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.
Highlights
High sodicity in surface and subsoil, high salinity and phytotoxic concentration of chloride (Cl) in subsoil, and alkaline surface soils with acidic subsoil are common soil constraints in many drylandVertosols of the semi-arid, sub-tropical regions of north-eastern Australia [1,2]
Soil constraints, especially in the subsoil, reduce the effective rooting depth and the amount of water and nutrients that plants can obtain from the soil, resulting in reduced crop yield [4,7]
Acidic subsoils at the sodic site containing toxic levels of aluminium (Al3+ ) or deficient amounts of calcium (Ca2+ ) restrict root proliferation [28]
Summary
High sodicity in surface and subsoil, high salinity and phytotoxic concentration of chloride (Cl) in subsoil, and alkaline surface soils with acidic subsoil are common soil constraints in many drylandVertosols of the semi-arid, sub-tropical regions of north-eastern Australia [1,2]. On the other hand, reduce the ability of the crop roots to extract water and nutrients from the deeper layers in the soil, especially from soils high in salt content and Cl concentration [4]. The yield of grain crops grown on Vertosols, which occupy 72% of the cropping soils of the region, is potentially limited by many factors; water supply is the dominant factor. Soil constraints, especially in the subsoil, reduce the effective rooting depth and the amount of water and nutrients that plants can obtain from the soil, resulting in reduced crop yield [4,7]. Several soil physiochemical constraints in the surface and subsoil interact with each other to determine the local environment for root growth at a given time. Variability in the impact on the crop growth and yield is compounded by the complex interactions between the physiochemical constraints and environmental factors, the timing and amount of rainfall relative to the crop development cycle
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