Climate response of radial growth and early selection of Larix olgensis at four trials in northeast China

The objective of this study was to evaluate the age trends of genetic variation in radial growth of different provenances and growth-climate relationship in different locations. Tree-ring cores of 10 L. olgensis provenances were sampled from four representative trials with different climatic conditions in 2019. The results of ANOVA show that significant differences for DBH at different ages were detected among provenances within sites, except for 10, 11, 37, and 38 years at LS. The phenotypic and genetic coefficient of variation in different sites were generally decreased with age. Although there were large fluctuations for provenance repeatability at different ages across sites, they all belonged to high repeatability. Age-age correlations show that the early selection for DBH could be made at the age of 10 years at the semi-arid area in Heilongjiang province and the southeast slope of Xiaoxing'an Mountains, while the ages for early selection at the southeastern slope of Daxing'an Mountains and the western slope of Zhangguangcai Mountain were 13 and 12 years old, respectively. The results of growth-climate relationships showed that temperature and precipitation played key roles in the radial growth of larch at each site. In the semi-arid area in Heilongjiang province, radial growth showed significant correlations with August temperature (positive) of the current year, and with previous May temperature (negative) and November temperature (positive), and previous December precipitation (positive). The current June temperature (negative) and precipitation (positive) were important factors affecting the radial growth at the southeastern slope of Daxing'an Mountains. July temperature of the current year had a negative relationship with larch growth at the southeast slope of Xiaoxing'an Mountains, while there were no significant correlations between radial growth and climatic factors at the western slope of Zhangguangcai Mountain. The results reported in this study provide a valuable insight about early selection for different sites and can serve as a reference for future breeding and improvement research.