Effect of Salinity and Silicon Doses on Onion Post-Harvest Quality and Shelf Life.

Salt stress during pre-harvest limits the shelf life and post-harvest quality of produce; however, silicon nutrition can mitigate salt stress in plants. Thus, we evaluated the effects of salinity and fertilization with Si, in pre-harvest, on the morpho-physiological characteristics of onion bulbs during shelf life. The experiment was set up in randomized complete blocks, with treatments arranged in split-split plots. The plots had four levels of electrical conductivity of irrigation water (0.65, 1.7, 2.8, and 4.1 dS m-1). The subplots had five fertilization levels with Si (0, 41.6, 83.2, 124.8, and 166.4 kg ha-1). The sub-sub plots had four shelf times (0, 20, 40, and 60 days after harvest). Irrigation water salinity and shelf time reduced firmness and increased the mass loss of onion bulbs during shelf life. Salt stress reduced the contents of sugars and total soluble solids of onion bulbs during storage; however, Si supply improved the contents of these variables. Salinity, Si supply, and shelf time increased the concentrations of pyruvic and ascorbic acids in onion bulbs during shelf life. Si doses between 121.8 and 127.0 kg ha-1 attenuated the impacts caused by moderate salinity, increasing the synthesis of metabolites and prolonging the onion bulbs' shelf life.

Production and Physiological Quality of Seeds of Mini Watermelon Grown in Substrates with a Saline Nutrient Solution Prepared with Reject Brine.

The economically profitable production of crops is related, among other factors, to seed quality, the production system, and the water used in irrigation or preparation of nutrient solutions. Therefore, the objective was to evaluate the phenology, production, and vigor of seeds of mini watermelons grown in saline nutrient solution and different substrates. In the fruit and seed production phase, the experiment occurred in a greenhouse with five electrical conductivities of water for nutrient solution preparation, ECw (0.5, 2.4, 4.0, 5.5, and 6.9 dS m-1), and two growing substrates (coconut fiber and sand). We evaluated the physiological quality of seeds previously produced under the five electrical conductivities of water and two substrates. High salinities for the hydroponic cultivation of the mini watermelon cultivar 'Sugar Baby' accelerated fruit maturation and crop cycle, decreasing fruit size. However, in both substrates, the seed production of mini watermelons, seed viability, and seed vigor occurred adequately with a reject brine of 6.9 dS m-1 in the hydroponic nutrient solution. The seed production of 'Sugar Baby' mini watermelons using reject brine in a hydroponic system with coconut fiber and sand substrates is viable in regions with water limitations.

Photosynthetic Responses, Growth, Production, and Tolerance of Traditional Varieties of Cowpea under Salt Stress.

Cowpea is the main subsistence crop-protein source-for the Brazilian semi-arid region. The use of salt-stress-tolerant varieties can improve crop yields. We evaluated the effect of irrigation with brackish water on the growth, photosynthetic responses, production, and tolerance of fifteen traditional varieties of cowpea. The experiment was conducted in randomized blocks, in a 15 × 2 factorial scheme, composed of 15 traditional varieties of cowpea and two salinity levels of irrigation water (0.5 and 4.5 dS m-1), with five replicates. Plants were grown in pots containing 10 dm3 of soil for 80 days. The reduction in the photosynthetic rate of cowpea varieties occurs mainly due to the decrease in stomatal conductance caused by salt stress. Salt stress increased the electron transport rate and photochemical quenching of cowpea varieties, but stress-tolerant varieties increased the CO2 assimilation rate and instantaneous carboxylation efficiency. The Ceará, Costela de Vaca, Pingo de Ouro, Ovo de Peru, and Sempre Verde varieties are tolerant to salt stress. Salt stress decreases 26% of the production of tolerant varieties to salt stress and 54% of susceptible varieties. The present findings show the existence of variability for saline stress tolerance in traditional varieties of cowpea and that Ceará, Costela de Vaca, Pingo de Ouro, and Ovo de Peru varieties are more suitable for crops irrigated with saline water.

Fertigation with fish farming effluent at the adequate phenological stages improves physiological responses, production and quality of cherry tomato fruit.

The use of effluent from fish farming in the greenhouse increases the availability of water and reduces the risk of environmental contamination due to improper disposal. Therefore, a study in a greenhouse was carried out to evaluate the effects of fertigation utilizing fish farming effluent at different phenological stages of cherry tomato. Plants of cherry tomato were fertigated with fish farming effluent (E) alternated with tap water (W) at the four phenological stages of the crop (growth, flowering, fruit formation and ripening). The growth, gas exchange, chlorophyll a fluorescence, chloroplast pigments, electrolyte leakage, production and postharvest quality were evaluated. The fertigation with fish farming effluents did not reduce the growth of tomato plants. The fertirrigated plants with fish farming effluents obtained photosynthetic rates and photochemical efficiency similar or superior to the control. There was no interference on photochemical quenching when the plants were fertigated with fish farming effluents. When applied at the flowering stage, fish farming effluent reduces the average fruit weight and increases acidity. For greenhouse cultivation, each application of fish farming effluents, two successive applications of tap water are required.Novelty statement: Use of fish farming effluent did not compromise the growth and photosynthetic activity of cherry tomato plants. Cherry tomato production was compromised when the effluent was applied during growth, flowering and, beginning of fruit set. The fish farming effluent can be used in irrigation without yield losses if alternating with tap water.

Physiological responses and production of mini-watermelon irrigated with reject brine in hydroponic cultivation with substrates.

The scarce availability of good quality water for irrigation in semi-arid regions leads to the reuse of waters, such as reject brine. Associated with this, the use of alternatives, such as hydroponic cultivation in substrates suitable for the development of profitable crops, such as watermelon, a species considered moderately sensitive to salinity, will allow new opportunities for communities assisted by desalination plants. An experiment was conducted in a plastic greenhouse to evaluate the growth, physiological responses, yield, and fruit quality of 'Sugar Baby' mini-watermelon cultivated in a hydroponic system with reject brine from desalination plants and different substrates. The experimental design was randomized blocks, with treatments arranged in a 5 × 4 factorial scheme, corresponding to five mixtures of reject brine (9.50 dS m-1) and tap water (0.54 dS m-1) applied to mini-watermelon plants, in an open hydroponic system, with four types of substrate and four replicates, with two plants per plot. Mini-watermelon plants grown in coconut fiber substrate showed the best growth and production. On the other hand, washed sand was the substrate that most hampered the development of plants in all mixtures. The use of reject brine to prepare the nutrient solution reduced the growth and production of mini-watermelon, mainly in mixtures with salinity above 4.00 dS m-1. The changes in gas exchange caused by salt stress in mini-watermelon were of stomatal nature. Mini-watermelon has high energy stability under conditions of salt stress.

Ethnopedology in production units at Canto da Ilha de Cima, São Miguel do Gostoso-RN, Brazil / Etnopedologia em unidades de produção canto da ilha de cima, São Miguel do Gostoso, RN, Brasil

Ethnopedological studies in family units tend to contribute to the academy with respect to the importance of knowledge exchange, allowing the understanding on the local reality of a community. The objective of this study was to conduct an ethnopedological study in production units at the Settlement Project Canto da Ilha de Cima ­ RN, Brazil, and to infer on their interrelationships of knowledge. Participatory workshops and transverse walks were carried out and soils were classified by means of Ethnopedology. The soils were classified using etic and emic approaches, respectively: Inceptisol - CAMBISSOLO HÁPLICO Carbonático típico (Terra Boa or Malhada de Boi) (P1); Oxisol - LATOSSOLO AMARELO Eutrófico típico(Terra de Arisco) (P2); Ultisol - ARGISSOLO VERMELHO AMARELO Eutrófico típico (Terra de Arisco Branco Amarelado) (P3); Oxisol - LATOSSOLO AMARELO Eutrófico típico (Terra de Piçarro) (P4); Ultisol - ARGISSOLO AMARELO Eutrófico abrúptico (Terra de Arisco) (P5) and Inceptisol - CAMBISSOLO HÁPLICO Tb Eutrófico típico (Terra Boa or Velha Chica) (P6 and P7). In the emic survey, farmers described as fertile and better for agricultural activities the soils in the following areas: "Terra Boa" or "Malhada do Boi" (P1) and "Velha Chica" or "Terra Boa" (P6 and P7), corroborating the etic classification, based on the parent material. The soils in these areas were classified as Inceptisols(CAMBISSOLOS), which have higher natural fertility.

Estudos etnopedológicos em unidade familiar tendem a contribuir com academia sobre a importância da troca de saberes, proporcionando a compreensão da realidade local de uma comunidade. Objetivou-se a realização de estudo etnopedológico no Projeto de Assentamento Canto da Ilha de Cima ­ RN, em unidades de produção e inferir sobre as suas inter-relações dos conhecimentos. Foram realizadas oficinas participativas e caminhadas transversais e a classificação dos solos por meio da Etnopedologia. Os solos foram classificados de forma eticista e emicista, respectivamente: CAMBISSOLO HÁPLICO Carbonático típico ­ Inceptisol (Terra Boa Malhada de Boi) (P1); LATOSSOLO AMARELO Eutrófico típico ­ Oxisol (Terra de Arisco) (P2); ARGISSOLO VERMELHO AMARELO Eutrófico típico ­ Ultisol (Terra de Arisco Branco Amarelado) (P3); LATOSSOLO AMARELO Eutrófico típico ­ Oxisol (Terra de Piçarro) (P4); ARGISSOLO AMARELO Eutrófico abrúptico ­ Ultisol (Terra de Arisco) (P5) and CAMBISSOLO HÁPLICO Tb Eutrófico típico ­ Inceptisol (Terra Boa Velha Chica) (P6 and P7). Os agricultores denominaram no levantamento emicista como terras férteis e melhores para o desempenho das atividades agrícolas, nas seguintes áreas: Terra Boa ou Malhada do Boi (P1) e as áreas denominadas de Velha Chica ou Terra Boa (P6 e P7), corroborando com a classificação eticista, em função do material de origem, sendo classificadas como CAMBISSOLOS, com maior fertilidade natural.

Growth and biomass production of prickly pear in the second cycle irrigated with treated domestic sewage / Crescimento e produção de biomassa da palma forrageira segundo ciclo irrigada com esgoto doméstico tratado

This study aimed to evaluate, in the second cycle, the growth and production of 'Orelha-de-elefante Mexicana' prickly pear (Opuntia sp.) under complementary irrigation with treated domestic sewage. The experiment was carried out in the Milagre Settlement, municipality of Apodi-RN, Brazil, from June 2016 to February 2017. Five treatments were evaluated, corresponding to four irrigation frequencies (2.3, 7.0, 14.0 and 21.0 days) to apply an effluent depth of 3.5 mm, and the control, rainfed cultivation (without irrigation). The experimental design was randomized blocks, with four replicates. After preliminary-primary treatment, the domestic sewage showed acceptable chemical and physical characteristics for fertigation under the conditions adopted in the prickly pear cultivation. 234 days after the 1st cut in the plants, the following morphometric characteristics were measured: plant height and length, width, perimeter, thickness and number of primary and secondary cladodes, and biomass accumulation. Complementary irrigation with treated domestic sewage effluent applied at intervals of 2.3, 7.0, 14.0 and 21.0 days allowed satisfactory growth and production of 'Orelha-de-elefante Mexicana' prickly pear; without irrigation, its development was substantially hampered during the dry period. Complementary irrigation with 3.5 mm of domestic sewage effluent applied at intervals of 2.3, 7.0 and 14.0 days led to highest growth and biomass accumulation in 'Orelha-de-elefante Mexicana' prickly pear.

Objetivou-se com esse trabalho avaliar, no segundo ciclo, o crescimento e a produção da palma forrageira orelha-de-elefante (Opuntia sp), conduzida sob irrigação complementar, com esgoto doméstico tratado. O experimento foi realizado no Assentamento Milagre, município de Apodi/RN, no período de junho/2016 a fevereiro/2017. Foram estudados cinco tratamentos, sendo quatro frequências de irrigação (2,3; 7; 14 e 21 dias), para aplicar uma lâmina de 3,5 mm de efluente, e a testemunha, cultivo em sequeiro (sem irrigação). Utilizou-se o delineamento de blocos casualizados com quatro repetições. A água de esgoto doméstico após passar pelo tratamento preliminar-primário apresentou características químicas e biológicas aceitáveis para a fertirrigação nas condições utilizadas no cultivo da palma. Após 234 dias do 1º corte realizado na palma, foram feitas medições das características morfométricas: altura de planta, comprimento, largura, perímetro, espessura e número de cladódios primário e secundário e acúmulo de biomassa. A complementação hídrica realizada por irrigação com intervalos de 2,3; 7,0; 14,0 e 21,0 dias, viabilizou satisfatoriamente o crescimento e a produção da palma forrageira orelha de elefante que, sem irrigação, teve seu desenvolvimento bastante comprometido no período seco. A complementação hídrica com 3,5 mm de água de esgoto doméstico tratado por irrigação, com intervalos de 2,3; 7,0 e 14,0 promovem o maior crescimento e acúmulo de biomassa da palma forrageira orelha de elefante.

Yield and quality of cherry tomato fruits in hydroponic cultivation / Produção e qualidade de frutos de tomate cereja em cultivo hidroponia

Because of the food and industrial importance of tomato, it holds great significance, and is one of the most produced species using the hydroponic cultivation systems. The objective of this study was to evaluate the effects of different concentrations of nutrient solution on the production and quality of cherry tomatoes (Lycopersicon esculentum 'Samambaia') grown in a hydroponic system in protected conditions. The experiment was conducted in pots filled with coconut fiber substrate using a randomized complete block design with four replications and six plants per plot. Five concentrations of nutrients were evaluated (50, 75, 100, 125, and 150% of the standard nutrient solution); the solutions produced the following electrical conductivities: 1.8, 2.0, 2.6, 3.4, and 3.9 dS m-1, respectively. At 90 days after transplanting, the tomato fruits were harvested, at which time the production variables and post-harvest quality of mature fruits were determined. The best production and post-harvest quality indexes of cherry tomatoes ('Samambaia') were found when using 111% of the standard nutrient solution, corresponding to the concentrations of 9.44, 2.44, 2.22, 6.44, 4.11, 2.44, and 2.78 mmolc L-1, of NO3 - , NH4 + , P, K, Ca, Mg, and S, respectively; and 66.6, 55.5, 14.4, 1.89, 0.56, and 0.44 mmolc L -1, of Fe, B, Mn, Zn, Cu, and Mo, respectively. Nutrient solutions with electrical conductivity above 2.89 dS m-1 severely reduced the fruit yield of cherry tomatoes.

Devido à importância alimentar e industrial do tomateiro, a cultura destaca-se entre as hortaliças, sendo uma das espécies mais produzidas em sistema hidropônico de cultivo. Nosso objetivo foi avaliar os efeitos da aplicação de diferentes concentrações de solução nutritiva na produção e na qualidade dos frutos de tomate cereja (Licopersicon esculentum, cv. Samambaia) em sistema hidropônico sobre condição de ambiente protegido. O experimento foi conduzido em vasos preenchidos com substrato de fibra de coco utilizando o delineamento de blocos casualizados, com quatro repetições e seis plantas por parcela. Foram avaliadas cinco concentrações de nutrientes na solução nutritiva hidropônica (50, 75, 100, 125 e 150% da solução nutritiva padrão) que, após a diluição dos nutrientes em água de torneira, estas produziram as seguintes condutividades elétricas: 1.8, 2.0, 2.6, 3.4 e 3.9 dS m-1, respectivamente. Aos 90 dias após o transplantio, os frutos de tomate foram colhidos, ocasião em que se determinaram as variáveis de produção e qualidade póscolheita de frutos maduros. A análise dos resultados indicou que os melhores índices de produção e qualidade dos frutos de tomate cereja cultivado em sistema hidropônico foram encontrados nas concentrações de macronutrientes da solução nutritiva correspondente a 9,44; 2,44; 2,22; 6,44; 4,11; 2,44 e 2,78 mmolc L-1 de NO3 - , NH4 + , P, K, Ca, Mg e S, respectivamente, e 66,6; 55,5; 14,4; 1,89; 0,56 e 0,44 mmolc L-1, de Fe, B, Mn, Zn, Cu e Mo, respectivamente. As soluções nutritivas com condutividade elétricas acima de 2,89 dS m-1 reduziram severamente o rendimento de frutos de tomate cereja

Variation of the water table and salinity in alluvial aquifers of underground dams in the semi-arid regio n of Rio Grande do Norte, Brazil / Variação do nível freático e da salinidade do aquífero aluvial em barragens subterrâneas no semiárido do Rio Grande do Norte

Despite the growing progress in the construction of underground dams, there are few studies to evaluate and monitor these reservoirs after their construction. Thus, a research study was carried out to evaluate the water table level in alluvial aquifers and water salinity in four underground dams selected in the Cobras river basin, Parelhas municipality, Rio Grande do Norte. Water level variation was monitored using the traditional method and the Ground Penetrating Radar with generation of 3D virtual models. Water samples were collected between the months of December 2010 and December 2011 for electrical conductivity analysis. The results indicate that the accumulation of groundwater and salinity (expressed by electrical conductivity) in the reservoirs were affected by the spatial position within the hydrographic basin (limited occurrence of alluvial aquifer recharge area in headwater sectors) and the presence of surface reservoirs (upstream dams), which promote a more continuous recharge, greater renovation, and reduction of the salinity of the waters of the alluvial aquifer downstream.

Apesar do crescente avanço na construção de barragens subterrâneas, há poucos estudos de avaliação e monitoramento das barragens subterrâneas após a sua construção. Assim, foi realizada uma pesquisa com o objetivo de avaliar a salinidade da água e a variação do nível freático em aquífero aluvial em quatro barragens subterrâneas selecionadas na microbacia do rio das Cobras, município de Parelhas, RioGrande do Norte. As amostras de água foram coletadas entre os meses de dezembro de 2010 a dezembro de 2011 para análise da condutividade elétrica. A variação do nível da água foi monitorada utilizando método tradicional e o Ground Penetrating Radar com geração de modelos virtuais 3D. Os resultados indicam que a acumulação da água subterrânea e a sua salinidade (expressa pela condutividade elétrica) nos reservatórios foram afetadas pela posição espacial dentro da bacia hidrográfica (ocorrência limitada de área de recarga do aquífero aluvial em setores de cabeceiras do rio) e pela presença de reservatórios superficiais (açudes à montante), os quais promovem uma recarga mais contínua, maior renovação, e redução da salinidade das águas do aquífero aluvial à jusante.

Emissão foliar, relações iônicas e produção do coqueiro irrigado com água salina / Leaf emission, ionic relations and production of coconut irrigated with saline water

A necessidade de uso de águas salinas na agricultura é crescente, devido à pressão sobre águas de boa qualidade, principalmente para consumo humano. Com este objetivo, foram estudados os efeitos de quatro níveis de condutividade elétrica da água de irrigação (CEa: 0,1; 5,0; 10,0 e 15,0dS m-1), obtidos mediante adição de NaCl sobre o desenvolvimento do coqueiro (Cocos nucifera L.) cv. "Anão Verde", com 3,5 anos de idade. O experimento foi conduzido em blocos casualizados, em solo arenoso, irrigado por microaspersão, no município de Parnamirim-RN, no período de janeiro de 2000 a março de 2001. A salinidade da água aumentou os intervalos de emissão foliar e de inflorescência e o número de flores femininas, bem como os teores de Na e de Cl na folha número 14, acompanhado de relações antagônicas entre Na-Ca, Na-K e Cl-N e sinergismo entre Na-Mg, mas sem manifestar sintomas visuais de efeitos tóxicos. Os teores ótimos de Na e Cl na folha 14 foram, respectivamente, 0,207 e 0,580 por cento.

The necessity to use saline waters in agriculture has increased due to pressure on good quality water, principally, for human consumption. With this objective, the effects of four levels of electrical conductivity (0.1, 5.0, 10.0 and 15.0dS m-1) of irrigation water obtained by addition of NaCl were studied on the development of 3.5 years old coconut (Cocos nucifera L.) cv. 'Anão Verde'. The experiment was conducted in a sandy soil adopting a completely randomized block design and micro sprinkler irrigation system in the municipality of Parnamirim - RN, Brazil, during the period of January, 2000 to March, 2001. The salinity of water increased the interval of leaf emission and inflorescences and the number of female flowers per inflorescence as well as the contents of Na and Cl in leaf 14, accompanied by antagonism between Na-Ca, Na-K and Cl-N, and synergism between Na-Mg but without any visual symptoms of toxic effects. The optimum levels of Na and Cl in 14th leaf were found to be 0.207 and 0.580 percent.