Provenance variation in carbon isotope discrimination of mature ponderosa pine trees at two locations in the Great Plains

2000 ◽  
Vol 30 (3) ◽  
pp. 428-439 ◽  
Author(s):  
Bert M Cregg ◽  
J Miguel Olivas-García ◽  
Thomas C Hennessey
Keyword(s):  
New Mexico ◽  
Carbon Isotope ◽  
Ponderosa Pine ◽  
Carbon Isotope Discrimination ◽  
Genotypic Variation ◽  
Environment Interaction ◽  
Isotope Discrimination ◽  
Seed Sources ◽  
Genotype Environment Interaction ◽  
Use Efficiency

We analyzed genotypic variation in carbon isotope discrimination (Δ), photosynthetic gas exchange, and needle morphology of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) trees from four seed sources growing in two 26-year-old provenance plantings near Plattsmouth, Neb., and Norman, Okla. The populations studied were from South Dakota, New Mexico, Wyoming, and Nebraska. Net photosynthesis (A) and needle conductance to water vapor (gwv), were measured during the growing season of 1994. Specific leaf area, stomatal density, and Δ were analyzed in needles grown from 1991 to 1994. The southernmost source (New Mexico) had the highest intrinsic water-use efficiency (A/gwv) among the sources studied. Carbon isotope discrimination was correlated with growth (r = -0.81, P < 0.05), A/gwv (r < -0.54, P < 0.001), and gwv (r > 0.46, P < 0.05) but not A. Variation in Δ was significant among seed sources and years (P < 0.001). We observed a strong genotype × environment interaction in Δ resulting from geographic location but not moisture availability within locations. We hypothesize that the genotype × environment interaction is related to variation in growth phenology among the seed sources. Improving water-use efficiency or growth of ponderosa pine via Δ will require an understanding in genotypic variation in growth rhythms.

Genotypic variation in carbon isotope discrimination and gas exchange of ponderosa pine seedlings under two levels of water stress

2000 ◽  
Vol 30 (10) ◽  
pp. 1581-1590 ◽  
Author(s):  
J Miguel Olivas-García ◽  
Bert M Cregg ◽  
Thomas C Hennessey
Keyword(s):  
New Mexico ◽  
Water Stress ◽  
Gas Exchange ◽  
Carbon Isotope ◽  
Ponderosa Pine ◽  
Carbon Isotope Discrimination ◽  
Seed Source ◽  
Isotope Discrimination ◽  
Seed Sources ◽  
Moisture Availability

As part of a program to select ponderosa pine (Pinus ponderosa Dougl. ex Laws.) genotypes for improved drought tolerance, we examined physiological and morphological characteristics of 12 half-sib families of ponderosa pine from four seed sources; New Mexico, South Dakota, Nebraska, and Wyoming. We analyzed genetic variation in carbon isotope discrimination (Δ), photosynthetic gas exchange, needle morphology, and growth of 2-year-old seedlings from the four seed sources grown under two levels of moisture availability. To gain a better understanding of within-provenance variation and identify opportunities to refine selection strategies, we also examined family within seed source variation in the traits. Water stress significantly (P < 0.05) reduced net photosynthesis (A), needle conductance to water vapor (gwv), carbon isotope discrimination (Δ), and growth of the seedlings as compared to well-watered seedlings. However, instantaneous water use efficiency (A/gwv) did not differ between water treatments. Seedlings from New Mexico had significantly lower gwv and higher A/gwv than seedlings from the other sources. Carbon isotope discrimination was lowest for seedlings from New Mexico and Nebraska. Families within seed sources varied significantly in A, gwv, stomatal density, needle length, height increment, and Δ. Carbon isotope discrimination was significantly correlated with gwv but not with A, supporting results from mature trees suggesting that variation in Δ in ponderosa pine is more related to gwv than to A. Seed source × water treatment interactions were not observed for any of the traits analyzed. These results support our previous assertion that genotype × environment interaction in Δ of mature ponderosa pine trees from these sources grown in Nebraska and Oklahoma was related to factors other than moisture availability.

Broad sense heritability and genotype × environment interaction for carbon isotope discrimination in field-grown wheat

1992 ◽  
Vol 43 (5) ◽  
pp. 921 ◽  
Author(s):  
AG Condon ◽  
RA Richards
Keyword(s):  
Carbon Isotope ◽  
Dry Matter ◽  
Carbon Isotope Discrimination ◽  
Genotypic Variation ◽  
Broad Sense ◽  
Environment Interaction ◽  
Broad Sense Heritability ◽  
Isotope Discrimination ◽  
Average Value ◽  
Plant Parts

Carbon isotope discrimination (-) has been proposed as a possible selection criterion for greater water use efficiency in breeding programs for water-limited environments because it provides an integrative assessment of genotypic variation in leaf transpiration efficiency. Considerable genotypic variation for - has been demonstrated in wheat, but environmental factors may cause even larger changes in the value of - measured in plant dry matter, which could compromise the effective use of - in breeding programs. In this study we assess broad-sense heritability of - and the significance of genotype x environment interaction for - in field-grown wheat. Another objective was to identify the most effective growth stage or plant part to characterize genotypic variation in -. Experiments were done using several large sets of genotypes (between 8 and 40, usually c. 20) grown in a range of field environments spanning the southern Australian wheat-belt. Carbon isotope discrimination was determined on unreplicated grain samples from seven Interstate Wheat Variety trials grown in 1983 and 1984 and on several plant parts taken from replicated experiments conducted at four locations in south-west New South Wales from 1985 to 1988. From these replicated experiments broad-sense heritabilities for - were calculated on a genotype mean basis h2-M) and on a single-plot basis (h2-P). In dry matter sampled from several environments, site-mean - ranged from 21.0 x 10-3 to 18.9 x 10-3 for early-formed dry matter and from 16.4 x 10-3 to 13.4 x 10-3 for grain. When followed in a single environment, the value of - fell from c. 20 x 10-3 in early-formed leaves to 15.4 x 10-3 in the grain. Variation among genotypes in - of different plant parts was always significant, and was typically c. 2 x 10-3 . Among Australian wheats, low values of - (implying greater transpiration efficiency) were strongly associated with the WW15 genetic background. Estimates of broad-sense heritability for - averaged over 95%, on a genotype mean basis, in experiments where common genotypes were grown in numerous environments. In individual trials, heritability was lowest for plant material sampled near anthesis (average value for h2-M, 83% and for h2-p, 62%) and greatest for dry matter laid down before or during early stem elongation (average value for h2-M, 95% and for h2-P 88%). Even though heritability for grain - was also relatively high (average value for h2-M, 92% and for h2-P, 79%), genotypic differences in grain - are difficult to interpret because of the likelihood of some changes in genotype ranking for - resulting from differences among genotypes in the degree of water stress encountered during grain filling. As well, the contribution of remobilized carbon to grain - may vary between environments and genotypes. We conclude that, for wheat, assessment of genotypic variation in - should be most effective under well-watered conditions using dry matter laid down early in plant development.

Correlation between carbon isotope discrimination and transpiration efficiency in lines of the C4 species Sorghum bicolor in the glasshouse and the field

1998 ◽  
Vol 25 (1) ◽  
pp. 111 ◽  
Author(s):  
S. Henderson ◽  
S. von Caemmerer ◽  
G.D. Farquhar ◽  
L. Wade ◽  
G. Hammer
Keyword(s):  
Sorghum Bicolor ◽  
Carbon Isotope ◽  
Carbon Isotope Discrimination ◽  
Negative Slope ◽  
Environment Interaction ◽  
Transpiration Efficiency ◽  
Isotope Discrimination ◽  
C4 Species ◽  
C3 Species ◽  
The Mean

Transpiration efficiency, W, the ratio of plant carbon produced to water transpired and carbon isotope discrimination of leaf dry matter, Δd, were measured together on 30 lines of the C4 species, Sorghum bicolor, in the glasshouse and on eight lines grown in the field. In the glasshouse, the mean W observed was 4.9 mmol C mol-1 H2O and the range was 0.8 mmol C mol -1 H2O. The mean Δd was 3.0 and the observed range was 0.4‰. In the field, the mean W was lower at 2.8 mmol C mol-1 H2O and the mean Δd was 4.6‰. Significant positive correlations between W and Δd were observed for plants grown in the glasshouse and in the field. The observed correlations were consistent with theory, opposite to those for C3 species, and showed that variation in Δd was an integrated measure of long-term variation in the ratio of intercellular to ambient CO2 partial pressure, pi/pa. Detailed gas exchange measurements of carbon isotope discrimination during CO2 uptake, ΔA, and pi/pa were made on leaves of eight S. bicolorlines. The observed relationship between ΔA and pi/pa was linear with a negative slope of 3.7‰ in ΔA for a unit change in pi/pa. The slope of this linear relationship between ΔA and pi/pa in C4 species is dependent on the leakiness of the CO2 concentrating mechanism of the C4 pathway. We estimated the leakiness (defined as the fraction of CO2 released in the bundle sheath by C4 acid decarboxylations, which is lost by leakage) to be 0.2. We conclude that, although variation in Δd observed in the 30 lines of S. bicolor is smaller than that commonly observed in C3 species, it also reflects variation in transpiration efficiency, W. Among the eight lines examined in detail and in the environments used, there was considerable genotype × environment interaction.

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