Hybridization Studies on Some Clementine (Citrus clementina) Cultivars

Abstract

The present study was conducted using three Clementine cultivars, namely, Fedela, Fina, and Spinosa as female parents, and four mandarin cultivars, namely, Kishu, Avana aprieno, Sunburst, and Willow leaf as male parents, to select the pollen source that has high cross-compatibility with the Clementine cultivars. The results showed that ‘Kishu’ has the highest viability in comparison with other cultivars. Both ‘Fedela’ with ‘Kishu’, ‘Spinosa’ and ‘Sunburst’ had the maximum initial fruit set. The highest percentages of retained fruit were registered when pollen of ‘Kishu’ was used to pollinate both ‘Fina’ and ‘Fedela’. When all pollens of tested Mandarin cultivars were used for ‘Spinosa’ Clementine, they did not obtain any retained fruit, and these hybridization combinations revealed the highest percentages of fruit drop. ‘Fedela’ fruits recorded a maximum value of the average number of developed and undeveloped seeds when they were cross-pollinated with ‘Kishu’ and ‘Sunburst’ pollens. Fluorescence microscopy examination showed that ‘Kishuʼ and ʻAvanaʼ as pollen sources had a high level of full cross-compatibility with ‘Fedela’, while ‘Sunburst’ and ‘Willow leafʼ have a high level of partial cross-compatibility with ʻFedelaʼ. ‘Fina’ showed a low degree of partial cross-compatibility, while ‘Spinosa’ showed some degree of cross-incompatibility with all studied pollen sources. It can be concluded that all studied Mandarin cultivars could be promising pollenizers for the self-incompatible ‘Fedela’ Clementine cultivar, thus it is recommended to culture these cultivars together in the same orchard.