The study was carried out to evaluate the photosynthetic efficiency and growth of yellow passion fruit, cultivated under different levels of irrigation water salinity and exogenous application of hydrogen peroxide. The experiment was carried out in greenhouse of the Universidade Federal de Campina Grande, PB, Brazil, using drainage lysimeters with capacity for 100 dm3, filled with Entisol of sandy texture. The experimental design was randomized blocks using a 4 x 4 factorial scheme, with three repetitions, corresponding to four water salinity (0.7; 1.4; 2.1 and 2.8 dS m-1) and four concentrations of hydrogen peroxide (0, 20, 40 and 60 µM). The different concentrations of hydrogen peroxide were applied by soaking the seed for a period of 24 h and spraying the leaves on the adaxial and abaxial sides. At 35 days after transplanting, the interaction between water salinity and hydrogen peroxide concentrations did not significantly interfere with plant physiology and growth, except for the number of leaves. The hydrogen peroxide did not cause significant effects on any of the evaluated plant variables. Increasing salinity of irrigation water led to reduction in gas exchanges at 61 and 96 days after transplanting. Water salinity inhibited the CO2 assimilation, transpiration, stomatal conductance, instantaneous carboxylation efficiency and stem diameter of passion fruit plants.

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.

The success of yellow passion fruit cultivation in the semi-arid region of Northeast Brazil is conditioned on the ability of this crop to develop under salt stress conditions, so it is necessary to identify techniques capable of attenuating the deleterious effects caused by irrigation with high-salinity waters. In this context, the present study aimed to evaluate the fluorescence, photosynthetic pigments and biomass of yellow passion fruit cultivated under salt stress and foliar application of hydrogen peroxide. The study was conducted in a greenhouse, with the experimental design in randomized blocks with three replicates, in a 4 × 4 factorial scheme, which consisted of four values of irrigation water electrical conductivity - ECw (0.7, 1.4, 2.1 and 2.8 dS m-1) and four concentrations of hydrogen peroxide (0, 20, 40 and 60 µM). Irrigation using water with ECw from 1.4 dS m-1 compromised the photochemical efficiency, photosynthetic pigments, and biomass production of yellow passion fruit. Application of hydrogen peroxide at concentration of 20 µM promoted the highest values for variable and maximum fluorescence and concentration of carotenoids, constituting an alternative for the acclimation of yellow passion fruit to salt stress. Application of hydrogen peroxide at concentrations above 20 µM intensified the salt stress on passion fruit.

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RESUMO: Em áreas com problemas de salinidade se torna importante à busca por culturas que produzam satisfatoriamente nesses ambientes, a cana-de-açúcar pode ser uma alternativa viável, necessitando, para tanto de pesquisas com esse intuito. Diante disso, objetivou-se com esse trabalho avaliar as trocas gasosas de cultivares de cana-de-açúcar irrigadas com águas salinizadas nos períodos de estiagem, no segundo ciclo de cultivo. O experimento foi conduzido no delineamento experimental em blocos ao acaso, num fatorial 2 x 5 (duas cultivares de cana-de-açúcar x cinco níveis de salinidade da água), resultando em dez tratamentos e quatro repetições, dispostos em 40 lisímetros, onde a parcela foi composta de quatro touceiras por lisímetros. As duas cultivares de cana-de-açúcar foram a 'SP81-3250' e 'RB92579'. Os cinco níveis de salinidades da água de irrigação foram: 0