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

Fair-planted garlic (Allium sativum L.) has a higher number of cloves per b ulb and higher bulb yield than spring-planted garlic. Many garlic growers, however, plant their crops in the spring to avoid losses associated with wi nterkill. Pre-plant storage temperature of cloves affects bulbing and clovi ng of the subsequent crop. Studies were conducted to determine the optimum duration of pre-plant chilling (4 degrees C) treatment for enhanced cloving and increased bulb yield of three spring-planted garlic cultivars (an unna med local selection, California Early and California Late). In a greenhouse study, California Early and California Late cloves were planted after rece iving low-temperature treatments of 4 degrees 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 c loving and bulb yield for all cultivars. In general, chilling treatment per iods exceeding 30 d (for field) and 45 d (for greenhouse) resulted in impro ved cloving in bulbs of all cultivars. Improved cloving resulted in a signi ficant increase in both bulb diameter and bulb yield per plant, particularl y in greenhouse-grown garlic. Pre-plant chilling was not a pre-requisite fa r bulb formation, but it was essential for cloving. In conclusion, results indicate that better cloving and bulb yields are obtained if cloves have be en stored at 4 degrees C for 45-60 d prior to field and greenhouse planting , respectively.