EFFECT OF CALCIUM ON THE SALT TOLERANCE OF DIFFERENT WHEAT (Triticum aestivum L.) GENOTYPES

In saline soil conditions the availability and uptake of Ca^2+ is reduced that results in the loss of membrane integrity and other disorders associated with Ca^2+ deficiency in plants. A wheat genotype efficient in uptake and utilization of calcium under saline conditions may be better able to withstand saline conditions in the field. Very little information is available on wheat response to salinity and low Ca^2+ as screening of wheat genotypes has usually been done against salinity alone. The present study was designed to evaluate the performance of different wheat genotypes against salinity at low and adequate calcium supply. The experiment was conducted in hydroponics with four treatments including T1: non-saline with adequate Ca^2+, T2: non-saline with low Ca^2+ (level of calcium was 1/4th of the adequate level), T3: saline (125 mM NaCl) with adequate Ca^2+ and T4: saline with low calcium. All the physical growth parameters including shoot length, root length, and shoot and root fresh weights were decreased significantly due to salinity and low calcium alone as well as in combination. Reduction was more pronounced under the combined stress of salinity and low calcium and different genotypes differed significantly in different stress treatments for shoot and root fresh weight production. In saline treatment (T3), the genotypes 25-SAWSN-39 and 25-SAWSN-31 showed better growth performance and accumulated lower Na+ and higher Ca^2+ where as the genotypes 25-SAWSN-35 and 25-SAWSN-47 showed less growth and had less accumulation of Ca^2+ and high accumulation of Na^+. In salinity + low calcium treatment the genotype 25-SAWSN-39 behaved as a tolerant genotype where as 25-SAWSN-31 behaved similar to the sensitive genotype and these differences were due to high accumulation of Ca^2+ in 25-SAWSN-39 and vice versa. This study shows that the salt tolerance of wheat genotypes differs with the availability and accumulation of calcium. Certain genotypes can better uptake and utilize calcium than the others under low calcium supply which improves their salt tolerance under saline conditions.