Induction of seedless fruits in cucurbits by the application of auxins

Abstract

The present investigation was planned in order to cause induction of seedlessness by the application of synthetic plant hormones to certain species of multiseeded cucurbits for deeper insight into the mechanism of hormone-control of the fruit growth. The experiments were conducted in the Departmental agricultural farm and were in progress during the period, from 1964 to 1968. The four plant hormones viz., NAA, NAAm, IBA and IAA were in concentrations, ranging from 0.5 to 10 percent applied upon pumpkin, ridge gourd, sponge gourd, Trichosanthes dioica, cucumber, watermelon, Momordica cochinchinensis and Momordica charantia. Lanolin paste method of application of auxin showed promise of successful result in majority of cases. Momordica cochinchinensis stood as an exception in its rapid response even to aqueous spraying of NAA. Seedless fruits obtained after the application of auxin showed reduction in fruit weight and size and this was found to be statistically highly significant in most cases. It was further, observed that the auxin-induced seedless fruits displayed early ripening by about one week or so in all the crops tried. The results were found to be statistically significant in most cases. It was also noted that the auxin treatment increased the fruit set percentage in most of the crops studied and the treatment effect of the various doses was found to be statistically significant. There was practically no variation in dry weight, total sugar and protein content of the fruits following auxin application. Of the four auxins tried, NAA ranked the first position followed by NAAm, then IBA and IAA stood in sequence in their effectiveness. Among the crops under investigation pumpkin was found to be the most responsive while cucumber and watermelon were the least responsive to auxin treatment.