The Effect of High Temperature on Pollen Tube Growth of Snake Melon and Cucumber1

Abstract

Abstract The optimum temperature for pollen tube growth in vitro was 32°C for 4 cultivars of snake melon (Cucumis melo var. flexuosus Naud.) and 21°C for ‘Biet Alpha’ cucumber (C sativus L.) regardless of plant growing temperature and season under which the pollen developed. The temperature range for cucumber pollen was 10 to 43°C; for snake melon pollen, 10 to 48°C. Studies in vivo with fluorescence microscopy of flowers from plants grown in greenhouses at 27/21 and 38/27°C showed that the pollen tube growth of snake melon was similar at both temperatures, However, pollen tube growth in cucumber flowers grown at 38/27°C was slower than in flowers grown at 27/21°C. Temperature responses of pollen tubes in excised flowers incubated at various temperatures differed from those in culture media. Growth of ‘Biet Alpha’ cucumber pollen tubes increased with temperature to a maximum at 32°C but no growth occurred at 38°C. The fastest pollen tube growth of ‘Mosuli’ snake melon occurred at 38°C. Observations at 43°C were limited by rapid deterioration of the excised flowers. Excised flowers examined with the fluorescence microscope provide a convenient technique to study pollen in vivo and the results can be applied to field conditions more confidently than results from in vitro studies.