solution , we used the method of canopy volume based on the dimensions of the trees in the field. In selecting the volume index was considered the crown volume and historical volume sprayed in the area , and adopted 50 mL m - 3 . The volume sprayed was 696 L ha -1 . The experiment was arranged in a randomized complete block design with three replications . Data were subjected to analysis of variance , the F test , and the averages compared by Tukey test at 5 % probability . The largest percentage of target coverage was 33 % in the range of pressure of water vapor in the air from 1.38 to 1.45 kPa deficit. The greater density of droplets was 341 cm 2 drops in the range of pressure of water vapor in air 2.10 to 2.17 kPa deficit. The greatest deposition of solution on the leaves was 2.6 cm -2 ¶ l observed in vapor pressure from 0.76 to 0.86 kPa deficit.