Salicylic acid concentrations and forms of application mitigate water stress in sour passion fruit seedlings.

The present study aimed to evaluate concentrations and forms of application of salicylic acid used for water stress mitigation on the gas exchange and growth of yellow passion fruit. The experimental design was arranged in randomized blocks in a 4 × 4 × 2 factorial scheme, with four concentrations of salicylic acid (SA) via foliar application (0.0, 0.7, 1.4, and 2.1 mM), four SA concentrations via fertigation (0.0, 0.7, 1.4, and 2.1 mM), and two irrigation depths estimated based on the actual evapotranspiration - ETr (50 and 100% of ETr), with three replications. Water stress negatively affected the physiology and growth of yellow passion fruit seedlings at 75 days after sowing (DAS). The application of salicylic acid, regardless of the form of application, attenuates the effects of water stress on gas exchange and growth of yellow passion fruit, with the best results obtained when applying a concentration of 1.30 mM via leaf or 0.90 mM via fertirrigation. The combination of foliar application of AS and fertigation contributed to improve photosynthetic and growth parameters under water conditions of 50 and 100% of ETr. The foliar application of AS presents superior responses to the application via fertigation. These results reinforce the hypothesis that the attenuation of water stress by salicylic acid is related to the maintenance of gas exchange, which depends on the concentration and form of application, and studies testing combinations throughout the crop cycle become promising for advances in knowledge from the action of this phytohormone on abiotic stress.

Mineral composition and production of guava under salt stress and salicylic acid.

The limitation in the quality of water sources for irrigation in the semi-arid region of northeastern Brazil is increasingly present, so it is necessary to use water with high concentrations of salts for agricultural production, which makes the use of elicitors essential to mitigate the harmful effects of salinity on plants. Given the above, the objective of this study was to evaluate the effects of foliar application of salicylic acid on the mineral composition and production of guava plants under salt stress conditions in the post-grafting phase. The experiment was carried out under greenhouse conditions, in a randomized block design, in a 2 × 4 factorial scheme, with two levels of electrical conductivity of irrigation water (0.6 and 3.2 dS m-1) and four concentrations of salicylic acid (0, 1.2, 2.4, and 3.6 mM), with three replicates. During the flowering stage of guava, N, P, and K contents accumulated in the leaves according to the following order of concentration: N > K > P. Foliar application of 1.2 mM of salicylic acid increases the leaf contents of N, P, and K in guava plants grown under irrigation with water of 0.6 dS m-1. Water salinity of 3.2 dS m-1 reduces the growth and production components of guava plants.

Morphophysiology and production of bell pepper grown under salt stress and salicylic acid foliar application.

Considering the relevance of bell pepper and the limitations imposed by the deleterious effects of salt stress, especially in semi-arid regions, it is extremely important to establish strategies that can facilitate the use of saline water in vegetable production. In this scenario, this study aimed to evaluate the effect of the frequency of foliar application of salicylic acid on the morphophysiology and production of the bell pepper cv. "All Big" irrigated with saline water. The study was conducted at a greenhouse in Campina Grande - PB. The treatments were distributed in a completely randomized design and set up in a 4 × 4 factorial arrangement with three replications, corresponding to four application frequencies of salicylic acid (F1- No application of salicylic acid, F2 - Weekly application, F3- fortnightly application, and F4- monthly application) and four levels of electrical conductivity of irrigation water - ECw (0.8, 1.6, 2.4 and 3.2 dS m-1). The fortnightly application of salicylic acid at a concentration of 1.0 mM mitigated the effects of salt stress on the morphophysiology and production components of bell pepper cv. All Big cultivated with ECw of up to 2.4 dS m-1, which reinforces the hypothesis that salicylic acid can act as a signaling molecule and reduce the effects of saline stress in bell pepper, enabling the use of brackish water in agricultural activity, mainly in semi-arid regions of northeastern Brazil, which have a shortage of fresh water.

Physiology and production of sugar-apple under water stress and application of proline.

The objective of this study was to evaluate the physiology and production of sugar-apple as a function of irrigation intervals and foliar application of proline under the conditions of Paraíba's semi-arid region. A randomized block design was laid out in a 4 × 2 factorial scheme, with treatments resulting from the combination of four irrigation intervals (1, 4, 8 and 12 days) and two concentrations of proline (0 and 10 mM), with four replicates, and the plot consisted of four usable plants. Increase in irrigation intervals reduced the gas exchange of sugar-apple plants at 298 days after transplanting. Exogenous application of proline at concentration of 10 mM increased contents of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids and fruit fresh mass in plants grown under 12-day irrigation intervals.

Irrigation with saline water in the cultivation of mini watermelon under phosphate fertilization.

The objective of this study was to evaluate the water status, photosynthetic pigments, and photochemical efficiency of mini watermelon plants under salt stress and phosphate fertilization. The experiment was conducted in pots under greenhouse conditions in Pombal, PB, Brazil. The experimental design used was randomized blocks in a 5 × 4 factorial scheme, with five levels of electrical conductivity of irrigation water - ECw (0.3, 1.3, 2.3, 3.3, and 4.3 dS m-1) and four doses of phosphorus (60, 80, 100, and 120% of the recommendation), with three replicates. The relative water content in the tissues decreased with the increase in ECw levels in all phosphorus doses, with decreases of 7.05, 7.81 and 8.83% per unit increase in ECw, in plants fertilized with 80, 100 and 120% P2O5. On the other hand, ECw levels increased electrolyte leakage, regardless of phosphorus doses of the recommendation. The synthesis of photosynthetic pigments and the quantum efficiency of photosystem II were inhibited by increasing water salinity from 0.3 dS m-1 in plants grown under phosphorus doses above 60% of the recommendation. Water salinity from 0.3 dS m-1 reduced chlorophyll b contents, initial, maximum, and variable fluorescence of mini watermelon plants, with a decrease of 11.86, 4.51, 4.53, and 4.54% per unit increment of ECw, respectively.

Salicylic acid does not relieve salt stress on gas exchange, chlorophyll fluorescence, and hydroponic melon growth.

The objective of this study was to evaluate the salicylic acid applications in attenuating the harmful effects of saline nutrient solution on the physiology and growth of 'Gaúcho' melon cultivated in the NFT hydroponic system. The experiment was conducted in a greenhouse, in Pombal-PB, Brazil. The cultivation system used was the Nutrient Film Technique - NFT hydroponics. A completely randomized split-plot design was used, with the plot referring to four levels of salinity in the nutrient solution - ECns (2.1 control, 3.2, 4.3, and 5.4 dS m-1) and the sub-plot four concentrations of salicylic acid (SA) (0, 1.5, 3.0, and 4.5 mM), applied via foliar spray, with six replications. Nutrient solution of 4.3 and 5.4 dS m-1 electrical conductivity promotes higher maximum and variable fluorescence, respectively. The stomatal conductance, transpiration, stem diameter, main branch length, leaf dry mass, and stem dry mass of 'Gaúcho' melon plants decrease with the increase in salinity of the nutrient solution. Salicylic acid increases the initial fluorescence and the main branch length of 'Gaúcho' melon plants in hydroponic cultivation. Salicylic acid at a concentration of 1.5 to 4.5 mM did not attenuate the effects of salt stress on the internal CO2 concentration, CO2 assimilation rate, and root dry mass of 'Gaúcho' melon plants.

Morphology of 'Crioula' guava seedlings under irrigation with increasing salinity water and nitrogen/potassium fertilization.

Several studies have been conducted evaluating the management of fertilizers as strategies to mitigate the deleterious effects of salt stress, so the objective of this work was to evaluate the quality of 'Crioula' guava seedlings under irrigation with water of different salinity levels and fertilized with combinations of nitrogen and potassium. The experiment was performed in a protected (screened) environment using a randomized block design and analyzed in a 5 × 4 factorial scheme, with four replicates, with the plot formed by two plants. The treatments were formed from the combination of the factor electrical conductivity of irrigation water (ECw 0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1), with the factor combinations (C) of nitrogen (N) and potassium (K2O) doses, being C1 = 70% N + 50% K2O, C2 = 100% N + 75% K2O, C3= 130% N + 100% K2O and C4= 160% N + 125% K2O. The recommended dose of 100% N and K, respectively, was 541.1 mg N dm-3 soil and 798.6 mg K dm-3 soil. The combinations of N and K fertilization corresponding to 70% N + 50% K2O and 100% N + 75% K2O of the recommended doses promoted greater growth of 'Crioula' guava seedlings. Water with ECw of 2.1 dS m-1 promotes the formation of quality 'Crioula' guava seedlings.

Hydrogen peroxide in attenuation of salt stress effects on physiological indicators and growth of soursop.

To mitigate the deleterious effects of salt stress, substances capable of acting as mitigators and/or inducers of tolerance to stress have been used, enabling the use of saline waters and contributing to the development of irrigated agriculture. In this context, the aim of the present study was to evaluate the effect of foliar spraying with hydrogen peroxide as an attenuator of salt stress effects on soursop morphophysiology. The experiment was conducted under greenhouse conditions in Campina Grande - PB, Brazil, using a randomized block design, in a 4 × 4 factorial arrangement, whose treatments resulted from the combination of four levels of electrical conductivity of irrigation water - ECw (0.8 - control, 1.6, 2.4, and 3.2 dS m-1) and four concentrations of hydrogen peroxide - H2O2 (0, 10, 20, and 30 µM), with three replicates. Foliar application of hydrogen peroxide at a concentration of 10 µM increased growth, chlorophyll synthesis, and relative water content in the leaves and consequently reduced the foliar water saturation deficit of soursop irrigated with ECw up to 1.6 dS m-1. The concentration of hydrogen peroxide of 30 µM intensified the salt stress on the electrolyte leakage in the leaf blade and the photosynthetic pigments of soursop, 270 days after transplanting.

Methods of application of salicylic acid as attenuator of salt stress in cherry tomato.

Salt stress caused by excess salts present in irrigation water, is one of the biggest barriers in agricultural production, especially in semi-arid regions. Thus, the use of substances, such as salicylic acid, that minimize the deleterious effects of salinity on plants can be an alternative to ensure satisfactory production. In this context, the objective of this study was to evaluate the effects of different methods of application of salicylic acid on the growth, production and water use efficiency of cherry tomato plants under salt stress. The study was conducted in a greenhouse, using an Entisol soil with a sandy loam texture. The treatments were distributed in a completely randomized design, in a 2×4 factorial arrangement, corresponding to two levels of electrical conductivity of irrigation water - ECw (0.6 and 2.6 dS m-1) and four methods of application of salicylic acid (Control - without application of SA; via spraying; via irrigation and via spraying and irrigation), with five replicates and one plant per plot. The salicylic acid concentration used in the different methods was 1.0 mM. Application of salicylic acid via foliar spraying increased the growth, production and water use efficiency of cherry tomato plants. The salt stress induced by the electrical conductivity of 2.6 dS m-1 was attenuated by the foliar application of salicylic acid. The use of water of 2.6 dS m-1 associated with the application of salicylic acid via irrigation water further intensified the adverse effects of salinity on cherry tomato plants.

Salicylic acid does not mitigate salt stress on the morphophysiology and production of hydroponic melon.

The excess of salts present in the water can limit the hydroponic cultivation of melon in semi-arid regions of the Brazilian Northeast, making it necessary to use strategies that allow the use of these waters. Among these strategies, the use of elicitor substances stands out, such as salicylic acid. In this context, this study aimed to evaluate the effect of foliar application of salicylic acid in mitigating the harmful effects of salt stress on the morphophysiology and production of 'Gaúcho' melon cultivated in a hydroponic system. A completely randomized design was adopted in a split-plot scheme, with four levels of electrical conductivity of the nutrient solution - ECsn (2.1, 3.2, 4.3, and 5.4 dS m-1) considered the plots and four salicylic acid concentrations - SA (0, 1.5, 3.0, and 4.5 mM), the subplots, with six replications. The foliar application of salicylic acid concentrations did not mitigate the deleterious effects of salt stress on the morphophysiology and yield of melon grown in hydroponic system. The concentration of 4.5 mM of salicylic acid intensified the harmful effects of the salinity of the nutrient solution on gas exchange and fresh weight of hydroponic melon.

Hydrogen peroxide in attenuation of salt stress effects on physiological indicators and growth of soursop / Peróxido de hidrogênio na atenuação do estresse salino nos indicadores fisiológicos e crescimento da gravioleira

To mitigate the deleterious effects of salt stress, substances capable of acting as mitigators and/or inducers of tolerance to stress have been used, enabling the use of saline waters and contributing to the development of irrigated agriculture. In this context, the aim of the present study was to evaluate the effect of foliar spraying with hydrogen peroxide as an attenuator of salt stress effects on soursop morphophysiology. The experiment was conducted under greenhouse conditions in Campina Grande - PB, Brazil, using a randomized block design, in a 4 × 4 factorial arrangement, whose treatments resulted from the combination of four levels of electrical conductivity of irrigation water - ECw (0.8 ­ control, 1.6, 2.4, and 3.2 dS m-1) and four concentrations of hydrogen peroxide - H2O2 (0, 10, 20, and 30 µM), with three replicates. Foliar application of hydrogen peroxide at a concentration of 10 µM increased growth, chlorophyll synthesis, and relative water content in the leaves and consequently reduced the foliar water saturation deficit of soursop irrigated with ECw up to 1.6 dS m-1. The concentration of hydrogen peroxide of 30 µM intensified the salt stress on the electrolyte leakage in the leaf blade and the photosynthetic pigments of soursop, 270 days after transplanting.

Para mitigar os efeitos deletérios do estresse salino, tem se utilizado substâncias capazes de atuar como atenuantes e/ou indutoras de tolerância ao estresse, viabilizando o uso de águas salinas e contribuindo para desenvolvimento da agricultura irrigada. Neste contexto, objetivou-se com presente estudo, avaliar o efeito da pulverização foliar com peróxido de hidrogênio como atenuante do estresse salino sobre a morfofisiologia da gravioleira. O estudo foi conduzido sob condições de casa de vegetação, em Campina Grande - PB, utilizando-se o delineamento de blocos casualizados, no arranjo fatorial 4 × 4, cujos tratamentos resultaram da combinação de quatro níveis de condutividade elétrica da água de irrigação - CEa (0,8 ­ controle; 1,6; 2,4 e 3,2 dS m-1) e quatro concentrações de peróxido de hidrogênio - H2O2 (0; 10; 20 e 30 µM), com três repetições. A aplicação foliar de peróxido de hidrogênio na concentração de 10 µM aumentou o crescimento, a síntese de clorofila e o teor relativo de água nas folhas e consequentemente reduziu o déficit de saturação hídrica foliar da gravioleira irrigada com CEa de até 1,6 dS m-1. A concentração de peroxido de hidrogênio de 30 µM intensificou o estresse salino sobre o extravasamento de eletrólitos no limbo foliar e os pigmentos fotossintéticos da gravioleira, aos 270 dias após o transplantio.

Salicylic acid concentrations and forms of application mitigate water stress in sour passion fruit seedlings / Concentrações e formas de aplicação de ácido salicílico mitiga o estresse hídrico em mudas de maracujazeiro-azedo

The present study aimed to evaluate concentrations and forms of application of salicylic acid used for water stress mitigation on the gas exchange and growth of yellow passion fruit. The experimental design was arranged in randomized blocks in a 4 × 4 × 2 factorial scheme, with four concentrations of salicylic acid (SA) via foliar application (0.0, 0.7, 1.4, and 2.1 mM), four SA concentrations via fertigation (0.0, 0.7, 1.4, and 2.1 mM), and two irrigation depths estimated based on the actual evapotranspiration - ETr (50 and 100% of ETr), with three replications. Water stress negatively affected the physiology and growth of yellow passion fruit seedlings at 75 days after sowing (DAS). The application of salicylic acid, regardless of the form of application, attenuates the effects of water stress on gas exchange and growth of yellow passion fruit, with the best results obtained when applying a concentration of 1.30 mM via leaf or 0.90 mM via fertirrigation. The combination of foliar application of AS and fertigation contributed to improve photosynthetic and growth parameters under water conditions of 50 and 100% of ETr. The foliar application of AS presents superior responses to the application via fertigation. These results reinforce the hypothesis that the attenuation of water stress by salicylic acid is related to the maintenance of gas exchange, which depends on the concentration and form of application, and studies testing combinations throughout the crop cycle become promising for advances in knowledge from the action of this phytohormone on abiotic stress.

O presente estudo teve como objetivo avaliar as concentrações e formas de aplicação do ácido salicílico como mitigador do estresse hídrico sobre as trocas gasosas e parâmetros de crescimento do maracujazeiro amarelo. O delineamento experimental foi em blocos casualizados, em esquema fatorial 4 × 4 × 2, com tratamentos constituídos por quatro concentrações de ácido salicílico (SA) via aplicação foliar (0,0, 0,7, 1,4 e 2,1 mM), quatro concentrações de SA via fertirrigação (0,0, 0,7, 1,4 e 2,1 mM) e duas lâminas de irrigação estimadas com base na evapotranspiração real - ETr (50 e 100% da ETr), com três repetições. O estresse hídrico afetou negativamente a fisiologia e o crescimento das mudas de maracujazeiro amarelo aos 75 dias após o semeio (DAS). A aplicação de ácido salicílico, independente da forma de aplicação, atenua os efeitos do estresse hídrico nas trocas gasosas e crescimento do maracujazeiro amarelo, com os melhores resultados obtidos ao se aplicar a concentração de 1,30 mM via foliar ou 0,90 mM via fertirrigação. A combinação de aplicação de AS via foliar e fertirrigação contribuiu para melhorar os parâmetros fotossintéticos e de crescimento nas condições hídricas de 50 e 100% da ETr. A aplicação via foliar de AS apresenta respostas superiores a aplicação via fertirrigação. Esses resultados reforçam a hipótese de que a atenuação do estresse hídrico pelo ácido salicílico está relacionada a manutenção das trocas gasosas, a qual depende da concentração e forma de aplicada, sendo que estudos testando combinações ao longo do ciclo da cultura se torna promissores para avanços nos conhecimentos provenientes da atuação desse fitormônio sobre o estresse abiótico.

Mineral composition and production of guava under salt stress and salicylic acid / Composição mineral e produção de goiabeira sob estresse salino e ácido salicílico

The limitation in the quality of water sources for irrigation in the semi-arid region of northeastern Brazil is increasingly present, so it is necessary to use water with high concentrations of salts for agricultural production, which makes the use of elicitors essential to mitigate the harmful effects of salinity on plants. Given the above, the objective of this study was to evaluate the effects of foliar application of salicylic acid on the mineral composition and production of guava plants under salt stress conditions in the post-grafting phase. The experiment was carried out under greenhouse conditions, in a randomized block design, in a 2 × 4 factorial scheme, with two levels of electrical conductivity of irrigation water (0.6 and 3.2 dS m-1) and four concentrations of salicylic acid (0, 1.2, 2.4, and 3.6 mM), with three replicates. During the flowering stage of guava, N, P, and K contents accumulated in the leaves according to the following order of concentration: N > K > P. Foliar application of 1.2 mM of salicylic acid increases the leaf contents of N, P, and K in guava plants grown under irrigation with water of 0.6 dS m-1. Water salinity of 3.2 dS m-1 reduces the growth and production components of guava plants.

A limitação na qualidade das fontes hídricas para irrigação na região semiárida do Nordeste é cada vez mais presente, tornando-se necessário o uso de águas com altas concentrações de sais para produção agrícola, o que torna indispensável à utilização de elicitores para atenuar os efeitos deletérios da salinidade sobre as plantas. Diante do exposto, objetivou-se com esse trabalho avaliar os efeitos da aplicação foliar de ácido salicílico na composição mineral e na produção de plantas de goiabeira sob condições de estresse salino na fase pós-enxertia. O experimento foi conduzido em casa de vegetação, no delineamento experimental de blocos casualizados, em esquema fatorial 2 × 4, sendo dois níveis de condutividade elétrica da água de irrigação (0,6 e 3,2 dS m-1) e quatro concentrações de ácido salicílico (0; 1,2; 2,4 e 3,6 mM), com três repetições. Durante a fase de floração da goiabeira, os teores de N, P, K, se acumularam nas folhas segundo a ordem de concentração N > K > P. A aplicação foliar de 1,2 mM de ácido salicílico aumentou os teores foliares de nitrogênio, fósforo e potássio nas plantas de goiabeira cultivadas sob irrigação com água de 0,6 dS m-1. A salinidade da água de 3,2 dS m-1 diminuiu o crescimento e os componentes de produção das plantas de goiabeira.

Morphophysiology and production of bell pepper grown under salt stress and salicylic acid foliar application / Morfofisiologia e produção de pimentão cultivado sob estresse salino e aplicação foliar de ácido salicílico

Considering the relevance of bell pepper and the limitations imposed by the deleterious effects of salt stress, especially in semi-arid regions, it is extremely important to establish strategies that can facilitate the use of saline water in vegetable production. In this scenario, this study aimed to evaluate the effect of the frequency of foliar application of salicylic acid on the morphophysiology and production of the bell pepper cv. "All Big" irrigated with saline water. The study was conducted at a greenhouse in Campina Grande - PB. The treatments were distributed in a completely randomized design and set up in a 4 × 4 factorial arrangement with three replications, corresponding to four application frequencies of salicylic acid (F1- No application of salicylic acid, F2 - Weekly application, F3- fortnightly application, and F4- monthly application) and four levels of electrical conductivity of irrigation water - ECw (0.8, 1.6, 2.4 and 3.2 dS m-1). The fortnightly application of salicylic acid at a concentration of 1.0 mM mitigated the effects of salt stress on the morphophysiology and production components of bell pepper cv. All Big cultivated with ECw of up to 2.4 dS m-1, which reinforces the hypothesis that salicylic acid can act as a signaling molecule and reduce the effects of saline stress in bell pepper, enabling the use of brackish water in agricultural activity, mainly in semi-arid regions of northeastern Brazil, which have a shortage of fresh water.

Considerando a relevância da cultura do pimentão e as limitações impostas pelos efeitos deletérios do estresse salino, principalmente em regiões semiáridas, é de suma importância o estabelecimento de estratégias que possam viabilizar o uso de águas salinas na produção de olerícolas. Neste contexto, objetivou-se com o presente estudo, avaliar o efeito da frequência de aplicação foliar de ácido salicílico sobre a morfofisiologia e a produção de pimentão cv. All Big irrigado com águas salinas. O estudo foi conduzido em casa de vegetação, em Campina Grande - PB. Os tratamentos foram distribuídos em delineamento inteiramente casualizados, em esquema fatorial de 4 × 4, com 3 repetições, sendo quatro frequências de aplicação de ácido salicílico (F1- Sem aplicação de ácido salicílico, F2 - Aplicação semanal, F3- quinzenal e F4- mensal) e quatro níveis de condutividade elétrica da água de irrigação - CEa (0,8, 1,6, 2,4 e 3,2 dS m-1). A aplicação quinzenal de ácido salicílico na concentração de 1,0 mM amenizou os efeitos do estresse salino sobre a morfofisiologia e os componentes de produção do pimentão cv. All Big cultivado com CEa de até 2,4 dS m-1, o que reforça a hipótese que o ácido salicílico pode atuar como uma molécula sinalizadora e reduzir os efeitos do estresse salino no pimentão, viabilizando o uso de água salobra na atividade agrícola, principalmente em regiões semiáridas do nordeste brasileiro, que possui escassez de água doce.

Physiology and production of sugar-apple under water stress and application of proline / Fisiologia e produção de pinheira sob estresse hídrico e aplicação de prolina

The objective of this study was to evaluate the physiology and production of sugar-apple as a function of irrigation intervals and foliar application of proline under the conditions of Paraíba's semi-arid region. A randomized block design was laid out in a 4 × 2 factorial scheme, with treatments resulting from the combination of four irrigation intervals (1, 4, 8 and 12 days) and two concentrations of proline (0 and 10 mM), with four replicates, and the plot consisted of four usable plants. Increase in irrigation intervals reduced the gas exchange of sugar-apple plants at 298 days after transplanting. Exogenous application of proline at concentration of 10 mM increased contents of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids and fruit fresh mass in plants grown under 12-day irrigation intervals.

Objetivou-se com este trabalho avaliar a fisiologia e a produção da pinheira em função dos turnos de rega e aplicação foliar de prolina em condições do semiárido Paraibano. Foi utilizado o delineamento de blocos casualizados em esquema fatorial 4 × 2, cujos tratamentos resultam da combinação de quatro turno de rega (1, 4, 8 e 12 dias) e duas concentrações de prolina (0 e 10 mM), com quatro repetições, cuja a parcela foi constituída de quatro plantas úteis. O incremento nos turnos de rega reduziu as trocas gasosas das plantas de pinheira, aos 298 dias após o transplantio. A aplicação de prolina na concentração de 10 mM aumentou o extravasamento de eletrólitos no limbo foliar, a condutância estomática e diminuiu a concentração interna de CO2 das plantas de pinheira. A aplicação exógena de prolina na concentração de 10 mM aumentou os teores de clorofila a, b, total e carotenoides e a massa fresca de frutos nas plantas cultivadas sob turno de rega de 12 dias.

Salicylic acid does not relieve salt stress on gas exchange, chlorophyll fluorescence, and hydroponic melon growth / O ácido salicílico não alivia o estresse salino nas trocas gasosas, fluorescência da clorofila e crescimento hidropônico do meloeiro

Abstract The objective of this study was to evaluate the salicylic acid applications in attenuating the harmful effects of saline nutrient solution on the physiology and growth of 'Gaúcho' melon cultivated in the NFT hydroponic system. The experiment was conducted in a greenhouse, in Pombal-PB, Brazil. The cultivation system used was the Nutrient Film Technique - NFT hydroponics. A completely randomized split-plot design was used, with the plot referring to four levels of salinity in the nutrient solution - ECns (2.1 control, 3.2, 4.3, and 5.4 dS m-1) and the sub-plot four concentrations of salicylic acid (SA) (0, 1.5, 3.0, and 4.5 mM), applied via foliar spray, with six replications. Nutrient solution of 4.3 and 5.4 dS m-1 electrical conductivity promotes higher maximum and variable fluorescence, respectively. The stomatal conductance, transpiration, stem diameter, main branch length, leaf dry mass, and stem dry mass of 'Gaúcho' melon plants decrease with the increase in salinity of the nutrient solution. Salicylic acid increases the initial fluorescence and the main branch length of 'Gaúcho' melon plants in hydroponic cultivation. Salicylic acid at a concentration of 1.5 to 4.5 mM did not attenuate the effects of salt stress on the internal CO2 concentration, CO2 assimilation rate, and root dry mass of 'Gaúcho' melon plants.

Resumo O objetivo deste trabalho foi avaliar as aplicações do ácido salicílico como atenuador dos efeitos deletérios da solução nutritiva salina sobre a fisiologia e o crescimento do melão 'Gaúcho' cultivado em sistema hidropônico NFT. O experimento foi conduzido em casa de vegetação, em Pombal - PB, Brasil. O sistema de cultivo utilizado foi a técnica do fluxo laminar de nutrientes - NFT. Foi utilizado um delineamento inteiramente casualizado em parcelas subdivididas, sendo a parcela referente a quatro níveis de salinidade de solução nutritiva - CEsn (2,1 controle, 3,2, 4,3 e 5,4 dS m-1) e a subparcelas quatro concentrações de ácido salicílico - AS (0, 1,5, 3,0 e 4,5 mM), aplicado via pulverização foliar, com seis repetições. A solução nutritiva de 4,3 e 5,4 dS m-1 condutividade elétrica promove maior fluorescência máxima e variável, respectivamente. A condutância estomática, a transpiração, o diâmetro do caule, o comprimento do ramo principal, a massa seca da folha e a massa seca do caule do meloeiro 'Gaúcho' diminuiu com o aumento da salinidade da solução nutritiva. O ácido salicílico aumenta a fluorescência inicial e o comprimento do ramo principal do meloeiro 'Gaúcho' em cultivo hidropônico. O ácido salicílico na concentração de 1,5 a 4,5 mM não atenuou os efeitos do estresse salino sobre a concentração interna de CO2, taxa de assimilação de CO2 e massa seca da raiz do meloeiro 'Gaúcho'.

Morphology of 'Crioula' guava seedlings under irrigation with increasing salinity water and nitrogen/potassium fertilization / Morfologia de goiabeira 'Crioula' sob irrigação com águas de salinidades crescentes e adubação nitrogenada-potássica

Abstract Several studies have been conducted evaluating the management of fertilizers as strategies to mitigate the deleterious effects of salt stress, so the objective of this work was to evaluate the quality of 'Crioula' guava seedlings under irrigation with water of different salinity levels and fertilized with combinations of nitrogen and potassium. The experiment was performed in a protected (screened) environment using a randomized block design and analyzed in a 5 × 4 factorial scheme, with four replicates, with the plot formed by two plants. The treatments were formed from the combination of the factor electrical conductivity of irrigation water (ECw 0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1), with the factor combinations (C) of nitrogen (N) and potassium (K2O) doses, being C1 = 70% N + 50% K2O, C2 = 100% N + 75% K2O, C3= 130% N + 100% K2O and C4= 160% N + 125% K2O. The recommended dose of 100% N and K, respectively, was 541.1 mg N dm-3 soil and 798.6 mg K dm-3 soil. The combinations of N and K fertilization corresponding to 70% N + 50% K2O and 100% N + 75% K2O of the recommended doses promoted greater growth of 'Crioula' guava seedlings. Water with ECw of 2.1 dS m-1 promotes the formation of quality 'Crioula' guava seedlings.

Resumo Diversos estudos vêm sendo desenvolvido avaliando o manejo de adubos como estratégias para mitigar os efeitos deletérios do estresse salino, neste sentido, objetivou-se com este trabalho avaliar a qualidade de mudas de goiabeira Crioula sob irrigação com águas de diferentes níveis salinos e adubadas com combinações de nitrogênio e potássio. O experimento foi conduzido em ambiente protegido (telado) utilizando-se o delineamento de blocos casualizados e analisados em esquema fatorial 5 × 4, com quatro repetições, com a parcela formada por duas plantas. Os tratamentos foram formados pela combinação do fator condutividade elétrica da água de irrigação (CEa), com valores de 0,3; 1,1; 1,9; 2,7 e 3,5 dS m-1; e o fator combinações (C) de doses de nitrogênio (N) e potássio (K2O), sendo C1 = 70% N + 50% K2O; C2 = 100% N + 75% K2O; C3= 130% N + 100% K2O e C4= 160% N + 125% K2O. A dose recomendada de 100% de N e K, respectivamente, foi de 541,1 e 798,6 mg de K dm-3 de solo. As combinações de adubação nitrogenada e potássica de 70% N + 50% K2O e 100% N + 75% K2O, em relação às doses recomendadas, resultaram em um maior crescimento de mudas de goiabeira Crioula. Água com CEa média de 2,1 dS m-1 foi capaz de promove a formação de mudas de qualidade de goiabeira Crioula.

Salicylic acid does not mitigate salt stress on the morphophysiology and production of hydroponic melon / Ácido salicílico não mitiga o estresse salino sobre a morfofisiologia e produção de meloeiro hidropônico

The excess of salts present in the water can limit the hydroponic cultivation of melon in semi-arid regions of the Brazilian Northeast, making it necessary to use strategies that allow the use of these waters. Among these strategies, the use of elicitor substances stands out, such as salicylic acid. In this context, this study aimed to evaluate the effect of foliar application of salicylic acid in mitigating the harmful effects of salt stress on the morphophysiology and production of 'Gaúcho' melon cultivated in a hydroponic system. A completely randomized design was adopted in a split-plot scheme, with four levels of electrical conductivity of the nutrient solution - ECsn (2.1, 3.2, 4.3, and 5.4 dS m-1) considered the plots and four salicylic acid concentrations - SA (0, 1.5, 3.0, and 4.5 mM), the subplots, with six replications. The foliar application of salicylic acid concentrations did not mitigate the deleterious effects of salt stress on the morphophysiology and yield of melon grown in hydroponic system. The concentration of 4.5 mM of salicylic acid intensified the harmful effects of the salinity of the nutrient solution on gas exchange and fresh weight of hydroponic melon.

O excesso de sais presentes na água pode limitar o cultivo hidropônico do meloeiro em regiões semiáridas do Nordeste brasileiro, fazendo-se necessária a utilização de estratégias que possibilitem o uso dessas águas, dentre essas estratégias, destaca-se a utilização de substâncias elicitoras, como ácido salicílico. Neste contexto, objetivou-se avaliar o efeito da aplicação foliar de concentrações de ácido salicílico na mitigação dos efeitos deletérios do estresse salino a morfofisiologia e produção do meloeiro 'Gaúcho' cultivado em sistema hidropônico. O experimento foi desenvolvido em casa de vegetação na Universidade Federal de Campina Grande, Pombal-PB. Adotou-se o delineamento inteiramente casualizado em esquema de parcelas subdivididas, sendo quatro níveis de condutividade elétrica da solução nutritiva - CEsn (2,1; 3,2; 4,3 e 5,4 dS m-1) considerados as parcelas e quatro concentrações de ácido salicílico - AS (0, 1,5; 3,0 e 4,5 mM), as subparcelas, com seis repetições. A aplicação foliar das concentrações de ácido salicílico não mitigaram os efeitos deletérios do estresse salino sobre a morfofisiologia e produção do meloeiro cultivado em sistema hidropônico. A concentração de 4,5 mM de ácido salicílico intensificou os efeitos deletérios da salinidade da solução nutritiva sobre as trocas gasosas e peso fresco de fruto do meloeiro hidropônico.

Methods of application of salicylic acid as attenuator of salt stress in cherry tomato / Métodos de aplicação de ácido salicílico como atenuantes do estresse salino em tomateiro cereja

Salt stress caused by excess salts present in irrigation water, is one of the biggest barriers in agricultural production, especially in semi-arid regions. Thus, the use of substances, such as salicylic acid, that minimize the deleterious effects of salinity on plants can be an alternative to ensure satisfactory production. In this context, the objective of this study was to evaluate the effects of different methods of application of salicylic acid on the growth, production and water use efficiency of cherry tomato plants under salt stress. The study was conducted in a greenhouse, using an Entisol soil with a sandy loam texture. The treatments were distributed in a completely randomized design, in a 2×4 factorial arrangement, corresponding to two levels of electrical conductivity of irrigation water - ECw (0.6 and 2.6 dS m-1) and four methods of application of salicylic acid (Control - without application of SA; via spraying; via irrigation and via spraying and irrigation), with five replicates and one plant per plot. The salicylic acid concentration used in the different methods was 1.0 mM. Application of salicylic acid via foliar spraying increased the growth, production and water use efficiency of cherry tomato plants. The salt stress induced by the electrical conductivity of 2.6 dS m-1 was attenuated by the foliar application of salicylic acid. The use of water of 2.6 dS m-1 associated with the application of salicylic acid via irrigation water further intensified the adverse effects of salinity on cherry tomato plants.

O estresse salino ocasionado pelo excesso de sais presentes na água de irrigação, é um dos maiores entraves para a produção agrícola, sobretudo em regiões semiáridas. Assim, a utilização de substâncias, como o ácido salicílico, que minimizem os efeitos deletérios da salinidade sobre as plantas pode ser uma alternativa para garantir uma produção satisfatória. Neste contexto, objetivou-se com este trabalho avaliar os efeitos de diferentes métodos de aplicação de ácido salicílico sobre o crescimento, a produção e a eficiência do uso da água de plantas de tomate cereja sob estresse salino. O estudo foi conduzido em casa de vegetação, utilizando-se de um solo Entisol de textura franco-arenosa. Os tratamentos foram distribuídos em delineamento inteiramente casualizados, em arranjo fatorial 2×4, sendo duas condutividades elétricas da água de irrigação - CEa (0,6 e 2,6 dS m-1) e quatro métodos de aplicação de ácido salicílico (Testemunha - sem aplicação de AS; via pulverização; via irrigação e pulverização e irrigação), com cinco repetições e uma planta por parcela. A concentração de ácido salicílico utilizada nos diferentes métodos foi de 1,0 mM. A aplicação de ácido salicílico via pulverização foliar, aumentou o crescimento, a produção de plantas de tomate cereja, e a eficiência do uso da água. O estresse salino induzido pela condutividade elétrica de 2,6 dS m-1 foi amenizado pela aplicação foliar de ácido salicílico. O uso de água de 2,6 dS m-1 associado a aplicação de ácido salicílico via lâmina de irrigação, intensificou os efeitos adversos da salinidade nas plantas de tomate cereja.

Gas exchange and growth of soursop under salt stress and H2O2 application methods / Trocas gasosas e crescimento de graviola sob estresse salino e métodos de aplicação de H2O2

The production of soursop seedlings in the Northeast region of Brazil has faced limitations due to the high concentrations of salts in the water, so it is necessary to use techniques that enable its cultivation, and the application of hydrogen peroxide to minimize the deleterious effects of salt stress stands out. In this context, the objective was to evaluate forms of application of hydrogen peroxide as an attenuator of salt stress on the gas exchange and growth of soursop seedlings cv. Morada Nova. The experiment was conducted under greenhouse conditions, in an Regolithic Neosol of sandy loam texture, from the municipality of Lagoa Seca - PB. A completely randomized design was used in a 5 × 4 factorial arrangement, whose treatments resulted from the combination of five levels of electrical conductivity of irrigation water - ECw (0.6 - control, 1.2, 1.8, 2.4 and 3.0 dS m-1) and four forms of hydrogen peroxide application (M1 - without H2O2 application, M2 - application by seed soaking, M3 - application by foliar spraying, and M4 - application by seed soaking + foliar spraying), with four replicates and two plants per experimental unit, totaling 160 plants. The concentration of H2O2 used in the different forms of application was 20 µM. Irrigation water salinity from 0.6 dS m-1 reduced the gas exchange and growth of soursop. The method of H2O2 application by foliar spraying minimized the effects of salt stress on gas exchange. The method of H2O2 application by seed soaking reduced the effect of salt stress on the growth of soursop at 85 days after sowing.

A produção de mudas de gravioleira na região semiárida do Brasil tem enfrentado limitações devido às elevadas concentrações de sais nas águas, sendo necessário o uso de técnicas que viabilizem seu cultivo, destacando-se a aplicação do peróxido de hidrogênio. Neste contexto, objetivou-se avaliar as formas de aplicação do peróxido de hidrogênio como atenuante do estresse salino nas trocas gasosas e no crescimento de mudas de gravioleira cv. Morada Nova. O estudo foi conduzido sob condições de casa de vegetação, em um Neossolo Regolítico de textura franco-arenosa, utilizando-se o delineamento inteiramente casualizado, no arranjo fatorial 5 × 4, cujos tratamentos resultaram da combinação de cinco níveis de condutividade elétrica da água de irrigação - CEa (0,6 - testemunha; 1,2; 1,8; 2,4 e 3,0 dS m-1) e quatro formas de aplicação de peróxido de hidrogênio (M1- sem aplicação de H2O2, M2 - aplicação via embebição das sementes, M3 -aplicação por pulverização foliar e M4 - aplicação via embebição das sementes + pulverização foliar), com quatro repetições e duas plantas por unidade experimental, perfazendo o total de 160 plantas. A concentração de H2O2 utilizada nas diferentes formas de aplicação foi de 20 µM. A salinidade da água de irrigação a partir de 0,6 dS m-1 diminuiu as trocas gasosas e o crescimento das plantas de gravioleira. O método de aplicação do H2O2 via pulverização foliar minimizou o efeito do estresse salino sobre as trocas gasosas. O método de aplicação do H2O2 via embebição das sementes diminuiu o estresse salino no crescimento de gravioleira aos 85 dias após o semeio.