Using Carbon Isotope Discrimination to Assess Genotypic Differences in Drought Resistance of Parental Lines of Common Bean

Abstract

Accurate assessment of crop water uptake (WU) and water use efficiency (WUE) is not easy under field conditions. Carbon isotope discrimination (Δ13C) has been used as a surrogate of WUE to examine crop yield responses to drought and its relationship with WU and WUE. A 2‐yr study was conducted (i) to characterize genotypic variation in Δ13C, grain yield, and other physiological parameters in common bean (Phaseolus vulgaris L.) parental lines, and (ii) to examine the relationships between grain Δ13C, shoot Δ13C, and grain yield under well‐watered and terminal drought stress conditions. All measured plant traits were strongly influenced by water availability, and genotypic differences in grain yield, shoot Δ13C, and grain Δ13C were found in both watered and terminal drought stress environments. The parental lines were classified into two drought adaptation groups, drought resistant and drought sensitive, based on a yield drought index. High yields under drought conditions were related to (i) greater water uptake, as indicated by high Δ13C in genotypes previously shown to have deeper roots (e.g., SEA 5 and BAT 477), and (ii) increased WUE, denoted by lower Δ13C and greater pod harvest index (PHI) (e.g., SER 16). Coupling of Δ13C measurements with measured yield and yield components analyses, such as PHI, provided an avenue to distinguish different physiological traits among drought resistant genotypes underlying adaptation to water deficit stress.

Performance of Mesoamerican bean (Phaseolus vulgaris L.) lines in an unfertilized oxisol

“…'Rojo Chortí' was released in El Salvador (Parada-Cardona et al, 2015) and in Honduras (Rosas et al, 2019) as a heat and drought tolerant small red bean cultivar. Greater water use efficiency was associated with bean genotypes having lower Δ 13 C values and greater harvest index (Sanz-Saez et al, 2019). The Δ 13 C values reported on Mesoamerican beans planted in field trials in Ontario, Canada in 2011 and 2012 were greater than the Δ 13 C values in this study (Farid and Navabi, 2015).…”

“…Because bean breeding programs in Central America and the Caribbean often screen lines on research stations and farms having poor soil fertility, some selection of bean lines having improved SNF or greater acquisition of nutrients from the soil may have occurred (Graham et al, 2003). Under drought conditions, bean genotypes that combine high seed yield and larger Δ 13 C values often have deeper roots and lower water use efficiency and may represent the "water user" response to drought stress (Polania et al, 2016a;Sanz-Saez et al, 2019).…”

Tolerance to mid‐season drought in peanut can be achieved by high water use efficiency or high efficient use of water

“…The fact that 2020 was a cooler and wetter year than 2019 likely explains why in this year the genotype differences in physiological parameters such Δ 13 C, photosynthesis, and g s under drought is significant but smaller than in 2019 (Tables 4 and 5). This smaller difference between genotypes has been shown before in common bean under irrigated conditions (Polania et al, 2016;Sanz-Saez et al, 2019) and is due to the fact that some genotypes with high plasticity only show significant differences when they are under extreme drought conditions (Tardieu et al, 2018).…”

“…These genotypes are called “water spenders” or “Anisohydric” and are characterized as having a higher transpiration rate, efficient use of water (EUW), and photosynthesis rate under drought, leading to higher growth and yield under drought (Blum, 2009; Tardieu et al., 2018). Although water spender genotypes have been described in other crops such as rice ( Oryza sativa L.) (Kobata et al., 1996), wheat ( Triticum aestivum L.) (Zhu et al., 2008), and common bean ( Phaseolus vulgaris L.) (Sanz‐Saez et al., 2019), there are no reports describing this drought‐tolerant mechanism in peanuts and evaluating if this mechanism can be more advantageous than water savers in an environment such as the southeastern United States.…”

Carbon isotope discrimination association with yield and test weight in Pacific Northwest–adapted spring and winter wheat

“…Similarly, Li, Chen, and Wu (2012) found a positive relationship (high ∆ or low TE and high yield) between flag leaf ∆ and yield in the PNW-adapted spring wheat cultivars tested under rainfed and irrigated conditions in southern Idaho. Under drought conditions, high ∆ is indicative of greater water uptake through deep roots, and low ∆ is indicative of increased WUE (Sanz-Saez et al, 2019). An important aspect of ∆ is that it is thought to be less influenced by the genotype × environment (G × E) interaction than many yield-associated traits.…”