In vitro culture of ovules with nucelli and embryos of Citrus

Citrus species are important not only as fruit crop species but also as ornamentals; therefore a study on Citrus regeneration capacity was conducted to evaluate the possibility to apply modern in vitro biotechnology to improve and preserve Citrus. Expiants from three Citrus species - Citrus Umonimedica Lush., satsuma man- darin ( Citrus unshiu Marc.) and Citrus sinensis Osb. cv. Valencia - were cultured in vitro. Cultures of ovules with nucelli from Citrus Umonimedica Lush., fully developed nucellar embryos from satsuma mandarin ( Citrus unshiu Marc.) and immature seeds from Citrus sinensis Osb. cv. Valencia were in vitro initiated. Citrus Umonimedica Lush, fruits were obtained from the ornamental citrus germplasm collection of Villa Reale at Castello, Florence, Italy. Fully developed plants were obtained from embryos regenerated from primary expiants. Although soma- tic embryos regenerated abundantly from expiants of Citrus sinensis Osb. cv. Valencia, very low regeneration was obtained from callus originated from nucelli of Citrus Umonimedica Lush. Fully developed nucellar embryos from satsuma mandarin ( Citrus unshiu Marc.) grew rapidly into plantlets without callus formation and secon- dary embryogenesis.