Effects of Ferrous and Phosphate Ions on Flowering in Lemna paucicostata 6746 in Diluted Hutner's Medium

In Lemna paucicostata 6746, P₂ (flower induction period) incontinuous darkness was largely extended by dilution of 1/2H1S medium (Hutner's medium supplemented with 1% sucrose) to1/10 strength. The dilution of 1/2 H1S medium to 1/10 strengthremoved completely the extension of P₁ (pre-flower inductionperiod) and P₂ due to a red light pulse given at the 7th h ofthe dark period, which was observed in 1/2 H1S medium. When iron and phosphate ions were added to 1/10 H1S medium upto the same concentration as in 1/2 H1S medium, the extensionof P₂ was removed completely. The red light pulse-induced extensionof P₁ was observed in 1/10 H1S medium only when iron ions wereadded. It is suggested that iron (Fe^{$ $}) and phosphate ionsare important in determining the rate of photoperiodic flowerinduction in L. paucicostata 6746. (Received December 23, 1983; Accepted June 6, 1984)