Weed interference period and seed rate influence on wheat productivity

Abstract

Wheat-weed competition depends on many factors including weed interference period and competitiveness of wheat which is mostly governed by seeding density of the crop. Increasing weed interference period decreases grain yield and vice versa. Seeding density is a management tool for minimizing weeding infestation and maximizing grain yield through maximum utilization of resources by the crop. Therefore, present study was undertaken to evaluate the effect of different weed interference periods and seed rates on the productivity of wheat cv. BARI Gom 26. The study was conducted during the Rabi season 2015-2016 at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh. Treatments included five seed rates of wheat namely, 100, 120, 140, 160 and 180 kg ha-1 and five weed interference periods namely, season-long-weed- free, weed-free up to 20 DAS, weed-free up to 40 DAS, weed-free up to 60 DAS and season-long-weedy. The field experiment was laid out in a randomized complete block design with three replications. The results showed that weed dry weight decreased gradually with the increase in wheat seed rate. The highest (101.7 g m-2) and lowest (92.19 g m^-2) weed dry weights were recorded with 100 and 180 kg seeds ha^-1, respectively. Weed dry weight also increased with increasing weed interference period. Season-long weed free resulted in the maximum weed dry weight (149.3 g m^-2), followed by weed-free up to 20 DAS (130.6 g m^-2), weed-free up to 40 DAS (121.3 g m^-2) and weed-free up to 60 DAS (92.5 g m^-2). Wheat grain yield decreased with increased weed interference period. As expected, weed-free treatment resulted in the maximum grain yield (2.78 t ha^-1) and the lowest one was found in weedy treatment (1.35 t ha^-1). The seed rate of 140 kg ha^-1 produced the highest grain yield (2.81 t ha^-1). The seed rate of 160 kg ha^-1 resulted in the lowest grain yield (2.04 t ha^-1). The highest grain yield (3.40 t ha^-1) resulted from the interaction of 140 kg seed ha^-1 with weedy treatment which was statistically identical to the obtained from 140 kg seed ha^-1 with weed free up to 40 DAS and 60 DAS. The lowest grain yield (1.76 t ha^-1) resulted from the interaction of 180 kg seed ha^-1 with weedy treatment which was statistically identical to 180 kg seed ha^-1 with weed free up to 20 DAS. Although weed-free regime produced the maximum yield but it is not economic to maintain weed-free condition throughout. Therefore, it can be concluded that BARI Gom 26 should be cultivated with 140 kg seeds ha^-1 keeping weed free up to 40 DAS for obtaining higher yield.