Genetic Diversity in Barley and Wheat for Tolerance to Soil Constraints

Abstract

Surface soil sodicity as well as subsoil salinity, acidity, and phytotoxic concentrations of chloride (Cl) are major soil constraints to crop production in many soils of sub-tropical, north-eastern Australia. The identification of genotypes tolerant to these soil constraints may be an option to maintain and improve productivity on these soils. We evaluated performance of 11 barley and 17 wheat genotypes grown on two sites <0.5 km apart. Compared to the non-sodic site, the sodic site had significantly higher Cl concentration (>800 mg·Cl·kg −1 ) in the subsoil (0.9-1.3 m soil depth) and higher exchangeable sodium percentage (ESP) (>6%) in the surface and subsoil. Barley grain yield and plant available water capacity (PAWC) were reduced between 5%-25% and 40%-66%, respectively, for different genotypes at the sodic site as compared to the non-sodic site. For wheat genotypes, grain yield was between 8% and 33% lower at the sodic site compared to the non-sodic site and PAWC was between 3% and 37% lower. Most barley and wheat genotypes grown at the sodic site showed calcium (Ca) deficiency symptoms on younger leaves. Analysis of the youngest fully mature leaf (YML) confirmed that genotypes grown at the sodic site with Ca concentration < 0.2% exhibited deficiency symptoms. Grain yields of both barley and wheat genotypes grown on the sodic and non-sodic sites increased significantly with increasing Ca and K in YML and decreased significantly with increasing Na and Cl concentrations in YML. Sodium (Na) concentrations in YML of wheat genotypes grown at the sodic site were 10-fold higher than those from the non-sodic site whereas this increase was only two-fold in barley genotypes. In step-wise regression, the PAWC of barley and wheat genotypes grown on sodic and non-sodic sites was the principal determinant of variability of barley and wheat grain yield. Including the Ca concentration in the YML of wheat genotypes and K:Na ratio in the YML of barley genotypes significantly improved the prediction of grain yield in the regression analysis. Barley genotypes, Mackay and Kaputar, were relatively susceptible while Baronesse and Grout were relatively more tolerant to sodicity. Wheat genotypes Gregory and Stampede were generally relatively more susceptible to sodicity, and genotypes Baxter, Hume, and the experimental line HSF1-255 were relatively more tolerant than the former group.

Greater emergence force and hypocotyl cross sectional area may improve wheat seedling emergence in sodic conditions

“…Our results are similar to those reported previously, where increases in soil ESP, or the soil solution SAR, reduced or delayed seed germination in sodic soils [38]. However, the tolerance of crop species or genotypes in sodic conditions varies widely [29,30,38].…”

“…The present study examined 16 wheat genotypes, comparing their emergence force in controlled conditions to determine if genetic variability exists in the ability of the seedling coleoptile to push or displace superficial mechanical obstacles. These 16 wheat genotypes were selected from those found previously to differ markedly in their growth and crop yield in a surface crusting sodic soil in the field [29]. Furthermore, these 16 genotypes have been found to differ markedly in their emergence from a surface crusted sodic soil in the glasshouse [30].…”

Understanding the physiological basis for improved wheat seedling growth on dispersive sodic soils

“…In some cases, these approaches were used successfully to increase soil fertility, improve crop yield or nutrient imbalance of the soils. However, the application of amendments generally influences the surface soil only in the short term and soluble salts need to be leached through to the subsoil to have a significant effect in deeper layers (Dang et al 2016).…”

“…Rather than ameliorating sodic soils, a complementary approach can be used to identify genotypes with improved productivity in these soils. Considerable variability exists concerning productivity on sodic soils, not only between different crops, but also between cultivars of a single crop (Porcelli et al 1995;Rahi et al 2013;Dang et al 2016). The use of genetic solutions to develop better adapted crops and/or genotypes of crops might provide a long-term effective solution to improve the productivity of sodic soils (Richard 2002).…”

“…In general, the development of genetic approaches to improve productivity in sodic soil requires the expression of tolerance to several soil constraints. Field studies performed with different crop varieties including wheat, barley (Hordeum vulgare), and lentil (Lens culinaris) in different regions of Australia where sodic soils commonly occur, have concluded that there was no obvious benefit in adopting species with potentially improved tolerance for single, specific soil constraints (Hochman et al 2007;Nuttall et al 2010;Dang et al 2016). Therefore, to develop sodicity tolerant crops and genotypes, both the physical and chemical constraints of sodic soils need to be considered.…”