Genotype � environment interaction in carbon isotope discrimination and seed yield in cowpea (Vigna unguiculata L. Walp.)

Euphytica ◽  
1994 ◽  
Vol 73 (3) ◽  
pp. 213-224 ◽  
Author(s):  
E. C. K. Ngugi ◽  
N. W. Galwey ◽  
R. B. Austin
2000 ◽  
Vol 30 (3) ◽  
pp. 428-439 ◽  
Author(s):  
Bert M Cregg ◽  
J Miguel Olivas-García ◽  
Thomas C Hennessey

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.


1994 ◽  
Vol 122 (2) ◽  
pp. 275-284 ◽  
Author(s):  
J. W. White ◽  
J. A. Castillo ◽  
J. R. Ehleringer ◽  
J. A. C. Garcia ◽  
S. P. Singh

SUMMARYAlthough direct selection for seed yield under water deficit can result in genetic gains in the common bean (Phaseolus vulgaris L.), progress could be enhanced through selection for additional traits that are related to underlying mechanisms of adaptation to water deficit. Carbon isotope discrimination (Δ) has received considerable attention as an indicator of water use efficiency and adaptation to water deficit. To test the utility of Δ as a selection criterion, Δ and other traits were measured in F2 and F3 generations of a nine-parent diallel grown under rainfed conditions at two locations in Colombia with contrasting soil types. An irrigated trial was also conducted at one location. Significant (P 0·05) differences among parents, F2 and F3 were found for carbon isotope discrimination (Δ), leaf optical density (OD), leaf nitrogen (N) and potassium (K) concentrations, relative duration of pod-filling period (RDPF), shoot dry weight (SDW) and harvest index (HI). Effect of location and water regime and their interactions with genotype were also frequently significant. Heritability estimates, determined by regressing the F3 on the F2, ranged from 0·11±011 (S.E.) to 0·33 ±0·10 for OD, 0·22 ± 0·07 to 0·44±0·09 for N, 0·04±0·05 to 0·29±0·08 for K, 0·40 ± 0·08 to 0·43 ± 0·15 for RDPF and 0·30±0·22 to 1·00±0·24 for SDW. All values for Δ and HI did not differ significantly from zero. Correlations between seed yield and OD and RDPF were negative, whereas those with N, K, SDW, and HI were positive. For all traits, mean square values for general combining ability (GCA) were usuall significant and larger than those for specific combining ability (SCA). All significant GCA effects for Δ for ‘Rio Tibagi’, ‘San Cristobal 83’ and ‘Apetito’ were negative, while those for ‘Bayo Rio Grande’, ‘Bayo Criollo del Llano’, ‘Durango 222’ and BAT1224 were positive. Although Δappears unsuitable as an indirect criterion for selection for yield under water deficit, further study of genotypes exhibiting contrasting values of A might reveal differences in mechanisms of adaptation to water deficits, thus leading to other selection criteria or identification of valuable parental lines.


1998 ◽  
Vol 25 (1) ◽  
pp. 111 ◽  
Author(s):  
S. Henderson ◽  
S. von Caemmerer ◽  
G.D. Farquhar ◽  
L. Wade ◽  
G. Hammer

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.


1999 ◽  
Vol 50 (7) ◽  
pp. 1263 ◽  
Author(s):  
J. Voltas ◽  
I. Romagosa ◽  
A. Lafarga ◽  
A. P. Armesto ◽  
A. Sombrero ◽  
...  

Carbon isotope discrimination (Δ) has been found to be either positively or negatively related to grain yield of small grain cereals when grown in contrasting environments. In order to clarify a possible association between grain yield of barley (Hordeum vulgare L.) and Δ of mature kernels, five 6-rowed and five 2-rowed barley cultivars were evaluated in 22 rainfed environments of northern Mediterranean Spain. Analyses of variance suggested that the genotypic Δ values were more consistent across environments than the genotypic yields. Genotype×environment (G×E) interaction for grain yield was further explored by fitting an AMMI (additive main effects and multiplicative interaction) model. The first 2 multiplicative axes were found significant. The AMMI2 model provided more accurate estimates of genotypic yields within environments than the conventional unadjusted means across replicates. AMMI2 estimates were used for input into cluster analysis, grouping environments that ranked genotypic yields similarly. Three major groups were obtained, with average yields of 2.42 t/ha (cluster I), 3.06 t/ha (cluster II), and 5.16 t/ha (cluster III). The genotypic ranking for Δ did not vary substantially across clusters, but it changed for grain yield. The average genotypic yields in the low-yielding cluster I ranked opposite to those in the high-yielding cluster III, suggesting the existence of a crossover point at an intermediate yield level. The association between grain yield and Δ for genotypic means within clusters was variable. In cluster I, yield and Δ tended to be negatively related, whereas they were positively related in clusters II and III. Genotypes with lower Δ, i.e. with higher transpiration efficiency, performed better in low-yielding environments (mostly those grouped in cluster I). On the contrary, a high genotypic Δ was of advantage in medium (cluster II) and high-yielding environments (cluster III). This observation supports the assumption that drought tolerance and high yield potential under non-limiting growing conditions may be antagonistic concepts in barley. Genotypic means for kernel number per m 2 and Δ were consistently and positively related within clusters, suggesting that a constitutively high Δ may have been driven by a large genotypic reproductive sink. The convenience of using Δ as a selection criterion in areas exhibiting a considerable G×E interaction for grain yield is discussed.


1992 ◽  
Vol 43 (5) ◽  
pp. 921 ◽  
Author(s):  
AG Condon ◽  
RA Richards

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.


2010 ◽  
Vol 149 (3) ◽  
pp. 273-281 ◽  
Author(s):  
J. T. TSIALTAS ◽  
I. I. PAPADOPOULOS ◽  
E. G. TAMOUTSIDIS ◽  
I. S. TOKATLIDIS

SUMMARYDry bean (Phaseolus vulgaris L.) is a traditional crop of north-western Macedonia, Greece, where two landraces (plaki Prespas and Chrisoupoli) in particular are grown. The aim of this study was to test whether the grain carbon isotope discrimination (Δ) and ash content (ASH) are related to grain yield (GY), protein content (PC) and mean grain weight (MGW) in dry bean. As a part of a honeycomb selection programme, 21 genotypes (19 lines derived via intra-landrace honeycomb selection for single plant yield at low density plus the two original populations) were grown at two densities, 1·2 and 4·8 plants/m2 under non-limiting water conditions in a glasshouse and in the field. Genotypes differed significantly for Δ, ASH and PC under the low density. In the dense stand, genotypes differed significantly only for ASH and PC. The environment (glasshouse or field conditions) affected all the traits significantly. Neither Δ nor ASH showed strong or consistent relationships with GY and thus, they cannot serve as reliable, indirect selection criteria for GY. Strong, negative relationships between Δ and PC were found especially in the dense stand, confirming analogous results in C3 cereals. Inconsistent genotypic ranking for grain physiological traits under the different densities and environments was indicative of large genotype×environment interaction. Genotypes performed consistently for GY and MGW under both densities, showing the strong stability of these traits.


2005 ◽  
Vol 32 (12) ◽  
pp. 1089 ◽  
Author(s):  
Jonathan P. Comstock ◽  
Susan R. McCouch ◽  
Bjorn C. Martin ◽  
Charles G. Tauer ◽  
Todd J. Vision ◽  
...  

Carbon isotope discrimination (Δ) is frequently used as an index of leaf intercellular CO2 concentration (ci) and variation in photosynthetic water use efficiency. In this study, the stability of Δ was evaluated in greenhouse-grown tomato and rice with respect to variable growth conditions including temperature, nutrient availability, soil flooding (in rice), irradiance, and root constriction in small soil volumes. Δ exhibited several characteristics indicative of contrasting set-point behaviour among genotypes of both crops. These included generally small main environmental effects and lower observed levels of genotype-by-environment interaction across the diverse treatments than observed in associated measures of relative growth rate, photosynthetic rate, biomass allocation pattern, or specific leaf area. Growth irradiance stood out among environmental parameters tested as having consistently large main affects on Δ for all genotypes screened in both crops. We suggest that this may be related to contrasting mechanisms of stomatal aperture modulation associated with the different environmental variables. For temperature and nutrient availability, feedback processes directly linked to ci and / or metabolite pools associated with ci may have played the primary role in coordinating stomatal conductance and photosynthetic capacity. In contrast, light has a direct effect on stomatal aperture in addition to feedback mediated through ci.


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