Evaluation of droplet deposition and efficiency of 28-homobrassinolide sprayed with unmanned aerial spraying system and electric air-pressure knapsack sprayer over wheat field

Abstract

Brassinolides are plant-specific Polyhydroxylated steroid hormones that play a vital role in plant growth regulation and actively participate in inducing various stress tolerance. Our objective was to investigate the influence of 28-Homobrassinolide (HBR) dosages and compare the droplet deposition of unmanned aerial spraying system (UASS) with electric air-pressure knapsack (EAP) sprayer over the wheat field. Three HBR dosages (19, 24, 30 mg a. i. ha−1) with spray volume (SV) of 15, 30 L ha−1 were applied by UASS, and HBR dosage of 24 mg a. i. ha−1 with a spray volume of 450 L ha−1 was applied by EAP. The droplet deposition of UASS 15 L ha−1 was 15.51 %, 33.57 % higher than UASS 30 L ha−1 and EAP. While spray distribution uniformity in both UASS spray volumes was less than EAP. HBR (24, 30 a. i. mg ha−1) significantly increased the photosynthetic traits, which led to a hastened grain filling rate and increased biomass of reproductive plant organs, yield, and yield components. HBR dosage of 24 mg a. i. ha−1 with a spray volume of 15 L ha−1 significantly increased grain yield by 17.94 %, 16.31 % than CK and 12.13 %, 15.31 % than EAP in two years, respectively. It is concluded that the application of HBR 24 ∼ 30 mg a. i. ha−1 with UASS 15 L ha−1 at the wheat anthesis stage could be an effective approach to improve the wheat yield.