The physiological and growth response of sugarcane to the sodium absorption ratio in flowing solution sand culture
The growth of sugarcane variety Q117 in sand culture using nutrient solutions with sodium absorption ratios of 0, 5, 10, 15, 20 and 30, each with a constant electrical conductivity of 1.5 dS/m was determined under glasshouse conditions. Increasing the SAR of nutrient solutions from 0 to 30 while holding EC and ionic strength constant, was found to have no significant effect on sugarcane grown in coarse sand for 12 weeks. Thus, sugarcane growth was not inhibited by Na+ concentrations up to 12 mM when Ca2+ and mg2+ were each present at 76uM. It can be tentatively concluded from these results that increasing levels of sodium, in the absence of high levels of soluble salts are not toxic to the variety Q117, as long as other major cations are present at concentrations uninhibitative to plant growth. The major growth effect on sugarcane of sodic soils occurs as a result of the physical limitations associated with soil structure deterioration.