Water resources in the semi-arid region of Northeast Brazil commonly contain high salt concentrations, compromising the quality of water for agriculture. Thus, adopting techniques that make the use of these resources feasible in agriculture is fundamental. The present study aimed to evaluate the gas exchanges, quantum yield and photosynthetic pigments of grafted West Indian cherry subjected to salt stress and potassium fertilization under greenhouse conditions in the municipality of Campina Grande, PB, Brazil. Treatments were distributed in randomized blocks, composed of two levels of electrical conductivity -ECw (0.8 and 3.8 dS m -1 ) of water and four doses of potassium (50, 75, 100 and 125% of the dose recommended for the crop), with three replicates. The dose relative to 100% corresponded to 19.8 g of K 2 O per plant. Gas exchanges, chlorophyll a fluorescence and photosynthetic pigments of West Indian cherry are negatively affected by irrigation using water with electrical conductivity of 3.8 dS m -1 , which compromises the photosynthetic apparatus of the plant, a situation evidenced by the reduction in photosystem II quantum efficiency. Increasing potassium doses led to increments in transpiration, chlorophyll a maximum fluorescence and chlorophyll b content in West Indian cherry grown under salt stress, but do not attenuate the negative effects of irrigation with 3.8 dS m -1 water on its potential photochemical efficiency.Keywords: Malpighia emarginata. Physiology. Potassium. Salinity. TROCAS GASOSAS, RENDIMENTO QUÂNTICO E PIGMENTOS FOTOSSINTÉTICOS DA ACEROLEIRA SOB ESTRESSE SALINO E ADUBAÇÃO POTÁSSICARESUMO -Os recursos hídricos da região semiárida do Nordeste Brasileiro comumente possuem elevadas concentrações de sais, comprometendo a qualidade da água para agricultura. Desta forma, a adoção de práticas de manejo que viabilizem o uso de tais recursos na agricultura é fundamental. Neste trabalho, objetivou-se avaliar as trocas gasosas, o rendimento quântico e os pigmentos fotossintéticos da acerola enxertada submetida ao estresse salino e adubação potássica em condição de casa de vegetação no município de Campina Grande-PB. Os tratamentos foram distribuídos em blocos casualizados, sendo constituídos de dois níveis de condutividade elétrica da água -CEa (0,8 e 3,8 dS m -1 ) e quatro doses de potássio (50, 75; 100 e 125% da dose recomendada para a cultura), com três repetições. A dose de 100% correspondeu a 19,8 g de K 2 O por planta. As trocas gasosas a fluorescência da clorofila a e os pigmentos fotossintéticos da aceroleira são afetados negativamente pela irrigação com água de condutividade elétrica de 3,8 dS m -1 que compromete o aparato fotossintético da planta, situação observada através da redução da eficiência quântica do fotossistema II. As doses de potássio crescentes promovem incremento na taxa de transpiração, fluorescência máxima da clorofila a e no teor de clorofila b da aceroleira cultivada sob estresse salino, porém não atenuam os efeitos negativos da irrigação com água de 3,8 dS m -1 sobre a...

The problem of the lack of adequate water resources for agriculture has intensified in recent years, making it necessary to use waters with relatively high concentration of salts for the irrigation of crops all over the world. The objective of this study was to evaluate the influence of potassium (K) fertilization as a salt stress attenuator on gas exchanges and photochemical efficiency of West Indian cherry. The crop was cultivated under greenhouse conditions in the municipality of Campina Grande, PB, in lysimeters filled with 250 kg of sandy loam soil. Treatments were distributed in randomized blocks, in a 2 x 4 factorial scheme, with two levels of electrical conductivity of irrigation water - ECw (0.8 and 3.8 dS m-1) and four K doses (50, 75, 100 and 125% of recommendation), in which the dose corresponding to 100% was equal to 19.8 g of K2O, with three replicates and one plant per repetition. Seedlings of the West Indian cherry cultivar BRS 366-Jaburu, grafted onto a locally developed rootstock from the clonal garden of the EMBRAPA Tropical Agroindustry, Pacajus, CE, were used. Irrigation with salinized water (electrical conductivity of 3.8 dS m-1) compromised the gas exchange and the photochemical efficiency of West Indian cherry plants. Potassium fertilization was not efficient at reducing the stress caused by water salinity on West Indian cherry plants.

to evaluate growth and production of cherry tomato cultivated under irrigation with water of different salinity levels and fertilized with different nitrogen (N) doses, in experiment conducted in drainage lysimeters under greenhouse conditions, at the Center for Agrifood Science and Technology of the Federal University of Campina Grande. The statistical design was randomized blocks in a 5 x 4 factorial scheme, with three replicates, and the treatments consisted of five levels of electrical conductivity of water (0.3, 1.5, 2.5, 3.5 and 4.5 dS m ). Growth and production variables of cherry tomato decrease linearly from the irrigation water salinity of 0.3 dS m -1 on. The longer exposure of plants to salt stress caused the highest reductions, and the root dry matter, leaf area and the number of clusters are the most sensitive variables. The highest value of plant height at 125 days after transplantation was obtained with the N dose of 139 mg kg -1 of soil. Increasing N doses reduced the effect of salinity on cherry tomato growth at 125 days after transplantation.Cultivo do tomateiro cereja sob irrigação com águas salinas e adubação nitrogenada R E S U M O Este trabalho foi desenvolvido entre agosto de 2013 e janeiro de 2014 objetivando avaliar o crescimento e a produção do tomateiro cereja cultivado sob irrigação com águas salinas e adubado com distintas doses de nitrogênio em ensaio conduzido em lisímetros de drenagem sob condições de casa de vegetação da UFCG, Pombal-PB. O delineamento estatístico utilizado foi o de blocos ao acaso, em arranjo fatorial 5 x 4, com três repetições cujos tratamentos constaram de cinco níveis de condutividade elétrica da água (0,3; 1,5; 2,5; 3,5 e 4,5 dS m ; o maior tempo de exposição das plantas ao estresse salino ocasionou as maiores reduções sendo a massa das raízes, a área foliar e o número de cachos as variáveis mais sensíveis; a maior altura de planta aos 125 dias após o transplantio foi obtida com dose de N de 139 mg kg -1 de solo; doses crescentes de nitrogênio reduziram o efeito da salinidade sobre o crescimento do tomateiro cereja, aos 125 dias após o transplantio.

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 .

ABSTRACT The objective of this study was to evaluate the growth and gas exchanges of white-fiber cotton cv. BRS 368 RF irrigated using waters with increasing levels of salinity under nitrogen-potassium combination in a greenhouse in the municipality of Campina Grande-PB, Brazil. The treatments were distributed in randomized blocks, corresponding to five levels of electrical conductivity of water - ECw (0.7; 2.2; 3.7; 5.2 and 6.7 dS m-1) and four combinations of fertilization nitrogen-potassium - N/K2O (70/50, 100/75, 130/100, 160/125% of the recommended dose for pot experiments), with three replicates. Irrigation with water of electrical conductivity from 0.7 dS m-1 compromised the growth and gas exchanges of cotton cv. BRS 368 RF, and dry biomass of leaf, stem and root were the most sensitive variables to salt stress. The nitrogen-potassium combination of 100/75% of the recommendation for pot experiments resulted in higher growth in plant height, but the highest stomatal conductance of cotton cv. BRS 368 RF was recorded in plants cultivated with 75/50% N/K2O, at 77 days after sowing. The variation in the N/K2O combination did not interfere with biomass accumulation in cotton plants. The treatment with water of lowest salinity (0.7 dS m-1) and the combination of 160/125% of the recommendation promoted greater leaf expansion, at 107 days after sowing.

Os solos das regiões áridas e semiáridas podem naturalmente conter sódio trocável em teores suficientes para reduzir significativamente o desenvolvimento e a produtividade das culturas; entretanto, diversos métodos podem ser empregados na recuperação destes solos, sendo a aplicação de melhoradores químicos e material orgânico associado ao emprego de espécies vegetais tolerantes, o meio mais efetivo para amenizar este problema. Neste sentido, objetivou-se com esta pesquisa avaliar a tolerância do algodoeiro de fibra colorida, cv. BRS Topázio, cultivado em solos com distintos percentuais de sódio trocável (PST) e doses de matéria orgânica em experimento conduzido em condição de casa de vegetação do CCTA/UFCG. O delineamento estatístico utilizado foi o de blocos ao acaso, testando-se cinco níveis de PST(13,6; 22,4; 30,1; 39,0 e 48,0%) e quatro doses de matéria orgânica (0; 5; 10 e 15%, base volume), em esquema fatorial 5 x 4, com três repetições. O algodoeiro colorido cv. BRS Topázio é tolerante ao sódio trocável, podendo ser cultivado em solo com PST de até 30%. Nível de esterco bovino de 10% atenuou o efeito do sódio trocável sobre a área foliar, fitomassa seca da parte aérea e massa de semente do algodoeiro respectivamente, sob PST de 31, 48 e 48. O diâmetro de caule, a altura de planta e a massa de pluma de algodoeiro tiveram incremento até o nível de esterco de 15%, já o maior índice de fiabilidade foi obtido sob 9% de esterco.

In Northeast Brazil, the cultivation of colored fiber cotton has stood out as one of the agricultural activities of expressive importance because its fiber has various applications in the industry and it is a labor-demanding crop. In this context, this study aimed to evaluate the growth, water consumption, water use efficiency and production of the colored fiber cotton cv. ‘BRS Rubi’, as a function of saline water irrigation and nitrogen (N) doses. The experiment was conducted in lysimeters, under greenhouse conditions, in eutrophic Regolithic Neosol, with a sandy loam texture, in Campina Grande-PB, Brazil. The plants were irrigated using water with electrical conductivities (ECw) of 5.1, 6.1, 7.1, 8.1 and 9.1 dS m-1 and fertilized with N doses (ND) of 65, 100, 135, 170 and 205 mg N kg-1 soil, in a completely randomized block design, with three replicates. Irrigation using water with an ECw above 5.1 dS m-1, hampered growth, water consumption and water use efficiency of ‘BRS Rubi’ cotton. Among the organs, the cotton root system was less affected by the salt stress in comparison to the shoots. N fertilization did not mitigate the deleterious effect of salt stress on cotton growth, water consumption, water use efficiency and production. The interaction between water salinity and N fertilization had positive effects on total weight of seeds and lint, and the highest values were obtained in plants irrigated with water of ECw 7.6 and 7.5 dS m-1 and ND of 65 mg N kg-1 of soil.

ABSTRACT: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 CO 2 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.