Phytotoxic effect of herbicides on gladiolus and their effectiveness against weed flora associated with the crop

Abstract

The present investigation was conducted during 2018-19 at Centre for Quality Planting Material, RDS Seed Farm CCSHAU, Hisar, Haryana. The experiment comprised of 16 treatments i.e. nine herbicidal treatments [viz. oxyfluorfen @ 500 g ha-1, pendimethalin @ 1000 g ha-1, butachlor @ 1000 g ha-1, carfentrazone @ 30 g ha-1 and metsulfuron-methyl @ 5 g ha-1 in combinations of pre and pre/post-emergence application at 50 DOP (days of planting) after the HW (hand weeding) or without HW], five mulch treatments (viz. mulching of black polyethylene sheet of 100 µ alone, and the paddy straw mulching @ 10 tonnes ha-1 in combinations with HW at 75 DOP or pre-emergence application of pendimethalin @ 1000, 1250 & 1500 g ha-1), and one treatment of hand weeding/hoeing (at 25, 50 & 75 DOP), and weedy check (control), laid out in simple randomized block design with three replications. Polypogon monspeliensis, Phalaris minor, Cyperus rotundus and Cynodon dactylon among monocots and Chenopodium murale, Convolvulus arvensis, Fumaria parviflora and Coronopus didymus in dicots were found dominant weeds in experimental field. Among the application of herbicides or mulch materials either alone or in combinations, black polyethylene mulch (T13) was found highly effective in controlling weeds followed by pendimethalin 1000 g fb HW + pendimethalin 1000 g (T12), straw mulch fb HW at 75 DOP (T14) and pendimethalin 1500 g/ha + straw mulch (T6). Amongst the herbicidal treatments, pendimethalin 1000 g fb HW + pendimethalin 1000 g (T12) was found comparatively more efficient in controlling weeds without any phytotoxic effect on crop. Interestingly, the applications of oxyfluorfen as a pre-emergence and metsulfuron-methyl as a post-emergence in different herbicidal combinations caused phytotoxicity in crop plants up to the level of growth check or one leaf burning, and the phytotoxic effect of metsulfuron-methyl was more than the oxyfluorfen. At 30 DOP the maximum level of phytotoxicity (1.70) was recorded with the pre-emergence application of oxyflurofen 500 g fb HW + oxyflurofen 500 g (T3), while at 60 DOP it was observed non-significant with most of the herbicidal applications, whereas at 90 DOP and 120 DOP, it was recorded highest (i.e. 2.73 and 2.97, respectively) with the application of oxyfluorfen 500 g fb metsulfuron-methyl 5 g (T2) and it was followed by post-emergence application of metsulfuron-methyl 5 g in combinations with pre-emergence application of other herbicides (T8 & T11). Overall, the application of mulch materials (either alone as a black polyethylene sheet of 100µ or paddy straw @ 10 tonnes ha-1 in the combination with HW or pendimethalin 1500 g ha-1) was found very effective with the aspect of weed control in gladiolus.