Elucidation of critical period of crop weed competition in groundnut (Arachis hypogaea) under mid-hills of Meghalaya

The experiment consisted of 12 treatments (weed interference until 15, 30, 45, 60, and 75 days after emergence (DAE), weedy until crop maturity, and weed-free until 15, 30, 45, 60, 75, and a weed-free until crop maturity) and the treatments were arranged in a randomized complete block design (RCBD) with three replications. This study indicated increased weed interference period reduced the pod yield by 6.5-36 and 0.7-32%, and haulm yield by 6.4 - 34 and 6.5 - 34% during rainy and winter season respectively. Further, reduction in total biomass production by crop due to weed interference declined the total nutrient uptake by crop, i.e. nitrogen by 7.8-52.1 and 9.6-54.5%, phosphorus by 4.8-45.4 and 6-47.5%, potassium by 6.9-43.7 and 6.3-44.4%, sulphur by 18.4-53.3 and 18.8-53.9%, during rainy and winter season respectively. However, weed-free until crop harvest increased RUE by 293% and 314%, chlorophyll content by 8.7 and 10.7%, respectively, during rainy and winter seasons. This study indicated critical duration for crop-weed interference under 5% relative yield loss (RYL) was 16 to 66 DAE in rainy and 15 to 63 DAE in winter. Similarly, at 10%, RYL were 23 to 62 and 21 to 61 DAE, respectively, during the rainy and winter seasons. As a result, farmers should keep their groundnut crop weed-free between 15 and 66 DAE during the rainy and winter seasons.