Dr. Flávio José Rodrigues Cruz is a native of Brazil and he received his Ph.D. in Agronomy (Crop Production) from São Paulo State University “Julio de Mesquita Filho”, Câmpus Jaboticabal, Brazil. He has a postdoctoral degree in Agronomy (Crop Production) from the São Paulo State University “Julio de Mesquita Filho”. He has expertise in water, salt and metal stress and his main research focuses are selenium biofortification and toxicity, water and salt stress.
Selenium is an essential mineral element to humans and animals because it is an important component of selenoproteins that are important for functioning of the metabolism. Because of poor soil conditions in various regions of the world, the enrichment of edible plants with selenium via the biofortification strategy has been implemented. However, selenium in the context of plant mineral nutrition appears twofold due to its biofortifying character at low concentrations and toxicity at high concentrations. In this sense, understanding of the functional mechanisms in which selenium is involved is important, ranging from its absorption and assimilation in organic compounds to its beneficial or harmful effects, considering its role in food security and human health. Therefore, this chapter addresses the key aspects related to selenium in the soil-plant-man environment and the narrow limit between biofortification and toxicity, as well as the main scientific findings on this mineral element in the biochemical, physiology and plant nutrition contexts.
Part of the book: Superfood and Functional Food
Although it is not an element with structural function in plants, potassium (K) is demanded in considerable quantities by plants due to multifunctional role in plant physiology and metabolism. Nevertheless, the interface of plant mineral nutrition and food safety evidences needs for a better understanding of functional mechanisms of this nutrient in plants, taking into account its management in hydroponic cultivation and food production with nutritional quality. Thus, the nutritional content of K in vegetables is indicative of post-harvest and nutritional quality. This fact is important considering that modern life has induced increased consumption of processed foods whose preparation implies reduction of K levels and increase of Na levels, with the consequent low K intake and appearance of diseases related to insufficient intake. Therefore, the present chapter aimed to address main nutritional, physiological, and biochemical aspects of K in a context of hydroponic plant production and importance of potassium nutrition to human health.
Part of the book: Potassium
Copper (Cu) is an essential micronutrient for plants because it participates in several redox reactions and the structural constitution of the Fe–Cu cluster. Although it is required in small concentrations at toxic levels, Cu triggers physiological and biochemical disorders that reduce plant growth. In higher plants, the normal range of Cu concentration is in the range of 2–20 mg Cu kg−1 DW. Above the upper limit of this range, Cu toxicity may occur if the plants are not tolerant to the stress caused by toxic levels of Cu. In view of the growing agricultural and industrial activity that are the main sources of Cu addition in nature, understanding the physiological and biochemical mechanisms of Cu toxicity in plants constitutes an important tool for the selection of more tolerant genotypes based on biochemical and physiological indicators to heavy metal stresses. In this chapter, we propose a systematic review of plants grown under toxic levels of Cu, based on the responses of physiological, biochemical, and nutritional variables. Understanding these responses will contribute to improving the understanding of the basic mechanisms of stress tolerance by toxic levels of Cu in higher plants, providing valuable information for the improvement of genotypes resistant to toxic levels of Cu in the plant culture medium.
Part of the book: Advances in Plant Defense Mechanisms
Human activity has contributed to the intensification of climate change. These climate changes cause a reduction in plant growth and agricultural production due to increasingly frequent periods of water restriction. This effect can be more severe in tropical regions where the acid pH of the soil and the toxic levels of aluminum have a natural origin due to the weathering of the soils. In this context, water deficiency and aluminum toxicity alone or together promote biochemical and physiological changes in plants. This suggests the need to adopt soil management strategies that minimize the joint impact of these two abiotic stresses. Thus, liming and gypsum contribute to improving the edaphic environment, because they reduce the availability of toxic aluminum but increase the soil pH. In this chapter, we propose a systematic review of the isolated and combined effects of water deficiency and aluminum toxicity in plants based on physiological, biochemical, and nutritional variables. Thus, the understanding of these responses will improve the understanding of the mechanisms of tolerance to the two abiotic stresses, indicating the need to use soil correctives to minimize the effects of water deficiency and toxic aluminum in the soil on plant growth.
Part of the book: Abiotic Stress in Plants