Abstract:

To explore the tolerance of hemp to heavy metals and provide data support for future phytoremediation of heavy metal contaminated soil, we used ‘Long Dama 5' and ‘Hei Nong 84' as experimental materials, conducted pot experiments to study the effect of spraying different contents of Cd²⁺ in the soil on the growth and development of hemp and soybean seedlings. The results show that low content of Cd²⁺ (≤ 0.6 mg/kg) could slightly promote the root activity and dry matter content of hemp and soybean. When the concentrate of Cd²⁺ is between 2.0-20 mg/kg in soil, the growth of hemp and soybean are inhibited. Compared with T₀ treatment (in hemp), the emergence rate of hemp of T2, T3 and T4 are decreased by 6.3%-100%, the root activity is decreased by 5.8%-77.8%, and dry matter content is decreased by 6.6%-40.2%. Compared with T₀ treatment (in soybean), the emergence rate of soybean of T2, T3 and T4 are decreased by 21.6%-100%, the root activity is decreased by 8.9%-100%, and the dry matter content is decreased by 27.4%-50.1%. When the content of Cd²⁺ in soil is more than or equal to 100 mg/kg, the emergence rate of hemp and soybean are zero. The tolerance of hemp to cadmium is higher than that of soybean. For the plots with serious heavy metal pollution, it is suggested that hemp should be planted prior to soybean.

Key words: soil, cadmium, hemp, soybean, seedling, growth and development