LAUSR

Implementation of manual plant protection in a Chinese solar greenhouse (CSG) is expensive and labor-intensive. Moreover, this system cannot realize the separation of people and drugs. In a CSG, plants are cultivated at different distances, directions, and heights. Consequently, pesticide application via air-spraying is not uniform because the volume of pesticide droplets that deposit on plants is disproportionate. In this study, a CSG inter-row sprayer was designed to realize the automation of plant protection and the uniformity of pesticide application. With a double-track suspension, the sprayer could move freely along the east and west directions of the CSG and perform two spraying modes, namely, fixed boom spray and lifting spray. These modes could be applied depending on different crop growth stages and protection requirements. Electromagnetic detection and positioning technology were used to detect crop rows and satisfy inter-row spraying requirements. Automatic lifting and spraying operations based on crop height as detected by the sensor were realized by a lifting motor. The effects of inter-row lifting and fixed boom sprays on droplet deposition and penetrability were tested using mature tomatoes cultivated in the CSG. Results demonstrate that the average volumes of droplets deposited on the obverse and reverse sides of tomato leaves are 1.77 and 0.817 μL per square centimeter in the inter-row lifting spray, and the average variation coefficients of droplet volume deposition are 7.3% and 19.53%, respectively. In the fixed boom spray, the average volumes of droplets deposited on the obverse and reverse sides of tomato leaves are 1.12 and 0.086 μL per square centimeter, respectively, and the average variation coefficients of droplet volume deposition are 33.2% and 74.7%, respectively. These findings indicate that inter-row lifting spray significantly increases droplet deposition on the reverse side of tomato leaves and improves the uniformity and penetrability of droplet deposition. This study improves the automation degree of plant protection and uniformity of pesticide droplet deposition, as well as provides supplementary options for plant protection in CSGs.