In spite of identified somatic variations, in commercial orchards and in collections of varieties, usually presenting undesirable charateristics such as low fruit productivity, atypical foliar morphology, or abnormal fruits, countless spontaneous mutations of unquestionable value have been identified, since the great majority of the commercial citrus varieties (scions and rootstocks) appeared as a consequence of some type of natural mutation. The present work is concerned about the use of this important way of obtention of new clones and varieties, as a part of the Citrus Breeding Program of Embrapa Cassava & Fruits. It refers to a new selection of 'Sunki' mandarin, named as 'Maravilha', identified inside a group of nucellar seedlings of 'da Flórida' selection. Comparisons were accomplished among 'Sunki Maravilha' and other three selections of this mandarin ('Common', 'da Flórida' and 'Tropical'), comprising the following characters: seed average number per fruit and embryos per seed, variation in the range of embryo number per seed, polyembryony percentage and embryo size. Comparisons were also carried out with other important commercial rootstocks, 'Rangpur' lime, 'Volkamer' lemon and 'Cleopatra' mandarin, related to seed germination and seedling vigor (height and number of true leaves). The obtained results allow to indicate the selection 'Sunki Maravilha' as an alternative in programs of rootstock diversification under the conditions where this mandarin presents good adaptation, mainly in function of its relatively high average number of seeds per fruit (7.7), predictable uniformity of seedlings as a result of its high percentage of polyembryony (100%), good seed germination and seedling vigor, and also a probable resistance to Phytophthora foot rot.
Citrus breeding; Citrus sunki; seeds per fruit; polyembryony; embryo size; seedling vigor; Phytophthora foot rot; rootstock diversification
