engleski

Uptake and distribution of Cd in soybean (Glycine max (L.) Merr.)

Heavy metal Cd is a cumulative poison and poses a threat to the environment due to its extreme toxicity, and is known to elicit an oxidative stress in plant cells. Almost 50% of Cd that enters the living organisms is introduced through food of plant origin (vegetables, fruits and grains). Besides other origins of soil contamination with Cd, it may be introduced into the soil solution by phosphorus fertilizers which may contain Cd as an impurity. Therefore, our aim was to assess the effect of Cd on growth of soybean plants and their potential to uptake and accumulate Cd from the nutrient solution. Seeds of four soybean cultivars (NS-OPTIMUS, NS-MAXIMUS, KORANA and TENA) were germinated in dark at 26°C in sterilized sand. After four days of germination, the seedlings were transferred to pots containing ½ strength Hoagland nutrient solution. Plants were grown in a greenhouse, under semi-controlled conditions. When the first trefoil developed, CdCl2 was added to the nutrient solution to attain 0 (control), 0.5, 5 or 50 µM final Cd concentrations. Twenty six days after treatment with Cd begun, plants were harvested. Cd content was analysed in dry matter of roots, stems, the youngest fully developed trefoil and the other leaves. Cd treatment reduced both fresh and dry mass of soybean plants. This reduction increased with Cd concentration in growth media. At 50 µM Cd in NS-OPTIMUS and NS-MAXIMUS root dry weight was only about 40% of the respective control whereas in Korana and Tena it was as much as 70%. Leaf dry weight, on the contrary, was much less reduced in NS-cultivars (80% and 93% of the control) whereas in Korana and Tena it was 45% and 57%, respectively. These two cultivars did not show plant dry weight decrease at 5 µM Cd. Percentage of dry matter increased in all cultivars and at all applied Cd concentrations, with the highest increase in leaves, implying tissue dehydration as an effect of Cd toxicity. Concentration of Cd in roots of all cultivars and at all Cd treatments was about 10 ppb. Surprisingly, concentration of Cd in stems and leaves was very similar to the one measured in roots. In general, higher differences were found in plant fresh and dry weight, as well as in dry matter percentage, depending on Cd treatment and cultivar, than in the concentrations of Cd in different tissues of tested soybean cultivars.

soybean ; cadmium ; heavy metal stress

nije evidentirano