Relationship between biomass, seed components and seed Cd concentration in various peanut (Arachis hypogaea L.) cultivars grown on Cd-contaminated soils

• Peanut cultivars exhibit large variations in Cd distribution and accumulation in seeds.
• Cd increases the protein content but does not affect the oil content in seeds.
• Cultivars with high biomass show low Cd accumulation in seeds.
• The content of soluble proteins is in positive correlation to Cd concentration in seeds.

Peanuts (Arachis hypogaea L.) exhibit high genotypic variations in seed Cd accumulation, but the mechanism remains unclear. This study aimed to reveal the main factors that determine Cd concentration in peanut seeds. The biomasses and Cd accumulation in plant tissues as well as the Cd distribution in the seeds of 15 peanut cultivars were analyzed in a pot experiment at 4 mg kg−1 Cd (treatment) and 0 mg kg−1 Cd (control). Peanuts exhibited large variations among cultivars in terms of Cd accumulation and distribution at the whole-plant and seed levels. The peanut cultivars were divided into three groups based on [Cd]embryos as follows: (i) high Cd accumulators (Zhenghong 3 and Haihua 1), (ii) low Cd accumulators (Qishan 208, Luhua 8, and Yuhua 15), and (iii) intermediate Cd accumulators (10 remaining cultivars). [Cd]embryos was significantly correlated with [Cd]testae and [Cd]oils at control conditions, whereas in the 4 mg kg−1 Cd treatment, [Cd]embryos was negatively correlated with plant biomass, total Cd and its proportion in vegetative organs, and seed oil contents. [Cd]embryos was positively correlated with protein contents, [Cd]oils, and proportion of Cd in protein extracts at 4 mg kg−1 Cd treatments. The attenuation of Cd by high biomass of vegetative tissues and Cd-binding proteins in seeds mainly determined the Cd concentration in peanut seeds.