Non-chemical weed management in chilli (Capsicum annuum L.)

Abstract

One of the major problems in any crop production system is weed infestation which causes reduction in both the yield and quality of produce. Although the use of herbicides provides effective and sustained weed control, it is not a preferred option because of environmental concerns. This is particularly true in the case of vegetables, some of which are consumed either partially cooked or raw. The research programme entitled ‘Non-chemical weed management in chilli (Capsicum annuum L.)’ was carried out with the objective of evaluation of non-chemical methods of weed management in chilli. The experiment was conducted at the Department of Agronomy, College of Agriculture, Vellanikkara from June 2020 to September 2020. The field was infested with broad leaf weeds, grasses and sedges. Randomized block design used for laying out the experiment, with seven treatments and three replications. The treatments were, T1: stale seed bed for 14 days followed by shallow digging and planting of chilli, followed by two hand weedings at 30 DAT and 60 DAT, T2: stale seed bed for 14 days followed by shallow digging and planting of chilli, followed by one hand weeding at 45 DAT, T3: black polythene mulch (30 microns), T4: straw mulch at 7.5 t/ha applied twice, at planting and one month after planting, T5: straw mulch at 7.5 t/ha applied twice, at planting and one month after planting followed by one hand weeding at 60 DAT, T6: hand weeding at 30 and 60 DAT and T7: unweeded control. Black polythene mulch (T3) recorded highest weed control efficiency and lowest weed density, weed dry matter production and weed index, whereas straw mulch when applied alone (T4) and when followed by one hand weeding (T5) were the next best treatments with high weed control efficiency and low weed index. The treatments hand weeding (T6), stale seed bed when followed by two hand weedings (T1) and one hand weeding (T2) were not effective in controlling weeds. The lowest weed control efficiency and the highest weed index values were recorded for the unweeded control (T7) at all stages of observation. Various weed management practices had significant effect on growth and yield parameters of chilli. At all stages of observation, the plant height of chilli in polythene mulching (T3) was found to be the greatest followed by straw mulching when done alone (T4) and when followed by one hand weeding (T5). Unweeded control (T7) had the lowest values. Chilli plants in polythene mulching (T3) recorded the highest number of fruits per plant (218) and fruit yield (22.44 t/ha), followed by straw mulching both when done alone (T4) (182 nos. and 18.89 t/ha respectively) and when followed by one hand weeding (T5) (177 nos. and 18.38 t/ha respectively). Hand weeding (T6) and stale seed bed when followed by two hand weedings (T1) recorded lower yields than straw mulching. Unweeded control (T7) recorded lowest values for fruit length, fruit girth, fruit weight, number of fruits per plant and fruit yield. The soil physico-chemical characteristics pH, EC, organic carbon, and available N, P and K were influenced by different weed management practices. The organic carbon content in soil was highest in polythene mulching (T3) at 60 DAT (1.45 %) and after the final harvest (1.49 %). At both stages of observation, straw mulching (T4) had highest values of available P (77 and 79 kg/ha respectively) and K (414 and 408 kg/ha respectively), whereas available N was found higher in black polythene mulch (T3) at 60 DAT (246 kg/ha) and in stale seed bed followed by one hand weeding (T2) after the final harvest (239 kg/ha). Considering the economics of cultivation, black polythene mulching (T3) recorded highest gross returns (Rs.22.44 lakhs/ha), net returns (Rs. 9.94 lakhs/ha) and B:C ratio (1.84) and was followed by straw mulching when done alone (T4) and when followed by a hand weeding (T5). Black polythene mulching was thus identified as the best non-chemical weed management technique in chilli, having highest weed control efficiency leading to enhanced growth and yield parameters and highest net returns and B:C ratio. Straw mulching when done alone or when followed by one hand weeding were the next best treatments with respect to weed control efficiency, growth, yield and net returns of chilli.