Screening And The Differences In Cadmium Accumulation,distribution Under Iron Application Of Cd Resistant And Sensitive Rice Cultivars

Cadmium contamination became a critical environmental concern around the globe.It poses a huge threat to human beings through the consumption of contaminated foods.Rice is the main source of dietary in China.However,the agricultural soils,mainly rice-producing provinces are polluted by heavy metal particularly Cd.Its consumption contributed to 56%of Cd intake in humans in China.To handle with the negative impact of Cd,screen out sensitive and resistant rice cultivars against Cd stress and Fe was supplied to two rice cultivars,to alleviate Cd toxicity effects on rice cultivars.First,the seed germination percentage,seedling growth parameters,relative water content and vigor index in all 10 rice cultivars under Cd treatments were significantly decreased.Although,the maximum uptake of Cd was recorded at 100?M of Cd in all cultivar while Lu 9803 and Qi 908 accumulated less Cd than other cultivars.The Lu 9803and Qi 908 attained the maximum biomass and relative water content,while non-significant difference was observed for germination percentage and vigor index among all cultivars.Subsequently,the maximum decreased in growth parameters and biomass was recorded in Shan 63.To support the above results,the same ten cultivars of rice were exposed to the same levels of Cd concentration in twenty days of seedling after germination.It was found that the Cd application reduced the root and shoot lengths,fresh and dry biomass and increased antioxidant enzyme activity in all ten cultivars.As the maximum reduction in growth and biomass was found at 100?M of Cd in Shan 63 cultivar and the minimum were observed in Qi 908 and Lu 9083.The antioxidant enzymes activities,superoxide dismutase?SOD?,peroxidase?POD?,and catalase?CAT?increased in aerial part under Cd toxicity especially in Qi 908 and Lu 9083.These results showed that the Cd toxicity,at germination and seedling stage drastically affected the plants growth,biomass,nutrient uptake and antioxidant enzyme activities.Furthermore,it was found that Lu 9803 cultivar proved to be resistant while Shan 63 was more sensitive vis-à-vis to Cd.Therefore,it is how they were selected to be used as tolerant and sensitive cultivars,respectively for the rest of our experiments.Secondly,the study about the evaluation of the interactive effects of Cd and Fe at seedling stage in rice showed that the biochemical and physiological processes were affected when Cd was applied alone while a significant increase was observed in growth and antioxidant enzyme activities when Fe was applied.The maximum growth index and antioxidant enzymes activities were observed in Lu 9803.The SOD,POD and CAT values were higher under 100?M Cd and gradually decreased with Fe application at 50and 100?M respectively in Lu 9803 and Qi 908.The Cd concertation in roots increased with the application of Fe while in shoots,its supplying reduced Cd uptake.Although,the total Cd uptake was higher in Lu 9803 under Fe application while most of the Cd concentration was accumulated in roots.The maximum Fe was recorded in Lu 9803 as compared to Shan 63.The results suggested that Fe application at a degree of concentration could antagonistically affect Cd on rice cultivars and decreases its uptake by blocking it in roots.Which is dependent on the genotypic variation of rice.Thirdly,to assess the rice cultivars response under Cd stress with or without Fe application and their interactive effects at maturity stage,a pot experiment was conducted in greenhouse.The results illustrated that the fresh and dry mass,biological yield,1000-grain weight,straw,and grain yield drastically decreased under Cd toxicity.While Fe application with or without Cd enhanced all these cited parameters however the maximum increased was recorded in Lu 9803.The Cd application reduced Fe concentration from an early stage to the vegetative stage.While Fe supply significantly enhanced Fe uptake in rice tissue during the growth period.The maximum Fe in grains was accumulated in Lu 9803 with and without Cd application.Shan 63 accumulated much more Cd in grains regardless of Fe application.It could be concluded that Lu 9803was a Fe responsive cultivar,since it accumulated more Fe.Furthermore,the addition of Fe decreased the Cd-induced toxic effects and improved the growth of rice cultivars under Cd stress.Subsequently the growth ratio of Lu 9803,biomass,Fe uptake,and yield production were much higher than those of Shan 63.These results suggested that the fact of uptake less Cd and more Fe in rice tissues might be due to competitive interaction between both Cd and Fe from soil to root and root to shoot.These findings suggested that the application of Fe in Cd polluted environment could be a useful/effective approach to counteract Cd effects.It also improves the rice growth and production therefore economically less cost-effective.In conclusion,this study enlightened that the context of remediation and alleviation of heavy metal instead of being limiting on chemical and physical approaches.The interactional effect of essential and non-essential element which might have potential as competitive element for divalent metal such as Cd²⁺and provide positive influence on both plant health and food security.