Evaluation of Growth Stimulants on Short-day Onions

Abstract

A 3-year study on the effects of growth stimulants on yield, bulb size, bulb quality, and storability of short-day onions (Allium cepa L.) was conducted at three locations. Treatments included 2-hydroxypropanoic acid, humic acids, humic acids in conjunction with micronutrients, and two formulations of cytokinin applied as a transplant dip and/or plant spray. There were no differences between 2-hydroxypropanoic acid and an untreated check at two different farm locations for onion yield, equatorial bulb diameter, or percent jumbos [≥3 inches (≥7.6 cm)] in 1997. Comparisons between untreated checks, 2-hydroxypropanoic acid, humic acids as a transplant dip or plant spray, and humic acids with micronutrients, all applied as transplant dip or plant spray, indicated there were no differences among treatments for yield, pungency, soluble solids, equatorial bulb diameter, or percent marketable bulbs after 6 months in controlled atmosphere storage in 1997-98. In a final experiment, these treatments were evaluated in a factorial arrangement using the short-day onion cultivar Pegasus and a mixture of cultivars WI-609 and WI-3115, which are referred to as Wannamaker cultivar mix. `Pegasus' displayed higher yield and lower soluble solids than the Wannamaker cultivar mix. Treatment with humic acids and micronutrients, or cytokinins resulted in greater percent marketable bulbs after 4.5 months of controlled atmosphere storage compared to the untreated check. No differences were observed among the treatments for pungency or bulb size. In addition, there was no treatment by cultivar interaction.