Sugarcane response to saline irrigation water

Salinity of irrigation water reduces yield and juice quality in sugarcane ( Saccharum spp. hybrids), but cultivars vary in the degree of reduction. Gen otypes which accumulate more potassium (K+) may be more resistant to salini ty than genotypes that accumulate less K+. We examined the effect of irriga tion water salinity on yield and juice quality in a cultivar with high cond uctivity, high K+ juice, 'NCo310', and a cultivar with low conductivity, lo w-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). Qu ality and component analyses were conducted on the juice of single stalks s ubdivided by length, and the juice from whole stalks. The two cultivars res ponded similarly to increased salinity, although juice of NCo310 had a high er mineral concentration, especially K+ and Cl-. Yield and most quality com ponents 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 num bers. The reduction in stalk height was due to decreases in number of inter nodes per stalk and mean internode length. Increasing salinity reduced tota l soluble solids and sucrose in juice, but increased Na+, K+, Mg+2, Ca+2 an d Cl-. Within a stalk, sucrose increased from top to bottom, while K+ decre ased. Sodium concentrations were sharply higher in the lowest section, espe cially in plants irrigated with saline water. Chloride concentration was ap proximately equal in all sections. An increase in K+ accumulation did not a ppear to increase the salt tolerance of NCo310.