Ação do priming em sementes de arroz frente à contaminação do solo com cádmio

Abstract

Contamination of agricultural areas by cadmium (Cd), leading to ecological imbalance and affects the field. Cd toxicity can interfere in photosynthesis and in the activity of the antioxidant system of plants, competing in the assimilation of nutrients such as iron (Fe). Rice (Oryza sativa L.) is one of the most cultivated cereals in the world, part of the feeding of the world population and is one of the agricultural crops affected by soil contamination. Recently, new technologies involving the use of nanoparticles have obtained effective results in the decontamination of agricultural systems. Thus, using them in seed priming techniques can offer an improvement in the germination process in contaminated soils. The hypothesis of the study is that the priming of seeds with water (hydropriming) and with FeNPs (Fe2O3) (nanopriming) can increase germination and benefit the growth and development of rice plants growing in a substrate contaminated by Cd. Seeds of two rice cultivars, IRGA424 and IRGA417, unconditioned and subjected to nanopriming (0 and 100 mg L-1 FeNP) were grown in soil contaminated by Cd (0 and 5 mg L-1 of Cd (NO3)2), evaluated for growth through total dry mass (TDM), leaf area (LA), root length (RL) and field, and to quantifying the levels of Cd and Fe in the leaves and analysis of gas exchange and chlorophyll a fluorescence during panicle differentiation ( R1). The results indicate that nanopriming impacted the reduction of TDM and RL in the initial stages and in greater AF during flowering for the cultivar IRGA417. Plants grown in soil contaminated by Cd, on the other hand, showed a greater accumulation of MST in the initial stages and a decrease in the period of physiological maturation of the seeds to cultivate IRGA424 and in the harvest in IRGA417. Fe contents were higher in plants from unconditioned seeds and cultivated in uncontaminated soil of the IRGA417 cultivar. Only Cd was detected in the leaves of the cultivar IRGA424, but without significant differences in any of the priming conditions. There were no changes in the fluorescence variables of chlorophyll a and gas exchange, except for the highest values of liquid photosynthesis (A) in the cultivar IRGA417 exposed to nanopriming, regardless of soil contamination. The mass of grains per plant was lower in plants grown in contaminated soil and subjected to the hydropriming and nanopriming of the cultivar IRGA424. When in conditions of uncontaminated soil, hydropriming can represent gains in productivity, since it is a technique of easy application and affordable for farmers.