Geographical Variation in the Growth and Nutritional Traits of Leaf Powder from Broussonetia papyrifera (L.) L’Hér. ex Vent. from Different Provenances

Broussonetia papyrifera (L.) L’Hér. ex Vent., a perennial deciduous tree, is used in feed, medicine, papermaking, environmental protection, and ecological restoration. This paper ttook 33 provenances from the natural distribution as the research objects, observes their growth and nutritional traits, and analyzes the laws of geographical variation. The repeatability was 0.80–0.88 and 0.48–0.91, respectively. The correlation was significant (the correlation coefficient was 0.764). The variation is greatly affected by the latitudinal direction. Through clustering, the 33 provenances were clustered into 4 groups and most provenances with relatively close geographical origins were clustered together, showing differences between different geographical regions. Using leaf biomass (0.4662 g) and crude protein content (14.39%) as the selection index, the Sichuan Mianyang (SCMY), Chongqing Kaizhou (CQKZ), Shanghai (SH), and Fujian Nanping (FJNP) provenances were selected as fast-growing, high-yield, and high-quality paper mulberry provenances. This study provides the basis for the selection of excellent paper mulberry trees.