Effect of nitrogen and weed management on weed dynamics, and mustard yield and profitability in semi-arid Afghanistan

Abstract

An experiment was conducted at the experimental farm of Afghanistan National Agricultural Sciences and Technology University (ANASTU), Kandahar during spring 2020 to study the effect on nitrogen and weed management practices in mustard under semi-arid region. Experimental treatments comprised four weed management practices (WMPs) in main-plot [viz. Weedy-check (WC), Weed-free check (WFC), Pendimethalin pre-emergence @ 1.0 kg ha-1 and Pendimethalin @ 0.75 kg ha-1 pre-emergence followed by one hand-weeding at 30 DAS and four N levels [120, 80, 40 and 0 kg ha-1] as sub-plot treatments. The experiment was laidout in a split-plot design with three replications. Among WMPs, the WFC recorded zero population of weeds, while significantly lower number of weeds (NLWs + BLWs) was recorded with WMPs, Pendimethalin 0.75 kg ha-1 (PE) followed by (fb) hand-weeding at 30 DAS (51.9 m-2). The highest number of weeds (NLWs + BLWs) was recorded with WFC (76.2 m-2). Among N management practices (NMPs), the significantly lower (p<0.05) number of weeds (NLWs+ BLWs) was recorded with 0 kg N ha-1 (36.5 m-2) followed by 40 kg N ha-1 (41.5 m-2) and 80 kg N ha-1 (47.0 m-2). The significantly lower dry weight of weed was observed with 0.75 kg ha-1 Pendimethalin (PE) followed by (fb) hand-weeding at 30 DAS (15.63 g m-2) fb Pendimethalin 1 kg ha-1 PE (16.88 g m-2) and higher weed dry weight (NLWs + BLWs) was observed with treatment, WC (20.91 g m-2). The results showed that significantly higher weed control efficiency was recorded with WMPs, 0.75 kg ha-1 Pendimethalin (PE) herbicide fb hand-weeding at 30 DAS (23.6 %), followed by Pendimethalin 1 kg ha-1 PE (14.1%). The higher WCE was recorded with NMPs, 0 kg N ha-1 followed by 40 kg N ha-1. The significantly higher plant height, leaf area index, dry matter accumulation, seed yield of mustard was recorded with WFC, then 0.75 kg ha-1 Pendimethalin (PE) herbicide followed by hand-weeding at 30 DAS. In among the NMPs significantly higher plant height, leaf area index, dry matter accumulation, seed yield and net returns of mustard was recorded with application of 120 kg N ha-1 followed by 80 kg N ha-1 and 40 kg N ha-1. Based on the experimental results, it is inferred that weed free-check and pre- emergence application of Pendimethalin 0.75 kg ha-1 fb hand-weeding at 30 DAS along with 120 kg N ha-1 resulted in higher crop growth, productivity and profitability of mustard crop in semi- arid region of Kandahar, Afghanistan.