ABSTRACT Using organic filters produced in local communities with low financial cost can reduce the environmental impacts caused by the disposal of untreated wastewater into receiving water bodies. In this study, the objective was to evaluate the efficiency of the filtration of swine wastewater (SWW) using banana stalk as an alternative material in an organic filter. SWW was applied to the organic filter and the filtered volume was converted into pore volume. Analyses of total solids, turbidity, color, total phosphorus, and total nitrogen were performed in the filter feed solution and effluent to evaluate treatment efficiency. Regression analyses were used to obtain equations in the estimation of the filtration performance in removing these variables from wastewater, with pore volume as an independent variable. The banana stalk filter did not remove total solids and color from the feed solution applied. Removal of 10–50% of SWW turbidity were obtained by the banana stalk. Banana stalk was highly efficient in removing nitrogen and phosphorus from SWW, reaching mean removals of 67% and 62%, respectively. In general, a banana stalk filter can be considered a promising alternative in the primary treatment of SWW.

ABSTRACT Little is known about the management of high-yield clonal Coffea canephora in the Amazonian Region, mainly for nutritional aspects and cultivation system efficiency. This study aimed to evaluate the influence of different nitrogen and potassium fertilization rates on coffee grain yield and fertilizer use efficiency of C. canephora trees. An experiment was performed at an experimental field of the Embrapa Rondônia in Porto Velho (RO), Brazil. It was carried out in a split-plot scheme with six doses of 20-00-20 NPK formulation (0; 250; 500; 1,000; 2,000; and 3,000 kg ha-1) and three years of evaluation (2014, 2015, and 2016). An interaction between fertilizer dose and crop year was observed. Fertilizer doses showed an exponential behavior, with maximum yields of 51, 114, and 79 bags ha-1 at 3,000 kg ha-1 in the crop years of 2014, 2015, and 2016, respectively. Such a behavior impacted average and accumulated yields in the three harvest seasons. As for crop year effect within each fertilizer dose, the highest yield was reached in the second harvest after pruning for renewal of orthotropic stems. Moreover, fertilizer use efficiency by plants decreased exponentially, with the highest value at the lowest dose. Increasing doses of 20-00-20 formulation promoted an exponential increase in grain yield but decreased its use efficiency by C. canephora plants. This management also stimulated a strong biannual production.

ABSTRACT Lignocellulosic residues are used to produce mushrooms, but they generate large amounts of spent mushroom substrate (SMS). The objective of this study was to evaluate they effect of SMS of Pleurotus ostreatus, combined with organic fertilization, on biomass production and essential oil yield of basil (Ocimum basilicum L.) plants. The fertilizer was formulated using combinations of organic compounds: SMS, organic compost (OC), and earthworm humus (EH). The treatments were applied using 35 g of the formulations, corresponding to an application of 20 Mg ha-1. The treatments used were: 100% OC; 100% EH; 100% SMS; 75% SMS + 25% OC (C1); 75% SMS + 25% EH (C2); 50% SMS + 50% OC (C3); 50% SMS + 50% EH (C4); 50% SMS + 25% OC + 25% EH (C5), and a control with no fertilizer application (CT). Plants grown with the soil fertilizers containing SMS, single or combined with OC and EH, presented higher average plant height (55.6 to 62.2 cm) and leaf area per plant (696.5 to 836.4 cm2). The treatment C3 resulted in plants with higher mean dry weight (10.9 g plant-1), and C2 resulted in the highest oil yield (5.0 kg ha-1), representing a gain of 324.8% in oil yield when compared to the control. Thus, SMS increases biomass production and essential oil yield of basil plants.

ABSTRACT The rational use of water while considering the increases in food production is a great challenge for agriculture currently. The aim of the present study was to evaluate the soil properties of rice paddy areas under different water management systems. For this, the rice cultivars BRS Tropical and IRGA 424 were grown under the following treatments: M1: Intermittent flooding; M2: Intermittent flooding, followed by continuous flooding; M3: Continuous flooding, followed by intermittent flooding; and M4: Continuous flooding for the entire plant cycle. As a control, a non-cultivated area, adjacent to the experimental plots was also evaluated. The variables analyzed were P, K+, Ca2+, Mg2+ and Al3+ contents, pH, soil organic carbon (SOC), total nitrogen (TN) Carbon Stock (C-Stock), nitrogen stock (N-Stock), Cation-exchange capacity (CEC), C/N ratio; CO2 emission, soil microbial biomass carbon (SMB), metabolic coefficient (qMic) and acid phosphatase and urease activities. There was not difference among the different water management systems for P, K+, Mg2+, CEC and C/N ratio. The SMB and the acid phosphatase and urease activities were lower under the different treatments when compared to the control. The CO2 emission under rice paddy system was influenced by the phenological phase of the crop. The variables SOC, C-Stock, SMB, C/N ratio, K+, acid phosphatase and usease activities are those most sensitive attributes observed in the soil under different water management systems during rice cultivation. Water management in the rice paddy system influenced soil by changing its quality.

ABSTRACT Water scarcity is one of the main problems in the Semiarid region of Brazil, which can be mitigated by water resource management strategies. The objective of this work was to classify waters of a watershed in the Semiarid region of Brazil and select the water attributes that most affect the quality of waters used for irrigation (QWI), using multivariate statistics. The study area was the Riacho da Bica watershed, which is between the municipalities of Portalegre and Viçosa, Rio Grande do Norte, Brazil. The QWI was determined using water samples from 15 collections carried out from 2016 to 2018, in five specific points of the watershed, starting in the spring and following the water course. The water attributes evaluated were: electrical conductivity (EC), potential hydrogen (pH), and sodium (Na+), potassium (K+), magnesium (Mg2+), calcium (Ca2+), carbonate (CO32-), chloride (Cl-), and bicarbonate (HCO3-) contents. The water quality data were subjected to multivariate statistics through factorial analysis (FA) and principal component analysis (PCA). The application of multivariate statistics through FA-PCA generated four principal components. The attributes that most explained the QWI variation were potassium, calcium, and pH for Factor 01, and sodium and RAS for Factor 02. The watershed waters were classified as low risk of salinity and medium risk of sodicity (C1S2) for irrigation purposes.

ABSTRACT This study was conducted with the objective of evaluating the quantum yield, photosynthetic pigments and biomass accumulation of mini watermelon cv. Sugar Baby, under strategies of irrigation with saline water and potassium fertilization. The experiment was conducted in a randomized block design, in a 8 × 3 factorial scheme, with three replicates, corresponding to eight strategies of irrigation with saline water applied at different phenological stages of the crop (control - irrigation with low-salinity water throughout the crop cycle, and salt stress in the vegetative, vegetative/flowering, flowering, flowering/fruiting, fruiting, fruiting/ fruit maturation and fruit maturation stage) and three potassium doses (50, 100 and 150% of the recommendation). The dose of 100% corresponded to 150 mg of K2O kg-1 of soil. Two levels of electrical conductivity of water were used: 0.8 and 4.0 dS m-1. Irrigation with water of 4.0 dS m-1 continuously in the vegetative and flowering stages increased the initial fluorescence and decreased the quantum efficiency of photosystem II of mini watermelon fertilized with 100 and 150% of K recommendation. Fertilization with 50% recommendation did not interfere in the fluorescence parameters of the mini watermelon, regardless of the irrigation management strategy. Chlorophyll a synthesis is inhibited by salt stress in the vegetative/flowering, flowering, flowering/fruiting, fruiting/maturation stages, as well as for total chlorophyll, except for the flowering stage. Application of 4.0 dS m-1 water in the flowering, fruiting/maturation and maturation stages promoted greater biomass accumulation in mini watermelon.

ABSTRACT The use of organo-mineral fertilizer is an alternative measure to mitigate salt stress in semiarid regions. Thus, the objective of this work was to evaluate the physiological indexes of peanut crops under irrigations with fresh and brackish waters and applications of organo-mineral fertilizers. The experiment was conducted from June to September, 2019, at the Universidade da Integração Internacional da Lusofonia Afro-Brasileira (UNILAB), in Redenção, state of Ceará, Brazil, using a completely randomized experimental design in a 5 × 2 factorial arrangement, with four replications. The treatments consisted of five soil fertilizers (F1= 100% NPK mineral fertilizer at the recommended rate; F2= 100% bovine manure-based biofertilizer; F3= 100% plant ash; F4= 50% mineral fertilizer and 50% bovine manure-based biofertilizer; and F5= 50% mineral fertilizer and 50% plant ash); and two salinity levels (electrical conductivities) of the irrigation water (1.0 and 5.0 dS m-1). Photosynthetic rate, transpiration, stomatal conductance, leaf temperature, internal CO2 concentration, water use efficiency, and chlorophyll index of the plants were evaluated at 40 and 54 days after sowing (DAS). Plants irrigated with fresh water presented higher stomatal conductance, photosynthetic rate, and transpiration, regardless of the fertilizer used. The use of 100% bovine manure-based biofertilizer resulted in decreases in salt stress and increases in water use efficiency at 40 DAS, and decreases in leaf temperature and increases in relative chlorophyll content at 54 DAS.

ABSTRACT Information on nutritional management of pitaya crops are scarce. However, understanding the growth and nutrient accumulation in these plants at different developmental stages can assist in the development of rational soil fertilizer application programs for pitaya crops and decrease production costs. Thus, the objective of this work was to evaluate the growth and nutrient accumulation in pitaya plants throughout the crop cycle. Cladodes of pitaya plants of the Hylocereus setaceus species were grown in polyethylene pots containing a Typic Hapludult (Argissolo Vermelho-Amarelo Eutrófico) under full sun. The treatments consisted of six sampling times: 0, 60, 120, 180, 240, 300, and 360 days after planting (DAP). A randomized block experimental design with four replications was used. Four plants were sampled and evaluated for growth and nutrient accumulation at each sampling time. The pitaya plants presented an exponential growth up to 360 DAP and high nutrient absorption between 300 and 360 DAP. The nutrient and Na accumulations in the cladodes, in decreasing order, were: 3.91 (K), 2.56 (Ca), 1.95 (N), 1.24 (P), 0.45 (Mg), 0.30 (S), and 0.06 (Na) g plant-1, and 14.86 (Zn), 12.72 (Fe), 12.37 (Mn), 5.37 (B), and 1.04 (Cu) mg plant-1. The highest relative growth rate and relative nutrient absorption rate were found between 60 and 120 DAP.

ABSTRACT The objective of this work was to evaluate the use of galactomannan from Caesalpinia pulcherrima as a binding agent for the restructuring of fishes. The effect of a frozen (-18 °C) storage of 120 days on the physical-chemical and mechanical properties of fishes was evaluated, restructured fish products with transglutaminase were used as a control. Two fish restructuring formulations were developed: Galactomannan, with 0.2% galactomannan and 1.8% refined salt; and Control, with 0.5% transglutaminase. The analyses were carried out after 24 hours of refrigerated storage (4 °C), corresponding to time zero, and after 30, 60, 90, and 120 days of frozen (-18 °C) storage. The use of galactomannan resulted in a higher pH, and lower total volatile basic nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARS), with no differences from zero to 120-day storage times for the L*, a*, and b* coordinates. Galactomannan easily bounds to hydrogen, enabling the obtaining restructured fish products with lower expressible water content and less weight losses by cooking, important characteristics for the acceptance of products that denote softness and succulence. Contrastingly, this easy bound to water molecules resulted in a lower hardness, cohesiveness, and elasticity, and higher adhesivity when compared to the control. The results showed the viability of using galactomannan to restructure fishes during frozen storage.

ABSTRACT To evaluate seed vigor, electrical conductivity and ethanol tests are fast and efficient methodologies. They have the potential to be used in several species, such as red rice. However, there are no protocols or information about their efficiency. Thus, the objective was to evaluate the efficiency, and define parameters of execution for electrical conductivity and ethanol tests, to evaluate the vigor of red rice seeds. The study was conducted using four lots of ‘BRS 901’ red rice, which was subjected to a germination test, as well as first count, accelerated aging, and field seedling emergence tests. The electrical conductivity test was performed with 25, 50, and 100 seeds soaked in 50 mL and 75 mL of water, at 25 °C and 30 °C, for 3, 6, 20, and 24 hours, respectively. The ethanol test was performed with 50 and 100 seeds soaked in a volume of water equivalent to 1.0, 1.5, 2.0, 2.5, and 3.0× the mass of the seed sample. To assess the vigor of red rice seeds, the electrical conductivity test is an efficient method when conducted with 50 seeds soaked in 50 mL of water at 25 °C for 20 hours. Meanwhile, the ethanol test is most effective when performed with 50 seeds, in a volume of water that is 2.5× the mass of the sample, at 40 °C for 24 hours.