Evaluation of Various Weed Control Techniques in Transplanted Onions Under Agro-Climatic Conditions of Peshawar—Pakistan

Weeds make it difficult for onions to compete, and large output losses are a result of weed infestations. Therefore, weed management is crucial to ensuring optimum crop development, particularly during the early growth stage. Additionally, there is a strong negative association between the dry matter of weeds and the crop’s grain production. A field trial was conducted at Horticulture Research Farm, The University of Agriculture Peshawar during spring 2021 to evaluate the effect of several weed control methods in transplanted onions under agro-ecological conditions of Peshawar. The experiment was laid out in a RCB Design, with 10 treatments and 3 replications. The treatments consisted of two pre-emergence herbicides (Hadaf 24% EC @ 0.26 L a.i ha⁻¹ and Stomp 330 EC @ 0.5 L a.i ha⁻¹), Parthenium hysterophorus L. leaf aqueous extract (PLE) @ 1:10 (w/v) as an allelopathic suppressant, weeds biomass mulch (WBM), cotton cloth mulch (CCM), color plastic mulch (CPM), transparent plastic mulch (TPM), hand weeding 20 (HW 1), 40 days (HW 2) after transplantation and weedy check (WC). All the treatments had a significant effect on weeds’ growth and onion yield. Minimum weed density (9 m⁻²) was noted in the CPM compared to WC (93 m⁻²), while the least weed frequency was recorded in TPM (3.1) followed by CCM (5.5), CPM (9.1), Stomp 330 EC (17.2), Hadaf 24% EC (18.2), HW 2 (19.1), WBM (20.5), HW1 (20.9) and PLE (26.6) as compared to WC (34.5). Similarly, minimum weed biomass was observed in TPM compared to other treatments. Taller onion plants (32.98 cm) were recorded in PLE whereas, maximum blub diameter (7.62 cm) was noted in CPM, and maximum chlorophyll content (0.44 mg/g) was recorded in CCM and hand weeding (40 DAT) plots. Maximum bulb yield (13,346.70 kg ha⁻¹) and CBR (2.77) were recorded in TPM. In conclusion, onion being a small canopy crop needs proper weed management in time to avoid maximum yield loss.