Pre-plant chilling requirements for cloving of spring-planted garlic

Abstract

Fall-planted garlic (Allium sativum L.) has a higher number of cloves per bulb and higher bulb yield than spring-planted garlic. Many garlic growers, however, plant their crops in the spring to avoid losses associated with winterkill. Pre-plant storage temperature of cloves affects bulbing and cloving of the subsequent crop. Studies were conducted to determine the optimum duration of pre-plant chilling (4 °C) treatment for enhanced cloving and increased bulb yield of three spring-planted garlic cultivars (an unnamed local selection, California Early and California Late). In a greenhouse study, California Early and California Late cloves were planted after receiving low-temperature treatments of 4 °C for 0 (control), 30, 45, 60 or 75 days, whereas, for field studies, cloves from greenhouse-grown bulbs of all three cultivars were planted, and chilling treatments were similar to those for the greenhouse study.Pre-plant chilling treatments of cloves produced significant increases in cloving and bulb yield for all cultivars. In general, chilling treatment periods exceeding 30 d (for field) and 45 d (for greenhouse) resulted in improved cloving in bulbs of all cultivars. Improved cloving resulted in a significant increase in both bulb diameter and bulb yield per plant, particularly in greenhouse-grown garlic. Pre-plant chilling was not a pre-requisite for bulb formation, but it was essential for cloving. In conclusion, results indicate that better cloving and bulb yields are obtained if cloves have been stored at 4 °C for 45–60 d prior to field and greenhouse planting, respectively. Key words: Allium sativum, bulbing, low temperature treatment