ABSTRACT
Heavy metal (HM) stress is an important abiotic stress along with drought, salinity, extreme temperature, etc. Specifically, HM pollution causes potential risk for crop yield and in turn for human beings. In the present study, screening of HMs on sorghum (Sorghum bicolor) and horse gram (Macrotyloma uniflorum) seed germination and seedling growth were carried out. Particularly, screening of non-essential chromium (Cr) on seeds of sorghum including horse gram and essential manganese (Mn) on seeds of sorghum were performed under in vitro conditions. In addition, physiological, and biochemical aspects were studied to assess the growth promotion or damage in both Cr and Mn treatments. The percentage of sorghum seed germination was reduced with increasing chromium concentration. In contrast, seed germination was unaffected in horse gram even in a high concentration of chromium. In extent, increasing chromium doses reduces the root and shoot lengths of both sorghum and horse gram seedlings but the impacts were more in an earlier one. High concentrations of essential manganese exhibit a minor reduction in germination of sorghum seeds and root and shoot lengths of seedlings. Total chlorophyll contents were reduced with high concentrations of chromium or manganese in sorghum seedlings. But interestingly minor augmentation of total chlorophyll contents was noticed in horse gram seedlings with increasing doses of chromium. Proline contents were increased in 206all the HM treatments, but horse gram generated more proline in chromium treatment which indicates its chromium tolerance nature.
