Age-related trends in genetic parameters for Larix kaempferi and their implications for early selection

Abstract

BackgroundJapanese larch (Larix kaempferi) has been introduced in China at the end of the 19th century, and as one successful exotic species, is becoming the preferred coniferous in northern China and sub-tropical alpine region. The rotation age is about 25-28 years for L. kaempferi as pulpwood in Henan province. Waiting for even one-half rotation age for final evaluation will be inefficient due to accumulated testing costs and delayed return on investment, which suggests that selection at an early age is highly desirable for L. kaempferi improvement programs in Henan province. In this study, we determined age trends of genetic parameters and evaluated early selection efficiency for L. kaempferi in Henan province to find out the appropriate trait for early selection and its selection age.ResultsGrowth traits of 78 clones were measured periodically from age 2 to age 15 in a clonal trial of Larix kaempferi establishted at Son town, Henan Province. The genetic variation among clones, age-age correlations, and age trends in genetic parameters for growth traits were analyzed. Variant analysis revealed that tree height (HGT) and diameter at breast (DBH) were significant (1% level) among clones at every ages. The clonal repeatability of growth traits varied year-by-year, reaching the highest levels at different ages for different traits (0.77 at age 2 for HGT, 0.70 at age 5 for DBH and 0.66 from age 8 to age 10 for volume, respectively). The age-age genetic correlations ranged from 0.904 to 1.000 for HGT, and from 0943 to 1.000 for DBH. DBH at different ages was more genetically correlated to volume-15 than HGT. At the phenotypic level, HGT was always less correlated to volume-15 than DBH. With the estimates of efficiencies of early selection, the recommendation from present study was that the optimum age of early selection was age 2 for HGT and age 5 for DBH.ConclusionsOur study showed that there were significant (1% level) on growth traits among clones at every ages. The genetic parameters for growth traits varied from age to age. We found dual trait selection was more efficient than single trait selection for early selection.

Transcriptome analysis provides insights into wood formation during larch tree aging

“…The growth rate changes with age (Lai et al 2014), indicating that the activity of meristem cells is affected by aging. The growth and development of a tree involve all the activities of a cell, such as division, expansion, cell wall formation, metabolic processes, responses to stimuli, and death, some of which are known to be regulated by aging.…”

Transcriptome-wide analysis to dissect the transcription factors orchestrating the phase change from vegetative to reproductive development in Larix kaempferi

“…Many aspects of tree growth and development change with age, such as wood formation (Xu et al 2016;Li et al 2013aLi et al , 2014Li et al , 2017Zeng et al 2017), growth rate (Lai et al 2014), rooting ability (Peer and Greenwood 2001), and the phase change (Brunner et al 2017), and these traits are important in forestry. So, revealing the underlying mechanisms is not only helpful to understand the processes of tree growth and development, but also helpful for wood, cutting seedlings, and seed production.…”

Age-related trends in genetic parameters for wood properties in Larix kaempferi clones and implications for early selection

“…Japanese larch (Larix kaempferi) was introduced at the end of the 19th century into China and is becoming an important timber species with increased plantation area. It grows faster and has higher wood density, longer fiber and stronger pest resistance than the Chinese native species (e.g., L. principis-rupprechtii and L. olgensis) and shows wider adaptation [15][16][17] . The age-age genetic corrections have been estimated for growth traits (i.e., tree height, HGT and diameter at breast height, DBH) of L. kaempferi in recent years [16,18] .…”

“…It grows faster and has higher wood density, longer fiber and stronger pest resistance than the Chinese native species (e.g., L. principis-rupprechtii and L. olgensis) and shows wider adaptation [15][16][17] . The age-age genetic corrections have been estimated for growth traits (i.e., tree height, HGT and diameter at breast height, DBH) of L. kaempferi in recent years [16,18] . Also, optimum ages of early selection were studied for spiral grain [19] and wood density [20] in hybrid larch, with estimated optimal selection ages of 3-4 years and 8-14 years, respectively.…”

“…We have studied optimal selection age for nursery rooting ability [22] , phenology [23,24] , and growth traits [16] of L. kaempferi clones. In this study, we estimated age-related trends of genetic parameters and selection efficiency for wood density, wall thickness to lumen area (T/D), MFA and MOE.…”