GROWTH, ION AND SOLUTE CONTENTS OF SORGHUM GROWN UNDER NACL AND NA2SO4 SALINITY STRESS

Sorghum (Sorghum bicolor (L.) Moench, cv. IS-4807) was grown in nutrient solution with or without supplemented NaCl (0-100 mmol L(-1)) or Na2SO4 (0-50 mmol L(-1)). The concentrations provided identical amounts of Na+, on equimolar basis, from both the salts. After four weeks of growth, biological yield was reduced at the higher level of salts and NaCl was more suppressive than Na2SO4. The concentrations of Na+ and Cl- ions were 29-36 times higher in plants raised under NaCl stress (100 mmol L(-1)), and increase in Na was accompanied by a loss of K+ in the leaves, stems and roots. Under Na2SO4 stress (50 mmol L(-1)), leaf Na+ and SO4- concentration was 21-23 times higher than those raised in the absence of the salt. On equimolar basis, Na+ uptake and K+ loss was less in Na2SO4 than in the NaCl stressed plants. Proline, betaine and sugars were enhanced, under both the salts, to similar extent.