Abstract
Changes of individual lipids and their fatty acid composition in flowers and fruitlets of Japanese pear ‘Nijisseiki’ were measured during the periods of flowering and fruit setting in 1995 to investigate their role in cold hardiness and reproductive growth. Following the increase of air temperature from flowering to fruit setting, cold hardiness decreased with the proportion variations of lipids and fatty acids. All kinds of individual galactolipids and phospholipids, especially phosphatidylcholine (PC) and phosphatidylethanolamine (PE), declined gradually after full bloom. The proportion of linolenic acid (C18: 3), as one of the most abundant fatty acids in flowers and fruitlets of pear, sharply declined about 25% in total lipid and more than 10% in phospholipids and galactolipids during the period of fruit setting. Significant increases of linoleic acid (C18: 2) in monogalactosyl diglyceride (MGDG), phosphatidic acid (PA), PC and PE and palmitic acid (C16: 0) in digalactosyl diglyceride (DGDG) and phosphatidylinositol (PI) occurred simultaneously. The decline in unsaturation of lipids resulted in lower level of cold hardiness in pear flower and fruitlet.
