investigation of cadmium uptake in root region and accumulation in different parts of common summer crops in iran

the main source of heavy metals in soil is the use of urban and industrial waste water, synthetic phosphate fertilizers, sludge from sewage treatment plants. most heavy metals accumulate in the top soil and in the long term, their increased concentration in the soil and accumulation in the plants. the quantity or level of absorption in plants, depends not only on the concentration levels of the metals in the physical and chemical composition of the soil, but also varies in different parts of the plant type. several studies have been conducted on the use of waste water and sewage, carrying heavy metals, for agriculture; however information regarding amount of absorption and accumulation of heavy metals in various parts of different crops and plant types, is limited. this study has been conducted with the objective of analyzing the impact of various levels of cadmium concentration in soil on the quantity of its absorption and accumulation in various parts of five different types of cucurbits, commonly used in iran. the experiments were carried out in a factorial experiment in completely randomized design, with three repetitions. the factors includes cd concentration in 4 levels (control treatment, without adding cd, soil with  50 mg kg-1 cd, soil with 50 mg kg-1 cd, soil with 50 mg kg-1 cd and irrigation water with 0.5 molar edta). and plants species (five summer crops) at the end of agriculture season, samples from different organs of species have been collected to measure the magnitude of cadmium accumulated in them. with spss software, variance analysis of the collected data was performed, and comparison of means was performed by duncan multiple range test (p ≤ 0.05 and p≤ 0.01). the obtained results indicate a direct relation between cd accumulation and cd concentration in root region. adding 0.5 molar edta to irrigation water causes more than 50 percent increase in cd accumulation in treatment of 50 ppm cd. also the results show (except in control treatment) that cd concentration is in excess of limit for human consumption.