Photoreversibility of Flower Initiation.

Abstract

Action-spectrum studies have shown that such diverse light-controlled plant responses as flower initiation (1,17,18), internode elongation (2,8,19), leaf expansion (8,19), and seed germination (4,23) the dark period, two short-day plants, soybean (Glycine Max (L.) AMerr. var. Biloxi) and pigweed (Amaranthus caudatus L.), and two long-day plants, barley (Hordeum vulgare L. var. Wintex) and Hyoscyamus niger L., were tested for evidence of the far-red action. A brief irradiation near the middle of an inductive dark period of 13 hours for soybean and 12 hours for pigweed prevented initiation of flowers, whereas a similar interruption near the middle of a non-inductive dark period of 12.5 hours for barley and 12 hours for Hyoscyamus induced flowering. In each case a far-red irradiation immediately following the dark-period interruption with red reversed the effect of the red light (table I).PLANT 'MATERIALS: Studies into the details of the photoreversible reaction controlling flower initiation were conducted principally with the short-day plants cocklebur, Xanthium pensylvanicum Wallr. (X. saccharatum Wallr.) and Biloxi soybean.There is considerable confusion arising from personal variations in the choice of the specific name for this species of Xanthium. Wallroth (24) described X. pensylvanicum and X. saccharatum as distinct species and published his descriptions in the same journal on the same date. According to Section 10 of the

Night-Break Experiments Shed Light on the Photoperiod1-Mediated Flowering

“…In some SD plants, the suppression of flowering by a single R light NB is completely reversible by immediate exposure to FR light (Downs, 1956;Cathey and Borthwick, 1957). In wheat, we found that a single FR exposure after NB had a limited effect on heading time (Fig.…”

Growth Regulators and Flowering. II. The Cobaltous Ion.

“…Again it can be seen that cysteine completely reverses the effects of cobaltous ion upon flowering. Cobaltous ion and far-red reversal of red inhibition: It has been shown by Downs (2) that the inhibition of flowering produced by red light interruption of the dark period may be reversed, to some extent at least, by far-red illumination following this interruption. The effect of cobaltous ion upon this response was studied.…”

Flavonoid Complexes in Pisum sativum. II. Effects of Red and Far-Red Light on Biosynthesis of Kaempferol Complexes and on Growth in Etiolated Plumules

“…The length of lag periods has been variously reported to range from about 30 minutes to several hours (5,7,14,15,16 (23) suggested that 2 different radiation-limited steps were involved in anthocyanin synthesis in apple skin, and Hendricks (12) further reported that anthocyanin synthesis in seedlings of Sorghum vulgare requires 2 photoreactions. These are an initial reaction in response to high energy irradiation, and a second reaction involving low intensity red irradiation which is reversible by far-red.…”