Publications - Faculty - Recently Submitted Faculty Publications 2008
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Albrigo - HortScience
Low Temperature and Drought Stress Interact in Flower Bud Induction to Modify Flowering Intensity in Citrus
Eduardo J. Chica and L. Gene Albrigo
Abstract. Growth chamber and field experiments were conducted to study the simultaneous effect of low temperatures and drought on flower bud induction in sweet orange (Citrus sinensis Osbeck) and grapefruit trees (Citrus paradisi L.). Four-year-old potted ‘Valencia’ orange trees were exposed to optimal inductive (15/12°C, day/night) and marginal inductive (23/18°C) temperatures with two levels of water availability (irrigated and drought) in growth chambers. The total numbers of sprouts, inflorescences, flowers/shoot, flowers/inflorescence and flowers/available node were counted. Significant interactions (p<0.05) were detected between temperature and water availability in most of these responses. Irrigated trees flowered more intensely at the lower temperatures than trees exposed to drought, whereas the opposite occurred at the higher temperature. In the field, adult ‘Marsh’ grapefruit, ‘Valencia’, and ‘Hamlin’ orange trees were subjected to different levels of water availability using irrigation, rain only, or no irrigation + covered soil for at least 80 days during the winter flower-bud induction season. No irrigation significantly increased the number of shoots, inflorescences, and flowers/shoot when compared with irrigated trees. Drought stress from covering the soil with rain exclusive material further increased shoots and flowers. Higher floral inductive temperatures (23/18°C) and drought interacted to enhance flower bud induction in potted citrus. In the field, flowering was also enhanced in trees exposed to drought during winter. The interaction between cool ambient temperature and drought can be used to modify the level of flower bud induction in humid subtropical climates where inductive temperatures are often marginal during winter.
