Salinity is still one of the main factors that limit the growth and production of crops. However, currently, hydrogen peroxide (H2O2) priming has become a promising technique to alleviate the ...deleterious effects caused by salt. Therefore, this study aimed to test different leaf spraying strategies with H2O2 for acclimation of sunflower plants to salt stress, identifying the main physiological and biochemical changes involved in this process. The experiment was conducted in a completely randomized design, with four replications. Initially, four concentrations of H2O2 were tested (0.1; 1; 10 and 100 mM) associated with different applications: 1AP - one application (48 h before exposure to NaCl); 2AP - two applications (1AP + one application 7 days after exposure to NaCl) and 3AP - three applications (2AP + one application 14 days after exposure to NaCl), besides this two reference treatments were also added: control (absence of NaCl and absence of H2O2) and salt control (presence of 100 mM of NaCl and absence of H2O2). The experiment was conducted in hydroponic system containing Furlani's nutrient solution. Salt stress reduced the growth of sunflower plants, however, the H2O2 priming through leaf spraying was able to reduce the deleterious effects caused by salt, especially in the 1 mM H2O2 treatment with one application. H2O2 acts as a metabolic signal assisting in the maintenance of ionic and redox homeostasis, and consequently increasing the tolerance of plants to salt stress.
Helianthus annuus L.; H2O2; Salinity; Oxidative stress; Physiological parameters; Cross-talk; Agricultural water management; Crop biomass; Crop production; Plant growth; Plant physiology
ABSTRACT Eggplant is a vegetable considered as moderately sensitive to salinity, and its production is affected by water deficit in the soil, mainly in the reproductive phase of the crop. The ...objective of this study was to evaluate the use of irrigation with brackish water using continuous drip and pulse in production, water consumption, water use efficiency, and soil salinization. The experimental design was in randomized blocks, in a 4 × 4 factorial scheme, with five replicates, totaling 80 plots. The treatments consisted of four forms of water application, continuous drip, and pulse throughout the cycle; continuous drip in the vegetative phase and pulse in the reproductive phase, and pulse in the vegetative phase and drip in the reproductive phase and four levels of irrigation water salinity - ECw (0.3; 1.5; 3.0; 4.5 dS m−1). The inversion of irrigation treatments occurred 65 days after transplanting. Increase in water salinity from 0.3 to 4.5 dS m−1, the total production (-11.96%), fruit length (-5.05%), and water use efficiency (-7.01%) reduced while there was no significant effect for the forms of water application and interaction between the studied factors. Pulse irrigation provided greater water savings and resulted in higher electrical conductivity in the soil saturation extract. The efficiency of water use did not show statistical difference when continuous drip or pulse irrigation was used throughout the cycle.
RESUMO A berinjela é uma hortaliça considerada moderadamente sensível à salinidade e sua produção é afetada pelo déficit hídrico no solo, principalmente na fase reprodutiva da cultura. Objetivou-se avaliar a influência do uso da irrigação com água salobra utilizando o gotejamento contínuo e pulsos na produção, consumo hídrico e eficiência do uso da água da berinjela e na salinização do solo. O delineamento experimental foi em blocos casualizados, arranjado em esquema fatorial 4 × 4, com cinco repetições, totalizando 80 parcelas. Os tratamentos foram compostos pela combinação de quatro formas de aplicação de água: gotejamento contínuo e pulsos durante todo o ciclo; gotejamento contínuo na fase vegetativa e por pulsos na fase reprodutiva e pulsos na fase vegetativa e gotejamento na reprodutiva; e quatro níveis de salinidade de água de irrigação - CEa (0,3; 1,5; 3,0; 4,5 dS m−1). A inversão das formas de irrigação ocorreu aos 65 dias após o transplantio. Com o aumento da salinidade da água de 0,3 a 4,5 dS m−1, a produção total (-11,96%), comprimento do fruto (-5,05%) e eficiência do uso da água (-7,01%) reduziram enquanto, não se verificou efeito significativo para a forma de aplicação de água e interação entre os fatores estudados. A irrigação por pulsos proporcionou maior economia de água, e resultou em maior condutividade elétrica do extrato de saturação do solo. O gotejamento contínuo ou por pulsos durante todo o ciclo não apresentaram diferenças estatísticas quanto a eficiência do uso de água, mas a irrigação por pulsos é a mais indicada por proporcionar economia de água.
Irregularity or shortage of rainfall in semi-arid regions forces farmers to use low-quality water to irrigate crops. The present study aimed to assess the water-use efficiency and post-harvest ...quality of ‘Sugar Baby’ mini watermelon in response to different electrical conductivities of the nutrient solution 2.5 (control), 3.5, 4.5, 5.5 and 6.5 dS m-1, in a floating hydroponic system. The experimental design was completely randomized, with four replicates. The water consumption, production and water-use efficiency were evaluated, as well as qualitative and physico-chemical variables of the fruits. The total water consumption of the plants during the crop cycle varied between 43 (6.5 dS m-1) and 54 (2.5 dS m-1) L plant-1among the treatments, with water-use efficiency of 0.031 kg L-1. The greatest reductions due to the nutrient solution salinity were observed for the rind thickness and fruit mass (8.80 and 5.69 %, respectively, per unit increase in dS m-1). The salinity of the nutrient solution did not influence the soluble solids content and fruit maturity index, but it had a negative effect on the pH and titratable acidity.
ABSTRACT Watermelon plays an important role in Brazilian agribusiness. The objective of present study was to evaluate the effect of different irrigation managements and water salinity levels, on the ...main productive and postharvest characteristics of mini-watermelon (Citrullus lanatus) cv. ‘Sugar Baby’. The experiment was conducted in a greenhouse in a completely randomized design, arranged in a 2 x 4 factorial scheme, with four replicates. The treatments consisted of two types of irrigation management (conventional and pulse) and four saline levels of nutrient solution of fertigation (2.5; 4.5; 5.5; 6.5 dS m-1). The control treatment corresponded to the electrical conductivity of the nutrient solution prepared with local supply water. The irrigation depth was calculated by the product of reference evapotranspiration and crop coefficient. The number of pulses were defined and fractionated according to the atmospheric demand. The salinity of the fertigation solution affects some variables of the production, but does not reduce the quality of the mini-fruit cv. ‘Sugar Baby’. The management of pulse irrigation shows better results in low salinity, while conventional drip management is more suitable for high salinity (6.5 dS m-1).
RESUMO A melancia tem um papel importante no agronegócio brasileiro. O objetivo do presente trabalho foi avaliar o efeito de diferentes manejos de irrigação e níveis de salinidade da água de irrigação, nas principais características produtivas e de pós-colheita de minimelancia (Citrullus lanatus) cv. ‘Sugar Baby’. O experimento foi conduzido em casa de vegetação em delineamento experimental inteiramente casualizado, arranjado em esquema fatorial 2 x 4, com quatro repetições. Os tratamentos consistiram de dois tipos de manejo de irrigação (gotejamento convencional e por pulsos) e quatro níveis salinos da solução nutritiva de fertigação (2,5; 4,5; 5,5; 6,5 dS m-1). O tratamento controle correspondeu à condutividade elétrica da solução nutritiva preparada com água de abastecimento local. A lâmina de irrigação foi calculada a partir do produto da evapotranspiração de referência e o coeficiente de cultivo. Os números de pulsos foram definidos e fracionados em função da demanda atmosférica. A salinidade da solução de fertigação afeta algumas variáveis de produção, mas não reduz a qualidade dos frutos de minimelancia cv. ‘Sugar Baby’. O manejo de irrigação por pulsos mostra melhores resultados em baixa salinidade, enquanto o manejo por gotejamento convencional é mais adequado para alta salinidade (6,5 dS m-1).
In order to generate information about the potential of ‘Biquinho’ pepper as an alternative crop for regions with limited supply of freshwater but with availability of brackish water, such as the ...semiarid region, a study was carried out with this crop grown in NFT (Nutrient Film Technique) hydroponic system for 120 days after transplanting (DAT). The experiment used nutrient solution prepared in water from the local municipal supply system (electrical conductivity of water –ECw = 0.34 dS m−1) and six other brackish waters prepared artificially by the addition of NaCl, with electrical conductivity of the nutrient solution -ECsol: 2.70 (control), 3.64, 4.58, 5.28, 6.09, 6.90 and 7.77 dS m−1, composing seven treatments repeated six times in randomized blocks. Fruit yield, salt tolerance and yield earliness index were evaluated. The yield of ‘Biquinho’ pepper cultivated in NFT hydroponic system, without restriction of salinity, was 2.87 kg per plant, corresponding to 46.1 Mg ha−1, considering an estimated area of 0.62 m2 per plant. A plateau followed by exponential decay model was fitted to determine the threshold salinity of ‘Biquinho’ pepper, which was 5.22 dS m−1 in the nutrient solution, corresponding to the relative potential yield. Salinity reduced the yield earliness index of ‘Biquinho’ pepper.
•Production of ‘Biquinho’ pepper is satisfactory in NFT hydroponic cultivation system.•The threshold salinity of ‘Biquinho’ pepper is 5.22 dS m−1 in the nutrient solution.•The increase in the salinity of the nutrient solution reduces the initial character of 'Biquinho' pepper production.•Nonlinear models better explained the reduction in the relative productivity of ‘Biquinho’ pepper, under NFT hydroponic cultivation.
ABSTRACT Salinity is one of the main limiting factors for crop growth. The metabolic responses to salt stress are variable and depend on species characteristics. This study aimed to select sunflower ...genotypes tolerant to salt stress and evaluate some mechanisms of salt tolerance in two contrasting (salt-tolerant and salt-sensitive) genotypes. In the first assay, the biomass production and the accumulation of Na+ and K+ in 26 sunflower genotypes were evaluated. Genotypes AG963, AG967, AG972, BRS321, BRS324, H251, H360 and H863 showed lower biomass production and were characterized as salt-sensitive and the genotypes BRS323, Catisol, EXP11-26, EXP44-49, EXP60050, EXP887, HLA860HO and Olisun 5 showed higher biomass production and were considered salt-tolerant. The high K+ content and the low Na+ content in the leaves were the ion traits related to salt tolerance and can be used in sunflower breeding programs for this purpose. In the second assay, the plants of salt-tolerant BRS323 had lower Na+ and Cl- contents and higher levels of K+ than plants of salt-sensitive AG967. A better homeostasis in the mechanisms of transport, distribution and accumulation of inorganic solutes in conjunction with a more efficient osmoregulation mechanism through the synthesis of organic solutes may, at least in part, explain the greater salt-tolerance of BRS323 genotype in comparison to AG967.
RESUMO A salinidade é um dos principais fatores limitantes para o crescimento das culturas. As respostas metabólicas ao estresse salino são variáveis dependendo das características da espécie. O presente estudo teve como objetivo selecionar genótipos de girassol tolerantes ao estresse salino e avaliar alguns mecanismos de tolerância ao sal em dois genótipos contrastantes (tolerantes e sensíveis ao sal). No primeiro ensaio, foram avaliados a produção de biomassa e o acúmulo de Na+ e K+ em 26 genótipos de girassol. Os genótipos AG963, AG967, AG972, BRS321, BRS324, H251, H360 e H863 apresentaram menor produção de biomassa e foram caracterizados como sensíveis ao sal e os genótipos BRS323, Catisol, EXP11-26, EXP44-49, EXP60050, EXP887, HLA860HO e Olisun 5 apresentaram maior produção de biomassa e foram considerados tolerantes ao sal. O alto teor de K+ e o baixo teor de Na+ nas folhas foram as características iônicas relacionados à tolerância ao sal e podem ser utilizados em programas de melhoramento de girassol para esse fim. No segundo ensaio, as plantas de BRS323 tolerantes ao sal apresentaram menor teor de Na+ e Cl- e maiores níveis de K+ do que as plantas de AG967 sensível ao sal. Uma melhor homeostase nos mecanismos de transporte, distribuição e acumulação de solutos inorgânicos em conjunto com um mecanismo de osmorregulação mais eficiente através da síntese de solutos orgânicos pode, ao menos em parte, explicar a maior tolerância ao sal do genótipo BRS323 em comparação com o AG967.
ABSTRACT Amaranthus cruentus L. is a forage species, with grains that exhibit excellent nutritional characteristics, being the 'BRS Alegria' the first cultivar recommended for cultivation in Brazil. ...This study aimed at evaluating the effect of salt stress on the growth and concentrations of organic and inorganic solutes in Amaranthus cruentus L. ('BRS Alegria' cultivar). Height, stem diameter, number of leaves, leaf, stem and root dry mass, leaf area, relative water content and membrane integrity percentage, as well as soluble carbohydrate, free amino acid, soluble protein, free proline, Na+, Cl- and K+ contents, were evaluated in different plant organs. Salinity significantly reduced the biomass yield and leaf area from the treatment with 25 mM of NaCl, indicating that the 'BRS Alegria' cultivar is sensitive to salt stress. Soluble carbohydrates in the leaves decreased by 59 %, while the other organic solutes showed no substantial increases. These results, coupled with the reduction in the relative water content and membrane integrity, suggest a low ability of this cultivar to adjust osmotically under salt stress. The K+/Na+ ratio abruptly decreased in 25 mM of NaCl, suggesting an ionic imbalance, which may partially explain the salt-induced growth reduction.
RESUMO O Amaranthus cruentus L. é uma espécie forrageira, com grãos que possuem ótimas características nutricionais, sendo a cultivar 'BRS Alegria' a primeira recomendada para cultivo no Brasil. Objetivou-se avaliar o efeito do estresse salino no crescimento e concentrações de solutos orgânicos e inorgânicos em Amaranthus cruentus L. cv. 'BRS Alegria'. Foram avaliados a altura, diâmetro do caule, número de folhas, massa seca das folhas, caule e raízes, área foliar, teor relativo de água, porcentagem de integridade das membranas e teores de carboidratos solúveis, aminoácidos livres, proteínas solúveis, prolina livre, Na+, Cl- e K+, nos diferentes órgãos da planta. A salinidade reduziu fortemente a produção de biomassa e a área foliar a partir do tratamento com 25 mM de NaCl, indicando que a cultivar 'BRS Alegria' é sensível ao estresse salino. Os carboidratos solúveis nas folhas diminuíram 59 %, enquanto os demais solutos orgânicos não apresentaram aumentos substanciais. Esses resultados, associados à diminuição do teor relativo de água e da integridade das membranas, sugerem uma baixa capacidade dessa cultivar para o ajustamento osmótico sob estresse salino. A razão K+/Na+ reduziu-se abruptamente em 25 mM de NaCl, sugerindo desequilíbrio iônico, o que pode, ao menos em parte, explicar a redução de crescimento induzida pelo sal.
ABSTRACT The use of resources derived from the agricultural property itself to meet the needs of producers promotes the reduction of costs with commercial inputs and recycling of by-products, among ...them the liquid waste from the cassava flour production, called cassava wastewater, which can be an important fertilization source. This study aimed to evaluate the growth and production of Capsicum chinense Jacq., as a function of cassava wastewater doses associated with mineral fertilizer proportions. The experiment was conducted in a greenhouse, in a completely randomized design, with treatments distributed in a 3 x 5 factorial scheme, corresponding to 3 doses (0, 50 and 100 %) of the mineral fertilization recommended for the crop and 5 doses (0, 25, 50, 100 and 150 m³ ha-1) of cassava wastewater, with 4 replicates. The cassava wastewater doses influenced the crop yield, showing a linear trend. The dose of 150 m3 ha-1 promoted a yield equivalent to that obtained with the application of 100 % of the mineral fertilization recommended for this crop, thus enabling the partial or total replacement of this fertilization by cassava wastewater.
RESUMO A utilização de recursos derivados da própria propriedade agrícola para suprir necessidades dos produtores proporciona a redução de custos com insumos comerciais e a reciclagem de subprodutos, dentre eles, o resíduo líquido da produção de farinha de mandioca, denominado manipueira, que pode configurar-se como importante fonte de adubação. Objetivou-se avaliar o crescimento e a produção de Capsicum chinense Jacq., em função de doses de manipueira associada a proporções de adubo mineral. O estudo foi conduzido em casa-de-vegetação, em delineamento inteiramente casualizado, com os tratamentos distribuídos em esquema fatorial 3 x 5, sendo 3 doses (0, 50 e 100 %) da adubação mineral recomendada para a cultura e 5 doses (0, 25, 50, 100 e 150 m³ ha-1) de manipueira, com 4 repetições. As doses de manipueira influenciaram na produtividade da cultura, apresentando tendência linear. A dose de 150 m3 ha-1 proporcionou produtividade equivalente à obtida com a aplicação de 100 % da adubação mineral recomendada para essa cultura, permitindo, assim, a substituição parcial ou total dessa adubação pela manipueira.
Salt-induced redox and ion imbalance may lead to increased oxidative stress and impair the plant growth. However, among the many reactive oxygen species (ROS) produced under stress, hydrogen peroxide ...(H
2
O
2
) plays a central role in several signal transduction pathways triggering a series of physiological mechanisms and increase plant tolerance to salt stress. Thus, this study aimed to evaluate the changes in the balance of inorganic and organic solutes induced by seed priming with H
2
O
2
in leaves and roots of sunflower plants grown under salt stress. In this study, six treatments were tested: T1 - control (absence of NaCl and absence of H
2
O
2
); T2 - salt control (presence of 100 mM NaCl and absence of H
2
O
2
); T3 − 100 mM H
2
O
2
(12 h) + 100 mM NaCl; T4 − 10 mM H
2
O
2
(12 h) + 100 mM NaCl; T5 − 1 mM H
2
O
2
(24 h) + 100 mM NaCl; T6 − 0.1 mM H
2
O
2
(36 h) + 100 mM NaCl. Our results show that, the role of H
2
O
2
in increase of the salt tolerance is directly associated with reduction on Na
+
(on average 46%) and Cl
-
(on average 24%) contents in the leaves, besides a positive regulation of K
+
and NO
3
-
absorption (for three harvests). In addition, H
2
O
2
priming also decreased the oxidative damage, mainly by increasing the activity of catalase enzyme (CAT) in leaves (on average 49% at 2
nd
and 3
rd
harvests) and roots (on average 39% at 3
rd
harvest).
Information and available knowledge of the soils of the Sertanejo pediplain are relatively scarce and restricted to survey data. Researches about soil characterization and classification contributes ...to the knowledge of different soil orders within a region and allows information to be obtained systemically based on the physical, chemical, and mineralogical properties of the soil. This study aimed to evaluate the genesis of the Sertanejo pediplain soils, through the characterization of the chemical and mineralogical properties and classification of the soils of the sisal-growing region. Five soil profiles located in Araci, Retirolândia, St. Dominic, and Valente, cities located in the sisal-growing areas of the Bahia semiarid region, were studied, described morphologically, and analyzed for chemical (pH H2O and KCl, Ca2+, Mg2+, K+, Na+, Al3+, H+ + Al3+, P, and TOC) and mineralogical attributes. Most evaluated soil classes were formed by lithological discontinuity of material. The main processes involved in the formation of such soil classes were: cumulization, accretion, and lessivage. The mineralogy of the clay fraction observed was complex and included a variety of minerals, with a predominance of kaolinite and bayerite. In addition, we also found goethite and illite in most of the studied profiles, both in the sediment, horizons P1 C2, and in the crystalline horizon P1 Cr, P2 Bi, P3 2Cr, and P5 Bi. The soils were classified up to the fourth category level, as Entisol Eutrophic Inceptisol (RRE), Alfisols Haplic typical Eutrophic (SXE), and Inceptisols Ta Eutrophic vertissólico (CXve).
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