Genomic analysis of carbon isotope discrimination, photosynthesis rate, stomatal conductance, and grain yield in wheat (Triticum aestivum L.) under water-stressed conditions

2012 ◽  
Vol 63 (6) ◽  
pp. 513 ◽  
Author(s):  
Shahram Mohammady ◽  
Roghayeh Aminian ◽  
Sadolla Hoshmand ◽  
Mahmood Khodombashi

Chromosomal substitution lines of wheat variety Timstein (Tim) into the genetic background of variety Chinese Spring (CS) were used to evaluate the chromosomal location of genes controlling carbon isotope discrimination (Δ), photosynthesis rate (PR), stomatal conductance (SC), and grain yield. The experiment was carried out in the field at Shahrekord University Research Station. Considerable variation was observed among the substitution lines and between the parents for all traits. Chinese Spring had smaller values for the characters under study than Timstein. Significant correlations were found for grain yield with PR (r = 0.556) and Δ (r = 0.619). The substitution line CS (Tim2B) was significantly different from CS for Δ (P < 0.01). The substitution of homeologous group 3 chromosomes produced significant differences from the recipient variety for PR. Substitution lines CS (Tim3A), CS (Tim3B), CS (Tim4B), and CS (Tim1D) were significantly different from CS for SC. Genomic comparisons indicated that genome B had higher values of all four characters compared with the A and D genomes. Homeologous effects of genomes were documented for Δ and PR only and not for SC and grain yield.

2016 ◽  
Vol 13 (18) ◽  
pp. 5183-5204 ◽  
Author(s):  
Brett Raczka ◽  
Henrique F. Duarte ◽  
Charles D. Koven ◽  
Daniel Ricciuto ◽  
Peter E. Thornton ◽  
...  

Abstract. Land surface models are useful tools to quantify contemporary and future climate impact on terrestrial carbon cycle processes, provided they can be appropriately constrained and tested with observations. Stable carbon isotopes of CO2 offer the potential to improve model representation of the coupled carbon and water cycles because they are strongly influenced by stomatal function. Recently, a representation of stable carbon isotope discrimination was incorporated into the Community Land Model component of the Community Earth System Model. Here, we tested the model's capability to simulate whole-forest isotope discrimination in a subalpine conifer forest at Niwot Ridge, Colorado, USA. We distinguished between isotopic behavior in response to a decrease of δ13C within atmospheric CO2 (Suess effect) vs. photosynthetic discrimination (Δcanopy), by creating a site-customized atmospheric CO2 and δ13C of CO2 time series. We implemented a seasonally varying Vcmax model calibration that best matched site observations of net CO2 carbon exchange, latent heat exchange, and biomass. The model accurately simulated observed δ13C of needle and stem tissue, but underestimated the δ13C of bulk soil carbon by 1–2 ‰. The model overestimated the multiyear (2006–2012) average Δcanopy relative to prior data-based estimates by 2–4 ‰. The amplitude of the average seasonal cycle of Δcanopy (i.e., higher in spring/fall as compared to summer) was correctly modeled but only when using a revised, fully coupled An − gs (net assimilation rate, stomatal conductance) version of the model in contrast to the partially coupled An − gs version used in the default model. The model attributed most of the seasonal variation in discrimination to An, whereas interannual variation in simulated Δcanopy during the summer months was driven by stomatal response to vapor pressure deficit (VPD). The model simulated a 10 % increase in both photosynthetic discrimination and water-use efficiency (WUE) since 1850 which is counter to established relationships between discrimination and WUE. The isotope observations used here to constrain CLM suggest (1) the model overestimated stomatal conductance and (2) the default CLM approach to representing nitrogen limitation (partially coupled model) was not capable of reproducing observed trends in discrimination. These findings demonstrate that isotope observations can provide important information related to stomatal function driven by environmental stress from VPD and nitrogen limitation. Future versions of CLM that incorporate carbon isotope discrimination are likely to benefit from explicit inclusion of mesophyll conductance.


2005 ◽  
Vol 143 (4) ◽  
pp. 275-282 ◽  
Author(s):  
J. T. TSIALTAS ◽  
I. S. TOKATLIDIS ◽  
E. TAMOUTSIDIS ◽  
I. XYNIAS

The objective was to explore, in lines derived from a bread wheat (Triticum aestivum L.) cultivar, the association of grain yield with carbon isotope discrimination (Δ) and ash content (Ash) determined in both flag leaf and kernel. Divergent selection within the cv. Nestos, based on individual plant yield under very low density (11547 plants/ha), produced 20 lines. Progeny evaluation was conducted in two sites of Northern Hellas (Greece) at both low (11547 plants/ha) and high (5000000 plants/ha) density. The results showed significant differences between lines for grain yield, Δ and Ash. However, only the conclusions on grain yield were similar in low and high density, perhaps because the selection criterion under low density was grain yield. This, combined with the lack of any strong relationship of grain yield with either Δ or Ash, failed to confirm the usefulness of these physiological traits as indirect selection criteria, when the within-cultivar variation for grain yield is exploited. The possible association of grain yield with Δ and Ash appeared to be influenced by various factors such as drought, level of grain yield and altitude. Results also showed that less plant-to-plant variability, as expressed by the coefficients of variation (CV) of single-plant yields, was associated with decreased drought response and higher yield stability. The less stressed lines were those that used water more conservatively till anthesis and maintained a high photosynthetic rate during grain filling.


Author(s):  
Lawrence Munjonji ◽  
Kingsley Kwabena Ayisi ◽  
Bram Vandewalle ◽  
Geert Haesaert ◽  
Pascal Boeckx

Crop Science ◽  
2001 ◽  
Vol 41 (3) ◽  
pp. 677-681 ◽  
Author(s):  
O. Merah ◽  
E. Deléens ◽  
I. Souyris ◽  
M. Nachit ◽  
P. Monneveux

2001 ◽  
Vol 149 (2) ◽  
pp. 275-282 ◽  
Author(s):  
Othmane Merah ◽  
Eliane Deléens ◽  
Irenée Souyris ◽  
Philippe Monneveux

2008 ◽  
Vol 59 (10) ◽  
pp. 941 ◽  
Author(s):  
Lin Zhu ◽  
Zong Suo Liang ◽  
Xing Xu ◽  
Shu Hua Li ◽  
Ji Hai Jing ◽  
...  

The relationships between carbon isotope discrimination (Δ) and some morphophysiological traits such as specific leaf dry weight (SLDW), gas exchange parameters, and relative water content (RWC) were studied in a collection of 20 bread wheat cultivars (landraces, released cultivars and advanced lines) in three locations of the Ningxia region (North-East China), i.e. Yinchuan (limited irrigation conditions), Huinong (limited irrigation conditions + salinity) and Guyuan (rain-fed conditions). Relationships between Δ, grain yield (GY), and harvest index (HI) and above-ground biomass (AGB) were also analysed. Differences in the measured traits between different locations were highly related to the variation in water availability. Positive correlations were noted between Δ and HI and grain yield. Flag leaf Δ was positively correlated with RWC at anthesis, and negatively associated with SLDW at grain filling. Significant and negative correlations between Δ and dry matter weight per plant at anthesis and biomass at maturity were noted. Leaf temperature (LT) was found to be negatively correlated with Δ and gs. The findings suggest that Δ may be a useful indicator reflecting wheat yield, harvest index, and water status under irrigation and rain-fed conditions in the Ningxia region.


2001 ◽  
Vol 37 (2) ◽  
pp. 241-252 ◽  
Author(s):  
J. I. FAHL ◽  
M. L. C. CARELLI ◽  
H. C. MENEZES ◽  
P. B. GALLO ◽  
P. C. O. TRIVELIN

Gas exchange, leaf carbon isotope discrimination, growth, yield and beverage quality were evaluated for two Coffea arabica cultivars (Catuai and Mundo Novo), grafted on to C. canephora and C. congensis progenies growing in open fields. During the years 1994 to 1997, grafting resulted in an average increase in bean yield of 151 and 89% for Catuai and Mundo Novo respectively. As analysed by sensory analyses and by the ratio between the mono-isomers and di-isomers of caffeoylquinic acid, beverage quality of the C. arabica was not altered by grafting. Shoot growth was significantly greater in grafted plants, showing an increase of 52% in total leaf area compared with the non-grafted plants. Under conditions of water excess in the soil there was little difference in the transpiration and stomatal conductance rates between the grafted and non-grafted plants, but the net photosynthesis was higher in grafted plants. With an accentuated water deficit in the soil in the dry period, the grafted plants showed significantly higher transpiration and stomatal conductance rates than the non-grafted plants, and similar values to those of C. canephora. Carbon isotope discrimination was greater in the grafted plants, suggesting greater root hydraulic conductance. The results suggest that the better performance of the grafted plants during the dry period was due to the greater capacity of the root system of C. canephora to provide water to the shoot thereby maintaining greater gas exchange in the leaves and consequently a greater carbon gain.


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