Cadmium-induced alterations in morpho-physiology of two peanut cultivars differing in cadmium accumulation

This study examines differences in the morpho-physiological responses of low- and high-cadmium (Cd) accumulating peanut (Arachis hypogaea L.) cultivars to Cd stress. The biomass, Cd accumulation, leaf gas exchange, root morphology, root respiration, and hydraulic conductivity of Qishan 208 (low-Cd accumulator) and Haihua 1 (high-Cd accumulator) were determined via a hydroponic experiment. Exposure of peanut plants to 2 and 20 mu M Cd considerably decreased their shoot biomass, net photosynthetic rate, transpiration rate, stomatal conductance, total root length, number of root tips, root respiration, and hydraulic conductivity. The root biomass, root surface area, and average diameter were unaffected by Cd exposure. The two cultivars differed in Cd accumulation and morpho-physiological responses to Cd stress. Qishan 208 accumulated less Cd in plant tissues but was more sensitive to Cd stress than Haihua 1. The total root length, surface area, average diameter, number of root tips, and root respiration rate of Haihua 1 were significantly higher than those of Qishan 208. The well-developed root system and higher root respiration of Haihua 1 may be responsible for its high Cd accumulation capacity.