Reasons and Geographical Variation Regulation of Leaf Discoloration of Liquidambar formosana

During September and November 2014, 592 lines of 41 provenances of Liquidambar formosana were collected from 15 provinces in China and were cold preserved. In April 2016, provenance test was conducted in Yuhang, Zhejiang province. Leaves were collected form each line on September 26, November 20, December 30 of 2016 to determine their pigment components. In November 2020, 9 colored leaves were collected from Hangzhou, Zhejiang province to determine the reasons of discoloration. The results showed that total chlorophyll and anthocyanin content in leaf of L. formosana resulted their discoloration, the coefficient of variation of total chlorophyll was 103.19%, and that of anthocyanin was 74.20%. The contents of chlorophyll, carotenoid and anthocyanin content in purple leaves were relatively high. Principal component analysis showed that the differences among provenances mainly caused by anthocyanin, total chlorophyll content and pH value. Correlation analysis showed that anthocyanin and total chlorophyll content had significant relation with geographical and environmental factors of different provenances (P < 0.05), but pH was not. The curve estimation demonstrated that the relationship between anthocyanin content after discoloration and longitude of different provenances was a quadratic function model, and that at other periods was a linear one. Longitude, latitude and the mean temperature of January of different provenances was the key factors for total chlorophyll and anthocyanin content in leaves. Before leaf discoloration, the variation pattern of total chlorophyll was east-west, and that of anthocyanin was south-north. Total chlorophyll content showed a south-north variation pattern, while anthocyanin content east-west before discoloration. After discoloration, the variation pattern of total chlorophyll content was from southeast to northwest, while that of anthocyanin was stable.