The impact of mineral accumulation, on the nutritive value of radish and lettuce

摘要

A study of the heavy accumulation of minerals in radishes and lettuce, using a randomized complete block the form of split-plot design, was commenced in three different areas south of Tehran and was repeated in three phases. The study considered three main factors including plots of land in the SALEHABAD district, DEHKHEIR village and TALEBABAD village, and two sub-factors including irrigation methods such as well water and sewage. Radish roots were found with high amounts of elements such as Nickel (Ni), Lead (Pb), Manganese (Mn), Chromium (Cr), Zinc (Zn) near wastewater irrigation areas in TALEBABAD district, whereas areas near SALEHABAD’s sewer system had the lowest uptake levels, thus resulting in different sizes of shoots. Also the size of roots and shoots varied substaintly by areas using sewer water, as there were differing accumulations of Ni and Pb, as well as Iron (Fe). It seems that radish leaves were able to control the transfer of Ni and Pb, but tend to guard against the transfer and accumulation of Fe. Thus, to prevent radish leaves absorbing high levels of Pb and Ni from roots, it is recommended not to use irrigation wastewater for radishes. Generally accumulated heavy transfers of minerals in radishes show that the control mechanisms of radishes have been very weak, and have often proven the weakest component of crops studied in the prevention of transmission of the root elements to the leaves, making it near impossible to use radish roots and shoots if wastewater irrigation has been used. All lettuce plants prevent transferring heavy accumulations of minerals in the soil and roots to their leaves, but this control mechanism does not include Ni, and Mn, thus large quantities of these elements were found, having been taken from the root to the leaves and gathered there. The area near SALEHABAD’s sewer system showed the highest concentration of Mn and other heavy elements among 10 regions, including the TALEBABAD. Mineral transfer control mechanisms were so severe that concentration of such minerals to lettuce leaves was much less than that accumulated in radish leaf. The study found among all the plants and vegetables grown for human use, lettuce plant has some of the best preventive measures against mineral accumulation in shoots.