Changes in Carbohydrate Concentrations in Basal Leaf Sheaths of Allium × wakegi Araki in Relation to Bulb Development and Dormancy

Abstract

Changes in carbohydrate concentrations in basal leaf sheaths (this part corresponds to a bulb after bulb development) of two Allium × wakegi Araki cultivars, 'Kiharabansei No.1'(dormant type) and 'Ginoza'(nondormant type) during bulb development and postharvest storage were investigated. There was little difference in the fructose, glucose, sucrose, and fructans concentrations throughout the experimental period between 'Kiharabansei No.1' and 'Ginoza'. Hence, only changes in the former are discussed. During bulb development, when plants of 'Kiharabansei No.1' became dormant, the concentrations of fructose and glucose decreased, while those of fructans and total carbohydrates increased ; there were no significant changes in sucrose concentrations. During postharvest storage of 'Kiharabansei No.1' bulbs, they were gradually released from dormancy and the concentrations of all the components remained constant. The percentage of fructans to total carbohydrates after bulb development exceeded 90% (w/w). This accumulation of fructans was specific to basal leaf sheaths. When bulbs of 'Kiharabansei No.1' planted in moist vermiculite began to sprout, the concentrations of fructose and glucose in the bulbs increased, while those of fructans and total carbohydrates decreased.