EXPERIMENTAL CONTROL OF FLOWERING IN LEMNA I. GENERAL METHODS. PHOTOPERIODISM IN L. PEPUSILLA 6746

Abstract

H illman , W illiam S. (Yale U., New Haven, Conn.) Experimental control of flowering in Lemna. I. General methods. Photoperiodism in L. perpusilla 6746. Amer. Jour. Bot. 46(6): 466–473. Illus. 1959.— Lemna perpusilla strain 6746 flowers as a typical short‐day plant when grown aseptically in Hutner's medium (containing ethylenediaminetetraacetic acid, [EDTA]) at 26–28°C. A method is described for quantitatively assaying the degree of flowering in a culture. Maximal flowering takes place under photoperiods of 6–11 hr., and none under photoperiods exceeding 15 hr. The flower‐promoting effects of long nights are inhibited by brief interruptions with red light, such interruptions being most effective in the middle of the dark period. A single long night will cause the subsequent production of flowering fronds, but vegetative growth in the culture is resumed after a time. Only frond primordia at a very early stage of development appear to be sensitive to induction. Quantitative flowering experiments lasting a week or less can easily be performed with this plant; it is ideally suited for studies of the effects of light, darkness, temperature, organic compounds and other factors under highly controlled conditions.