Abstract
We investigated the influence of the amount of applied nitrogen on cold hardiness and lipid content of Japanese pear ‘Nijisseiki’ and ‘Hosui’. ‘Hosui’ was more sensitive to excessive nitrogen application than ‘Nijisseiki’ as shown by the increase of nitrogen contents in the shoot, decrease of cold hardiness and growth inhibition the next spring. Total lipid content and phosphatidylcholine (PC) content of ‘Hosui’ were lower than ‘Nijisseiki’. An increase in lipid PC and unsaturated lipid content induced by chilling were inhibited by excessive nitrogen application in both cultivars. Thus, excessive nitrogen application may induce a decrease in cold hardiness by decreasing the lipid content and the unsaturated index.
