Relation between Fruit Yield and Amino Acid and Carbohydrate Contents of Leaves and Spurs of Japanese Apricot Tree

Abstract

Seasonal changes in amino acids and carbohydrates levels in spurs and leaves of individual trees of different apricot (Prunus mume Sieb. et Zucc.) cultivars were followed over a 12 month period. The levels of these reserve nutrients in the spurs and leaves after fruit harvest were compared with the yields of the individual trees.
1. Post-harvest amino acid contents in leaves and spurs, respectively, from Sep. to Nov. and from Oct. to Jan. correlated positively, whereas, carbohydrate contents in spurs during Jan. correlated negatively with crop yield.
2. Aspartic acid and proline contents in leaves reached maximum levels in June through July but thereafter decreased drastically. Arginine content in spurs increased rapidly from July and attained maximum level in October.
3. Aspartic acid, glutamic acid, and glycine in leaves made up about 10% of toal amino acids, whereas, all other amino acids were less than 10%. All amino acid concentration in spurs were less than 10%, except for arginine, which was about 20%.
4. After apricots were harvested and while reserve nutrients were being stored, the levels of aspartic acid in leaves and arginine in spurs were higher in high-yielding trees than they were in low-yielding trees.
It is, therefore, considered that these two amino acids are the key to diagnosing the nutritional status of trees for nitrogen.