Induction of flowering by nitrogen deficiency in Lemna paucicostata 441

Lemna paucicostata 441, a short-day plant, flowered even under continuous light in nitrogen-deficient, half-strength Hutner’s medium, when the endogenous level of nitrogen was decreased to 1.4μg/mg fr wt or lower, but no flowering occurred in nitrogen-deficient, modified Hoagland medium when the endogenous level of nitrogen was similarly reduced. The failure to flower in this medium can be ascribed to the presence of high concentrations of calcium, the absence of EDTA, and low pH. Daylength-independent flowering induced by nitrogen deficiency was greatly enhanced by the addition to the growth medium of micronutrients and EDTA at high concentrations. Among the micronutrients, zinc seemed to be the most important.