Effect of Drone Application of Pendimethalin on Microbial Population, Nodulation, Weed Control and Yield of Green Gram (Vigna radiata L.)

A field experiment was conducted at Anbil Dharmalingam Agricultural College and Research Institute, Tiruchirappalli, during Winter, 2023 to study the effect of pendimethalin application using drone on soil microbial population, nodulation, weed control and yield of green gram. The experiment was laid out in RBD with 12 treatments and 3 replications. The treatments consisted two levels of pendimethalin dosage (0.75 and 1.0 kg ha-1), five levels of spray fluids (40, 50, 60, 70 and 80 litres ha-1) for drone spray compared with manual spray of pendimethalin at 1.0 kg ha-1 with 500 litres ha-1 spray fluid and control. The results revealed that significantly higher microbial population such as bacteria (17.60 × 106 cfu/g of soil), fungi (14.90 × 103 cfu/g of soil), actinomycetes (42.60 × 104 cfu/g of soil) and rhizobium (21.30 × 105 cfu/g of soil) were recorded with no herbicide application (unweeded control) at 30 DAS than pendimethalin 1.0 kg ha-1 application either manual or drone. The lower dose of pendimethalin 0.75 kg ha-1 with spray fluid of 60 litres ha-1 was on par with no herbicide application treatment. Significantly higher root nodules per plant-1 (17.56 and 22.51) at 30 and 45 DAS was registered under drone spray of pendimethalin 0.75 kg ha-1 with spray fluid of 60 litres ha-1. Higher weed control efficiency (72.6 %) and grain yield (747 kg ha-1) were statistically superior under drone spray of pendimethalin 1.0 kg ha-1 with spray fluid of 60 litres ha-1 over 40 or 80 litres ha-1 spray fluids and was comparable with lower dose of pendimethalin (0.75 kg ha-1) with 60 litres ha-1. Thus, it can be inferred that pendimethalin at 0.75 kg ha-1 with spray fluid of 60 litres ha-1 was considered as ideal dose and spray fluid for drone application to get better soil microbial population, nodulation, weed control efficiency and grain yield of green gram.