Trends in bisexual and male flower production and fruit set during blooming of pomegranate

The pomegranate tree has bisexual and male flowers on the same tree and limitations in yield has been related with low abundance of bisexual flowers. Often the pomegranate gender expression is reported as the percentage bisexual/total flowers, however little is known whether values are constant during the pomegranate prolonged blooming period. In the present study the patterns of flower type and fruit set during blooming were studied in ‘Wonderful’ and ‘Ermioni’ cultivars and local accessions, during two growing seasons. Results showed that flowers evolved in one wave for 44-56 days and most of them appeared during the short time of one or two weeks. The bisexual flower production (percentage bisexual/total bisexual) did not vary during blooming in all studied cultivars and accessions. Instead, the male flower production (percentage male/total male), followed a bell shape curve, with the maximum value being at the middle time of blooming. Therefore, the percentage bisexual/total flowers varied during blooming with lower values at the mid-flowering period. In both years, lower fruit set rate was registered during the first part of blooming period and coincided with light rain events. In the widely grown pomegranate cultivars ‘Wonderful’ and ‘Ermioni’ bisexual/total flowers accounted for 19% of total flowers, being substantially lower compared to the maximum value of 65% found in a local accession, yet they had a relatively high fruit set rate. In conclusion, the trends in bisexual and male flower production during pomegranate blooming did not affect fruit set, but rather this was substantially reduced by slight rain events. It was also possible to identify local accessions with high bisexual flower type rate, a characteristic with high impact on fruit yield.