Analysis of the stability and superiority of five-year-old birch crossbreed families based on a multi-site test.

Multi-site forestation testing is a key step in the evaluation of stability and growth traits of tree family or clone. Tree height (H) and diameter at breast height (DBH) of ten families of five-year-old birch planted in Huinan County, Linghai and Dandong cities were measured and jointly analyzed. The results showed that differences in tree height among sites and families, and interaction between sites and families, were significant (P0.05). The differences in DBH were only significant among sites at the level P0.05. Families 201, 203, 204, 316 and 318 had excellent traits in Huinan, as did families 201, 202, 314, 316, 318 and 319 in Linghai and 202, 315, 318 and 319 in Dandong. We used AMMI model to evaluate the stability of tree height of tested families. Results indicated that families 203, 204, 318, 319 and 316 are high-yield and stable types, 201 and 202 high-yield but instable types, 320 and 315 low-yield yet stable types, and 314 low-yield and instable types. These results provide a theoretical basis for selection and a reference for the spread of birch crossbreeds.