Hydrogen Peroxide Alleviates Salt Stress Effects on Gas Exchange, Growth, and Production of Naturally Colored Cotton.

Cotton is one of the most exploited crops in the world, being one of the most important for the Brazilian Northeast. In this region, the use of irrigation is often necessary to meet the water demand of the crop. Water is often used from underground wells that have a large amount of salt in their constitution, which can compromise the development of crops, so it is vital to adopt strategies that reduce salt stress effects on plants, such as the foliar application of hydrogen peroxide. Thus, the objective of this study was to evaluate the effects of foliar application of hydrogen peroxide on the gas exchange, growth, and production of naturally colored cotton under salt stress in the semi-arid region of Paraíba, Brazil. The experiment was carried out in a randomized block design in a 5 × 5 factorial scheme, with five salinity levels of irrigation water-ECw (0.3, 2.0, 3.7, 5.4 and 7.1 dS m-1)-and five concentrations of hydrogen peroxide-H2O2 (0, 25, 50, 75 and 100 µM), and with three replicates. The naturally colored cotton 'BRS Jade' had its gas exchange, growth, biomass production, and production reduced due to the effects of salt stress, but the plants were able to produce up to the ECw of 3.97 dS m-1. Foliar application of hydrogen peroxide at the estimated concentrations of 56.25 and 37.5 µM reduced the effects of salt stress on the stomatal conductance and CO2 assimilation rate of cotton plants under the estimated ECw levels of 0.73 and 1.58 dS m-1, respectively. In turn, the concentration of 12.5 µM increased water-use efficiency in plants subjected to salinity of 2.43 dS m-1. Absolute and relative growth rates in leaf area increased with foliar application of 100 µM of hydrogen peroxide under ECw of 0.73 and 0.3 dS m-1, respectively. Under conditions of low water salinity (0.3 dS m-1), foliar application of hydrogen peroxide stimulated the biomass formation and production components of cotton.

The Effects of Irrigation Water Salinity on the Synthesis of Photosynthetic Pigments, Gas Exchange, and Photochemical Efficiency of Sour Passion Fruit Genotypes.

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).

Effect of Hydrogen Peroxide Application on Salt Stress Mitigation in Bell Pepper (Capsicum annuum L.).

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.

Salicylic Acid as a Salt Stress Mitigator on Chlorophyll Fluorescence, Photosynthetic Pigments, and Growth of Precocious-Dwarf Cashew in the Post-Grafting Phase.

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.

Production and Fiber Characteristics of Colored Cotton Cultivares under Salt Stress and H2O2.

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.

Optimization of Extraction Method of Anthocyanins from Red Cabbage.

Among the vegetables that stand out for their high concentration of anthocyanins, red cabbage appears as one of the most-used sources of these pigments in food production and it is considered a suitable raw material for the extraction of natural dye. Therefore, the objective was to carry out the production of natural extracts from red cabbage, under different conditions, varying the solvent, type of pre-treatment, pH range, and processing temperature during the concentration of the extracts. The anthocyanins were extracted from red cabbage using the following solvents: distilled water, 25% ethyl alcohol, and 70% ethyl alcohol. The raw material was divided into two groups, the first was subjected to a drying pre-treatment at 70 °C for 1 h and for the second group, the extraction was performed with the raw material in natura. Two pH ranges of 4.0 and 6.0 and extraction temperatures of 25 °C and 75 °C were used in the extracts, resulting in 24 formulations. The extracts obtained were analyzed for colorimetric parameters and anthocyanins. The results of anthocyanins show that the methodology that uses 25% alcohol, pH 4.0, and processing temperature of 25 °C produces a reddish extract and better results in the extraction, presenting average values of 191.37 mg/100 g of anthocyanins, being 74% higher compared to the highest values obtained in the other extracts where the same raw material was used and the solvents differed.

Influence of Foliar Application of Hydrogen Peroxide on Gas Exchange, Photochemical Efficiency, and Growth of Soursop under Salt Stress.

Hydrogen peroxide at low concentrations has been used as a salt stress attenuator because it induces a positive response in the antioxidant system of plants. This study aimed to assess the gas exchange, quantum yield, and development of soursop plants cv. Morada Nova grown with saline water irrigation and foliar hydrogen peroxide application. The experiment was carried out under greenhouse conditions using a randomized block design in a 4 × 4 factorial scheme corresponding to four levels of electrical conductivity of irrigation water, ECw (0.8, 1.6, 2.4, and 3.2 dS m-1), and four doses of hydrogen peroxide, H2O2 (0, 10, 20, and 30 µM), with three replicates. The use of irrigation water with electrical conductivity above 0.8 dS m-1 inhibited stomatal conductance, internal CO2 concentration, transpiration, maximum fluorescence, crown height, and vegetative vigor index of the Morada Nova cultivar of soursop. Compared to untreated plants, the hydrogen peroxide concentration of 30 µM resulted in greater stomatal conductance. Water salinity of 0.8 dS m-1 with hydrogen peroxide concentrations of 16 and 13 µM resulted in the highest variable fluorescence and quantum efficiency of photosystem II, respectively, of soursop plants cv. Morada Nova at 210 days after transplantation.

Water salinity and nitrogen fertilization in the production and quality of guava fruits / Salinidade da água e adubação nitrogenada na produção e qualidade de frutos de goiabeira

Using nitrogen (N) to increase plant tolerance to salinity has been tested in many species. However, in addition to controversial results, most studies are conducted with annual species and/or in the initial growth stage and there are almost no studies with perennial fruit crops in the production stage. Thus, this study aimed to evaluate the production components and post-harvest quality of 'Paluma' guava irrigated with water of increasing salinity in soil fertilized with N. The experiment was carried out for two years in drainage lysimeters in an experimental area of the Federal University of Campina Grande (UFCG), Pombal, PB, Brazil. The experimental design was in randomized blocks, in 5 x 4 factorial scheme, with of five levels of water salinity ­ ECw (NaCl)(0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1) and four N doses (ureia) (70, 100, 130 and 160% of the recommended dose - 541.1 mg of N dm-3 of soil per year), with three replicates. Number of fruits, mean fruit weight, production per plant, polar and equatorial diameters of fruit and contents of soluble solids and ascorbic acid (vitamin C) decreased linearly with the increase in irrigation water salinity from 0.3 dS m-1. The interaction between water salinity and N doses and the isolated action of N did not interfere statistically with the studied variables.

O uso de nitrogênio como forma de aumentar a tolerância das plantas à salinidade tem sido testado em muitas espécies. No entanto, além de resultados controversos, se observa que a maioria dos estudos são realizados com espécies anuais e, ou na fase inicial de crescimento, sendo praticamente inexistentes estudos com frutíferas perenes em fase de produção. Nessa direção, o trabalho teve como objetivo avaliar os componentes de produção e a qualidade pós-colheita de goiabeira 'Paluma' irrigada com águas de salinidade crescente no solo com nitrogênio. O experimento foi conduzido durante dois anos em lisímetros de drenagem numa área experimental da Universidade Federal de Campina Grande (UFCG), Pombal, PB. O delineamento experimental foi em blocos casualizados, em esquema fatorial 5 x 4, com salinidades de água ­ CEa (NaCl) de 0,3, 1,1, 1,9, 2,7 e 3,5 dS m-1 e quatro doses de nitrogênio (ureia) de 70, 100, 130 e 160% da dose recomendada de 541,1 mg de N dm-3 por ano, com três repetições. A interação salinidade da água x doses de nitrogênio e ação isolada de N não influenciaram estatisticamente as variáveis estudadas. O número de frutos, a massa média de frutos, a produção por planta, o diâmetro polar e equatorial dos frutos, os teores de sólidos solúveis e ácido ascórbico (vitamina C), decresceram linearmente com o aumento da salinidade da água de irrigação a partir de 0,3 dS m-1.

Photosynthesis, photochemical efficiency and growth of west indian cherry cultivated with saline waters and nitrogen fertilization / Fotossíntese, eficiência fotoquímica e crescimento da aceroleira cultivada com águas salinas e adubação n itrogenada

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.

Saline water and potassium fertilization in cultivation of grafted west indian cherry ˜BRS 366 Jaburu / Águas salinas e adubação potássica no cultivo de aceroleira 'brs 366 jaburu' enxertada

Agricultural exploitation in the semi-arid region of Northeast Brazil depends on the use of irrigation to guarantee safe production of crops. Nevertheless, the waters commonly used in this region have high levels of salts and require management strategies that make their use possible in agriculture. In this context, the present study aimed to evaluate water relations, photosynthetic pigments and growth of grafted West Indian cherry as a function of saline water irrigation and potassium (K) fertilization. The study was conducted under greenhouse conditions in lysimeters filled with eutrophic Regolithic Neosol with sandy loam texture, in the municipality of Campina Grande-PB, Brazil. Treatments were distributed in randomized blocks and consisted of two factors: two levels of irrigation water electrical conductivity ­ ECw (0.8 and 3.8 dS m-1) and four K doses (50, 75; 100 and 125% of the recommendation), with three replicates and one plant per plot. The 100% dose corresponded to 19.8 g of K2O per plant per year. The West Indian cherry crop was sensitive to water salinity of 3.8 dS m-1 in the post-grafting phase, resulting in a decline in photosynthetic pigment content and growth. Increasing K doses reduced the percentage of cell membrane damage and promoted increase in the synthesis of chlorophyll a and carotenoids in West Indian cherry plants. There was significant interaction between salinity levels and K doses for the leaf osmotic potential, water saturation deficit, percentage of cell membrane damage and chlorophyll b content in West Indian cherry plants.

A exploração agrícola na região semiárida do Nordeste brasileiro depende do uso da irrigação para garantir a produção das culturas com segurança; entretanto, nesta região, as águas utilizadas comumente possuem níveis elevados de sais e necessitam de estratégias de manejo que possibilitem sua utilização na agricultura. Neste contexto, objetivou-se com este trabalho avaliar as relações hídricas, os pigmentos fotossintéticos e o crescimento da aceroleira enxertada em função da irrigação com águas salinas e adubação potássica. A pesquisa foi realizada em condição de casa de vegetação em lisímetros preenchidos com um Neossolo Regolítico Eutrófico de textura franco-arenosa, no município de Campina Grande-PB. Os tratamentos foram distribuídos em blocos casualizados, e consistiram de dois fatores, sendo dois níveis de condutividade elétrica da água de irrigação - CEa (0,8 e 3,8 dS m-1) e quatro doses de potássio (50, 75; 100 e 125% da recomendação), com três repetições e uma planta por parcela. A dose de 100% correspondeu a 33,0 g de K2O por planta por ano. A cultura da aceroleira é sensível a salinidade da água de 3,8 dS m-1, na fase pós enxertia, resultando-se em declínio nos teores de pigmentos fotossintéticos e crescimento. Doses crescentes de potássio diminuíram o percentual de dano na membrana celular e promoveram aumento na síntese de clorofila a e carotenoides nas plantas de aceroleira. Houve interação significativa entre os fatores níveis salinos e doses de potássio para potencial osmótico foliar, déficit de saturação hídrica, percentual de dano na membrana celular e teor de clorofila b da aceroleira.

Ecophysiology of west indian cherry irrigated with saline water under phosphorus and nitrogen doses / Ecofisiologia da aceroleira irrigada com água salin a sob doses de fósforo e nitrogênio

The quantitative and qualitative scarcity of water resources is a frequent problem in the semi-arid region of the Brazilian Northeast. The availability of water for irrigation with high content of dissolved salts is common, affecting the growth and development of the crops. Thus, it is necessary to adopt strategies that allow the establishment of irrigated agriculture in this region. The objective of this study was to evaluate the effect of water salinity and phosphorus/nitrogen combinations on the ecophysiology of the West Indian cherry grafted in the first year of cultivation. The research was carried out in a protected environment, in lysimeters filled with a Regolithic Neosol of loamy clay texture, having low initial phosphorus content. The experiment was arranged in a randomized block design, arranged in a 5x4 factorial scheme, with five levels of electrical conductivity of the irrigation water - ECw (0.6, 1.4, 2.2, 3.0 and 3.8 dS m -1) and four managements of fertilization with phosphorus and nitrogen (100:100; 140:100; 100:140 and 140:140% P/N of the recommendation), with three replications, each plot consisting of one plant. Increased salinity of irrigation water reduced growth, photosynthesis and the production of West Indian cherry. Fertilization with 140% of recommendation of the phosphorus and nitrogen minimizes the deleterious effect of salinity on West Indian cherry irrigated with water up to 3.0 dS m-1.

A escassez quantitativa e qualitativa dos recursos hídricos é um problema frequente na região semiárida do Nordeste brasileiro, sendo comum a disponibilidade de água para irrigação com elevados teores de sais, afetando o crescimento e o desenvolvimento das culturas. Assim é necessário adoção de estratégias que viabilize o estabelecimento de cultivo irrigado nessa região.Com isso,objetivou-se com este trabalho avaliar o efeito da salinidade de água e manejos da combinação fósforo/nitrogênio sobre a ecofisiologia da acerola enxertada no primeiro ano de cultivo. A pesquisa foi realizada em ambiente protegido, em lisímetros preenchidos com Neossolo Regolítico de textura franco-argilosa, possuindo baixo teor inicial de fósforo. O experimento foi instalado em delineamento de blocos casualizados, arranjados em esquema fatorial 5x4, sendo cinco níveis de condutividade elétrica da água de irrigação - CEa (0,6; 1,4; 2,2; 3,0 e 3,8 dS m-1) e quatro manejos de adubação com fósforo e nitrogênio (100:100; 140:100; 100:140 e 140:140% da recomendação de P/N), com três repetições, sendo cada parcela constituída de uma planta. O aumento da salinidade da água de irrigação reduziu o crescimento, a fotossíntese e a produção da aceroleira. Adubação com 140% da recomendação de fósforo e nitrogênio minimiza o efeito deletério da salinidade sobre a produção de aceroleira irrigada com água de até 3,0 dS m-1.

NPK and sodium content in sesame under salt stress and nitrate/ammonium fertilization / Teores de NPK e sódio no gergelim sob estresse salino e adubação com nitrato/amônio

This study aimed to evaluate the effects of saline water irrigation and fertilization with different nitrate/ammonium proportions on the contents of nitrogen (N), phosphorus (P), potassium (K+) and sodium (Na+) and Na+/K+ ratio in the sesame cv. CNPA G3, through an experiment conducted in drainage lysimeters under greenhouse conditions, in eutrophic Regolithic Neosol with sandy loam texture, in the municipality of Campina Grande-PB, Brazil. Treatments were distributed in randomized blocks, in 5 x 5 factorial scheme, with three replicates, relative to five levels of irrigation water salinity - ECw (0.6; 1.2; 1.8; 2.4 and 3.0 dS m-1) and five nitrate/ammonium proportions - NAP (200:0,150:50, 100:100, 50:150, 0:200 mg kg-1 of NO3 --N/NH4+-N). Increasing ECw levels caused increment in Na+ contents and reduction in N, P and K+ contents in leaf and stem tissues of the sesame cv. CNPA G3. The increase in the Na+/ K+ ratio in leaves and stem of sesame under irrigation with ECw water up to 3.0 dS m-1 can be considered as a mechanism of tolerance to salt stress. There was interaction between the factors (ECw x NAP) for the N content in the leaf tissues, and its highest accumulation was obtained with ECw of 0.6 dS m-1 and NO3 --N/NH4 +-N proportion of 200:0 mg kg-1.

Objetivou-se, neste trabalho, avaliar os efeitos da irrigação com águas salinas e adubação com diferentes proporções de nitrato e amônio sobre os teores de NPK, sódio e relação Na/K no gergelim cv. CNPA G3, em experimento conduzido em lisímetros de drenagem sob condições de casa de vegetação, no Neossolo Regolítico Eutrófico, textura franco-arenosa, no município de Campina Grande, PB. Os tratamentos foram distribuídos em blocos casualizados, em esquema fatorial 5 x 5, com três repetições, referentes a cinco níveis de condutividade elétrica da água de irrigação ­ CEa (0,6; 1,2; 1,8; 2,4 e 3,0 dS m-1) e cinco proporções de nitrato e de amônio - PNA (200:0, 150:50, 100:100, 50:150, 0:200 mg kg-1 de N-NO3-/N-NH4+). Níveis crescentes de CEa promoveu aumento nos teores de Na+ e diminuição nos teores de N P K nos tecidos foliares e caulinar do gergelim cv. CNPA G3; o aumento na relação Na+/K+ nas folhas e caule do gergelim sob irrigação com água de CEa até 3.0 dS m-1 pode ser considerado como mecanismo de tolerância ao estresse salino; houve interação entre os fatores (CEa x PNA) para teor de nitrogênio nos tecidos das folhas, sendo o maior acúmulo obtido com CEa de 0,6 dSm-1 e proporções de 200:0 mg kg-1 de N-NO3- e N-NH4+.

Gas exchanges and production of colored cotton under salt sress and nitrogen fertilization = / Trocas gasosas e produção do algodoeiro colorido sob estresse salino e adubação nitrogenada

This study was conducted with the objective of evaluating the gas exchanges and production components of colored-fiber cotton as a function of irrigation with water of different saline levels and nitrogen (N) doses. The experiment was carried out in drainage lysimeters, filled with eutrophic Regolithic Neosol of sandy loam texture, in the municipality of Campina Grande-PB, Brazil. The statistical design was randomized blocks and the treatments resulted from the combination of five levels of irrigation water electrical conductivity - ECw (5.1, 6.1, 7.1, 8.1 and 9.1 dS m-1) and five N doses - ND (65; 100; 135; 170; 205 mg of N kg-1 of soil) in a 5 x 5 factorial scheme, with three replicates. The interaction between the saline levels of the irrigation water and the N doses did not influence significantly any of the analyzed variables. The gas exchanges and production components of the cotton cultivar 'BRS Rubi' were negatively affected by the ECw higher than 5.1 dS m-1; the CO2 assimilation rate and total number of seeds per plant were the variables most sensitive to the effects of salt stress; N doses above 65 mg kg-1 led to decrease of stomatal conductance in the cotton crop.

Conduziu-se esta pesquisa com o objetivo de avaliar, as trocas gasosas e os componentes de produção do algodoeiro de fibra colorida em função da irrigação com águas de diferentes níveis de salinidades e doses de nitrogênio. O experimento foi desenvolvido em lisímetros de drenagem, preenchidos com um Neossolo Regolítico Eutrófico de textura franco-arenosa, no município de Campina Grande, PB. O delineamento estatístico utilizado foi em blocos casualizados, cujos tratamentos resultaram da combinação de cinco níveis de condutividade elétrica da água de irrigação ­ CEa (5,1; 6,1; 7,1; 8,1 e 9,1 dS m-1) e cinco doses de nitrogênio ­ DN (65; 100; 135; 170; 205 mg de N kg-1 de solo) em esquema fatorial 5x5, com três repetições. A interação entre os níveis salinos da água de irrigação e as doses de nitrogênio não influenciaram de forma significativa nenhuma das variáveis analisadas; as trocas gasosas e os componentes de produção do algodoeiro cv. BRS Rubi foram afetadas negativamente pela CEa superior a 5,1 dS m-1; a taxa de assimilação de CO2 e o número total de sementes por planta foram as variáveis mais sensíveis aos efeitos do estresse salino; doses de nitrogênio acima de 65 mg kg-1 promoveu diminuição na condutância estomática do algodoeiro.

Growth and production of sunflower as a function of cationic nature of the water and nitrogen / Crescimento e produção do girassol em função da natureza catiônica da água e nitrogênio

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.

Physiological indices and production of sesame under salt stress and nitrate/ammonium proportions / Índices fisiológicos e produção do gergelim sob estresse salino e proporções de nitrato e amônio

In semi-arid regions, the occurrence of water with high concentration of salts is common, which compromises the growth and consequently the production of crops. Thus, this study aimed to evaluate the gas exchanges and production of sesame, cv. CNPA G3, irrigated with saline water and fertilized with different proportions of nitrate and ammonium, in an experiment conducted using lysimeters in a greenhouse in the municipality of Campina Grande-PB, Brazil. The treatments were arranged in randomized blocks and analyzed in a 5 x 5 factorial scheme, with three replicates, relative to five levels of electrical conductivity of the irrigation water ­ ECw (0.6, 1.2, 1.8, 2.4 and 3.0 dS m-1) and five proportions of nitrate/ammonium - NO3 -/NH4 + (200/0, 150/50, 100/100, 50/150 and 0/200 mg of N kg-1 of soil). Irrigation with water of salinity level higher than 0.6 dS m-1 promoted negative effect on gas exchanges and production components of the sesame cv. CNPA G3. Fertilization with N exclusively in the form of NH4 + promoted increment in CO2 concentration and reduction in its assimilation rate and instantaneous carboxylation efficiency. The highest rate of CO2 assimilation, transpiration and instantaneous carboxylation efficiency were obtained when the plants were irrigated with water of 0.6 dS m-1 and fertilization with 200/0 of NO3 -/NH4 +. Increasing levels of water salinity promoted a decrease in the total seed mass, regardless of the proportion of NO3 -/NH4 +. The sesame cv. CNPA G3 is classified as sensitive to salt stress from the electrical conductivity of water of 0.6 dS m-1.

Nas regiões semiáridas é comum a ocorrência de águas com elevada concentração de sais que comprometem o crescimento e consequentemente a produção das culturas. Deste modo, objetivou-se avaliar as trocas gasosas e a produção do gergelim cv. CNPA G3 irrigado com águas salinas e adubado com diferentes proporções de nitrato e amônio em um ensaio conduzido em lisímetros dispostos em casa de vegetação no município de Campina Grande, PB. Os tratamentos foram distribuídos em blocos ao acaso e analisados em esquema fatorial 5 x 5, com três repetições, relativos a cinco níveis de condutividade elétrica da água de irrigação ­ CEa (0,6; 1,2; 1,8; 2,4 e 3,0 dS m-1) e cinco proporções de nitrato e amônio - NO3 -/NH4 + (200/0; 150/50; 100/100; 50/150 e 0/200 mg de N kg-1 de solo). A irrigação com água de salinidade superior a 0,6 dS m-1 promoveu efeito negativo sobre as trocas gasosas e os componentes de produção do gergelim cv CNPA G3. A adubação com N exclusivamente na forma de NH4 + proporcionou incremento na concentração de CO2 e redução na taxa de assimilação de CO2, eficiência instantânea de carboxilação. A maior taxa de assimilação de CO2, transpiração e eficiência instantânea de carboxilação foram obtidas quando as plantas foram irrigadas com água de 0,6 dS m-1 e adubação com 200/0 de NO3 -/ NH4 +. Níveis crescentes de salinidade da água promoveram diminuição na massa total de sementes, independente da proporção de NO3 - e NH4 +. O gergelim cv. CNPA G3 foi classificado como sensível ao estresse salino, a partir da condutividade elétrica da água de 0,6 dS m-1.