Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/1999
Publication Date: N/A
Interpretive Summary: Excess salt, especially sodium, in soil and irrigation water decreases yield of sugarcane and the quality of the juice. However, excess salt is not uncommon where sugarcane is grown under irrigation. Varieties differ in the amount of salts that accumulate in their juice. Plants that accumulate more potassium may be able to exclude more sodium from the roots, and thus be more salt tolerant. We grew a high potassium variety and a low potassium variety in a field and irrigated both with water with three salinities, and compared them with the same varieties grown with rain water (nonsaline). The mildest saline treatment did not significantly differ from rain water for most traits studied. Further increases in salinity decreased stalk weight and sugar in the juice and increased salts in the juice. The two cultivars responded the same to salinity. Therefore, it appeared that in the case of sugarcane, the ability to take up potassium is not related to tolerance to salt in irrigation water. Farmers will benefit from this technology.
Technical 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 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 high-K+ cultivar, 'NCo310', and a low-K+ cultivar, '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.