Formation of jujube assortment in the humid subtropics of Russia

Introduction . The results of a long-term research of the jujube collection ( Ziziphus jujuba Mill .) in the humid subtropics of the Russian Federation are presented. The collection is from the Federal Research Centre “Subtropical Scientific Centre of the Russian Academy of Sciences” (FRC SSC RAS, Sochi). Twenty-one cultivars from China, Tajikistan, Azerbaijan, Georgia, the USA and Russia became the oblects of the research. The goal of the research was evaluation of economically valuable traits (phenology, yield, biochemical composition, resistance to cracking) and selection of promising varieties for the southern regions of Russia. The results and discussion . It has been found that jujube is characterized by a late onset of vegetation (1st-2nd decade of April), which helps avoid spring frosts. This crop is characterized by late flowering, which occurs in June-August at a temperature of 22-24°C, the fruits ripen from September to early November. The fruits of the samples were ranked into three groups according to ripening time: early (second-third ten-day period of September), middle (second-third ten-day period of October) and late (late October early November). The highest yield (96.0-141.4 c/ha) was shown by the varieties “U-Xing-Hong”, “Ta-Yan-Zao”, “Yuzhanin” and “Burnim”. The maximum fruit weight was noted by the variety ‘U-Xing-Hong’ (up to 28.0 g). Biochemical analysis of the fruits revealed a high content of sugars (19.12-30.95%), vitamin C (206.18-524.48 mg%), low acidity (0.26-0.57%) and a sugar-acid ratio of up to 110.53. Small-fruited forms accumulated more sugars than large-fruited ones. The table varieties “U-Xing-Hong”, “Ta-Yan-Zao”, “Khurmai”, and “Vakhsh” were distinguished by their taste. Universal varieties (“Yuzhanin”, “Burnim”, “Da-Bai-Zao”) were suitable for fresh consumption and processing. The varieties “Kitaisky-2A”, “Gissarsky”, and Forma-201 were the most resistant to fruit cracking. The varieties “Gissarsky”, “Forma-201”, and “Dekorativnyy 98” were recommended for landscaping. Based on a number of economically valuable traits, the varieties “Ta-Yan-Zao”, “Yuzhanin”, “Burnim”, and “U-Xing-Hong” are recommended for cultivation in the humid subtropics of Russia. Small-fruited varieties and forms are recommended for producing rootstock material. They also have high ornamental value and can be widely used in urban and rural landscaping.

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