Phenotyping in flower and main fruit traits of Chinese cherry [Cerasus pseudocerasus (Lindl.) G.Don]

Chinese cherry [Cerasus pseudocerasus (Lindl.) G.Don], native to China, is an economically important tetraploid fruiting cherry species. In order to perfect the cherry germplasm descriptors system, and effectively rate on characters in DUS (distinctness, uniformity, stability) testing, we comprehensively investigated and analyzed 38 Chinese cherry phenotypes, including phenological records, flower, pit and main fruit quality traits, of 59 germplasm collections and 950 individuals from four cross F1 populations. An index system for Chinese cherry DUS test was firstly established by statistically phenotyping 26 traits. The results showed that the fruit development period ranged from 43 to 69 days, which could be well applied to evaluate the maturity time and were divided into five ratings. Thirteen qualitative characters, including two in flower, five in fruit, and six in pit, were classified into two to six ratings, respectively. Significant variations were detected among these characters, with Shannon-Wiener indexes ranging from 0.37 to 1.49. The average coefficient of variation was 20.94% ranging from 5.48 to 76.56% among 22 quantitative traits. The fruit weight, size, firmness, pit weight, titratable acid and soluble solid mainly contributed to the phenotypic variations by principal component analysis. Eight fruit and pit characters, which were in accordance with the normal distribution, were rating by the least significant difference method, while four fruit characters, being out of the normal distribution, were rating by the range method. The establishment of phenotyping protocol will enrich cherry descriptors system and DUS test guideline, and provide important basis for marker-assisted breeding in Chinese cherry.