Abstract
Three sorghum (Sorghum bicolor (L.) Moench.) cultivars namely Mr. Buster, Honey Graze and Extra Sweet of Australian origin were tested for their salinity tolerance. Their seedling growth was tested in a sand culture experiment n pots under saline irrigation with 0, 50, 100, and 150 mM NaCl prepared in half strength Hoagland solution. The parameters like number of leaves per plant and total leaf area per plant declined with salinity. Salt tolerance sequence, on the basis of 50 % loss of leaf area per plant over control, of the cultivars in hand was as - Cv. Buster > Cv Extra Sweet > Cv Honey Graze. Fifty per cent reduction in growth, in terms of dry weight of seedling phytomass, corresponded with 82.895, 82.089, and 72.65 mM NaCl in cultivars Extra Sweet, Honey Graze and Mr. Buster, respectively. Salt tolerance sequence, on the basis of 50 % losses of seedling phytomass over control, of the cultivars in hand was as - Cv. Honey Graze ≈ Cv Extra Sweet > Cv. Mr. Buster The relative turgidity of the plants remained unchanged under salinity treatments. Overall photosynthetic pigments were reduced significantly although chlorophyll – a remained statistically unchanged in concentration. Carotenoids level was reduced under salinity. The total soluble sugar contents in treated plants appeared not to vary with salinity. Protein contents declined. Although proline contents increased by 23.5% in Cv Mr. Buster under high salinity; in other varieties proline declined with salinity. There was an increase of phenolic contents up to 34.66 % in Honey Graze and 11.92% in Mr. Buster at NaCl concentration of 150 mM. The phenols, however, declined in Extra Sweet (6.14% in 50 mM NaCl and 19.67% in 100 mM NaCl. The electrolyte leakage from leaves of three varieties didn’t vary significantly among the varieties and under the salinity. Sodium, Potassium and chloride ions increased greatly with NaCl concentration. The results are discussed in eco-physiological context.
