Effects of Mulching and Micronutrient Management on Growth and Yield of Onion

Onion (Allium capa L.) belonging to the family Alliaceae is one of the most important spices as well as vegetable crops in the world including Bangladesh. As the bulb yield of onion is insufficient in Bangladesh, we have to depend on imports to meet the shortage. Artificial mulching by using polythene sheet and micronutrient management are very important for successful onion production. The experiment was conducted at the farmer’s field of Gobindopur, Rajshahi, Bangladesh, under High Ganges River Floodplain Soils (AEZ-11) to study the effects of mulching and some micronutrients (boron/B and zinc/Zn) on the growth and yield of onion during the period from November 2011 to April 2012. The trial with one onion cultivar (Taherpuri) involved two separate experiments using different micronutrient levels (3 levels of B: 0, 0.20, 0.40 g·m^-2 and 4 levels of Zn: 0, 0.50, 0.80, 1.25 g·m^-2) with plastic mulch without irrigation, and without mulch with irrigation. The experiments were laid out in a split-split plot design with three replications.  Results demonstrated that most of the yield and yield contributing parameters were significantly influenced by applying plastic mulch, and different doses of B and Zn. The plant height (35.55 cm) at 60 DAP (days after planting), number of leaves (5.53), fresh weight of leaves (12.13 g), dry weight of leaves (1.41 g), fresh weight of bulb (27.78 g), dry weight of bulb (2.54 g), pseudo-stem diameter (1.16 cm), diameter of bulb (4.04 cm), and bulb yield (14.86 t·ha^-1) were found to be greater when grown in plastic mulching.  Interaction between mulching and boron, mulching and zinc, boron and zinc, and mulching and boron with zinc at different levels had significant effects on all growth and yield parameters with few exceptions. The combination of the highest doses of B at 4 kg·ha^-1 and Zn at 12.50 kg·ha^-1 with plastic mulching gave higher yield (18.71 t·ha^-1) of onion bulb and other parameters than those of yield without mulching (15.56 t·ha^-1). However, it can be concluded that most of the yield contributing characters and yield were significantly influenced by plastic mulching along with the interaction effect of different levels of B and Zn with it.