RESUMO

Guava is a fruit tree with high potential in the semi-arid region of northeast Brazil. However, qualitative and quantitative water scarcity is a limiting factor for the expansion of irrigated agriculture. Thus, it is necessary to use techniques to mitigate the effects of salt stress, such as foliar application of proline. The objective of this study was to evaluate the effect of foliar application of proline as a mitigator of salt stress effects on the morphophysiology of guava cv. Paluma. The experiment was carried out under field conditions at the 'Rolando Enrique Rivas Castellón' Experimental Farm in São Domingos, PB, Brazil, using a randomized block design in a 5 × 4 factorial scheme referring to five levels of electrical conductivity of irrigation water, ECw (0.8, 1.5, 2.2, 2.9, and 3.5 dS m-1) and four concentrations of proline (0, 8, 16, and 24 mM). Salinity above 0.8 dS m-1 compromised gas exchange, photosynthetic pigment synthesis, photochemical efficiency, and growth of guava plants at 360 days after transplanting. Foliar application of proline at a concentration of 24 mM mitigated the effect of salt stress on the relative water content, stomatal conductance, and carotenoid contents in plants irrigated with 3.6 dS m-1 water. Meanwhile, a proline concentration of up to 18 mM resulted in higher transpiration, CO2 assimilation rate, instantaneous carboxylation efficiency, and absolute growth rate in stem diameter under ECw of 0.8 dS m-1. Proline concentration of up to 24 mM increased the biosynthesis of photosynthetic pigments and the relative growth rate in stem diameter of guava in the period from 190 to 360 days after transplanting.

RESUMO

The objective of this study was to evaluate the synthesis of photosynthetic pigments, gas exchange, and photochemical efficiency of sour passion fruit genotypes irrigated with saline water under the conditions of the semi-arid region of Paraíba state, Brazil. The experiment was conducted at the experimental farm in São Domingos, PB. A randomized block design was adopted, in a 5 × 3 factorial scheme, with five levels of electrical conductivity of irrigation water-ECw (0.3, 1.1, 1.9, 2.7, and 3.5 dS m-1)-and three genotypes of sour passion fruit (Gigante Amarelo-'BRS GA1'; Sol do Cerrado-'BRS SC1'; and Catarina-'SCS 437'. The increase in the electrical conductivity of irrigation water negatively affected most of the physiological characteristics of the sour passion fruit at 154 days after transplanting. Significant differences were observed between sour passion fruit genotypes when its tolerance was subjected to the salinity of irrigation water. There was an increase in the percentage of damage to the cell membrane with the increase in the electrical conductivity of irrigation water, with maximum values of 70.63, 60.86, and 80.35% for the genotypes 'BRS GA1', 'BRS SC1', and SCS 437', respectively, when irrigated with water of 3.5 dS m-1. The genotype 'BRS Sol do Cerrado' showed an increase in the synthesis of photosynthetic pigments when irrigated with water of 3.5 dS m-1, with maximum values estimated at 1439.23 µg mL-1 (Chl a); 290.96 µg mL-1 (Chl b); 1730.19 µg mL-1 (Chl t); and 365.84 µg mL-1 (carotenoids). An increase in photosynthetic efficiency parameters (F0, Fm, and Fv) of the genotype 'BRS Gigante Amarelo' was observed when cultivated with water with high electrical conductivity (3.5 dS m-1).

RESUMO

The present study aimed to evaluate the effects of the foliar application of hydrogen peroxide on the attenuation of salt stress on the growth, photochemical efficiency, production and water use efficiency of 'All Big' bell pepper plants. The experiment was conducted under greenhouse conditions in Campina Grande, PB, Brazil. Treatments were distributed in a randomized block design, in a 5 × 5 factorial scheme, corresponding to five levels of electrical conductivity of irrigation water (0.8, 1.2, 2.0, 2.6 and 3.2 dS m-1) and five concentrations of hydrogen peroxide (0, 15, 30, 45 and 60 µM), with three replicates. Foliar application of hydrogen peroxide at concentration of 15 µM attenuated the deleterious effects of salt stress on photochemical efficiency, biomass accumulation and production components of bell pepper plants irrigated using water with an electrical conductivity of up to 3.2 dS m-1. Foliar spraying of hydrogen peroxide at a concentration of 60 µM intensified the effects of salt stress. The 'All Big' bell pepper was classified as moderately sensitive to salt stress, with an irrigation water salinity threshold of 1.43 dS m-1 and a unit decrease of 8.25% above this salinity level.

RESUMO

Salicylic acid is a phytohormone that has been used to mitigate the effects of saline stress on plants. In this context, the objective was to evaluate the effect of salicylic acid as a salt stress attenuator on the physiology and growth of precocious-dwarf cashew plants in the post-grafting phase. The study was carried out in a plant nursery using a randomized block design in a 5 × 4 factorial arrangement corresponding to five electrical conductivity levels of irrigation water (0.4, 1.2, 2.0, 2.8, and 3.6 dS m-1) and four salicylic acid concentrations (0, 1.0, 2.0, and 3.0 mM), with three replications. Irrigation water with electrical conductivity levels above 0.4 dS m-1 negatively affected the relative water content in the leaf blade, photosynthetic pigments, the fluorescence of chlorophyll a, and plant growth and increased electrolyte leakage in the leaf blade of precocious-dwarf cashew plants in the absence of salicylic acid. It was verified through the regression analysis that salicylic acid at a concentration of 1.1 mM attenuated the effects of salt stress on the relative water content and electrolyte leakage in the leaf blade, while the concentration of 1.7 mM increased the synthesis of photosynthetic pigments in precocious-dwarf cashew plants.

RESUMO

Salt stress reduces the yield and quality of colored fiber cotton production, but this problem can be mitigated by the foliar application of hydrogen peroxide in adequate concentrations. In this context, the objective of the present study was to evaluate the production and characteristics of fibers of naturally colored cotton cultivares under irrigation with low- and high-salinity water and leaf application of hydrogen peroxide. The experiment was carried out in a greenhouse under a randomized block design, arranged in 4 × 3 × 2 factorial scheme, corresponding to four concentrations of hydrogen peroxide (0, 25, 50, and 75 µM), three cultivares of colored fiber cotton ('BRS Rubi', 'BRS Topázio', and 'BRS Verde'), and two electrical conductivities of water (0.8 and 5.3 dS m-1), with three replicates and one plant per plot. Irrigation with water of 0.8 dS m-1 associated with a foliar application of 75 µM of hydrogen peroxide favored the lint and seed weight, strength, micronaire index, and maturity of 'BRS Topázio'. The 'BRS Rubi' cotton cultivar showed higher tolerance to salinity, followed by the 'BRS Topázio' and 'BRS Verde' cultivares regarding the yield of seed cotton weight, with reduction below 20% under water of 5.3 dS m-1.

RESUMO

Bell pepper is a vegetable of great socioeconomic importance in the Brazilian market. However, in the semi-arid region of northeast Brazil, its cultivation is limited by the high concentrations of salts in water sources. On this basis, this study was developed to determine the effect of foliar application of hydrogen peroxide in mitigating salt stress by evaluating gas exchange, photosynthetic pigments, and growth in 'All Big' bell pepper plants. The experiment was conducted in greenhouse conditions in Campina Grande - PB, Brazil. Treatments were distributed in a randomized block design with a 5 × 5 factorial arrangement corresponding to five levels of irrigation-water electrical conductivity (ECw: 0.8, 1.2, 2.0, 2.6, and 3.2 dS m-1) and five concentrations of hydrogen peroxide (H2O2: 0, 15, 30, 45, and 60 µM), with three replicates and one plant per plot. Foliar application of hydrogen peroxide at the concentration of 15 µM attenuated the effects of salt stress in 'All Big' bell pepper plants irrigated with saline water at ECw of up to 1.4 dS m-1. Hydrogen peroxide at a concentration of 15 µM associated with water salinity of 0.8 dS m-1 increased stomatal conductance, CO2 assimilation rate, instantaneous carboxylation efficiency, and the growth of the bell pepper plants. Application of hydrogen peroxide at concentrations greater than 15 µM intensified the deleterious effects of salt stress in 'All big' bell pepper at 90 days after sowing.

O pimentão é uma hortícola de grande importância socioeconômica no mercado brasileiro. Contudo, no semiárido do Nordeste brasileiro seu cultivo é limitado devido a ocorrência de fontes hídricas com elevadas concentrações de sais. Deste modo, objetivou-se com o presente estudo, avaliar o efeito da aplicação foliar de peróxido de hidrogênio na mitigação do estresse salino nas trocas gasosas, nos pigmentos fotossintéticos e no crescimento das plantas de pimentão 'All Big'. O experimento foi conduzido em condições de casa de vegetação, em Campina Grande-PB. Os tratamentos foram distribuídos no delineamento de blocos casualizados, em esquema fatorial 5 × 5, correspondendo a cinco níveis de condutividade elétrica da água de irrigação ­ CEa (0,8; 1,2; 2,0; 2,6 e 3,2 dS m-1) e cinco concentrações de peróxido de hidrogênio ­ H2O2 (0, 15, 30, 45 e 60 µM), com três repetições e uma planta por parcela. A aplicação foliar de peróxido de hidrogênio na concentração de 15 µM atenuou os efeitos do estresse salino em plantas de pimentão 'All Big' irrigadas com águas salinas em CEa de até 1,4 dS m-1. O peróxido de hidrogênio na concentração de 15 µM associado à salinidade da água de 0,8 dS m-1 proporcionou aumento na condutância estomática, na taxa de assimilação de CO2, na eficiência instantânea de carboxilação e no crescimento das plantas de pimentão. Aplicação de peróxido de hidrogênio em concentrações maiores que 15 µM, intensificou os efeitos deletérios do estresse salino em pimentão 'All big', aos 90 dias após o semeio.

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RESUMO

Two experiments were carried out to evaluate the effects of organic fertilization as an alternative to the chemical on the yield and quality of cherry tomato grown under different irrigation depths in protected environment, in 2013 and 2014. The experimental design was in randomized blocks (5 x 3 factor), with five irrigation depths as the factors (70%, 85%, 100%, 115% and 130% of ETc) and three types of fertilization: no fertilized soil (control), NPK fertilized soil (Chemical) and earthworm humus fertilized soil (organic). The following were evaluated in this study: water use efficiency, number of aborted flowers, total soluble solid content, transverse and longitudinal diameter of the fruits, number of fruits and fruit yield per plant. Organic fertilization is an alternative to the chemical with no losses in yield and fruit quality. The increase in water depth enhanced yield and fruit diameters and reduced water use efficiency. Water use efficiency was more sensitive to the increments in water depth than to different types of fertilization. The values ​​of °Brix obtained in the experiment were classified as acceptable for the domestic and international market when submitted to organic fertilization.

Assuntos

RESUMO

Irrigation with saline water causes a reduction in yield, especially in semi-arid regions. Cultivation strategies have been developed to mitigate salt stress on plants, such as the use of hydrogen peroxide. The objective of this study was to evaluate the attenuating effect of hydrogen peroxide on the gas exchange and growth of 'BRS Rubi do Cerrado' sour passion fruit cultivated under irrigation with saline water. The design was completely randomized in split-plot plots, with water salinity levels ECw (0.6, 1.2, 1.8, 2.4, and 3.0 dS m-1) considered the plots and the concentrations of hydrogen peroxide H2O2 (0, 15, 30, and 45 µM) considered the subplots, with three replicates. Gas exchange (stomatal conductance, transpiration, CO2 assimilation rate, intercellular CO2 concentration, instantaneous water use efficiency, and instantaneous carboxylation efficiency), and absolute and relative growth rates in stem diameter were evaluated. An increase in irrigation water salinity from 0.6 dS m-1 reduced gas exchange, and exogenous application of hydrogen peroxide did not promote a significant effect on gas exchange. However, foliar application of hydrogen peroxide at 15 µM increased the growth of 'BRS Rubi do Cerrado' sour passion fruit.(AU)

A irrigação com águas salinas causa redução na produtividade, principalmente nas regiões semiáridas. Estratégias de cultivo vêm sendo desenvolvidas, a exemplo uso de peróxido de hidrogênio para mitigar o estresse salino sobre as plantas. Objetivou-se avaliar o efeito atenuante do peróxido de hidrogênio sobre as trocas gasosas e o crescimento do maracujazeiro-azedo 'BRS Rubi do Cerrado' cultivado sob irrigação com águas salinas. O delineamento foi inteiramente casualizados em parcelas subdivididas, sendo os níveis de salinidade da água - CEa (0,6, 1,2, 1,8, 2,4 e 3,0 dS m-1) consideradas as parcelas, e as concentrações de peróxido de hidrogênio ­ H2O2 (0, 15, 30 e 45 µM) as subparcelas, com três repetições. Foram avaliadas as trocas gasosas (condutância estomática, transpiração, taxa de assimilação de CO2, concentração intercelular de CO2, eficiência instantânea no uso da água e eficiência instantânea de carboxilação), e a taxa de crescimento absoluto e relativo do caule. O aumento na salinidade da água de irrigação a partir da salinidade de 0,6 dS m-1 reduziu as trocas gasosas; a aplicação exógena de peróxido de hidrogênio não promoveu efeito significativos sob as trocas gasosas. A aplicação foliar de 15 µM de peróxido de hidrogênio aumentou o crescimento do maracujazeiro-azedo 'BRS Rubi do Cerrado'.(AU)

Assuntos

RESUMO

The objective of this study was to evaluate the production and quality of 'Sugar Baby' watermelon fruits under different strategies of irrigation with saline water and nitrogen (N) fertilization in an experiment conducted in a protected environment in Campina Grande, Paraíba, Brazil. The experimental design adopted was in blocks with a 6 × 2 factorial scheme, corresponding to six strategies of irrigation with saline water applied at different phenological stages of the crop (SE irrigation with low-salinity water throughout the cycle; salt stress at the vegetative stage VE; vegetative and flowering VE/FL; flowering FL; fruiting FR; fruit maturation MAT) and two N doses (50 and 100% of the recommendation, equivalent to 50 and 100 mg of N kg-¹ of soil) with five replicates. Two levels of irrigation water salinity were studied, one with low and the other with high electrical conductivity (ECw = 0.8 and 3.2 dS m-¹). The salt stress applied at the vegetative and flowering stages reduced the contents of ascorbic acid and total soluble solids in 'Sugar Baby' watermelon fruits. The dose equivalent to 50% of the N recommendation promoted a greater fresh weight of watermelon fruits. Fertilization with 100% of N increased the hydrogen potential of watermelon fruits under salt stress at the vegetative and flowering stages. The anthocyanin content of watermelon fruits decreased under salt stress, regardless of the development stage; however, with 50% of recommendation of N, there was an increase in this variable.

Objetivou-se com este trabalho avaliar a produção e a qualidade de frutos de melancieira 'Sugar Baby' sob diferentes estratégias de irrigação com águas salinas e adubação nitrogenada, em experimento conduzido em ambiente protegido em Campina Grande, Paraíba, PB. Adotou-se o delineamento experimental em blocos casualizados, arranjados em esquema fatorial 6 x 2, sendo seis estratégias de irrigação com águas salinas aplicadas nos estádios fenológicos da cultura (irrigação com água de baixa salinidade durante todo o ciclo - SE; estresse salino na fase vegetativa - VE; vegetativa e na floração- VE/FL; - floração - FL; - frutificação - FR; maturação dos frutos - MAT) e duas doses de nitrogênio (50 e 100% da recomendação, equivalente a 50 e 100 mg de N kg-¹ de solo), com cinco repetições. Foram estudados dois níveis de salinidade da água de irrigação, um com baixa e outro com alto nível de condutividade elétrica da água de irrigação (CEa = 0,8 e 3,2 dS m-¹). O estresse salino aplicado nas fases vegetativa e de floração reduziu o teor de ácido ascórbico e de sólidos solúveis totais nos frutos da melancieira 'Sugar Baby'. A dose de 50% da recomendação de N proporciona maior massa fresca dos frutos da melancieira. Adubação com 100% de N proporcionou incremento no potencial hidrogeniônico dos frutos de melancieira sob estresse salino nas fases vegetativa e de floração. O teor de antocianinas dos frutos de melancieira reduziu com o estresse salino, independente da fase de desenvolvimento; contudo, com 50% da recomendação de N houve aumento nesta variável.

Assuntos

RESUMO

The objective of this study was to evaluate the production and quality of 'Sugar Baby' watermelon fruits under different strategies of irrigation with saline water and nitrogen (N) fertilization in an experiment conducted in a protected environment in Campina Grande, Paraíba, Brazil. The experimental design adopted was in blocks with a 6 × 2 factorial scheme, corresponding to six strategies of irrigation with saline water applied at different phenological stages of the crop (SE irrigation with low-salinity water throughout the cycle; salt stress at the vegetative stage VE; vegetative and flowering VE/FL; flowering FL; fruiting FR; fruit maturation MAT) and two N doses (50 and 100% of the recommendation, equivalent to 50 and 100 mg of N kg-¹ of soil) with five replicates. Two levels of irrigation water salinity were studied, one with low and the other with high electrical conductivity (ECw = 0.8 and 3.2 dS m-¹). The salt stress applied at the vegetative and flowering stages reduced the contents of ascorbic acid and total soluble solids in 'Sugar Baby' watermelon fruits. The dose equivalent to 50% of the N recommendation promoted a greater fresh weight of watermelon fruits. Fertilization with 100% of N increased the hydrogen potential of watermelon fruits under salt stress at the vegetative and flowering stages. The anthocyanin content of watermelon fruits decreased under salt stress, regardless of the development stage; however, with 50% of recommendation of N, there was an increase in this variable.(AU)

Objetivou-se com este trabalho avaliar a produção e a qualidade de frutos de melancieira 'Sugar Baby' sob diferentes estratégias de irrigação com águas salinas e adubação nitrogenada, em experimento conduzido em ambiente protegido em Campina Grande, Paraíba, PB. Adotou-se o delineamento experimental em blocos casualizados, arranjados em esquema fatorial 6 x 2, sendo seis estratégias de irrigação com águas salinas aplicadas nos estádios fenológicos da cultura (irrigação com água de baixa salinidade durante todo o ciclo - SE; estresse salino na fase vegetativa - VE; vegetativa e na floração- VE/FL; - floração - FL; - frutificação - FR; maturação dos frutos - MAT) e duas doses de nitrogênio (50 e 100% da recomendação, equivalente a 50 e 100 mg de N kg-¹ de solo), com cinco repetições. Foram estudados dois níveis de salinidade da água de irrigação, um com baixa e outro com alto nível de condutividade elétrica da água de irrigação (CEa = 0,8 e 3,2 dS m-¹). O estresse salino aplicado nas fases vegetativa e de floração reduziu o teor de ácido ascórbico e de sólidos solúveis totais nos frutos da melancieira 'Sugar Baby'. A dose de 50% da recomendação de N proporciona maior massa fresca dos frutos da melancieira. Adubação com 100% de N proporcionou incremento no potencial hidrogeniônico dos frutos de melancieira sob estresse salino nas fases vegetativa e de floração. O teor de antocianinas dos frutos de melancieira reduziu com o estresse salino, independente da fase de desenvolvimento; contudo, com 50% da recomendação de N houve aumento nesta variável.(AU)

Assuntos

RESUMO

In the semi-arid region of Northeast Brazil, water salinity is one of the main abiotic factors limiting crop growth and development. However, given the water scarcity affecting this region, the use of waters with moderate to high salt contents becomes necessary to irrigate crops. Thus, generating technologies that enable the use of saline waters is an essential alternative to the agricultural development of this region. In this context, this study aimed to evaluate photosynthesis, photochemical efficiency and growth of West Indian cherry, as a function of irrigation with saline waters and nitrogen (N) fertilization, in the post-grafting stage. The experiment was carried out in drainage lysimeters under greenhouse conditions, using a typic eutrophic Regolithic Neosol with sandy loam texture, in the municipality of Campina Grande-PB, Brazil. Treatments consisted of the combination between five levels of electrical conductivity of water ­ ECw (0.8; 1.6; 2.4; 3.2 and 4.0 dS m-1) and four N doses ­ ND (50; 75; 100 and 125 g of N plant-1 per year), arranged in a randomized block design, with 3 replicates. Gas exchanges, chlorophyll a fluorescence and growth of West Indian cherry were compromised by saline water irrigation, regardless of N dose. Irrigation with ECw higher than 0.8 dS m-1 caused damages to the photosystem II reaction centers of West Indian cherry. Nitrogen doses did not mitigate the deleterious effects caused by irrigation water salinity on photosynthesis, photochemical efficiency and growth of West Indian cherry.

Na região semiárida do Nordeste brasileiro, a salinidade da água é um dos principais fatores abióticos que restringem o crescimento e o desenvolvimento das culturas. Contudo, diante do quadro de escassez hídrica que afeta esta região, a utilização de águas com teores salinos de moderado a alto, faz-se necessário na irrigação das culturas. Desse modo, a geração de tecnologias que permitam o uso de águassalinas, constitui uma alternativa essencial para o desenvolvimento agrícola desta região. Neste contexto, objetivou-se com este trabalho avaliar a fotossíntese, eficiência fotoquímica e o crescimento da aceroleira, em função da irrigação com águas salinas e adubação nitrogenada, na fase pós-enxertia. O experimento foi conduzido em lisímetros de drenagem sob condições de casa-de-vegetação, utilizando-se um Neossolo Regolítico Eutrófico típico de textura franco-arenosa, no município de Campina Grande-PB. Os tratamentos foram constituídos da combinação entre cinco níveis de condutividade elétrica da água - CEa (0,8; 1,6; 2,4; 3,2 e 4,0 dS m-1) e quatro doses de nitrogênio ­ DN (50; 75; 100 e 125 g de N planta-1 por ano), distribuído no delineamento de blocos casualizados, com 3 repetições. As trocas gasosas, a fluorescência da clorofilaa e o crescimento da aceroleira foram comprometidos pela irrigação com águas salinas, independentemente da adubação com nitrogênio. A irrigação com CEa superior a 0,8 dS m-1 provocou danos nos centros de reação do fotossistema II da aceroleira. As doses de nitrogênio não mitigaram os efeitos deletérios ocasionados pela salinidade da água de irrigação sobre a fotossíntese, eficiência fotoquímica e o crescimento da aceroleira.

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RESUMO

In the Brazilian semi-arid region, it is common to find water with high concentration of salts and with variation in its cationic nature. Thus, we aimed to evaluate the growth and production components of sunflower, cv. BRS 324, as a function of irrigation water of different salinity levels and cationic nature associated with doses of nitrogen (N). The experiment was conducted in pots, under open field conditions, in the municipality of Campina Grande-PB, Brazil, in a randomized block design in 5 x 5 factorial scheme, with three replicates, based on five treatments of salinity and cationic nature of the water - S (S1 - Control; S2 - NaCl; S3 - CaCl2; S4 - KCl and S5 ­ NaCl+CaCl2+MgCl2) combined with five N doses (50; 75; 100; 125 and 150 mg of N kg-1 of soil). Irrigation was performed using water with electrical conductivity - ECw of 0.5 dS m-1 for the control and 5.0 dS m-1 for the other treatments. The growth and production of sunflower cv. BRS 324 were reduced when the crop was irrigated with water of electrical conductivity of 5.0 dS m-1, independent of the cationic nature of water; nitrogen fertilization did not attenuate the deleterious effects of salt stress caused by irrigation waters of 5.0 dS m-1 on sunflower cv. BRS 324; The methods of comparison of means through contrasts and Tukey's test were efficient and can be used together to evaluate the growth and the production of sunflower.

No semiárido brasileiro é comum encontrar águas com elevadas concentrações salinas e com variação na sua composição catiônica. Neste sentido, objetivou-se com este trabalho, avaliar o crescimento e os componentes de produção do girassol cv. BRS 324, em função da irrigação com água de diferentes salinidades e natureza catiônica associada a doses de nitrogênio, em experimento conduzido em vasos, sob condições abertas de campo, no município de Campina Grande, PB, no delineamento de blocos ao acaso, em esquema fatorial 5 x 5, com três repetições, sendo cinco tratamentos de salinidade e natureza catiônica da água - S (S1 - Testemunha; S2 - NaCl; S3 - CaCl2; S4 - KCl e S5 ­ NaCl+CaCl2+MgCl2) combinados com cinco doses de nitrogênio (50; 75; 100; 125 e 150 mg de N kg-1 de solo). Utilizou-se na irrigação, água com condutividade elétrica ­ CEa de 0,5 dS m-1 para a testemunha (S1) e 5,0 dS m-1 para os demais tratamentos. O crescimento e a produção do girassol cv. BRS 324 foram reduzidos quando a cultura é irrigada com água de condutividade elétrica de 5,0 dS m-1, independente da natureza catiônica da água; a adubação nitrogenada não atenuou os efeitos deletérios do estresse salino causado por irrigação com água de 5,0 dS m-1 sobre o girassol cv. BRS 324. Os métodos de comparação de médias através de contrastes e teste de Tukey foram eficientes e podem ser utilizados em conjunto para avaliar o crescimento e a produção de girassol.

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RESUMO

The aim of the present study was to evaluate hydraulic characteristics such as manufacturing and flow variation coefficient, characteristic equation of self-compensating emitters and the variation between nominal flow and that obtained by the emitter equation using waters of different salt concentrations. The research was conducted in the greenhouse of the Academic Unit of the Agricultural Engineering, Federal University of Campina Grande-PB. Treatments consisted of five salinity levels in the irrigation water (ECwi) (0.6; 1.5; 2.5; 3.5 and 4.5 dS m-1 at 25 ° C) and four working pressures (60, 100, 140, and 160 kPa), with three replicates. The flow variations of emitters were considered small over time, being within recommendation of ± 7% of the nominal flow with “x” exponent values between 0.02 and 0.09, as recommended by the manufacturer, which was classified as self-compensating. The manufacturing and flow variation coefficients were considered excellent in all evaluations and the operating time did not influence the hydraulic performance of emitters. At pressure of 60 kPa and electric conductivity of 0.6 dS m-1, flow rates near values provided by the manufacturer and more economically viable to the farmer were obtained.(AU)

Objetivou-se, com o presente estudo, avaliar as características hidráulicas, como coeficiente de variação de fabricação e vazão, equação característica do emissor autocompensante e a variação entre a vazão nominal e a obtida pela equação do emissor utilizando águas de diferentes concentrações salinas. A pesquisa foi conduzida na casa de vegetação da Unidade Acadêmica de Engenharia Agrícola, Universidade Federal de Campina Grande-PB. Os tratamentos foram compostos por cinco níveis de salinidade da água de irrigação (CEai) (0,6; 1,5; 2,5; 3,5 e 4,5 dS m-1 a 25 °C) e quatro pressões de serviço (60, 100, 140, e 160 kPa), com três repetições. As variações de vazão dos emissores foram consideradas pequenas ao longo do tempo, de modo que estavam dentro da recomendação de ± 7% da vazão nominal, com valores de expoente “x” entre 0,02 e 0,09, segundo recomendação do fabricante, que os classificou como autocompensantes . Os Coeficientes de variação de fabricação e de vazão foram considerados excelentes em todas as avaliações e o tempo de funcionamento não influenciou no desempenho hidráulico dos emissores. Na pressão de 60 kPa associada à condutividade elétrica da água de 0,6 dS m-1, obtiveram-se vazões dos emissores mais próximas da declarada pelo fabricante e a mais economicamente viáveis ao produtor.(AU)

Assuntos

RESUMO

The aim of the present study was to evaluate hydraulic characteristics such as manufacturing and flow variation coefficient, characteristic equation of self-compensating emitters and the variation between nominal flow and that obtained by the emitter equation using waters of different salt concentrations. The research was conducted in the greenhouse of the Academic Unit of the Agricultural Engineering, Federal University of Campina Grande-PB. Treatments consisted of five salinity levels in the irrigation water (ECwi) (0.6; 1.5; 2.5; 3.5 and 4.5 dS m-1 at 25 ° C) and four working pressures (60, 100, 140, and 160 kPa), with three replicates. The flow variations of emitters were considered small over time, being within recommendation of ± 7% of the nominal flow with “x” exponent values between 0.02 and 0.09, as recommended by the manufacturer, which was classified as self-compensating. The manufacturing and flow variation coefficients were considered excellent in all evaluations and the operating time did not influence the hydraulic performance of emitters. At pressure of 60 kPa and electric conductivity of 0.6 dS m-1, flow rates near values provided by the manufacturer and more economically viable to the farmer were obtained.

Objetivou-se, com o presente estudo, avaliar as características hidráulicas, como coeficiente de variação de fabricação e vazão, equação característica do emissor autocompensante e a variação entre a vazão nominal e a obtida pela equação do emissor utilizando águas de diferentes concentrações salinas. A pesquisa foi conduzida na casa de vegetação da Unidade Acadêmica de Engenharia Agrícola, Universidade Federal de Campina Grande-PB. Os tratamentos foram compostos por cinco níveis de salinidade da água de irrigação (CEai) (0,6; 1,5; 2,5; 3,5 e 4,5 dS m-1 a 25 °C) e quatro pressões de serviço (60, 100, 140, e 160 kPa), com três repetições. As variações de vazão dos emissores foram consideradas pequenas ao longo do tempo, de modo que estavam dentro da recomendação de ± 7% da vazão nominal, com valores de expoente “x” entre 0,02 e 0,09, segundo recomendação do fabricante, que os classificou como autocompensantes . Os Coeficientes de variação de fabricação e de vazão foram considerados excelentes em todas as avaliações e o tempo de funcionamento não influenciou no desempenho hidráulico dos emissores. Na pressão de 60 kPa associada à condutividade elétrica da água de 0,6 dS m-1, obtiveram-se vazões dos emissores mais próximas da declarada pelo fabricante e a mais economicamente viáveis ao produtor.

Assuntos