effects of silicon on the physiological, quality and quantity characteristics of common bean (phaseolus vulgaris) under salinity stress

salinity is the major limiting factor for plant growth and crop productivity. salt stress is effective on physiological characteristics, morphology, anatomy, chemical composition and water content of plant tissue. pulses are the second of food source after the cereals for human. among the pulses, the bean has special importance. in order to investigate the effect of silicon on the physiological, quality and quantity characteristics of common bean, an experiment was conducted as factorial based on randomize completely design with 3 replications in the research greenhouse of agriculture faculty of birjand university in 2011. treatments were including of 5 levels soil salinity (1, 2, 3, 4, 5 ds.m-1) and 4 levels silicon (0, 0.5, 1, 2 mm). the results of analysis of variance showed that the increasing of salinity caused significant reduce in leaf water content, total dry weight, protein content, protein yield and grain yield. but in contrast, salinity caused a significant increase in proline concentration and the concentration of soluble sugars of the plant. silicon is also imposed a significant effect on leaf water content and proline concentration in leaves. finally it could be concluded that using of si in salinity condition reduced harmful effects of salinity on the physiological, quality and quantity characteristics of the bean plant.