Calcium and photoperiodic flower induction in Pharbitis nil

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Abstract
The relationship between phytochrome‐mediated induction of flowering, Ca2+ transport and metabolism in Pharbitis nil Chois cv. Violet seedlings has been investigated. Ethyleneglycol‐bis‐(β‐aminoethylether)‐N,N,N′, N′‐tetraacetic acid (EGTA), a specific Ca+ chelator, caused a 30–40% inhibition of flowering in Pharbitis subjected to complete photoperiodic induction. It was most effective when applied during the light period preceding along inductive dark period. The agonist of calcium channels. Bay K‐8644, did not affect flowering, while Nifedipine, Verapamil and La3+ (antagonists of calcium channels) only slightly inhibited this process. A similar small effect has been found when the plants were treated with Li+ (inhibitor of the membrane phospholipids pathway), and with chlorpromazine (a camodulin inhibitor). Except for EGTA, the effect of the other substances did not depend on the timing of their application. The results of the present study suggest that the effect of all the substances applied was not specific, and flowering is not directly dependent on transport and intracellular metabolism of Ca2+.