Effect of nitrogen regimes on the yield and quality of onion (Allium cepa L.) through set to bulb method

Abstract

The experiment was conducted at the Spices Research Sub-Centre (SRSC), Bangladesh Agricultural Research Institute (BARI), Faridpur during winter season of 2023-2024 from October to January to find out the optimum dose of nitrogen for higher yield and quality of onion (var. BARI Piaz-4) through set to bulb method. The experiment comprised 7 levels of nitrogen, viz. T2: 0 kg N/ha, T2: 30 kg N/ha, T3: 60 kg N/ha, T4: 90 kg N/ha, T5: 120 kg N/ha, T6: 150 kg N/ha and T7: 180 kg N/ha. The experiment was laid out in the Randomized Complete Block Design with three replications. The results revealed that characteristics studied were influenced by N regimes. Growing onion without N exhibited yellowing in colour on the leaves of plants under the score 5 significantly followed by 30 kg N/ha (score 3). While, onion plants receiving N @ 60-180 kg/ha had no sign of yellowing on the plant. Instead of yellowing, plants with higher doses of N showed dark green colour. Days to maturity were increased with increasing N up to 150 kg N/ha ranging from 75.33 to 82.33 days. And then it was decreased to 81.07 days at 180 kg N/ha. Incorporation of 150 kg N/ha produced the highest bulb yield (22.15 t/ha) closely followed by 180 kg N/ha (21.08 t/ha), 120 kg N/ha (20.74 t/ha) and 90 kg N/ha (17.32 t/ha). Plants with 120 kg N/ha gave 16.43% split bulb which was statistically similar to the 90 kg N/ha (14.96%) and 150 kg N/ha (18.22%). Incidence of bolting gradually decreased with the increase in N rates. In the economic point of view, the highest gross return (Tk. 890295), net return (Tk. 624968) and benefit-cost ratio (3.36) were observed at 150 kg N/ha. It is concluded that 150 kg N/ha was optimum for the production of onion (var. BARI Piaz-4) through set to bulb method.

Bangladesh J. Agril. Res. 49(2): 189-201, June 2024