Abstract
Cadmium (Cd), being a heavy toxic metal present in soil-plant system, not only abridged the bio-availability of nutrients but also retarded plant growth by instigating modulations in rhizospheric zone. The main objective of present research was to evaluate the Cd induced variations in rhizospheric soil and plant ion dynamics as well as in planta physico-biochemical traits of two maize hybrids differing in Cd tolerance. One Cd-tolerant (3062) and one Cd-sensitive (31P41) maize cultivar was grown in soil spiked with 0, 20, 40, 60 and 80 mg/kg CdCl2. The plants were harvested at after thirty days of cultivation and analyzed for various elemental, physiological and biochemical parameters. The experimental soil samples were analyzed for different characteristics before and after cultivation. The results revealed that the maize cultivars were significantly modulating the rhizospheric ion dynamics, when stressed by Cd. Cadmium toxicity in sensitive cultivar (31P41) exhibited more prominent reduction in leaf area, chlorophyll a, b, carotenoids, root and shoot biomass, total protein contents and catalase activity as compared to the tolerant one. Increase in applied Cd stress significantly elevated the production of MDA, total proline, phenolic content and production of antioxidant enzyme (SOD, POD) in tolerant cultivar as compared to the sensitive one. The uptake and translocation of N, P, K, Ca2+, Mg2+, Zn2+ and Fe2+ from rhizosphere and root cell sap was found significantly higher in tolerant cultivar (3062) in contrast with sensitive one (31P41) under Cd stress. The summary of the outcomes elaborated that the Cd as a divalent ion which compete with other nutrients and reduced there uptake and translocation factor, which in response retarded the growth and metabolism in maize plant. The results are more devastating in sensitive 31P41 as compared to the tolerant one. The translocation and bio-accumulation of Cd point out the relevance of Cd tolerant cultivar (3062) to be used in future remediation plans.
Key Words: Maize, Rhizosphere, Ion dynamics, Biogeochemistry, Biochemical attributes.