EFFECT OF SUCROSE INDUCED OSMOTIC STRESS ON CALLUS GROWTH AND BIOCHEMICAL ASPECTS OF TWO WHEAT GENOTYPES

The research work was carried out to study the effect of sucrose induced osmotic stress on callus growth and biochemical aspects of two wheat genotypes (S-24 and MH-97). The seeds were cultured on Linsmaier and Skoog medium containing 30g sucrose, 8g agar, 5mg L -1 thiamine HCl and 3mg L -1 2, 4-Dichlorophenoxyacetic acid. One month old calli were subcultured for 15 d in liquid LS-medium supplemented with same concentration of thiamine HCl and 2,4-D. and different concentrations of sucrose [control, (3%), 4%, 6% 5% and 8%]. After 15 d of sucrose induced osmotic stress the results revealed that relative growth rate (fresh), macro cations (K + , Ca 2+ , Mg 2+ )and micro cations (Mn 2+ , Fe 2+ ) significantly decreased, while dry weight, free proline, total soluble carbohydrates contents and water relation parameters significantly increased (more negative) as concentration of sucrose increased in the culture medium. The effects of sucrose induced osmotic stress was greater on MH-97 than S-24.It is concluded that increasing sucrose concentrations in the medium above control caused osmotic stress and it also been found that accumulation of free proline and total soluble carbohydrates accumulated in greater amount responsible for turgor maintenance and increase in callus dry weights.