Effect of Hypocotyl Length on Morphogenesis of Explants of Cucumber (Cucumis sativus L.) in vitro

Abstract

Explants of cucumber seedlings having different lengths of hypocotyl attached were grown axenically on Murashige and Skoog medium supplemented with kinetin (2 mg L^-1). Multiple shoots developed from the apical regions of all explants. In this tissue shoots may also develop at the base of the hypocotyl, but this response is strongly dependent upon the length of the hypocotyl. As the length of the hypocotyl increased beyond 5 mm, there was a rapid reduction in basal shoot numbers and a concomitant increase in root production. We suggest that these responses are related not to the ratio or concentration of endogenous growth regulators but to different regions of sensitivity to growth regulators along the hypocotyl.