Effect of nitrogen levels and herbicides on productivity and economics ofsesame (Sesamum indicum) and residual effects on succeedingchickpea (Cicer arietinum)

Abstract

A field experiment was carried out to investigate the effect of nitrogen levels and different herbicides on weed dynamics, growth and productivity of sesame (Sesamum indicum L.) and their residual effects on succeeding chickpea (Cicer arietinum L.). It was conducted during the 2022–23 and 2023–24 at the Instructional Farm, College of Agriculture, Swami Keshwanand Rajasthan Agricultural University, Bikaner, Rajasthan. Twenty different treatment combinations were tested with main-plots assigned four different nitrogen levels (control, 20, 40 and 60 kg/ha) and the sub-plots were divided into five different weed control methods (weed-free treatment, pendimethalin @750 g/ha pre-emergence (PE), flumioxazin @75 g/ha PE, imazethapyr @50 g/ha applied 25 days after sowing, and weedy check). The results demonstrated that applying 40 kg N/ha significantly enhanced multiple growth metrics. These metrics included plant height, dry matter accumulation, crop growth rate, relative growth rate, seed yield, stalk yield
and oil content of sesame but it was at par with 60 kg N/ha. The seed yield percentage increase by 68.4 and 18.5%, net return registered 216.5 and 35.9% increase over control and 20 kg N/ha, respectively. A maximum benefit-cost ratio (2.39) was recorded with the application of nitrogen 60 kg/ha, which was at par with 40 kg N/ha (2.29). Among herbicide treatments, pendimethalin at 750 g/ha, showed a significant improvement in plant height, dry matter accumulation, crop growth rate, relative growth rate, seed yield, stalk yield, net return and benefit-cost ratio of sesame over flumioxazin, weedy check and imazethapyr, whereas it was at par with weed free treatment. Maximum partial factor productivity, agronomic efficiency and physiological efficiency was observed in 20 kg N/ha followed by 40 kg N/ha and 60 kg N/ha. Lowest weed index was reported under pendimethalin (5.18%), however highest weed control efficiency (88.50%) was observed under imazethapyr. Furthermore, the succeeding chickpea crop was unaffected
by the nitrogen and herbicide that had been sprayed in pervious chickpea crop. It was concluded that the application of nitrogen at 40 kg/ha along with pendimethalin at 750 g/ha as a PE treatment is recommended for reduce weed dynamics and achieving higher productivity, along with improved quality and profitability, in the hyper-arid regions of Rajasthan, considering its economic importance.