Salt stress is a major environmental factor which adversely affects the crop yield and quality. However, adequate regulation of mineral nutrients may ameliorate the deleterious effects of salts and help to sustain crop productivity under salt stress. Salt-sensitive (SPF 213) and salt-tolerant (HSF 240) sugarcane genotypes were grown in gravel at 0 and 100 mM NaCl by supplying 0, 1.4 mM, 2.1 mM and 2.8 mM of Si as calcium silicate. Results revealed that plants treated with NaCl alone showed a significant (P≤0.05) reduction in dry matter production, K + concentration, cane yield and juice quality in both genotypes but the magnitude of reduction was relatively more in salt-sensitive genotype than salttolerant. Addition of Si significantly (P≤0.05) reduced the uptake and translocation of Na + but increased K + concentrations particularly in shoots of both sugarcane genotypes. Cane yield and yield attributes were significantly (P≤0.05) higher where Si was added. Juice quality characteristics were significantly (P≤0.05) improved in salt-sensitive and salt-tolerant sugarcane genotypes with the application of Si. The results suggested that added Si interacted with Na + , reduced its uptake and transport to shoots and consequently improved cane yield and juice quality in salt-sensitive and salt-tolerant sugarcane genotypes under salt stress.

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Soil salinity is a major abiotic stress which adversely affects the yield and juice quality in sugarcane. However, the mineral nutrient status of plant plays a crucial role in increasing plant tolerance to salinity. We investigated the effects of K and/or Si on plant growth, yield and juice quality in two sugarcane genotypes differing in salinity tolerance. Addition of K and Si significantly (P ≤ 0.05) increased K and Si concentrations and decreased the accumulation of Na+ in plants under salt stress. Cane yield and yield attributes were significantly (P ≤ 0.05) higher where K and Si were added. Juice quality characteristics like Brix (% soluble solids in juice), Pol (% sucrose in juice), commercial cane sugar (CCS) and sugar recovery in both sugarcane genotypes were also significantly (P ≤ 0.05) improved with the supplementation of K and Si. For most of the growth parameters, it was found that K either alone or in combination with Si was more effective to alleviate salt stress in both sugarcane genotypes than Si alone. Moreover, the beneficial effects of K and Si were more pronounced in salt sensitive genotype than in salt tolerant genotype. The results suggested that K and Si counteracted the deleterious effects of high salinity/sodicity in sugarcane by lowering the accumulation of Na+ and increase in K+ concentration with a resultant improvement in K+/Na+ ratio which is a good indicator to assess plant tolerance to salinity.

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