| ii) Seedlings growth. Sodium chloride and sodium sulphate salinization has a definite effect on shoot and root length (Tables 2 and 3). Increasing salinity levels from 0.2 to 1.0% significantly decreases shoot and root growth of all the genotypes. At higher concentrations (0.8 to 1.0%) shoot and root growth is considerably retarded. It was also observed that the degree of reduction increased proportionally with the increasing concentration of salt. Inhibition of plant growth by salinity is due to the inhibitory effect of ions. As a result of this inhibition carbohydrates and nitrogenous substances are not fully utilized (STROGONOV 1962). Another reason for reduced shoot and root development may be due to toxic effects of the salts used as well as unbalanced nutrient uptake by the seedlings. Osmotic effects may also contribute to low growth rates under saline conditions (EPSTEIH 1977). Generally the genotype Sind-81 seemed to be the most tolerant during shoot and root growth at the highest salinity level (1.0%), while the genotypes Sind-83, Sonalika and LU-26-S were proved to be the most salt-sensitive at the maximum salinity level. At the highest salinity (1.0%) the average shoot and root length is reduced by almost 51% Of the control. The degree of decrease was higher in the case of shoot length which indicates that salinity inhibits shoot growth more than the root growth (STROGONOV 1962) and this could be due to the reduction in physiological availability of water with increases in solute suction. Genotypic response to shoot and root growth at different salinity levels are obvious and one genetically controlled (EPSTEIN & NORYLIN 1977). References BISHNOI, U.R. & D.R. PANCHOLY. 1980. Comparative salt tolerance in triticale, wheat and rye during germination. Plant and Soil. 55: 491-493. EPSTEIN, E. 1977. Genetic potentials for solving problems of soil mineral stress: adaptation of crops to salinity. pp 73-82 EPSTEIN, E. & J. D. NORYLIN. 1977. Sea water based crop production a feasibility study. Science 197: 249-251. HELAL, M.H. & K. MENGEL. 1981. Interaction between light intensity and NaCl salinity and their effects on growth, CO2 assimilation and photosynthetic conversion in young broad beans. Plant Physiol. 67: 999-1002. JANA, M.K., S. JANA & S.N. ACHARYA. 1980. Salt tolerance in heterogeneous populations of barley. Euphytica 29: 409-417. MAAS, E.V. & G.J. HOFFMAN. 1977. Crop salt tolerance - current assessment. ASCE. J. Irng. & Drainage Div. 103, 115-134. MAAS, E.V. & R.H. NIEMAN. 1978. Physiology of plant tolerance to salinity. In: Crop Tolerance & suboptimal land conditions. Chap. 13: 277-299. STROGONOV, B.P. 1962. Physiological basis of salt tolerance of plants. Jerusalem: Trs. Program for Sci. Transl. 279. |
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