Phenotypic evaluation of putative zygotic seedlings in different Inter-specific crosses between sweet orange (Citrus sinensis L. Osbeck) and mandarin (Citrus reticulata Blanco)

An investigation was carried out to examine the morphological features of molecularly confirmed putative hybrids derived from different cross combinations of sweet orange and mandarin varieties. The results revealed that phenotypic leaf characters of F1 zygotic hybrid seedlings in all the crosses had a simple type of leaf division. The shape of leaves in all the hybrids was either elliptic or lanceolate, without any clear-cut differentiation. Results indicated a significant variation in leaf lamina shape in hybrids, elliptical and lanceolate form was observed in Mosambi ×Mukaku Kishu and Jaffa × Mukaku Kishu, elliptical and obovate leaf lamina type was observed in Mosambi × W. Murcott and Jaffa × W. Murcott cross. Leaf lamina shape in hybrids of Mosambi × Clementine and Jaffa × Clementine was lanceolate and elliptical type. Leaf apex shape that dominates in Mosambi ×W. Murcott hybrids were acute and obtuse types. In Mosambi × Clementine hybrids, acuminate and acute forms were more dominant. Leaf apex that dominates in hybrids of Jaffa × Mukaku Kishu cross was acute and acuminate type. Hybrids derived from Jaffa × W. Murcott cross had acute and obtuse leaf apex. While in Jaffa × Clementine cross, hybrids had acuminate and acute as the most dominant forms. Hybrid progenies derived from all the crosses showed variation for the presence and absence of a spine. Results indicated that spiny hybrids ranged from 0 to 20.00 % whereas spineless zygotic hybrids ranged from 80.00 to 100 % in all the crosses. These potential hybrids may be recommended for commercial citriculture after thorough horticultural evaluation. The information obtained is expected to contribute to the early identification of zygotic hybrid seedlings derived from different cross combinations involving polyembryonic parents like sweet oranges. The valuable information gained from this study may help in shortening the breeding cycle and reduce the costs of the scion breeding programme in sweet oranges.