Interactive effect of salinity stress and IAA on growth, water content (WC) and some relevant metabolic activities of three sorghum cultivars (45-days old) were studied. Dry matter (DW), water content and tolerance index (TI) of the tested sorghum cvs. differed in response to salinity. Cvs. Dorado and Hagen Shandawil tolerated salinity up to the level of 4 and 2 bar NaCl, respectively, while cv. Giza 113 did not show tolerance to salinity stress. This was accompanied with differences in accumulation of carbohydrate and nitrogen compounds. Proline accumulation seems to be in response to injury. It was positively correlated with the growth criteria in cv. Dorado (the most resistance cultivar) and to some extent in cv. Hagen Shandawil, while negatively correlated in cv. Giza 113 (the most sensitive cultivar). Salinity stress increased markedly the protein content in the salt sensitive cultivar (Giza 113), which was accompanied with a drastic reduction in growth and pigmentation. IAA ameliorated the inhibitory effect of salinity on the growth, increased carbohydrates and protein content of all the three cultivars. IAA, also markedly retarded the accumulation of proline in most cases. The relationship between salt tolerance of sorghum cultivars and the changes in proline content is discussed.
Amino acids, carbohydrate, indole acetic acid, protein, tolerance index, water content
