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Interaction of genotype and environment in carbon isotope discrimination and gas exchange of ponderosa pine (Pinus ponderosa Doug. ex Laws.)
Abstract
The analysis of carbon isotope discrimination $(\Delta)$ may be a better technique for identifying genotypic variation in water use efficiency than most instantaneous physiological assays. The objectives of this research were to: determine whether genotype x environment (G x E) interaction in $\Delta$ and gas exchange exists in four ponderosa pine sources; determine if there is a correlation between $\Delta$ and intrinsic water use efficiency $(A/g\sb{wv})$ in ponderosa pine; and compare gas exchange and $\Delta$ in seedlings and mature trees. Gas exchange, water relations, specific leaf area (SLA), stomatal density, and $\Delta$ were analyzed in 26-year-old trees grown at Nebraska and Oklahoma; and in 2-year-old seedlings greenhouse-grown under two water treatments. Source differences in $A/g\sb{wv},\ \Delta,$ and needle morphology were observed in seedlings and mature trees. Seedlings also exhibited source differences in net photosynthesis (A), needle conductance to water vapor $(g\sb{wv}),$ and transpiration (E). Water stress reduced $A,\ g\sb{wv},\ E,$ growth, and $\Delta$ of seedlings. Source x water treatment interaction was not detected for any of the traits. In seedlings, families within seed source varied significantly in every trait except SLA. Carbon isotope discrimination was negatively correlated with $A/g\sb{wv}$ and positively correlated with $g\sb{wv}$ in seedlings and mature trees. Thus, $\Delta$ variation in ponderosa pine is more related to $g\sb{wv}$ than to A. Needle morphology did not explain $\Delta$ variation. Trees exhibited source x location interaction in $\Delta$ indicating G x E interaction in this trait, but the year x source interaction was not significant. It is concluded that G x E interaction of mature trees may be more related to latitude, photoperiod, temperature, or edaphic characteristics than to precipitation. Seed source rankings in $A/g\sb{wv}$ and $\Delta$ in seedlings and mature trees grown at Oklahoma were the same, suggesting a strong juvenile-mature tree correlation in these traits.
Subject Area
Botany|Forestry|Genetics
Recommended Citation
Olivas Garcia, Jesus Miguel, "Interaction of genotype and environment in carbon isotope discrimination and gas exchange of ponderosa pine (Pinus ponderosa Doug. ex Laws.)" (1995). ETD collection for University of Nebraska-Lincoln. AAI9609432.
https://digitalcommons.unl.edu/dissertations/AAI9609432