Effects of Certain Growth Substances on the Growth and Morphogenesis of Immature Embryos of Capsella in Culture

In an earlier paper (7) the development of isolated heart-shaped and older embryos of Capsella4 (> 80 ,u long) when grown in a sterile nutrient medium containing mineral salts, vitamins and 2 % sucrose was described. It was also shown that supplementing the basal medium with a mixture of growth substances like indoleacetic acid (IAA), kinetin and adenine sulfate permitted development of still smaller globular embryos (40-80 ,u long) in vitro. From this evidence it seemed reasonable to assume that growth substances play a role in the development of embryos through various stages in their ontogeny. The present study describes the effects of externally applied IAA and other auxins, gibberellic acid (GA), kinetin and adenine sulfate on the growth and morphogenesis of heart-shaped and older embryos of Capsella cultured in vitro. The effects of the conditions of illumination on development are also briefly considered. The results show that embryos of different developmental stages and their respective organs show different responses to exogenous supplies of plant growth substances.