-a 0,5 mM ou 8,0 mM) x 2 (NaCl a 0 mM ou 100 mM), com cinco repetições. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey a 5% de significância. A salinidade reduziu a área foliar e a massa seca da parte aérea e das raízes, sendo as plantas nutridas com NO 3 -a 8,0 mM menos afetadas que aquelas com NO 3 -a 0,5 mM. A condutância estomática, a fotossíntese, a transpiração e a relação entre a concentração interna e externa de CO 2 foram aumentadas pela melhor nutrição de NO 3 -. Os teores de Na + e Cl -foram significativamente aumentados pela salinidade em folhas e em raízes e os de K + foram reduzidos apenas nas raízes. Apesar disso, as plantas nutridas com NO 3 -a 8,0 mM apresentaram os menores teores de Na + e Cl -nas folhas sob estresse salino. A salinidade aumentou os teores de prolina e N-aminossolúveis e a maior concentração de NO 3 -no meio favoreceu o acúmulo desses solutos nas raízes de plantas estressadas. Uma adequada nutrição com NO 3 -foi capaz de reduzir os efeitos deletérios da salinidade nas plantas de sorgo sudão. Palavras-chave -Crescimento. Estresse salino. Nitrogênio. Solutos inorgânicos e orgânicos. Sorghum sudanense.Abstract -This work aimed to study the effect of NO 3 -nutrition on growth, on gas exchange and on inorganic and organic solutes accumulation of sudangrass plants subjected to salinity. Plants were grown in hydroponic medium and kept in a greenhouse. The experiment was a completely randomized design, following a factorial arrangement of 2 (NO 3 -at 0,5 mM or 8,0 mM) x 2 (NaCl at 0 mM or 100 mM), with five replications. All data were subjected to analysis of variance and the means were compared by Tukey's test at 5% of significance. Salinity reduced leaf area and dry weight of shoots and roots. However, plants growing in the 8.0 mM NO 3 -increased more than those growing in 0.5 mM. The stomatal conductance, photosynthesis, transpiration and the relationship between internal and external concentration of CO 2 were increased by better nutrition NO 3 -. Na + and Cl -contents were significantly increased by salinity in leaves and roots and the K + content was reduced only in the roots. Nevertheless, plants fed with 8.0 mM NO 3 -had the lowest contents of Na + and Cl -in leaves under salt stress. Salinity increased proline and amino acid contents and the higher NO 3 -concentration promoted the accumulation of these solutes in roots of stressed plants. Proper nutrition for NO 3 -was able to reduce deleterious effects of salinity in sudangrass plants.

ResumoO objetivo deste trabalho foi estudar o efeito do nitrato no crescimento e no acúmulo de solutos inorgânicos e orgâ-nicos em plantas de milho submetidas à salinidade. O delineamento experimental foi o inteiramente casualizado, com cinco repetições, sob esquema fatorial 2×4, constando de oito tratamentos: dois níveis de salinidade (NaCl a 0 e 75 mM) e quatro concentrações de NO 3 -(0,5; 2,5; 5,0 e 7,5 mM) em sistema hidropônico. A massa seca da parte aérea e das raízes foi reduzida pela salinidade, porém isso foi menos evidente quando as plantas foram submetidas a concentrações de NO 3 -abaixo de 2,5 mM. O melhor crescimento das plantas foi observado na concentração aproximada de NO 3 -a 5,0 mM. Os teores de Na + e Cl -aumentaram com a salinidade em todos os órgãos estudados, havendo maior acúmulo desses íons nas raízes. De modo geral, os teores de K + foram pouco afetados por esse estresse. Com o aumento da concentração de NO 3 -no meio, houve melhora na absorção desse íon, levando à redução da absorção de Cl -e ao acúmulo de prolina e N-aminossolúveis. O estresse nutricional é mais limitante ao crescimento das plantas de milho que o estresse salino, cujos efeitos prejudiciais são minimizados por uma nutrição de NO 3 -adequada.Palavras-chave: estresse salino, nitrogênio, solutos inorgânicos e orgânicos, Zea mays. Nitrate modulates the contents of chloride and N-compounds in maize plants under salinity AbstractThis work aimed to study the effect of nitrate (NO 3 -) on growth and accumulation of inorganic and organic solutes in maize plants subjected to salinity. The experiment was carried out in a completely randomized design, with five replications, and a 2×4 factorial scheme, consisting of eight treatments: two salinity levels (NaCl at 0 or 75 mM) and four different concentrations of NO 3 -(0.5, 2.5, 5.0 or 7.5 mM) in nutrient solution. The dry mass of shoots and roots was reduced by salinity, however, this was less evident when plants were exposed to concentrations of NO 3 -below 2.5 mM. The best growth was observed in the approximate concentration of 5.0 mM NO 3 -. The Na + and Cl -contents increased with salinity in all organs studied, and the highest accumulation of these ions was observed in the roots. In general, the K + content was not severely affected by this stress. With the increase of NO 3 -concentration in the medium, there was an improvement in the absorption of this ion, leading to reduced uptake of Cl -and the accumulation of proline and soluble amino acids. Nutritional stress is more limiting to plant growth of maize than the salt stress, with harmful effects being alleviated by an adequate nutrition of NO 3 -.

The use of agricultural pesticides in Brazil has significantly increased during recent decades, especially due to the competition between the internal Brazilian market and that for exports. Pesticides are among the most important risk factors for the health of the general population, especially workers, and the environment, resulting in a scenario of increased public spending on health and social damage due to pollution by such chemicals, with emphasis on organophosphates and carbamates. When these substances are managed incorrectly, such as when personal protection equipment (PPE) is not used, or when they are inadequately discarded without adhering to sanitary disposal guidelines, they can cause pollution and short- and long-term damage to health. This paper therefore surveys the knowledge base of small-scale farmers with respect to exposure to agrochemicals and the importance of use of PPEs. This qualitative and transversal study relied upon the voluntary participation of 64 residents of a rural area. The study was initiated after having received approval of the Committee for Ethics in Research, and after the participants signed an informed consent form. A questionnaire was given to the participants which used multiple choice and open-ended questions. All the participants stated that they use fertilizers and other agrochemicals, and that they do not use or only sporadically use PPEs. All the participants related that they have not had access to specialized technical assistance to help with proper use of agrochemical products, and that they store these products inadequately in their house or in other inappropriate places. These small-scale farmers do not use PPEs and underestimate the damage to their health and that of their family that can be caused by improper use of agrochemicals, and also demonstrate a lack of technical knowledge with respect to adequate management of these products.