The seasonal changes in P concentration in the particular parts of plum shoots taken from mature trees of the cultivar Bistrica were observed over two growing seasons. Samples were taken from trees that were growing in grass sward and from trees under improved management (with pruning, manure and fertilize application, soil cultivation under the trees and mowing of the grass sward between the alleys).
The biggest change in P concentration occurred in the vegetative and generative buds in the period from the beginning of vegetation until the end of blooming. During this period P concentration was increasing and reached a maximum value at full blooming. In the same period there was also an appreciable decrease in the P level in the wood and bark tissues of the previous year shoot. A sharp fall in P concentration occurred in the bark and wood of the new growth from the period when the shoot growth ceased to the end of July when it reached its minimum and then gradually rose to the end of vegetation. There was simultaneous minimum of P in the wood and bark of the previous year shoots.
The concentration of P in the leaf blade and leaf petiole was the highest at the time of new shoot growth cessation in May, rapidly declined to the period when stone in the fruit was hardened and then decreased fairly smoothly to leaf fall.
Phosphorus concentration in whole fruits was the highest in the period when terminal shoots stopped growing. After that, phosphorus concentration rapidly declined to the middle of the June, and then decreased proportionally to the time of fruit ripening.
The investigation showed that management had no effect on the seasonal tendency and on P concentration level.

Prunus domestica; cultivar Bistrica; mineral nutrition; phosphorus; orchard management

Published by University of Zagreb, Faculty of Agriculture, Zagreb, CROATIA
Sponsored by Ministry Science and Education of the Republic of Croatia