Combined effects of potassium and wastewater application on the yield and quality of Bermuda grass (Cynodon dactylon) in the Mediterranean regions

The reuse of treated wastewater is considered as an alternative disposable to potable water in the mediterranean agriculture and landscape, namely in golf courses. Bermuda grass (Cynodon dactylon, Peers) is used very often on the fairways, roughs and tees of golf courses of the Mediterranean Basin due to its tolerance to drought, salinity, high temperatures and damages. The objective of this work is to study the response of this cultivar to the combined effects of municipal wastewater and two levels of potassium fertilization, during Spring and Summer. The experimental design known as sprinkle point source was used to simulate the various levels of wastewater application, expressed by the crop coefficient kc. This procedure is characterized by the assumption that a point creates a linear irrigation gradient from the water point source, producing a gradual change in water application, and a high degree of irrigation uniformity must be obtained in parallel isohyets. Chemical analysis of wastewater irrigation water was monitored through all the experimental period (from April to September). Climatic data was also recorded. Yield (aboveground biomass) and the good visual appearance (GVA) of the lawn were assessed in two sampling dates, May and July. Municipal wastewater can be used to irrigate Bermuda grass, without an apparent decrease on grass quality. As concluding remarks, it may be seen that the irrigation water amount is the most pronounced limiting production factor of bermuda grass (Cynodon dactilon, Peers), when compared with potassium fertilization, but it is possible that there is a positive interaction between water and irrigation. This response is modulated by evaporative air conditions since lower yields were obtained in summer. On the other hand, if the potassium fertilization is increased, two situations may occur: 1) with high amounts of water application, leaching problems may occur, mainly on sandy soils, and production may decrease; 2) if potassium fertilization increases, and irrigation water decreases, yield decreases due to the increase of salinity (potassium fertilizers are salts), mainly on salt affected soils

The impact of salt concentration on the mineral nutrition of Tetragonia tetragonioides

The purpose of the experiment was to study the e ect of salinity (NaCl) on growth, biomass production (total yield), mineral composition (macro- and micronutrient contents in leaves and the soil in which the plant is grown) of Tetragonia tetragonioides during the vegetation period. The experimental work was conducted in the greenhouse at the University of Lille 1, France, from 2 November 2015 to 25 January 2016. Three salinity treatments (T1 (50 mM NaCl), T2 (100 mM NaCl), T3 (200 mM NaCl)) and a control treatment (T0 (0 mM NaCl)) were applied. Analysis of the results showed that the total yield of the crop had low variation between the salinity treatments and the control treatment. The salt concentrations had an e ect on the macro- and micronutrient contents in leaves and soil. In conclusion, T. tetragonioides exhibited good potential for use as a species to remove salt. This is the main important finding of this research.Erasmus Mundus Euro-Asian CEA project for support of the European Joint Doctorate Program; JST CREST Grant Number JPMJCR17O2info:eu-repo/semantics/publishedVersio

Saline stress and cell toxicity evaluation using suspended plant cell cultures of horticultural crops grown in a bioreactor

Crop salt damage consists, usually, of leaf burn and defoliation, and it is associated with accumulation of toxic levels of sodium and/or chloride in leaf cells (Storey and Walker, 1999). The cell and tissue culture are simple biological systems that offer a direct approach to the metabolic changes. The plant cell growth in a controlled environment, as a bioreactor, is a unique tool for cell ion transport studies. Cell suspension culture of citrus cell line was exposed to a medium containing different sodium chloride concentrations (0mM, 42.7mM and 85.5mM). The growth profile of control cells (absence of NaCl) and 85.5mM cells were similar. The lack of inhibition of biomass accumulation, of all tested saline conditions clearly showed that the level of NaCl concentration used was not toxic for the cell metabolism. Also its ability to resist to 85.5mM NaCl can be on evidence that this suspension cel culture might have salt tolerance characteristics

The combined effects of salts and calcium on growth and mineral accumulation of Tetragonia tetragonioides - A salt removing species

High soil salinity levels have drastic effects on the growth and yield of horticultural crops. Salination may be controlled by environmentally safe and clean techniques as the use of salt removing species. Tetragonia tetragonioides, a wild halophytic species has been studied for this purpose. It was studied the effect of high salt concentrations on growth and mineral composition and the influence of high calcium concentration on plant response. Plants were grown in 5 litters in randomized pots and were daily irrigated. The NaCl concentration of the irrigation solution ranged from 0 up to 200 mM. Additionally, the irrigation solution provided plants with two calcium concentrations: 2 and 10 mM of CaCl2. T. tetragonioides present high ability for sodium and chloride leaf accumulation. Besides that, the species provide more advantages: 1) high biomass production potential; 2) several harvests during the year (summer and winter); 3) high content of minerals; 4) horticultural importance, as a leaf vegetable crop; 6) easy multiplication (seed propagation) and easy crop management; 7) tolerance to drought and warm conditions; 8) soil erosion control due to its excellent soil covering. The obtained results suggest that plants supplemented with the high calcium level had longer stems than plants in the low calcium level, accumulated greater amounts of calcium at high salinity levels and present similar leaves dry matter

Effects of salinity on the Macro- and Micronutrient contents of a Halophytic Plant Species (Portulaca oleracea L.)

The main purpose of the two consecutive experimental studies presented here was to compare the effect of salinity on nutrients in leaves of the halophytic plant species Portulaca oleracea L. and in soil. The first experiment was conducted to study the effect of salinity on plant growth, biomass accumulation, yield, root layer development, salt accumulation, and the dynamics of changes in mineral substances in plants and soil. In the second experiment, P. oleracea seeds were sown directly into salinized soil (treated immediately before plant growth) to determine the nutrient levels in leaves and soil. Three salinity treatments (saline water solution with NaCl: T1, 5 dS m−1 ; T2, 9.8 dS m−1 ; and T3, 20 dS m−1 ) and a control treatment (T0, 1 dS m−1 ) were used in the first experiment. The soil in the second experiment was used in a previous study (performed immediately before P. oleracea growth) (salinized soil: T1, 7.2 dS m−1 ; T2, 8.8 dS m−1 ; T3, 15.6 dS m−1 ; T0, 1.9 dS m−1 ). The plants were irrigated with tap water at amounts in the range of 0.25–0.50 L/pot. Analysis of the experimental results showed that P. oleracea is resistant to salinity, is able to remove ions (400–500 kg ha−1 NaCl), and can be grown in saline soil. The results indicated that P. oleracea is able to grow in high-salinity soil. This finding was confirmed by the dry matter obtained under high-salinity conditions. Salinity stress affected nutrient uptake in leaves and soil.Erasmus Mundus European Joint Doctorate Programinfo:eu-repo/semantics/publishedVersio

Avaliação do comportamento agronómico de porta-enxertos tolerantes à tristeza dos citrinos

A detecção no nosso país de alguns núcleos de plantas infectadas com o citrus tristeza virus (CTV), impôs a necessidade de desenvolver um plano de prevenção, nomeadamente através do incentivo da substituição progressiva dos porta-enxertos susceptíveis por porta-enxertos tolerantes. Com a identificação do seu principal vector (Toxoptera citricidus Kirk.) em finais 2003, nas regiões de Entre-Douro e Minho e de Trás-os-Montes é de prever que a dispersão da doença ocorra mais rapidamente. As novas plantações utilizam na sua maioria as citranjeiras Troyer e Carrizo, que nem sempre se mostram adequadas às condições edafo-climáticas existentes. Considerando esta problemática, a Direcção Regional de Agricultura do Algarve, em colaboração com outras entidades (Universidade do Algarve e Centro de Citricultura), tem vindo a desenvolver estudos conducentes à adaptação de novos porta-enxertos, com o objectivo de diversificar as opções existentes relativamente aos condicionalismos da região. Com este objectivo foi instalado em Tavira, em Maio de 1998, num solo calcário, um ensaio de campo para avaliação do comportamento de 11 clones de porta-enxertos (T. Sunki x P. trifoliata FAO 30590; Citranjeira Troyer B2 FAO 31655; T. Cleopatra x P. trifoliata FAO 30584; T. Cleopatra x C. Carrizo FAO 30575; Laranjeira Gou Tou B7; Citrandarineira 31443; Laranjeira azeda B6C-T1; Tangerineira Changsa; Tangerineira Sunki; Tangerineira Cleópatra; Citranjeira Troyer 4 AS). Durante três anos, as plantas foram submetidas a três níveis de salinidade da água de rega, expressos pela condutividade eléctrica da água de rega ECw – 1; 3 e 6 dS.m-1, obtidos através de um esquema experimental fonte dupla gota-a-gota. Foram medidos vários parâmetros agro-ambientais, como o desenvolvimento vegetativo das plantas e o aumento da condutividade eléctrica do extracto de saturação do solo (medido no extracto aquoso). Os resultados obtidos mostram que os porta-enxertos com maior tolerância à salinidade foram o clone de laranjeira azeda B6C-T1 e a laranjeira Gou Tou.info:eu-repo/semantics/publishedVersio

Influence of climatic phenomena and deforestation on hydroenvironmental fragility, Gurupi River watershed, Northern Brazil

In recent decades, climatic and anthropogenic pressures have caused serious environmental problems. The joint analysis of geo-environmental variables, through geoprocessing techniques, can support the estimation of the contribution of each environmental component to hydro-environmental fragility (HF). The aim of this work was to analyze the contribution of climatic phenomena and deforestation in the HF of the Gurupi River Watershed (GRW). Precipitation data were extracted from the Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS); land use and cover were obtained from the MapBiomas Project; drainage network was acquired from the National Water and Sanitation Agency (ANA); slope data were gathered from the National Institute for Space Research (INPE); soil data were obtained from the Brazilian Agricultural Research Corporation (EMBRAPA); geomorphological units were extracted from the Brazilian Institute of Geography and Statistics (IBGE); and rock data were based on the Geological Survey of Brazil (CPRM). For the mapping of HF, the Analytic Hierarchy Process (AHP) was adopted to weigh the importance of each variable in four extreme precipitation year scenarios (1989, 2012, 2015, and 2019). It was observed that spatial precipitation is considerably different in extreme years. Results showed that deforestation has increased over the years; and that static geo-environmental variables (drainage, slope, soils, geomorphological units, and rocks) have larger feature domains that favor the increase of HF in the GRW. The HF of the GRW showed significant differences in the analyzed scenarios. Policies and environmental conservation programs are needed in the GRW.Nas últimas décadas as pressões climáticas e antrópicas vêm causando sérios problemas ambientais. A análise conjunta de variáveis geoambientais, por meio de técnicas de geoprocessamento, pode subsidiar a estimativa da contribuição de cada componente ambiental na fragilidade hidroambiental (FHA). O objetivo do trabalho foi analisar a contribuição dos fenômenos climáticos e do desmatamento na FHA da Bacia Hidrográfica do rio Gurupi (BHG). Utilizaram-se dados de precipitação do Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS); o uso e cobertura do solo foram obtidos do Projeto MapBiomas; a rede de drenagem foi adquirida na Agência Nacional de Águas e Saneamento Básico (ANA); a declividade foi obtida do Instituto Nacional de Pesquisas Espaciais (INPE); os dados de solos foram obtidos da Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA); foram consideradas as unidades geomorfológicas do Instituto Brasileiro de Geografia e Estatística (IBGE) e os dados de rochas do Serviço Geológico do Brasil (CPRM). Para o mapeamento da FHA, adotou-se a Analytic Hierarchy Process(AHP) com a finalidade de ponderação de importância para cada variável, em quatro cenários de anos extremos de precipitação (1989, 2012, 2015 e 2019). Observou-se que a precipitação espacial é consideravelmente diferente nos anos extremos. Os resultados mostram que o desmatamento aumentou ao longo dos anos; que as variáveis geoambientais estáticas (drenagem, declividade, solos, unidades geomorfológicas e rochas) possuem maiores domínios de feições que favorecem o aumento da FHA na BHG. A FHA da BHG apresentou diferenças significativas nos cenários analisados. A BHG necessita de políticas e programas de conservação ambiental

Physical growth of schoolchildren from the Jequitinhonha Valley, Minas Gerais, Brazil: Comparison with the CDC-2000 reference using the LMS method

Objective: To analyse the physical growth of a representative school population sample from the Jequitinhonha Valley, Minas Gerais, Brazil, in comparison with the reference proposed by the Centre for Disease Control and Prevention (CDC-2000). Methods: The sample was composed of 5100 individuals (2730 girls and 2370 boys), aged 6-18 years. Body weight-for-age and height-for-age percentiles were obtained using the LMS method. Statistical and graphical comparisons were made with the corresponding percentiles of the CDC-2000 reference, estimated using the same method. Results: Overall, the calculated values of the L (asymmetry) and the S (variability) parameters were quite similar to the CDC-2000 reference values. However, M(median) was substantially different from the reference used in the study, mainly in schoolchildren over 12-13 years of age of both genders. The magnitude of the deficits of height-for-age and body weight-for-age observed in the schoolchildren from the Jequitinhonha Valley, Minas Gerais, Brazil, varied from 4 to 6 cm and from 3 to 6 kg, respectively. Conclusion: The body weight-for-age and height-for-age percentiles of schoolchildren population in the Jequitinhonha Valley, Minas Gerais, Brazil differed substantially from those referenced

Physiological and qualitative response of Cucurbita pepo L. to Salicylic Acid under controlled water stress conditions

Limited water stress is one of the most important environmental stresses that affect the growth, quantity and quality of agronomic crops. This study was undertaken to investigate the effect of foliar applied salicylic acid (SA) on physiological responses, antioxidant enzymes and qualitative traits of Cucurbita pepo L. Plants exposed to water-stressed conditions in two years of field studies. Irrigation regimes at three soil matric potential levels (−0.3, −1.2 and −1.8 MPa) and SA at four levels (0.0, 0.5, 1.0 and 1.5 mg/L) were considered as main plot and sub-plots, respectively. The soil matric potential values (MPa) was measured just before irrigation. Results showed that under water stressed conditions alone, the amounts of malondialdehyde (MDA), hydrogen peroxide (H2O2) and ion leakage were higher compared with control treatment. However, spraying of SA under both water stress and non-stress conditions reduced the values of the above parameters. Water stress increased CAT, APX and GR enzymes activity. However foliar application of SA led to the decrease of CAT, APX and GR under all soil matric potential levels. The amount of carbohydrates and fatty acids increased with the intensity of water stress and SA modulated this response. By increasing SA concentration both in optimum and stress conditions, saturated fatty acids content decreased. According to our data, the SA application is an effective approach to improve pumpkin growth under water stress conditions.info:eu-repo/semantics/publishedVersio