A Possible Role for Abscisic Acid in Controlling Dormancy in Jojoba Flower Buds

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Abstract
Jojoba flower buds break dormancy in response to low temperatures in the presence of adequate water. The possibility that abscisic acid (ABA) is involved in the regulation of dormancy was examined by following endogenous ABA levels in flower buds and leaves and by applying synthetic (±)-ABA. Under controlled conditions endogenous levels of ABA were high in dormant flower buds and decreased under conditions of low temperatue that led to flowering. Similar results were obtained in the field. Levels in the leaves were low and changes in response to environmental treatments were small. Daily spraying of the plants with water containing 0.01% Tween enhanced flowering while water stress inhibited it. The application of (±)-ABA delayed flowering and reduced the percentage of flowers open at the end of the experiment. An experiment aimed at distinguishing between the effects of temperature and of water status was inconclusive and part of the effect of temperature on ABA may be related to the effect of temperature on the water status of plant.