Co-Authors:
Friedman, H., Hebrew Univ. of Jerusalem, Dept. of Horticulture, P.O. Box 12, Rehovot, 76100, Israel
Goldschmidt, E.E., Hebrew Univ. of Jerusalem, Dept. of Horticulture, P.O. Box 12, Rehovot, 76100, Israel
Spiegelstein, H., Hebrew Univ. of Jerusalem, Dept. of Horticulture, P.O. Box 12, Rehovot, 76100, Israel
Halevy, A.H., Hebrew Univ. of Jerusalem, Dept. of Horticulture, P.O. Box 12, Rehovot, 76100, Israel
Abstract:
Previous work with modulators of Ca2+ and pH has indicated that elevated levels of cytoplasmic Ca2+ and pH are required during the first 4‐5 h of the dark period for successful floral induction in Pharbitis nil Chois cv. Violet. In the present study we further examined the effect of modulators of Ca2+ and pH by supplying them at various times prior to the inductive dark period. Peaks of inhibition by the Ca2+ chelator, EGTA, were observed in seedings treated 8, 18‐and 34 h before the start of the dark period. When seedlings of slightly different ages (within one diurnal cycle) were treated with EGTA, maximum inhibition was always obtained in plants treated 8 h before the start of the dark period. Peaks of inhibition by the acidifying agents, salicylic acid and Na‐propionate, were observed at ‐2 to ‐6 h and at ‐10 to ‐ 14 h. Treatment with the alkalizing agent, trisodium citrate, enhanced the flowering response with maximum enhancement at ‐6 to ‐8 h and at ‐ 18 to ‐ 20 h. We hypothesize that treatment with modulators starts an oscillation in endogenous levels of Ca2+ and pH. The levels of Ca2+ and pH prevailing at the commencement of the inductive dark period will influence the ability of the plant to perceive or to respond to the photoperiodic induction. Copyright © 1992, Wiley Blackwell. All rights reserved