Saline stress is a frequent phenomenon in the arid and semi-arid regions of the globe, affecting the agricultural production of these regions, and it is necessary to use strategies that minimize the impacts of saline stress under agriculture. This requires the incorporation of species, variety and genotypes tolerant to increase agricultural production in those regions. This study aimed to evaluate germination and initial growth of cowpea genotypes under salt stress. The experimental design was completely randomized in 19 x 3 factorial scheme, composed of nineteen cowpea cultivars and three osmotic potentials, with four replicates of 50 seeds each. The germination test lasted for eight days, when the seeds were evaluated for germination percentage, germination speed index, length of shoot and root, accumulation of dry mass of shoot and root. The increase in salinity affected germination and initial growth of the cowpea genotypes. The genotypes 6 -MNCO2-689F-2-8, 10 -MNCO2-675F-4-10, 12 -MNCO3-737F-5-9, 16 -MNCO2-677F-2, 18 -BRS-Pajeú and 19 -Paulistinha exhibited higher tolerance to salt stress in the stage of germination and initial growth. The genotypes 11 -MNCO2-675F-9-5, 13 -BRS-Tumucumaque, 15 -MNCO3-736F-7 and 17 -BR17-Gurgueia were more susceptible to the effects of salt stress in the stage of germination and initial growth.

Currently there is a great need for reuse of water in agricultural activity, aiming at reducing environmental impacts and production costs. The objective of this study was to evaluate the fruit production of hybrid Satrapo bell pepper, under fertilization with yellow water and cassava wastewater. The experiment was conducted in a greenhouse located at Campina Grande city, PB. The experimental design was completely randomized, with eight treatments and five replications, totaling 40 experimental plots. The treatments were characterized by fertilization with cattle manure (EB); NPK; human urine (HU); cassava wastewater (M); cassava wastewater and human urine (UH+M); the double volume of human urine (2xUH); the double volume of cassava wastewater (2xM); and the double volume of human urine and cassava wastewater (2xUH+M). At 60 day after transplanting (DAT) were evaluated the diameter, thickness of mesocarp, fresh and dry phytomass and number of lobes of yellow bell pepper fruits.According to the results, there were significant differences in the variables analyzed due to the treatments applied. The treatment corresponding to 2xM provided the highest results for length, diameter, thickness of the mesocarp, fresh and dry phytomass of the bell pepper fruits. On the contrary, 2xUH was the treatment that provided the lowest values for these variables and provided the highest number of lobes.

Sour passion fruit is a fruit crop widely cultivated throughout Brazil, due to its adaptation to the tropical climate. However, in semi-arid regions its development is limited by the high concentration of soluble salts in the waters commonly used in irrigation. In this context, exogenous application of low concentrations of hydrogen peroxide can attenuate the damage caused by salt stress. The objective of this study was to evaluate electrolyte leakage, photosynthetic pigments and photochemical efficiency in sour passion fruit cv. BRS Rubi do Cerrado under irrigation with saline waters and foliar application of hydrogen peroxide. A completely randomized design was used, with treatments arranged in split plots, corresponding to five levels of irrigation water salinity - ECw (0.6; 1.2; 1.8; 2.4 and 3.0 dS m−1) and four concentrations of hydrogen peroxide - H2O2 (0; 15; 30 and 45 μM of H2O2) in plots and subplots, respectively. Irrigation with saline water reduced chlorophyll a and total chlorophyll contents of sour passion fruit plants cv. BRS Rubi do Cerrado, at 240 days after transplanting. Hydrogen peroxide at concentration of 15 μM stimulated chlorophyll a and total chlorophyll biosynthesis and, at 45 μM, relieved the effect of 3.0 dS m−1 water salinity on electrolyte leakage in the leaf blade of sour passion fruit. Salt stress did not affect the initial, maximum, variable fluorescence and quantum efficiency of photosystem II of sour passion fruit cv. BRS Rubi do Cerrado.

This study aimed to evaluate the contents of macronutrients (NPK and S) and the growth of ‘Potiguar’ corn fertigated with human urine, cassava wastewater and their associations with NPK. The experiment was set up in greenhouse located on Campus I of Universidade Federal de Campina Grande. A completely randomized experimental design was used, consisting of eight treatments, corresponding to fertigation with mineral fertilizer NPK formula; organic, composed of yellow water, cassava wastewater and human urine associated with cassava wastewater; organomineral, composed of human urine associated with phosphorus and potassium, cassava wastewater associated with nitrogen and phosphorus and human urine associated with cassava wastewater and phosphorus, with five repetitions. At 50 days after sowing (DAS), plants were evaluated for the leaf NPK and S concentrations and growth variables: number of leaves, plant height, stem diameter, leaf area, fresh and dry mass of leaves, mass of stem and shoots. Nitrogen and phosphorus concentrations and the growth variables number of leaves, plant height, fresh and dry mass of leaves, mass of stem and of shoot were influenced by fertigation with human urine, cassava wastewater concentrations and their associations with NPK. In the leaves of corn cultivar Potiguar the accumulated concentrations of N, P and K, at 50 DAS, varied in the sequence N > K > P. Human urine has potential as source of N in fertigation of corn and cassava wastewater can be used if associated with other sources of nutrients.

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Agricultural utilization of yellow waters associated with cassava wastewater is a sustainable technique, since it allows reduction of costs related to acquisition of industrialized fertilizers and minimizes the environmental pollution caused by the inadequate disposal of these effluents. In this context, this study evaluated the macronutrient macronutrient content and growth of cowpea fertigated with yellow water associated with cassava wastewater and NPK as source of nutrients. The experiment was set up in a greenhouse located at Campus I of the Federal University of Campina Grande. The experimental design was completely randomized, composed of five treatments characterized by: fertigation with mineral fertilizers, in the form of NPK; organic fertigation composed of human urine, cassava wastewater, human urine plus cassava wastewater; and organo-mineral fertigation composed of urine, cassava wastewater and mineral phosphorus, with four replicates. At 36 days after sowing, the following parameters were determined: contents of nitrogen, phosphorus, potassium, sulfur and the variables number of leaves, plant height, stem diameter, leaf area, shoot fresh matter and shoot dry matter. The use of yellow waters promotes significant increases for growth and production variables for nitrogen and potassium contents mainly, as well as for growth and production variables. The contents of nitrogen, phosphorus and potassium were higher than the levels considered as adequate for the cowpea crop. The use of human urine and cassava wastewater have potential to meet the needs for the main macronutrients required by cowpea and the irrigation via fertigation with these biofertilizers positively influences the development of cowpea.

RESUMOUso agrícola de águas amarelas e manipueira é uma opção atrativa do ponto de vista econômico, em razão da ciclagem dos nutrientes e redução de custos com aquisição de fertilizantes minerais. Este trabalho objetivou avaliar a produção da alface Crespa Cristina cultivada em substrato fertirrigado com urina humana e manipueira tratadas por processo de digestão anaeróbica, como fonte alternativa de fertilizante. O experimento foi conduzido em casa de vegetação, o delineamento experimental foi o inteiramente casualizado, composto por oito tratamentos e três repetições. Os tratamentos consistiram por apenas o substrato (Testemunha); e o substrato fertirrigado com solução mineral composta por NPK, urina humana, manipueira, urina humana mais manipueira, duas vezes a dose de urina humana, duas vezes a dose de manipueira e duas vezes a dose de urina humana mais manipueira. O substrato foi composto por solo e esterco bovino não curtido na proporção de 2: 1 v/v. Aos 38 dias após o transplantio foram avaliadas número de folhas, altura de plantas, diâmetro caulinar, massa fresca da parte aérea, massa fresca comercial, massa seca da parte aérea e raízes da alface. A análise estatística indicou que só não houve diferença estatística significativa para a variável altura de planta. As maiores médias foram obtidas através do substrato fertirrigado com urina humana mais manipueira, duas vezes manipueira e duas vezes as doses de urina humana mais manipueira, respectivamente. Concluiu-se que tanto as doses duplas de manipueira e a associação dos dois efluentes apresentam potencial fertilizador para a cultura da alface, podendo ser utilizados como fonte de nutrientes. Palavras-chave:Lactuca sativa L., urina humana, uso agrícola de resíduos orgânicos, ecossaneamento.

The objective of this study was to evaluate the effects of different levels of salinity on the production of two cultivars of crisp lettuce under hydroponic cultivation. The research was performed in a protected environment at the Federal University of Campina Grande (UFCG), state of Paraíba, during in the period from 1 to 22 September 2016. The experimental design was completely randomized (CRD) which involved 4 × 2 factorial scheme with four levels of electrical conductivity of the nutrient solution (1.6, 3.6, 5.6 and 7.6 dS m -1 ) and two lettuce cultivars, Valentina (C1) and Alcione (C2), that totalized 8 treatments with 3 replicates. The evaluated variables were fresh and dry biomass of leaves, stems and roots. The results were subjected to analysis of variance by F-test (p < 0.05), the averages were compared by Tukey's test (p < 0.01 and p < 0.05), and quantitative variables data were submitted to regression test. It was observed that the fresh leaves biomass and fresh stem biomass were significantly affected by salinity in all evaluated periods. However, cultivar factor singly presented significant statistical difference only for fresh root biomass. There was statistical interaction between the factors at 15 DAT for dry leaves biomass and at 21 DAT for dry stem biomass. It was concluded that, although some variables were significantly affected by the salinity of the nutritive solution, the hydroponic lettuce production was satisfactory in NFT system for electrical conductivity up to 3.5 dS m -1 for variables with commercial relevance.