Genotypic differences in effects of cadmium on yield and nutrient composition in Brassica plants

Cadmium (Cd) is one of the most toxic non-essential and mobile metallic elements found in soils which affects plant growth. A greenhouse experiment was carried out to determine the genotypic differences in effects of different levels of Cd application on yield and on the uptake of Cd and other nutrients in various Brassica plant parts. The B. juncea (Indian mustard) genotypes produced higher biomass of different plant parts than B. rapa. Significant differences in yield of various plant parts were noted between the treatments. The significant interaction was found between Cd treatment and genotype for yield in all the plant parts. Genotype Vardan had a much greater yield than other genotypes. There were significant reduction in yield of about 42% for seed, 41% for leaf, 14% for stem and 32% for root at 80 mg Cd kg soil than the control. Increase in Cd concentration of about 5 times in seed, 6 times in leaves and stem and 9 times in roots was noted significantly at 20 mg Cd kg than in control without affecting the respective dry matter yield. Root had higher concentrations of Cd at all the Cd levels than in other plant parts of Brassica genotypes indicating that there is limited transport of Cd from the root system to the above ground plant parts. The application of Cd increased concentration of Zn, Fe and Mn at lower levels but decreased at higher levels irrespective of genotype and plant part, however, the effect on P was negative even at lower levels of Cd. The B. juncea genotype Vardan outyielded all other genotypes at all Cd levels tried and was found to be most resistant to Cd toxicity and it had also much higher Cd concentration in different plant parts indicating that it has better absorbing ability than others and has higher potential for removing Cd from moderately Cd contaminated soils. The results of this study also show large, exploitable genotypic variation for tolerance to Cd toxicity in Brassica plants.