Effect of ethrel 48 on sex expression and yield in pumpkins

Abstract

Application of Ethrel (2-chloroethylphosphonic acid) at 100mg/l to pumpkin (Cucurbita maxima Duchesne cv. Crown) plants at the 4 expanded-leaf stage increased the number of pistillate flowers on the main stem and on primary and secondary laterals. The increase in pistillate flower number was due to a change in the ratio of staminate to pistillate flowers rather than to an increase in vegetative growth and the total number of flowers per plant. Pistillate flowering on the main stem of Ethrel-treated plants occurred earlier (nodes 1–12) and more frequently than on untreated plants. Subsequently, there was a period of enhanced staminate flower production (nodes 13–18) and on plants maintained as a single stem this was not reversed by further Ethrel applications when 16 leaves had expanded. The pattern of pistillate and staminate flowering on nodes 19–50 was similar on both control and Ethrel-treated plants. Although the total number of fruit per plant was not increased with Ethrel treatment, the majority of fruits set and developed on nodes 4–12 and so had sufficient time before harvest to reach full maturity. © 1979 Taylor & Francis Group, LLC.