Document Type : Original Article

Authors

• Faezeh Zaefarian ¹
• Maryam Sadegh ²
• Roghayeh Hasanpour ³

¹ Associate Professor, Department of Agronomy, Sari Agricultural Sciences and Natural Resources University, Sari, Iran

² M.Sc of Agronomy, Sari Agricultural Sciences and Natural Resources University, Sari, Iran

³ PhD of Agronomy, Sari Agricultural Sciences and Natural Resources University, Sari, Iran

Abstract

Introduction
Cadmium (Cd) is the most mobile heavy element in the soil. This element in plants has a negative effect on the main function of the plant such as photosynthesis, cell proliferation, and water uptake by plant roots. Resistance adaptation of some plants allows them to store high concentrations of heavy metals in their tissues without symptoms of poisoning, which eliminates them and revitalizes the environment. Corn (Zea mays L.) is able to continuously extract metals from contaminated soils by transferring them from roots to shoots. Corn was also a promising crop for phytoremediation due to its extensive root system, high biomass, and compatibility with cadmium soils. Also, legumes such as soybeans (Glycine max L.) can accumulate heavy metals in their tissue, and their interaction with B. japonicum is an important aspect influencing the behavior of soybeans under heavy metal stress. Mixed culture is a common cropping method that increases biomass. The use of this method in plants intended for plant extraction is of great importance because in contaminated soils it affects the uptake of heavy elements by plants. Therefore, due to the importance of soil contamination with heavy elements, this study was designed to investigate the effect of mono and mixed corn and soybean culture on cadmium contaminated soil.
Materials and methods
This experiment was performed in the greenhouse of Sari Agricultural Sciences and Natural Resources University as a factorial in a completely randomized design with four replications. The first factor of cadmium concentrations was 0, 50, 100, 150 and 200 mg kg-1. The second factor was corn and soybean cultivation ratios (maize in pure cultivation, soybean in pure cultivation, corn in mixed cultivation and soybean in mixed cultivation with a ratio of 50: 50). The seeds were planted in 5 kg pots. The density was four plants in the pot was considered. Two months after sowing, the plants were harvested. Pre-harvest measurement traits included plant height and stem diameter and post-harvest measurement traits included shoot dry weight, root dry weight, cadmium concentration of shoot and root, and cadmium concentration in soil.
Results and discussion
The results showed that the concentration of cadmium in maize shoots in both mono-culture and mixed culture systems was higher than soybean and mixed cultivation, especially at high levels, increased the concentration of cadmium in maize and soybean shoots. Also, with increasing the levels of heavy metal, the concentrations of cadmium in the roots increased linearly in all culture systems. Maize had more ability to uptake and concentrate metals in its roots than soybeans, and mixed cultivation of maize and soybeans increased the concentration of cadmium in the roots of maize and soybeans. In this experiment. The highest concentrations of root cadmium in mixed maize and soybean crops were recorded 105.97 and 60.46 mg kg-1, respectively.
Conclusion
Dry weight of maize and soybeans was lower in mixed than pure cultivation, which seems to be the main cause of the higher uptake of cadmium in plant organs under mixed culture conditions. In general, the ability of maize to phytoextraction is higher than soybeans due to its higher biomass.

Keywords

• Dry weight
• Heavy metals
• Root
• Shoot

20.1001.1.22287604.1402.16.2.10.3

Main Subjects

• Heavy metals