EFFECT OF TEMPERATURE ON INDUCTION AND PRODUCTION OF FLOWERS IN LEMNA-PAUCICOSTATA 6746 IN UNINTERRUPTED AND INTERRUPTED DARKNESS

Effects of temperatures (16-31.degree. C) on induction and production of flowers in L. paucicostata 6746 were studied in uninterrupted and interrupted darkness. In uninterrupted darkness, the growth rate (a) and flowering ratio (.vphi.) increased and the flower production period (P4) decreased as the temperature rose. The pre-flower induction period (P1) and the flower induction period (P2) were independent of temperature except that P2 was remarkably extended at 31.degree. C. Thus, a, .vphi. and P4 may be rate-limited by chemical reactions and P1 and P2 by physical reactions. P2 started at the onset of darkness. A red light pulse given 7 h after the start of the dark period extended P1, P2 and P4 without modifying a and .vphi. at any temperature. The pulse extended P1 by 1 day irrespective of temperature, and the sensitivity of P1 to the pulse was constant at all temperatures. The red light pulse caused obvious extensions of P2 and P4 at 21-26.degree. C, but no extension at lower and higher temperatures. Thus, the extension of P1 by red light seems to be rate-limited by a physical reaction and those of P2 and P4 by chemical reactions.