HERBICIDAL WEED MANAGEMENT ALTERS WEED DYNAMICS AND ENHANCES WHEAT (TRITICUM AESTIVUM L.) PRODUCTIVITY UNDER CONSERVATION AGRICULTURE IN VERTISOLS OF CENTRAL INDIA

Abstract

Field experiments were conducted to evaluate the effect of different herbicides on weed management and productivity of   wheat (Triticum aestivum L.) under conservation agriculture (CA). The treatment combinations comprised: absolute control (T1), two hand weedings at 20 and 40 days after sowing (T2),  pre-emergence (Pre E) application of pendimethalin @ 1000 g a.i. ha-1 (T3), Post- emergence  (PoE) application of metsulfuron @4 g a.i.ha-1 + clodinafop- propargyl @60 g a.i. ha-1 at 20 DAS (T4), PoE application of mesosulfuron+ idosulfuron @ 400 g a.i. ha-1 at 20 DAS (T5), Pre-E application of pendimethalin @ 750 g a.i. ha-1 followed by (fb) PoE 2,4-D amine salt 1000 g a.i. ha-1 at 30 DAS (T6),  and Pre-E pendimethalin @ 750 g a.i. ha⁻¹ fb PoE metsulfuron @ 4 g a.i. ha⁻¹ at 30 DAS (T7).  The experiment was laid out in a randomized block design with three replications. Results revealed that weeds can be effectively managed under CA systems through application optimum herbicide rates at the right time. Two hand weeding treatment (T2) proved to be the best among all weed control treatments, recording the highest weed control efficiency (89.40%) and grain yield (37.97 qha-1). Weed control treatments created a congenial environment for better crop growth by reducing competition for nutrients, water, space and light compared with control, thereby improving plant growth and yield parameters in both hand-weeded and herbicidal treatment plots. Among herbicidal treatments, PoE application of mesosulfuron+ idosulfuron @ 400g a.i. ha-1 at 20 DAS (T5) was the most effective achieving weed control efficiency of 74.90% and grain yield of 36.95 qha-1. The lowest values for these parameters were recorded under absolute control (21.58 q ha-1). Thus, the weed-free treatment produced an absolute yield advantage of 16.39 q ha⁻¹ over the weedy check, equivalent to 75.94 % higher grain yield than the weedy check.