Inheritance of Dwarfness in Hybrids of Chinotto Sour Orange

Abstract

Chinotto is a selection of sour orange (Citrus aurantium L.) with short internodes and small leaves and fruit. Mature fruiting trees of Chinotto grafted on standard rootstocks produce healthy, but dwarf, trees. Most seedlings recovered from Chinotto fruit are of nucellar (maternal) origin and will faithfully grow to reproduce the Chinotto genotype and phenotype. Vigorous greenhouse-grown nucellar seedlings of Chinotto have internodes 5 to 10 mm in length and leaves 30 to 40 mm in length, about 30% the dimensions of the corresponding organs on standard sour orange nucellar seedlings. Sexual hybrids with Chinotto have been produced by controlled crosses with several other parents. Some hybrids with shortened internodes and small leaves were recovered among all hybrid progenies, regardless of whether Chinotto was used as seed or pollen parent. In some cases, segregation among Chinotto hybrids was about 1 normal: 1 dwarf. In other progenies, some intermediate forms were recovered along with normal and dwarf plants.