Abstract
In all the varieties of Morus species employed (8 varieties of Morus bombycis Koidz., 8 varieties of Morus alba L. and 10 varieties of Morus Lohu (Ser.) Koidz), asparagine was quantitatively the major amino acid of exudates after stem-pruning. Smaller amounts of glutamine, aspartic acid and glutamic acid were also found, but other amino acids were scarcely detected. Asparagine was the predominant free amino acid in the upper leaves of the Morus species, when determined in late May and late August. Proline, glutamic acid, glutamine and pipecolic acid were also the main amino acids of the growing upper leaves. Free amino acids were decreased in late October, except for leucine, isoleucine and valine. The importance of asparagine in nitrogen nutrition and metabolism in Morus species during the growing season is discussed.
