Effects of Melatonin-Soaked Seeds on the Cadmium Accumulation in Broadbean (Vicia faba) Seedlings

Abstract

In order to discuss the melatonin (MT) on the growth and cadmium (Cd) accumulation in vegetables, broadbean (Vicia faba) seeds were soaked in five doses (0, 50, 100, 150 and 200 µmol/L) of MT and then planted in pots containing Cd-contaminated soil. Different doses of MT increased the biomasses of broadbean seedlings' roots and shoots compared with the control, with 200 µmol/L of MT producing the maximum values. MT effectively decreased the Cd contents in roots and shoots of broadbean seedlings compared with the control, and the maximum reduction rate of 29.29% occurred at the 200-µmol/L MT dose. Thus, MT could promote broadbean growth and reduce Cd accumulation in broadbean, with 200 µmol/L being the optimum dose in this experiment. Materials and Methods Materials. Local varieties of broadbean grown in Chengdu, Sichuan Province, China were used in this study. The soil samples were fluvo-aquic soils, which were collected from the Chengdu Campus Farm of Sichuan Agricultural University (30°42′ N, 103°51′ E) in October 2015. The soil basic properties and its Cd content were described in Liu et al. (2015) [7]. Then, 0.5 kg of air-dried soil was placed into each polyethylene pot (10-cm high, 8-cm diameter). Cd (CdCl 2 •2.5 H 2 O) was added to the soil samples at a dose of 10 mg/kg according to [8]. The soil moisture was maintained at 80% of field capacity for one month. Experimental Design. In November 2015, the seeds of broadbean were soaked in different doses (0, 50, 100, 150 and 200 µmol/L) of MT for 48 h. A 50-mL solution soaked approximately 15 seeds.