THE GROWTH STRATEGY OF A PEACH TREE AND SOME IMPLICATIONS FOR THE USE OF GROWTH REGULATORS

Growth by a peach tree and its fruit can be interpreted in terms of the strategy the tree has employed to ensure the development (or survival) of the seed. The seed can not compete with the fruit for assimilate (for anatomical reasons) and must suppress fruit growth if the seed is to grow. The growth of the tree however, is competitively inter-related with the growth of the fruit, and only the latter is regulated by the seed. Hence, when the seed prevents growth by the fruit, the tree grows vegetatively, and in so doing accumulates increased potential to compete with growth by the fruit later in that season. On the other hand, growth by peach tree roots regulates the vegetative vigour of the tree frame and annual growth in the top of the tree while having little direct effect on the potential for fruit growth.

Hence there are at least two approaches to optimizing the harvest index and controlling the vegetative potential of peach trees (necessary for successful close planting). (a) One may increase the competitive potential of the fruit. (b) Alternatively one may suppress vegetative vigour by reducing sink strength directly, or by reducing root growth, both of which will reduce competition with the fruit.