Tangerine (<i>Citrus reticulata</i> Blanco var. <i>unshiu</i> Tan.) selection for fruit quality

Abstract

Citrus horticulture in Russia is confined to the humid subtropical conditions of the Black Sea coast of Krasnodar Region, with tangerine (Citrus reticulata Blanco var. unshiu Tan.) as a major market crop. The past decade has witnessed a steady increase in the production and consumption of fresh, easy-peeled tangerines. The bulk of existing evidence on the citrus fruit quality traits is built on research on oranges and grapefruits as main market crops, and relatively little is known on the unique qualities of tangerine. The article discusses the key quality traits of tangerine, including the fruit mass, size, colour, flavour and major biochemical quality indices. We justify the importance of breeding tangerine, specify the crop model and identify priorities, including the biochemical fruit improvement. The study involved 12 elite tangerine forms obtained by distant hybridisation at the Subtropical Research Centre of the Russian Academy of Sciences. The new promising forms received a brief pomological description and qualitative assessment. The preliminarily selected large-fruit and high-yield forms are 2-2-1, 99-2, 99-4 and 99-8. Specimen with a higher sugar content (>9 %): 99-2, 99-4, 99-8; higher ascorbate content (>75 mg/100): 97-3, 98-1, 98-2, 98-9; dry matter content: 2-2, 99-2, 99-4, 98-8, 2-1; balanced sugar-acid ratio: 2-1, 99-2, 99-4, 99-8 (sugar-acid index 9.8-10.3). The elite forms obtained by directed breeding are of equal or superior fruit quality to the zoned “Kowano-Wase” cultivar. These forms are competitive on today’s fruit market and promising for further breeding work towards improved fruit quality.