Sugarcane response to saline irrigation water

Abstract

Salinity of irrigation water reduces yield and juice quality in sugarcane (Saccharum spp. hybrids), but cultivars vary in the degree of reduction. Genotypes which accumulate more potassium (K+) may be more resistant to salinity than genotypes that accumulate less K+. We examined the effect of irrigation water salinity on yield and juice quality in a cultivar with high conductivity, high K+ juice, ‘NCo 310’, and a cultivar with low conductivity, low‐K+ juice, ‘TCP 87–3388 ‘. Plants were grown in lysimeters containing 793 L of soil and irrigated with water of 0.01, 1.25, 2.93, or 4.70 dS m‐1. Quality and component analyses were conducted on the juice of single stalks subdivided by length, and the juice from whole stalks. The two cultivars responded similarly to increased salinity, although juice of NCo310 had a higher mineral concentration, especially K+ and Cl‐. Yield and most quality components were not significantly reduced by 1.25 dS m‐1 water. The 2.93 and 4.70 dS m‐1 treatments reduced stalk height and weight but not stalk numbers. The reduction in stalk height was due to decreases in number of internodes per stalk and mean internode length. Increasing salinity reduced total soluble solids and sucrose in juice, but increased Na+, K+, Mg+2, Ca+2 and Cl‐ Within a stalk, sucrose increased from top to bottom, while K+ decreased. Sodium concentrations were sharply higher in the lowest section, especially in plants irrigated with saline water. Chloride concentration was approximately equal in all sections. An increase in K accumulation did not appear to increase the salt tolerance of NCo310.