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Irrigation of agricultural crops without the control of some quality parameters, associated with the indiscriminate use of artificial fertilizers, tends to increase the pollution of surface and groundwater. However, the present study aimed to evaluate the quality of groundwater levels of an agricultural property, melon production irrigated, located in the community of PauBranco in Mossoró (RN). To accomplish this study, water samples were collected from 13 drilled tube wells in an area located in the limestone Jandaíra domain, held during the year of 2012. Water samples collected were subjected to some physicalchemical analysis of water quality parameters according to the APHA (2005), especially the electric conductivity; concentration of nitrate and potential hydrogen. Data were analyzed using descriptive statistics using, the mean (M) of the standard deviation (SD) and the minimum and maximum values of the data. To assess the accuracy of the experimental data, we used the coefficient of variation (CV), according to the classification proposed by Pimentel- Gomes(1985).Were used non parametric tests in order to adjust the data to a normal distribution with 5% significance. The parameters studied were also evaluated by the quality control charts of Shewhart From this statistical assessment and according to the classification proposed by Ayers and Westcot (1999), it is noted that the results in the evaluated period, of the values of salinity and water nitrate concentration of these wells were classified as to the degree of restriction for use as mild to moderate. The results of the mean pH values exhibited acceptable limits within a normal range for use in irrigation water, culture melon. [ABSTRACT FROM AUTHOR]

Apesar de ser uma planta com necessidades hídricas relativamente baixas, o abacaxizeiro tem demanda permanente de água, variável ao longo do ciclo e dependente do seu estádio de desenvolvimento. Assim, objetivou-se analisar volumes de irrigação no desenvolvimento vegetativo, no rendimento da fruta e na otimização do abacaxizeiro cv. Pérola. O experimento foi realizado na Universidade Federal de Sergipe, município de São Cristóvão (11degrees01'S, 37degrees12'W), no delineamento em blocos ao acaso, com quatro tratamentos (lâminas de água) (100% da evaporação do tanque Classe A (523,7mm ano-1); 75% da evaporação do tanque Classe A (392,8mm ano-1), 50% da evaporação do tanque Classe A (261,8mm ano-1) e 0% da evaporação do tanque Classe A, seis repetições e 12 plantas úteis por parcela. O sistema de irrigação foi por aspersão convencional disposto em linha, com pressão de 20mca e vazão de 1,33m3 h-1. A área foliar (cm²) mínima atingida de 4552,6cm² foi observada no volume de água de 122,9mm ano-1, enquanto a massa seca das folhas (147,6g) foi constatada com 17mm ano-1. O máximo comprimento da folha D (88,9cm) foi estimado com 532,7 mm ano-1. Já o máximo comprimento do fruto (23cm) foi observado na lâmina de 296,9mm ano-1. A massa do fruto máxima estimado de 1.736g foi constatado na lâmina de 356,4mm ano-1. No contexto, a irrigação contribui de forma positiva no desenvolvimento vegetativo e rendimento da fruta do abacaxizeiro. Ressalta-se remuneração mensal líquida de R$ 1.161,17ha-1, quando se adota lâmina de irrigação de 356,4mm ano-1.

Plant endogenous mechanisms are not always sufficient enough to mitigate drought stress, therefore, the exogenous application of elicitors, such as salicylic acid, is necessary. In this study, we assessed the mitigating action of salicylic acid (SA) in cowpea genotypes under drought conditions. An experiment was conducted with two cowpea genotypes and six treatments of drought stress and salicylic acid (T1 = Control, T2 = drought stress (stress), T3 = stress + 0.1 mM of SA, T4 = stress + 0.5 mM of SA, T5 = stress + 1.0 mM of SA, and T6 = stress + 2.0 mM of SA). Plants were evaluated in areas of leaf area, stomatal conductance, photosynthesis, proline content, the activity of antioxidant enzymes, and dry grain production. Drought stress reduces the leaf area, stomatal conductance, photosynthesis, and, consequently, the production of both cowpea genotypes. The growth and production of the BRS Paraguaçu genotype outcompetes the Pingo de Ouro-1-2 genotype, regardless of the stress conditions. The exogenous application of 0.5 mM salicylic acid to cowpea leaves increases SOD activity, decreases CAT activity, and improves the production of both genotypes. The application of 0.5 mM of salicylic acid mitigates drought stress in the cowpea genotype, and the BRS Paraguaçu genotype is more tolerant to drought stress.

Global climate changes have intensified water stress in arid and semi-arid regions, reducing plant growth and yield. In this scenario, the present study aimed to evaluate the mitigating action of salicylic acid and methionine in cowpea cultivars under water restriction conditions. An experiment was conducted in a completely randomized design with treatments set up in a 2 × 5 factorial arrangement corresponding to two cowpea cultivars (BRS Novaera and BRS Pajeú) and five treatments of water replenishment, salicylic acid, and methionine. After eight days, water stress decreased the Ψw, leaf area, and fresh mass and increased the total soluble sugars and catalase activity in the two cultivars. After sixteen days, water stress increased the activity of the superoxide dismutase and ascorbate peroxidase enzymes and decreased the total soluble sugars content and catalase activity of BRS Pajeú plants. This stress response was intensified in the BRS Pajeú plants sprayed with salicylic acid and the BRS Novaera plants with salicylic acid or methionine. BRS Pajeú is more tolerant to water stress than BRS Novaera; therefore, the regulations induced by the isolated application of salicylic acid and methionine were more intense in BRS Novaera, stimulating the tolerance mechanism of this cultivar to water stress.

The association between population increase and the exploitation of natural resources and climate change influences the demand for food, especially in semi-arid regions, highlighting the need for technologies that could provide cultivated species with better adaptation to agroecosystems. Additionally, developing cultivation technologies that employ waste materials is highly desirable for sustainable development. From this perspective, this study aimed to evaluate whether seed priming with glass waste microparticles used as a silicon source under red light irradiation mitigates the effects of thermal and water stress on seedlings of Moringa oleifera . The experimental design was set up in randomized blocks using a 2 × 2 × 2 factorial arrangement consisting of seed priming (NSP-no seed priming, and SPSi-seed priming with glass microparticles under red light irradiation), soil water replenishment (W50-50%, and W100-100% of crop evapotranspiration-ETc), and temperature change (TC30°-30 °C day/25 °C night and TC40°-40 °C day/35 °C night). Seed priming with glass microparticles under red light irradiation mitigated the effects of thermal and water stress on seedlings of Moringa oleifera seedlings through the homeostasis of gas exchange, leaf water status, osmotic adjustment, and the antioxidant mechanism.

Improving plant germination is essential to guarantee better quality seedlings. Thus, this research aimed to evaluate whether the seed priming with light quality (LIQ) and the aqueous extract of Cyperus rotundus (AEC) tuber could modulate the germination and initial growth of Moringa oleifera L. seedlings. The experimental design was a completely randomized in the 4x4 factorial scheme, composed of four LIQ conditions (white, blue, red, and distant red light) and four AEC concentrations (0, 25, 50 and 100%). Seed priming with red light reduced the average emergence time, while blue, red, and extreme red lights associated with 50% of aqueous extract of C. rotundus increased shoot initial length and photosynthetic pigment accumulation. Seed priming with blue light resulted in seedlings with a shorter final shoot length. However, application of 100% of aqueous extract of C. rotundus reversed this. The white light in combination with concentrations of 50 and 100% of AEC promoted a higher relative shoot growth rate of seedlings. The research revealed that seed priming with light quality and aqueous extracts of C. rotundus tubers modulates the germination and initial growth of M. oleifera seedlings. More work needs to be done to determine the responsible compounds in AEC that is responsible for priming growth as phytohormones.