Effect of herbicides on weed control and performance of wheat

An experiment was conducted to evaluate the weed control efficiency and wheat performance as affected by different types of herbicides at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh from November 2016 to March 2017. The experiment was laid out in a randomized complete block design and consists of four replications and eleven treatments viz. no weeding (T0), L–Quat 20 SL as pre-emergence herbicide at 2 DAS (T1), Affinity 50.75 WP as post-emergence herbicide at 23 DAS (T2), T1 + T2 (T3), T3 + hand weeding at 40 DAS (T4), Panida 33 EC as pre–emergence herbicide at 2 DAS (T5), U–46D fluid as post-emergence herbicide at 23 DAS (T6), T5 + T6 (T7), T7 + hand weeding at 40 DAS (T8), T5 + T1 + T5 + T6 (T9), T5 + T2 (T10). Fourteen weed species namely Echinochloa cruss–galli, Echinochloa colona Cynodon dactylon, Digitaria sanguinalis, Paspalum distichum, Parapholis incurva, Cyperus rotundus, Chenopodium album, Polygonum hydropiper, Alternanthera sessilis, Oldenlandia corymbosa, Vicia sativa, Physalis heterophylla and Commelina diffusa were infested the experimental field belonging to 9 families where six were grasses, one was sedge and seven were broadleaves. Five most dominant weed species based on importance value in unweeded conditions at 15 DAS were Polygonum hydropiper > Cyperus rotundus > Echinochloa colona > Chenopodium album > Cynodon dactylon. But at 40 DAS and harvest the rank and order of above mentioned five most dominant weed species was differed and Commelina diffusa and Echinochloa cruss–galli were found at 40 DAS and at harvest, respectively instead of Chenopodium album. Both the weed density and dry weight were lowest in T8 treatment followed by T4 treatment at 15 DAS, 40 DAS and harvest. In case of weed control efficiency, these treatments along with T3, T4, T7, T8, T9 and T10 treatments produced the best result as “good control” in comparison to others which produce “fair control” efficiency at 40 DAS. But at harvest, only T4 and T8 produced as “good control” efficiency. The yield and yield components of BARI Gom 24 (Prodip) were statistically significant except the number of non–effective tillers hill–1. The highest grain yield (5 t ha–1) was recorded in the treatment T8 which was statistically identical to the treatment T4 due to having higher number of effective tillers hill–1, higher number of spikelets spike–1, higher number of filled grains spike–1 and 1000-grain weight. The lowest grain yield (2.9 t ha–1) was observed from the control (no weeding) treatment. The highest net returns (61473tk) and BCR (1.64) were obtained under the weed control T8 treatment. It can be concluded that the treatment T8 (Panida 33EC pre-emergence + U 46 D Fluid post–emergence + hand weeding once at 40 DAS) could be applied as the promising practice in wheat cultivation in terms of effective weed control, highest yield, highest economic returns and highest BCR.