Miguel Ferreira Neto

Melon yield in a hydroponic system with wastewater from desalination plant added in the nutrient solution

To use of waster water from desalting in the hydroponic cultivation, an experiment was carried out at the Department of Environmental Science of the Universidade Federal Rural do Semi-Arido-UFERSA, in the municipal district of Mossoro-RN, in pots with substrates of coconut fiber under greenhouse conditions. The experimental design was in randomized blocks, with three repetitions. Treatments were composed of five levels of salinity of the nutrient solution obtained with, and without, dilution of the waster water from desalting (2.1, 3.6, 4.9, 6.0 and 7.0 dS m-1). The variables plant height, stem diameter, leaf area, mean weight of fruit and total and marketable yield were detemined. In general, the variables decreased linearly with the increase of the salinity of the nutrient solution, showing that the salinity with waster water from desalting reduces the absorption of water by the plants due to the osmotic effect.

Crescimento de cultivares de melão amarelo irrigadas com água salina

The effect of five irrigation water salinity levels (N: 1.51, 2.79, 3.93, 5.15 and 7,22 dS m-1), on initial development of two yellow melon cultivars (Gold mine and AF646) was studied. The trial was conducted under field conditions in an orchard belonging to Department of Phytotechnic - ESAM, at Mossoro in the State of RIo Grande do Norte, Brazil, during the period of November 4 to December 12, 1998. Plastic pots with 9 L capacity filled with Alfisol soil (horizon Ap1) were used. Experimental design was a completely randomized block in a factorial scheme, with three replications. Shoot dry matter, leaf area, mean soil salinity and final soil salinity were evaluated through variance and regression analysis. Salinity tolerance was similar for Gold mine and AF646, with a loss of 6.8% of shoot dry matter for unit increase of electrical conductivity of irrigation water. A similar behavior was observed for leaf area. Irrigation water salinity induced linear effect on mean soil salinity and quadratic effect on final soil salinity.

Qualidade de frutos do coqueiro-anão verde fertirrigado com nitrogênio e potássio

Field experiments were conducted to investigate the effect of fertirrigation using nitrogen and potassium on the average weight of coconut and pH, soluble solids content, volume and electrical conductivity of coconut water. The experiment was carried out in a three-year old experimental field of green dwarf coconut (Cocos nucifera) located at Parnamirim, RN between April 2000 and May 2002. A Plan Puebla matrix was used in order to generate experimental groups with different combinations of nitrogen and potassium concentrations within a range of 135 g plant-1 year-1 to 2565 g plant-1 year-1. The statistical design consisted of randomized blocks with four replications. Nitrogen and potassium levels affected the average weight of coconut. The highest weight (2.23 kg) was reached when 881 g of nitrogen plant-1 year-1 and 1689 g of potassium plant-1 year-1 were used. Coconut water volume was also affected by both nutrients, since the maximum volume observed (417.75 mL) was found when 818 g of nitrogen plant-1 year-1 and 1487 g of potassium plant-1 year-1 were tested. Nitrogen and potassium levels also demonstrated a linear effect on the soluble solids content of coconut water, where nitrogen had a negative and potassium a positive effect on it. A negative linear effect was observed between nitrogen concentration and electrical conductivity of coconut water, while it was observed that potassium levels showed a quadratic effect on this same parameter.

Spatial variability and seasonality of the water quality in the Lagoa do Apodi Lagoon, RN, Brazil

The objective of this study was to evaluate the water quality of the Apodi lagoon, in the State of Rio Grande do Norte, Brazil, at points along its surface. The monitoring of the water quality is emphasized as it is under influence of the urban basin of Apodi and due to incorporation of material by the influx of continental waters that lead to eutrophization of the lagoon water in periods of extreme temperatures and precipitation. Systematic samples were collected from the lagoon water surface throughout its length. The electrical conductivity of the Apodi water varies along the surface, mainly in the west and southeast extremities. The water salinity increased with the beginning of the dry period and decreased after the rains. There is a great spatial variability in the physical and chemical characteristics, mainly for pH, CE, RAS and Na and Cl contents. In the lagoon, the most frequent ions were sodium and chloride, both for sample points and time of collection. The change in the bacteriological quality of water compromises the balneary of the Apodi lagoon, especially after the rainy season.

Qualidade do fruto do coqueiro anão verde em função de nitrogênio e potássio na fertirrigação

The objective of this study was to evatuate the effects of doses of N and K applied via fertigation on quality of green fruits of coconut (Cocos nucifera L.) cultivar Anao Verde of Jiqui, 7 years old in a Quartzarenic Neosol of Coastal Table Lands. The study was carried out in the municipality of Parnamirim, in the State of Rio Grande do Norte - Brazil, during April, 2003 to March, 2004. The experiment was conducted in a randomized block, using for the combination of treatments the Plan Puebla III experimental matrix, consisting of 10 combinations of doses of nitrogen and potassium supplied through urea and potassium chloride, respectively. The doses of N varied from 256 to 4874 g plant-1 year-1 and that of K2O from 258 to 4872 g plant-1 year-1 applied via fertigation by micro-sprinkler irrigation system. The quality of green fruits was evaluated on the basis of mean weight of fruit, volume of water, oBrix, pH and salinity (electrical conductivity) of the coconut water. The mean weight of fruit was not influenced by the application of N and K in fertigation. The increase in dose of N decreased the volume and oBrix and increased pH of the coconut water, while increase in dose of K decreased the salinity and increased oBrix of coconut water.

Crescimento e produção de coqueiro Anão verde fertigado com nitrogênio e potássio

ABSTRACT In irrigated coconut, similar to trend in other crops the use of technique of fertigation is increasing. Theobjective of this study was to evaluate the effect of N and K 2 O doses under fertigation in development andthe production of Anao Verde coconut palm. In April of 2002 until March of 2004, an experiment wascarried out at the Empresa de Pesquisa Agropecuaria do Estado do Rio Grande do Norte, Brazil. Theadopted statistical design was in randomized blocks, with 4 repetitions, using for composition of treatmentsPuebla Plan III experimental matrix, consisting of combination of two factors: nitrogen and potassiumdoses in the form of urea and potassium chloride, respectively, testing 10 treatments. The interval of Nbeing 256 the 4874 g plant -1 year and 258 to 4872 g plant year -1 of K 2 O applied through fertigation. Thenumber of leaves, diameter of canopy, height and circumference of estipe were favored with 2910 gplant -1 year of K 2 O and 2353 g plant -1 year -1 of N representing highest productions in 6

MECANISMOS CONTROLADORES DA QUALIDADE DAS ÁGUAS SUPERFICIAIS NA SUB-BACIA HIDROGRÁFICA DO RIO DAS COBRAS DO NORDESTE BRASILEIRO

Stream water quality is dependent on many factors, including the source and quantity of the streamflow and the types of geology and soil along the path of the stream. This study aims to evaluate the origin and the mechanisms controlling the input of ions that effect surface water quality in the sub-basin of the Rio das Cobras, Rio Grande do Norte state, Northeastern Brazil. Thirteen ponds were identified for study: three in the main river and ten in the tributaries between, thus covering the whole area and lithology of the sub-basin. The samples were collected at two different times (late dry and rainy periods) in the hydrological years 2009 and 2010, equating to total of four collection times. We analyzed the spatial and seasonal behavior of water quality in the sub-basin, using Piper diagrams, and analyzed the source of the ions using Guibbs diagram and molar ratios. With respect to ions, we found that water predominate in 82% sodium and 76% bicarbonate water (cations and anions, respectively). The main salinity control mechanism was related to the interaction of the colloidal particles (minerals and organic sediment) with the ions dissolved in water. Based on the analysis of nitrates and nitrites there was no evidence of contamination from anthropogenic sources.

AVALIAÇÃO NUTRICIONAL DA PALMA FORRAGEIRA FERTIRRIGADA COM EFLUENTE DE ESGOTO DOMÉSTICO

The northeastern semiarid region faces some of the droughts of the last centuries, resulting in serious reductions of agriculture yields. The water scarcity for agricultural requires rational use practices and reuse of water, such as use of domestic effluent sewage. Alternatively, the use of treated domestic sewage effluent utilizing for irrigation of forage species, such as the forage cactus, can be highlighted. In order to evaluate the effects of fertirrigation with treated sewage effluent on mineral nutrient composition of forage cactus (Opuntia Tuna L. Mill, Mexican elephant ear), an experiment was carried out utilizing a split plot 3 x (4 + 1) with a randomized complete block design randomized block and four replications, being three planting density (66,667.00, 52,282.00 and 33,333.00 plants ha) and two water sources associated with irrigation frequency of plates fixed on 3.5 mm per irrigation (Frequencies of 2.3 days with water tap and 7, 14 and 21 days with Sewage Effluent) and cactus cultivated in Rainfed agriculture rainfed (control). The analyze of the nutritional contents of cladodes indicated that there was a significant effect of the intervals from irrigation events only for Ca and Mg concentrations. The highest levels of Ca and Mg were found with the irrigation frequency of 2.3 using tap water. The macronutrients concentration in greater quantity by the forage cactus were N e, K followed by, Ca, Mg and P. The nutritional balance indicated excess of K and P and deficiency of N, Ca and Mg, in this order.

Light Availability and Salt Stress on Hazel Sterculia Seedlings

The objective of this study was to evaluate the effect of light availability and salt stress on the growth and quality of hazel sterculia seedlings. The experiment was conducted with two light conditions – full sun (L1), and 50% shading (L2) – and five salinity levels in the irrigation water – 1.0 (S1), 2.2 (S2), 3.2 (S3), 4.2 (S4), and 5.1 (S5) dS m-1. The environment with 50% shading was the most suitable to produce hazel sterculia seedlings, even under high salinity (5.1 dS m-1). Increasing salinity negatively affects the growth and quality of hazel sterculia seedlings. Therefore, controlling sunlight availability and irrigation water saline conditions increases rooting potential and seedling survival in the field.

Productive and morphogenetic characteristics of sunflower irrigated with domestic treated wastewater on northeast semiarid area.

The present study aimed to evaluate the agronomic performance of the sunflower crop irrigated with treated domestic wastewater and normal water (well-water) in a inceptisol of Apodi, State of Rio Grande do Norte, Brazil. The experiment was conducted in a randomized block experimental design, consisting of five treatments and five replications, using the H-251 sunflower cultivar from Embrapa. The treatments consisted of the application of five proportions of wastewater/well-water (T1 - 100% wastewater; T2 - 75% wastewater and 25% well water, T3 - 50% wastewater and 50% well-water, T4 - 25% wastewater and 75% well-water and T5 - 100% well-water plus chemical fertilizer, control). The variables such as plant height, leaf number, diameter of stem and the head, yield, oil production, thousand-grain weight and head weight were evaluated. The combined use of wastewater and well-water is an alternative for the substitution of mineral fertilization with minimal damage to the productive potential and development of the sunflower crop. In general, the T4 treatment was the most adequate to improve agronomic performance of the sunflower.