Inheritance of foliar stable carbon isotope discrimination and third-year height in Pinus taeda clones on contrasting sites in Florida and Georgia

摘要

Quantifying foliar stable carbon isotope discrimination (A) is a powerful approach for understanding genetic variation in gas exchange traits in large populations. The genetic architecture of △ and third-year height is described for more than 1,000 clones of Pinus taeda tested on two contrasting sites, h~2 for A was 0.14 (±0.03), 0.20 (±0.07), and 0.09 (±0.04) at Florida, Georgia, and across sites, respectively. H2 for stable carbon isotope discrimination ranged from 0.25 (±0.03) at the Florida site to 0.33 (±0.03) at the Georgia site, while the across-site estimate of H~2 was 0.19 (±0.02). For third-year height, h~2 ranged from 0.13 (±0.05) at the Georgia site to 0.20 (±0.06) at the Florida site with an across-site estimate of 0.09 (±0.05). Broad-sense heritability estimates for third-year height were 0.23 (±0.03), 0.28 (±0.03), and 0.13 (±0.02) at the Florida site, Georgia site, and across sites, respectively. Type B total genetic correlation for △ was 0.70±0.06, indicating that clonal rankings were relatively stable across sites, while for third-year height, rankings of clones were more unstable across the two trials (r_(BTG); = 0.55 ± 0.08). Third-year height and A were negatively correlated at the parental (r_(add) = -0.42 ± 0.33), full-sib family (r_(FS) = -0.54± 0.25), and clonal (r_(tg) =-0.30 ± 0.11) levels, suggesting that genetic variation for △ in P. taeda may be a result of differences in photosynthetic capacity. We conclude that △ may be a useful selection trait to improve water-use efficiency and for guiding deployment decisions in P. taeda.