INTRODUCTION TO STERILE CULTURE IN VITRO OF HYBRID SEEDSFROM DISTANT CROSSES OF CITRUS RETICULATA BLAN.VAR UNCHIU

Abstract

Breeding of citrus crops in Russia has been carried out at the Federal Research Center "Subtropical Scientific Center of the Russian Academy of Sciences" since 1994. As a rule, seeds from distant crosses of Citrus reticulata Blan. var unchiu (mandarin) contain nucellar embryos and, rarely, a weak zygotic one. Nucellar seedlings are of great importance in breeding aimed at developing early-ripening varieties with high-quality fruits. When multi-embryonic seeds germinate in situ, one or two embryos usually develop, while the rest die due to lack of nutrients. In such a case, it is possible to save the embryos in vitro culture. Hybrid mandarin seeds obtained from 7 crossing combinations (C. reticulata 01 – 04 and 3252; C. reticulata ‘Solnechny’ abd pollen mixture; C. reticulata 98 – 9 and pollen mixture; C. reticulata 202– 5 and pollen mixture; C. reticulata 204 – 1 and C. medica; C. reticulata 2025 and C. limon ‘New Zealand’; C. reticulata 99-04 and C. medica) were introduced into sterile culture. The aim of the study was to develop a sterilization protocol, introduce seeds from distant crossing combinations into in vitro culture, and induce the growth of nucellar seedlings. The sterilization option (Domestos gel (5 min), 96% ethyl alcohol and fruit burning) showed a result with a higher yield of sterile culture – 96%. Contamination in the options was relatively low and varied from 4,0 to 16,7%. The percentage of seed germination on the Murashige and Skoog medium + 6-BAP (1,0 mg/l) + mesoinositol 100 (mg/l) was 63,1-87,2 %. The highest seed germination was noted in the combination 98-9 and pollen mixture (87,2 %). On average, 3–4 full-fledged nucellar seedlings without noticeable anomalies were obtained from 1 seed.