Item

Regulation of emergence of the primordial shoot and initiation of inflorescences in the grapevine by exogenous phytohormones

McArtney, S. J.
Date
1989
Type
Thesis
Fields of Research
ANZSRC::070302 Agronomy , ANZSRC::070604 Oenology and Viticulture , ANZSRC::070602 Horticultural Crop Improvement (Selection and Breeding) , ANZSRC::079902 Fertilisers and Agrochemicals (incl. Application)
Abstract
The experiments reported investigate the response of latent buds on the grapevine shoot to treatment with various plant growth regulating chemicals (PGR's). PGR's were applied either to the soil (PP333) or directly to the latent bud (GA₃, GA₄, NAA, ACC, BA) on a current seasons shoot. Percent emergence of the primordial shoot and inflorescence number per bud were recorded in the season following treatment. These responses were recorded at five bud positions on the shoot (three, five, seven, nine and eleven nodes from the base) and for five levels of each PGR (0, 1, 10, 100, 1000 μg per bud). Shoot emergence was measured by forcing single-node cuttings in plastic trays filled with tap water in the greenhouse in the spring following treatment. Inflorescence number per bud was measured by adopting the technique of Mullins (1966). A second experiment was undertaken to establish the importance of ontogeny in determining the ultimate physiological response of a plant tissue to a given level of applied PGR. The response measured was the surge in ethylene production following application of ACC to buds at three positions (basal, mid and upper) on the grapevine shoot. Results from these investigations showed that: 1. PP333 application resulted in emergence of the primordial shoot from a greater percentage of buds. 2. Application of GA₃, GA₄ and NAA all led to a reduced emergence of the primordial shoot from buds treated the previous season. This inhibitory effect was most evident at higher levels of these PGR's. The percentage of buds which emerged was approximately halved following GA₃ application at 10 μg per bud or higher. 3. Application of PP333 to the soil media of potted grapevines resulted in a significant increase in the number of inflorescences produced per node in the subsequent season. 4. Application of GA₃ led to a reduction in the mean number of inflorescences per node in the season following treatment. 5. Application of GA₄ led to an increase in the mean number of inflorescences per node, only in plants which had been treated with PP333. 6. Ethylene evolution from grapevine buds occupying a basal position on the shoot was considerably less than those buds closer to the shoot apex.
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