Effects of Plant Growth Regulators on Sex Expression and Flower Development in Pomegranates

Abstract

The effects of external treatments with gibberellin, brassinosteroid and auxin on sexual determination and flower development in pomegranate (Punica granatum L. cv. Çekirdeksiz) were investigated. Eigth treatments with three growth regulators, viz., epibrassinolide at 0.01 and 0.1 ppm, homobrassinolide at 0.01 and 0.1 ppm, GA3 at 10 and 25 ppm, NAA at 5 and 15 ppm and control (water spray) were sprayed at the time of initiation of new sprouts. Effects of the plant growth regulators on the percent of the flowers types were not clear. Plants produced considerably more male flowers. Although no statistical importance was detected, it was clear that all growth regulators decreased bisexual flowers and increased male flowers. There were no significant effects of growth regulators on the formation of bisexual flowers at different positions in the plants. The percentage of single bisexual flower was significantly higher than terminal or lateral bisexual flower in a cluster in the control plants. Effects of the plant growth regulators on the size of the parts of the bisexual pistils were, however, found important. The smallest ovaries were obtained from 0.1 ppm HBr, base to sepal notch was the only characteristic which was not influenced by the treatments and stayed between 15 and 18 mm. Total pistil length of the bisexual flowers was greatest with EBr applications and the shortest with the HBr treatments (about 27.5 mm). Length of the style and stigma was mostly shorter, but 0.1 ppm EBr boosted it up comparably more than the rest of the applications including the control. Stigma, on the other hand, was widest in the control flowers, closely followed by all except 0.1 ppm EBr application.