Objective By comparing and analyzing the phenotypic traits of different varieties of chestnut, we screened out the indicators with large phenotypic differences and not easily affected by the environment for providing reference for the identification and accurate application of chestnut varieties in production practice.

Method The differences and diversity of 21 phenotypic characters of 3 200 nuts from 80 varieties in different Chinese chestnut producing areas were analyzed. The correlation between phenotype and environmental factors was analyzed, and the stability index with a small coefficient of variation was screened out. The stability of three varieties cultivated in multiple fields was verified.

Result (1) There were significant differences in the phenotypic indexes of chestnut in different regions and the nut size and hilum size of varieties in Hubei, Jiangsu and Anhui were significantly higher than those in other regions. (2) The variation of 21 phenotypic indexes ranged from 4.05% to 42.28%, and 9 relatively stable indicators with small variation coefficient were screened out, namely nut index, nut roundness, hilum roundness and correlation ratio index, excluding indicators of significant differences within and between groups. (3) Correlation analysis showed that the correlation indexes of nut size and hilum size were positively correlated with mean annual temperature, mean temperature in growing season, annual precipitation and precipitation in growing season, and negatively correlated with annual sunshine duration and growing season sunshine duration. (4) The variation coefficients of 9 phenotypic indexes of nuts from 3 cultivars from different regions ranged from 1.13% to 5.99%. The results of variance analysis showed that the other 8 indexes had no significant differences between regions and individuals except the hilum roundness.

Conclusion Different chestnut varieties have rich diversity and significant differences in 21 nut phenotypic indexes, among which 8 nut phenotypic indexes, including nut index, nut roundness, hilum length-to-width ratio, relative hilum size, hilum arc length / nut perimeter, hilum area / transverse area, hilum length/transverse diameter and hilum width / thickness, are stability indexes. It can be applied to the identification of chestnut varieties in production practice.