Especially under low energy input conditions, loss of meristematic activity in the embryonic or plantlet stage of greenhouse vegetable crops can cause a severe loss of production and reduction of quality of the plantlets. This loss of meristematic activity has both a genetic and an environmental origin. The aim of the project is to understand the genetic and physiological factor that influence the response of the shoot apical meristem (SAM) to environmental conditions. This acquired knowledge will support seed companies to breed for varieties that are adapted to growth under low energy input conditions, including varieties that are less susceptible to shoot apical meristem determination (blindness, budless or shoot-less). This project will also enable seed companies to improve their seed treatment protocols for varieties susceptible for blindness and will provide nurseries with information regarding critical environmental factor which induce shoot apical meristem determination during transplant (or plantlets?) production. Brassica and tomato are chosen as model species because they allow a combination of physiological and genetic approaches and the fact that with both crop species considerable economic losses occur as the result of the appearance of blind plants.