Germination, seedling growth, some organic solutes and peroxidase expression of different Vicia faba lines as influenced by water sterss

Abstract

The effect of water stress on the germination, seedling growth, organic solutes, peroxidase pattern and peroxidase activity of different Vicia faba lines was studied. Studies on germination in polyethylene glycol and in soil indicated that lines such as Line 2/4 which were able to germinate under water stress caused by high concentrations of polyethylene glycol, were also able to germinate and grow in soil with a low water content. While the fresh and dry masses of all the lines were markedly decreased as the water stress level increased, Line 2/4 exhibited higher dry matter than the other lines tested. Pigment contents were more or less unchanged in some lines (102, 159 and 2/4) but increased in others (67 and 103) as the stress level increased. In general, the soluble sugar, soluble protein, free amino acid and proline contents in the shoots and roots of all the tested lines progressively increased as the stress level increased. These values were higher in the plant shoots than in the roots except for Line 2/4, which was the only one that could be grown at 30 % field capacity, and which accumulated soluble sugars and free amino acids in the roots rather than in the shoots Differences in the peroxidase (POX) pattern were found among the roots and shoots of the tested lines. Under drought stress, the number and staining intensity of the POX bands as well as the POX activity were lower in the shoots than in the corresponding unstressed control plants, especially in the sensitive line (159). In the plant roots, while the number of peroxidase isoenzymes and peroxidase activity were reduced in the sensitive line, they were unaffected in the resistant line (2/4).