Adaptation of sugarcane plants to saline soil

Sugarcane is an important crop in tropical regions of the world, often being exposed to environments with high salinity, but little is known of genetic variation in salt tolerance. The aim of this work was to compare the performance of two genetically diverse cultivars of sugarcane under different concentrations of salinity (0, 40, 80 and 160 mM NaCl) over a period of 30 days. SP 81–3250 was more salt-tolerant and maintained its rate of biomass production, photosynthesis and leaf area up to 160 mM NaCl, whereas IAC 87–3396 was sensitive to 80 mM NaCl. SP 81–3250 maintained very low concentrations of Na ⁺ in both leaves and roots with increasing time and salinity, whereas in IAC 87–3396 the Na ⁺ concentrations were 2–5 times higher. SP 81–3250 ha d a greater accumulation of proline, and lower lipid peroxidation, whereas glycine betaine and sucrose concentrations were similar in the two cultivars. This suggests that the tolerance of SP 81–3250 to high salinity was due to its ability to exclude Na ⁺ while taking up water from the soil, and that measurements of Na ⁺ concentration in leaves could be used to select salt-tolerant genotypes for saline areas.