Triploid frequency of sexual hybridization and pollen and ovary development in mandarins

Abstract

This work aimed to ascertain the triploid frequency of sexual hybridization and the pollen and ovary development in Citrus. The ‘Fortune’ mandarin (Citrus clementina Hort. ex Tan. × C. tangerina Hort. ex Tan.) accession was selected as female parent for this study based on its reproductive characteristics, mainly the monoembryony and self-incompatibility. The male parents used were the ‘Cravo’ (C. reticulata, Blanco) and ‘Dancy’ (C. reticulata) mandarins. The pollinations were always manually performed in the morning, and the pollinated flowers were identified for control. During the flowering period, flower samples at different stages of development of the ‘Fortune’ variety were collected for histological analysis. Microspore development occurred regularly in the 4–5 mm (length) phase of the floral buds, and a bicellular microgametophyte was formed in the floral buds with 5–6 mm in length. The formation of the female gametophyte occurred later, in flower buds with approximately 10 mm in length. The hybridizations resulted in 19 triploid plants: five when the ‘Cravo’ mandarin was used as the male parent and 14 when ‘Dancy’ mandarin was used as the male parent, evidencing the importance of the male genitor also in this process.