Effects of transplanting time on the yield and quality of onion (Allium cepa L.)

A field experiment was conducted at Spices Research Sub-Centre (SRSC), Bangladesh Agricultural Research Institute (BARI), Faridpur, Bangladesh during the winter season of 2018-2019 to investigate the influences of transplanting times of seedlings and the varieties on the yield and quality of onion bulbs. There were six levels of transplanting time such as T1: November 15, T2: November 30, T3: December 15, T4: December 30, T5: January 14 and T6: January 29 under the trial. The varieties used in the study were: BARI Onion-1 and BARI Onion-4. The experiment was laid out in a randomized complete block design (RCBD) of factorial concept with three replications. The results revealed that dates of transplanting, varieties and their combined effects had significant effect on the parameters studied with minor exception. The plant height, number of leaves/plant and incidence of bolting were decreased with the passage of transplanting time. The maximum values (54.51 cm, 8.53 and 71.28%) of the aforementioned traits were recorded at early transplanting on November 15, respectively. The reduced percent of bolting (2.22%) was observed at December 30. While no incidence of bolting was found under transplanting on 14-29 January. Bulb diameter, individual bulb weight, yield, total soluble solid content and dry matter content of bulb were increased up to transplanting on December 15. Afterwards the values of aforesaid parameters were gradually decreased. The highest yield (17.65 t/ha), total soluble solid content (17.02 0brix) and dry matter content of bulb (15.95%) were obtained from December 15 insignificantly followed by December 30 (16.30 t/ha). The delayed transplanting on 29 January markedly reduced the yield (6.72 t/ha), total soluble solid content (12.58 0brix) and dry matter content of bulb (11.61%) as well. The variety BARI Onion-4 performed better in respect of yield and yield attributes but it showed inferior quality. The combined effect of December 15 x BARI Onion-4 gave the highest yield attributes and yield of onion followed by the combination of November 30 x BARI Onion-4 and December 30 x BARI Onion-4 while the values among the three treatments were statistically similar.