Pedigree analysis of strawberry cultivars released in China

Astract:【Objective】Strawberry breeding in China was initiated in the 1950 s, and has achieved rapid development in the 21 stcentury. However, the main cultivars used in production are cultivars introduced from the oversea. In order to provide reference for future strawberry breeding, the survey of strawberry cultivars bred in China from 1953 to 2016 were investigated and summarized. The parentages of 105 cultivars were analyzed based on the pedigree data to reveal the most important varieties used as parents for breeding strawberry varieties in China.【Methods】Literatures were used to trace the parents of released cultivars. The genetic contribution of ancestral parents for each released cultivar was calculated based on the deduced direct parents. The genetic contribution value of all the cultivars of parents bred through seedling selection or self-bred was 1 and that of the cultivars of parents bred through conventional crossing was 0.5. The parents of every parent were deduced till to the ultimate ancestral parents according to the equal segmentation methods and the total value of genetic contribution was 1. The calculation methods of genetic contribution value for all the parent cultivars bred through sport selection or induced mutation were the same as the parent cultivars bred by seedling selection.【Results】There were 108 strawberry cultivars released in China from 1953 to 2016, including 9 everbearing type cultivars, and 99 june-bearing type cultivars. Cultivars were classified according to purpose as fresh type, ornamental and fresh type, processing and fresh type, processing type, the proportions of the four types were 88.9%, 4.6%, 4.6% and1.9%, respectively. Among those cultivars, 95 were bred by hybrid breeding, 11 by seedling selection, 1 by bud sport selection and 1 by mutation breeding, respectively. The parental records of 3 cultivars were unclear, therefor, statistical analysis was only carried out on 105 cultivars with clear parental recordes.The 105 cultivars could be ultimately traced to 85 direct parents, including imported strawberry cultivars (71.6%) , bred cultivars (22.7%) and domestic cultivars (2.3%) . These cultivars could be ultimately traced to 68 ancestral parents, of whom 91.6% were imported strawberry cultivars and 2.8% were domestic cultivars, respectively. In 95 cultivars from hybridization, the proportion of crossing between Western cultivars and Japan-Korea cultivars was higher than that between western cultivars and Chinese cultivars. 17 cultivars were derived from‘Benihoppe'. The genetic contribution value of‘Benihoppe'was 8.1%. On the other hand, the production area of‘Benihoppe'was the largest in China. 14 cultivars were derived from‘Sweet Charlie'. The genetic contribution value of‘Sweet Charlie'was 7.7%. In total, the proportion of cultivars derived from‘Benihoppe'or‘Sweet Charlie'was 26.9%. Moreover, there were 3 cultivars bred by the crossing between‘Benihoppe'and‘Sweet Charlie'.【Conclusion】The main breeding methods of strawberry in China was hybrid breeding. The most important cultivar used as parents for breeding new varieties in China were‘Benihoppe'and‘Sweet Charlie'. American cultivars have played a leading role in the selection of everbearing cultivars with smart fruits, high yielding, and long storage life. Wild germplasm have not been used in strawberry breeding in China so far, although they could contribute.