Morph-physiological responses of two switchgrass (Panicum virgatumL.) cultivars to cadmium stress

Abstract

Two cultivars of switchgrass, ‘Alamo’ (lowland type) and ‘Cave-in-Rock’ (upland type), were used to examine the morph-physiological responses of plants to different cadmium (Cd) levels under hydroponic condition treated with 0, 10, 20 and 40 μmol L−1 CdCl2 for 2 weeks. The main results showed that both seedlings of ‘Alamo’ and ‘Cave-in-Rock’ can survive even in 40 μmol L−1 CdCl2 treatment. However, the growth of the two cultivars was significantly (at least P < 0.05) inhibited by Cd stress. The plant biomass, water content, photosynthetic pigments content, total root length (RL), root surface area (RA), root volume (RV) and number of root tips of two tested cultivars were significantly decreased after treatment with Cd. ‘Alamo’ showed higher capability of Cd translocation from root to shoot than ‘Cave-in-Rock’, but ‘Cave-in-Rock’ had higher capability of Cd uptake and accumulation than ‘Alamo’. ‘Cave-in-Rock’ accumulated higher Cd in root than ‘Alamo’, the root average diameter, RL, RA and RV at the root segment in 0.3–0.9 mm diameter in ‘Cave-in-Rock’ were dramatically higher than those of ‘Alamo’, which indicates that a well-developed root system may contribute to higher Cd accumulation in ‘Cave-in-Rock’. Above all, both ‘Alamo’ and ‘Cave-in-Rock’ could be cultivated in Cd polluted area. At the same time, they have bioremediation function, especially, this function of seedling in ‘Cave-in-Rock’ should be greater than ‘Alamo’, since the amount of Cd absorption and accumulation in ‘Cave-in-Rock’ was significant higher than ‘Alamo’.