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Toxic metals such as cadmium (Cd) are detrimental for growth of the crops. The differential sensitivity of maize and rice, the two vital cereals, which also belong to C₄ and C₃ plant types, respectively, to a similar degree of Cd stress is not known that comprised the objective of this study. Maize and rice genotypes were grown hydroponically in the presence of 5 and 10 μM cadmium (Cd) concentrations to examine their relative sensitivity to this metal at growth and metabolic levels. The shoots of maize genotypes accumulated relatively greater cadmium than those of rice while the roots of both the plant types did not differ significantly in cadmium accumulation. The shoots and roots of maize genotypes showed higher growth than rice genotypes under both Cd levels. At similar Cd level, the rice shoots showed greater damage to membranes and chlorophyll than maize shoots. The activities of RUBP carboxylase and phosphoenolpyruvate carboxylase were significantly greater in maize than in rice under Cd stress. Maize genotypes also possessed greater sucrose content and sucrose phosphate synthase activity in their shoots than rice genotypes. The oxidative damage as malondialdehyde and hydrogen peroxide was higher in rice genotypes. The rice genotypes showed greater induction of antioxidants such as superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and ascorbic acid than maize genotypes. On the other hand, glutathione, proline, metallothioneins, total thiols content and glutathione-s-transferase activity were significantly higher in maize genotypes under Cd stress suggesting their superior capacity to deal with Cd toxicity. The observations indicated that the maize genotypes representing C₄ plant type appear to have greater Cd tolerance than the rice genotypes representing C₃ plant type. The findings speculate that C₄ plant species may adapt to toxic metals such as Cd in a better way than C₃ ones but further study involving several representatives of these plant types need to be carried out to corroborate it.

Maydis leaf blight (MLB), a serious foliar fungal disease of maize, may cause up to 40% losses in yield. The present studies were undertaken to identify the stable sources of MLB resistance, its inheritance study, and testing of MLB resistance linked markers from diverse background in the Indian adapted tropical maize genotypes. A set of 112 inbred lines were screened under artificially created epiphytotics conditions at three hotspot locations. Analysis across multi-locations revealed significant effects of genotypes and environments, and non-significant effects due to genotypes × environment interaction on disease incidence. A total of 25 inbred lines with stable resistance were identified across multi-locations. Inheritance of resistance was studied in six F₁s and two F₂s of resistant and susceptible parents. The null hypothesis of segregation of resistance and susceptible for mono and digenic ratios in two F₂ populations was rejected by Chi-square test. The non-significant differences among the reciprocal crosses depicted the complete control of nuclear genome for MLB resistance. Partial dominance in F₁s and normal distribution pattern in F₂s of resistant and susceptible parents suggested polygenic nature of MLB resistance. Correlation studies in F₂ populations exhibited significant negative correlation between disease score and days to flowering. Five simple sequence repeats (SSRs) markers, found associated to MLB resistance in different studies were unable to differentiate amongst MLB resistance and susceptible parents in our study. This emphasizes the need of fine mapping for MLB resistance in Indian germplasm. The identified stable sources of resistance and information on inheritance study can be used further in strengthening of resistance breeding against MLB.