Spices Research Center,BARI, Shibganj, Bogra
The experiment was conducted at the spices research centre, Shibgonj, Bogra during rabi season, 2010-11 and 2011-12. The experiment was laid out in a split-plot design with three replications. In 2010-11, six planting time viz., 20 December, 30 December, 10 January, 20 January, 30 January and 10 February were assigned to the main-plot and seven plant spacing viz., 20cm x 10cm, 20cm x 7.5cm, 15cm x 10cm, 15cm x 7.5cm and 10cm x 10cm, 10 cm x 7.5 cm and 7.5 cm x 7.5 cm were assigned to the sub-plot. In 2011-12, the treatments were slightly modified where five planting time viz., 20 December, 30 December, 10 January, 20 January and 30 January were assigned to the main-plot and seven plant spacing viz., 15cm x 10cm, 15cm x 7.5cm, 15cm x 5cm, 10cm x 10cm, 10cm x 7.5cm, 10 cm x 5cm and 7.5 cm x 7.5 cm were assigned to the sub-plot. The unit plot size was 2.5 m x 2.0m. The cv. BARI Piaz 1 was used as test crop. To control thrips `Gain’ @ 0.25ml/L of water was sprayed at 35, 45, 55 and 65 DAP in 2010-11 and at 30, 40, 50 and 60DAP in 2011-12. Similarly, to control purple blotch disease, the crop was sprayed with `Rovral’ @ 2g/L o water at 40, 50, 60 and 70 DAP in both the years. Depending on maturity the crop was harvested through 10-25 April in 2011and 2012. Data on plant population, plant height, number of leaves per plant, bulb weight per plant, diameter of bulb, length of bulb, bulb yield were recorded.
The percent bolting was increased with wider spacing while the same was decreased with closer spacing. Similarly, irrespective of spacing, the percent bolting was increased with early planting while the same was decreased with late planting Irrespective of planting time, the percent splitting was increased with wider spacing while the same was decreased with closer spacing. Similarly, irrespective of spacing, the percent splitting was increased with early planting while the same was decreased with late planting. The highest gross return, net return and benefit-cost ratio was obtained from 20 December planting which was very close to 30 December and 10 January planting. Similarly, the highest gross return, net return and benefit-cost ratio was obtained from 7.5cm x7.5 cm spacing in 2010-11 and 10cm x5cm in 2011-12.
Onion cultivation could be done on 20 December or 30 December or 10 January along with 10cm x 5cm spacing.