Abstract:

This study is to investigate and verify the optimum breeding strategy of edible-type sweet potato with purple flesh. A new edible-type sweet potato cultivar with purple flesh and good quality ‘Rongzishu No.5’ was bred from female parent ‘Chuanshanzi’ with purple flesh and good quality from Japan, and male parent ‘Jishu No.6-8’ with high yield and high sugar content by sexual hybridization and systemic selection. The cultivar was selected, compared and identified through multi-spots trial from 2011 to 2013, and tested in Fujian Provincial Sweet Potato Regional Trial from 2014 to 2015. The morphological characteristics, agronomic characteristics, quality characteristics, disease resistance, productivity and adaptability of ‘Rongzishu No.5’ were studied. The results show that ‘Rongzishu No.5’ is a mid-late ripening variety, its growth period is 135 days, it has strong sprouting capacity and medium branching ability, the canopy is steady vigor during the whole growth period and the tuberization is concentrative. In Fujian Provincial Sweet Potato Regional Trial (2014-2015), the average yield of fresh tuberous root of ‘Rongzishu No.5’ was 30.24 t/hm ², the average dry matter rate was 30.12%, the average starch rate was 19.84%, the test value of cooked taste was 81.6 and 1.6 points higher than CK, the test value of extrinsic feature was 81.3 and 1.3 points higher than that of CK. The concentration of anthocyanin was 26.95 mg/100 g FW. The rate of large and medium-sized tuberous root was 68.7%. The results of comprehensive identification in Fujian Provincial Sweet Potato Regional Trial indicate that ‘Rongzishu No.5’ has a semi-erect architecture with medium length vine; the yield of fresh tuberous root, dry tuberous root and starch are higher than those of CK, the dry matter rate and starch rate are equivalent to those of CK, the qualities of cooked taste and extrinsic feature are superior to those of CK. ‘Rongzishu No.5’ has resistance to Fusarium oxysporum and moderate resistance to Ralstonia solanacearum wilt, the storability of tuberous root is fine. The variety meets the approval standard of edible-type sweet potato varieties and could be widely cultured in south China.

Key words: good quality, purple fleshed sweet potato, ‘Rongzishu No.5’, breeding, cultivation technique