Water uptake, water use efficiency, plant growth and ionic balance of wheat, barley, canola and chickpea plants on a sodic vertosol with variable subsoil NaCl salinity

Salinity in topsoil and subsoil is one of the major abiotic environmental stresses to crop production. To investigate the comparative tolerance ability of wheat, barley, canola and chickpea to subsoil NaCl salinity and its impact on water uptake, water use efficiency, plant growth and ionic balance, a pot experiment was conducted on a heavy texture soil (sodic vertosol) having 20 ESP (exchangeable sodium percentage), 3.5dS/m ECe and 400mg/kg Cl with additional NaCl applied in subsoil at 500, 1000, 1500 and 2000mg/kg soil. Plants were harvested 40 days after sowing and assessed for different parameters. Increasing levels of subsoil NaCl salinity had significant depressing effect on shoot and root biomass, root/shoot ratio, water uptake and water use efficiency (shoot biomass production with a unit amount of applied water), leaves K:Na ratio and Ca:Na ratio of all the four species, but the magnitude of effect varied considerably among the species. Chickpea was affected most followed by wheat, barley and canola at the highest level of subsoil NaCl salinity. There was 64%, 49%, 37% and 34% reduction in shoot dry weight of chickpea, wheat, barley and canola respectively by highest subsoil salinity. Similarly water uptake declined by 61%, 36%, 31% and 26% respectively in chickpea, wheat, barley and canola. Water use efficiency of four species was in order of barley>canola>wheat>chickpeas on this sodic vertosol. The cumulative effects of reduced osmotic potential of soil solution, ion toxicity (high concentrations of Cl and Na) in soil/plants and ionic imbalance (reduced K:Na and Ca:Na ratio) within plant system under increased subsoil NaCl salinity contributed to reduce water uptake and plant growth in all the four crops, and the effects were more severe in chickpeas. Wheat despite having considerably lower Na and Cl in their leaves suffered greatly in plant growth and water uptake compared with barley and canola indicating better tolerance ability of barley and canola to high Cl and Na build up at tissue level. Results suggest chickpea to be the most sensitive to subsoil NaCl salinity. The growing of comparatively tolerant species like barley and canola may be the better option for sustaining crop production and higher water use efficiency on sodic vertosols with high subsoil NaCl salinity.