Relationships between Water Use Efficiency, Carbon Isotope Discrimination, and Turf Performance in Genotypes of Kentucky Bluegrass during Drought

Abstract

Carbon‐13 discrimination (Δ) and water use efficiency (WUE) have been largely ignored in turfgrass. Turfgrass performance under drought may be improved by selecting for low Δ, which has been shown to be negatively correlated with WUE. The objectives of this 2‐yr greenhouse study were (i) to compare Δ and WUE in 12 genotypes of Kentucky bluegrass (Poa pratensis L.) with evapotranspiration (ET) and rooting for assessing turf performance under drought, and (ii) to determine the relative importance of ET in drought resistance by comparing diverse ET genotypes (6 low and 6 high) during drydown. Clipping dry weight to ET ratio (WUE) was evaluated with sand‐filled weighing lysimeters (20‐cm diam. by 65‐cm depth) during two 4‐d periods (Days 1 to 4 and 5 to 8) in 2002 and 2003. Carbon (13C/12C) analysis of leaf clippings was used to derive Δ values. Time domain reflectometry (TDR) was used to measure changes in volumetric soil moisture content (VSMC) at the 8.25‐, 17.5‐, 35.0‐, and 52.5‐cm depths to indicate moisture uptake and rooting activity. Drought resistance was visually assessed as wilt and leaf‐firing symptoms. Low‐ and high‐ET genotypes were similar in wilt and leaf firing, suggesting low ET may not be relevant in drought survival. Deep rooting at the 52.5‐cm depth and higher ET as soils dried were associated with less leaf firing. The WUE at Days 5 to 8 was comparable in some years with rooting. The Δ was not always reliable in assessing WUE, but turf performance under drought was correlated with Δ. Low Δ values were associated with less wilt (r = 0.59, P ≤ 0.05) and leaf firing (r = 0.58, P ≤ 0.05), suggesting that Δ may be a useful selection criterion for superior performance under limiting soil moisture.

Turfgrass and Climate Change

“…The combined effect of improved water use efficiency and improved growth will enhance growth and survival under water limited conditions. Coupling these observations with the findings from Ebdon and Kopp (2004) and Fuentealba et al (2016) suggest genetic variation in water use efficiency of turfgrass species could be evaluated as a strategy to cope with climate change. Increased CO 2 effects on water use efficiency would increase the number of days a perennial grass could maintain non-limiting transpiration, thereby, making more efficient use of water in the soil profile.…”

“…Xin et al (2013) suggested that screening turfgrass species for water use efficiency and drought resistance using a combination of phenotypic studies (morphology, growth rate, and cell physiology), gene quantitative trait loci (QTL) mapping for the morphological and physiological characteristics of different species, and quantifying the understanding of the molecular mechanisms of water use efficiency in turfgrass would provide a path toward breeding genotypes to withstand drought stress. Ebdon and Kopp (2004) demonstrated the value of different physiological techniques to screen turfgrass germplasm for drought tolerance. The results presented by Fuentealba et al (2016) demonstrated differences among genotypes to show the potential for screening to cope with water shortages.…”

Genotypic Variability in Carbon Isotope Discrimination and Water Use Efficiency among Recombinant Inbred Lines of Sunflower (Helianthus annuus L.)

“…Nevertheless, the problem has been overcome since Farquhar, Ehleringer, & Hubick (1989) proved the negative correlation between WUE and CID in tissue of C3 plant species. CID during plant growth and development could be used as an excellent surrogate for determining WUE, which is usually directly measured in the field Brendel et al, 2008;Brugnoli, Hubick, von Caemmerer, Wong, & Farquhar, 1988;Chen, Chang, & Anyia, 2011;Ebdon & Kopp, 2004).…”

“…Genotypic variability of CID in C3 plant has received increasing attention of WUE Ebdon & Kopp, 2004;Farquhar, Ehleringer, & Hubick, 1989;Rebetzke, Condon, Farquhar, Appels, & Richards, 2008). Plants discriminate toward the heavier carbon isotope ( 13 C), during assimilation processes, because the process depends on the intercellular and atmospheric carbon dioxide partial pressure (Pi and Pa).…”

Water deficit modifies the carbon isotopic composition of lipids, soluble sugars and leaves of Copaifera langsdorffii Desf. (Fabaceae)

“…Evaluation of δ 13 C of vegetative structures and carbon compounds allows the detection of changes in the content of stable 13 C/ 12 C carbon isotopes in response to a water shortage. Water deficit changes the isotopic ratio of 12 C/ 13 C due to low photosynthetic rate and stomatal closure (Ebdon & Kopp 2004). Therefore, this study aimed to evaluate the effect of changes in the assimilation of CO 2 during water deficit on the δ 13 C of soluble sugars, lipids and vegetative structures in C. langsdorffii.…”