Flower-bud initiation in deciduous fruit trees : with particular reference to apricot

Abstract

In this thesis the author has two aims: (a) to review the literature on flowering in deciduous fruit trees, and (b) to record and discuss, in the light of previous work, experiments designed to elucidate the role of carbohydrates, and the possible role of hormones, in the process of flower-bud initiation in apricot (Prunus armeniaca, L.). The experiments were conducted over the period December 1968, to February 1970. The review is more detailed than may be required for an introduction to the experimental section. This is because most previous work on flower-bud initiation in deciduous fruit trees was carried out some time ago, and there are no recent large reviews on the subject. The review also illustrates how little is known on the process in stone fruits , as most investigations have centred on initiation in apple. The author in the experimental section has looked at the following factors affecting flower-bud initiation in apricot; shading, defoliation, temperature, light, level of carbohydrate metabolites, level of nitrogen compounds. In further experiments the herbicide diuron (DCMU) was used to inhibit photosynthesis and so determine the importance of leaf-produced carbohydrates on initiation of flower-buds in the axil of that leaf. The isotope Carbon-14 was also used to substantiate the results of diuron treatment and to demonstrate translocation patterns within the apricot tree. The experimental results are not recorded chronologically but appear in the following order: Part 1 : Determination of the importance of shading and defoliation on flower-bud initiation in apricot. Part 2: The role of temperature and light in flower-bud initiation in apricot. Part 3 : The role of carbohydrates in flower-bud initiation in apricot.