Induction and Production of Flowers in a Short-Day Duckweed, Lemna paucicostata 6746, in Diluted Hutner's Medium in Uninterrupted and Interrupted Darkness

Kinetics of induction and production of flowers were studiedin Lemna paucicostata 6746 cultured in 1/4, 1/10, 1/20 and 1/80H1S media (Hutner's media supplemented with 1% sucrose). In continuous darkness, the floral parameters a (vegetativegrowth rate), (flowering ratio), P₁ (pre-flower induction period)and P₄ (flower production period) in diluted media were similarto those in 1/2 H1S medium. However, P₂ (flower induction period)was greatly extended by the dilution of the medium up to 1/10strength and was gradually shortened by further dilution upto 1/80 strength. P₁ and P₂ in 1/4 H1S medium were extended by 1.0 and 2.5 days,respectively, by the interruption of the dark period with 5-minred light at the 7th h. However, the extension of P₁ and P₂due to dark period interruption was not observed in more dilutedH1S medium. It is suggested that certain ions in H1S medium are affectingthe timing mechanism of flower induction in L. paucicostata6746. (Received December 23, 1983; Accepted June 6, 1984)