Onion Development and Yield in Response to Manual Cultivation, Herbicides, or Colored Mulches

ABSTRACT The extent of onion (Allium cepa L.) bulb and seed production varies with different production management practices. Field experiments were conducted during the 2000–2001 and 2001–2002 growing seasons to evaluate bolting and yield in onion grown with blue, red or white mulch in comparison to those grown with manual cultivation or chemical weed control treatment without mulch. The role of low temperature at the post-juvenile growth stage in bolting induction was also examined. Bolting was sometimes higher under mulch as compared to plots receiving manual hoeing or herbicide treatments. No particular mulch color appeared to consistently favor bolting. There was an inverse relationship between bolting and yield. Treatments did not affect germination of harvested seeds. Onion plants which were exposed to low temperature after attaining the critical growth stage for vernalization produced more inflorescences.