Studies on tree nutrition of Prunus mume 'Nanko', 2: Changes in content of nutrients in trees of various vigors

To elucidate the physiology of tree nutrition of Primus Mume 'Nanko', we studied the relationship between tree vigor (extremely weak, weak, above average) and the content of total nitrogen, water-soluble nitrogen,total sugar,starch and carbohydrates after harvesting,for two years from 1997 to 1998. 1. Orchards with trees of different tree vigor revealed that total nitrogen and water-soluble nitrogen content was lower in new branches (10-20cm) and roots (under 5mm diameter) in orchards with trees of extremely weak vigor than in the orchards with average and weak vigor trees after December, 1997. 2. In orchards with extremely-weak-vigor trees, the content of total sugar and starch during the leaf-shedding period was higher in new branches than in orchards with trees of the other vigors. Also in orchards with average-vigor trees, the content of starch and carbohydrates was higher than that in orchards with weak-vigor trees in July and December of 1997, and the content of total sugar increased in December. 3. In orchards with extremely-weak-vigor trees, the carbohydrate/nitrogen ratio in new branches increased after December, 1997; it was also higher in roots after June 1998. 4. Our study of trees with different tree vigor in the same orchards showed that the content of total nitrogen and water-soluble nitrogen was lower in lower-vigor than in average-vigor trees, during the leaf-shedding period. The content of water-soluble nitrogen in roots was lower than that in average-vigor trees in any period. 5. From June to September, the content of nitrogen in leaves of lower-vigor trees was significantly lower than in average-vigor trees. 6. The content of total sugar in new branches of lower-vigor trees inceased more than in branches of average-vigor trees. The content of starch was higher during the leaf shedding period;also, the content of starch and carbohydrates increased more than in average-vigor trees in September. 7. The carbohyrate/nitrogen ratio in new branches of lower-vigor trees was higher than that of average-vigor trees 8. The content of inorganic components in the fruit of lower-vigor trees was lower than in the fruit of average-vigor trees: N and Mg in fruit and genes, and K in the fruit. The content of P and Ca could not be accurately determined in trees of different vigor. 9. The rate of photosynthesis in individual leaves decreased in proportion with lower tree vigor; the same condition was observed in the conductance by stoma.