Changes of Amino Acid Compositions In the Leaf and Fruit of 'fuji' Apple Trees as Influenced by Applications of Amino-Acid Fertilizer

   The aim of the study was to examine whether ‘Fuji’ apple tree can take up amino acid from foliar spray. Different proline concentrations in liquid amino acid fertilizer were sprayed on ‘Fuji’ apple trees grafted on M.26 rootstock. The applied amino acid fertilizer contains hydroxyproline, serin, cystine, leucins, lysine and nitrogen.  Leaf, fruit skin, and fruit flesh were collected and stored at -70^oC until the contents of amino acids were analyzed. Apple leaves mainly had phophoserine, hydroxyproline, serin, and lysine. The amounts of amino acid in leaves did not show any statistical differences among treatments. However, the contents of amino acids on fruit peel and flesh were affected by foliar spray of amino acid fertilizer. Compared with control, all of amino acid fertilizer treatments increased the phosphoserin contents in apple peel. The fruit peels treated with 50 or 100 mg∙L^-1 of proline amino acid fertilizer had significantly higher citruline than those on control. And the fruit peels treated with 10 or 25 mg∙L^-1 of proline amino-acid fertilizer showed higher contents of lysine than those on the other treatments. The contents of hydroxyproline and lysine in apple flesh were significantly increased in the all treatments of the fertilizer. But there was no hydroxyproline contents in the fruit flesh of control trees. The application of 10 mg∙L^-1 proline amino-acid fertilizer showed the highest glutamic acid contents in the ‘Fuji’ apple flesh.