Characterization of water stress and low temperature effects on flower induction in citrus

Experiments were conducted with containerized ;Tahiti' lime (Citrus latifolia Tan.) trees in order to define conditions needed to induce flowering. Cyclical or continuous water stress for 4 to 5 weeks induced flowering. Moderate (-2.25 megapascals, midday) or severe (-3.5 megapascals, midday) water stress as measured by leaf xylem pressure potential, for as little as 2 weeks induced flowering, but the response was more significant in severely stressed trees. Low temperature (18 degrees C day/10 degrees C night) induced a time dependent flowering response much like that of moderate water stress. Significantly negative leaf xylem pressure potentials as compared to controls were found only under water stress treatment, suggesting that a common stress-linked event, separate from low plant water potential is involved in floral induction. Leafless, immature cuttings from mature, field-grown trees were induced to flower by water stress treatment, suggesting that leaves are not essential for a flower inductive response.