ACTION OF LIGHT AND TEMPERATURE ON GROWTH OF PLANT TISSUE CULTURES IN VITRO

Abstract

THE IMPORTANCE of physical factors in the development of plants is explicitly pointed out by Went (1954) when he says, Because of the enormous advances made in biochemistry during the last twenty years, there is a tendency to overlook or discount the role of physical factors in plant growth and development in particular. If this is true for the intact plant, it must surely be true for plant tissue cultures, whose delicate structure, lacking epidermis or other differentiated tissues, might be even more sensitive to external factors. Now that this tissue culture technique is frequently used to study problems arising in various branches of plant biology, i.e., morphology (Camus, 1949; Skoog, 1948), physiology (Kulescha, 1951) and pathology (Morel, 1948), it was decided to study the effects of temperature and light intensity on growth and development of several in vitro plant tissue cultures. In addition there are described the effects of low temperature upon anthocyanin formation in vitro. MATERIAL AND METHODS.-In the present investigations callus cultures of Helianthus annuus (crowngall, Hildebrandt strain) , Parthenocissus tricuspidata and Daucus carota (Gautheret strain) were used. For the study of the low temperature effects upon anthocyanin formation in vitro, transplants of root tissues of Daucus carota were employed. The experimental technique utilized was that developed by Gautheret (1942). The sterilization of the roots of Daucus carota was effected by 5.25 per cent commercial sodium hypochlorite. For cultures of Helianthus annuus (crown-gall), the nutrient of Hildebrandt et al. (1946) was used (table 1) ; for cultures of Daucus carota and Parthenocissus tricuspidata that of Heller (1953) (table 1). The research was carried out in the Earhart Plant Research Laboratory (Went, 1950) where it was possible to compare the growth of various tissue cultures under different conditions of temperature and light intensity. The new tissue transplants were divided into three major groups, those in natural light, those in artificial light and those in darkness, each of which consisted of five sub-groups, one sub-group