Abstract: Soapberry (Sapindusmukorossi) is widely distributed in southern China, the economic traits of fruits of which from different provenances are significantly different. It is not clear which environmental factors drive the variation of economic traits. In this study, we examined the economic traits of the fruits of 47 natural germplasms from four provinces on the east, west, south, and north of its natural distribution borders in China. Pearson correlation and redundancy analysis were used to analyze the relationship between fruit economic traits and environmental factors. There was a significantly positive correlation between the pericarp saponins content (PSC) and mean annual temperature and extreme low temperature, and a negative correlation with latitude and relative air humidity, indicating that higher PSC fruits tend to develop in areas with relatively higher temperature and dry air. Kernel oil content (OC) was significantly negatively correlated with longitude and positively with altitude. The results of RDA ranking model showed that longitude, latitude, and relative humidity were the main factors explaining the differences in the economic traits of fruits from different provenances. Latitude was the most important factor affecting the fruit economic traits, with a variance explanation rate of 29.1%. In selection and breeding of superior germplasm of Sapindusmukorossi, superior germplasm for saponin can be found at areas with relatively high temperature and low humidity, while higher OC germplasm always grow in high-altitude areas. To achieve higher economic benefits in production, we suggest plant soapberry in relatively low latitude, low longitude and low relative humidity areas.

Key words: Sapindus mukorossi, economic trait, environmental factor, RDA.