Time filter

Source Type

Cruz das Almas, Brazil

Nascimento P.S.,Sao Paulo State University | Bassoi L.H.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria | Paz V.P.S.,NEAS

The irrigation scheduling is basically the adoption of pre-established criteria to define the time and the amount of water to be applied through irrigation systems. Hence, the objective of this work was to develop and test a spreadsheet of easy comprehension, handling and interpretation by growers, which uses as inputs the physical-hydric soil attributes and tensiometer readings to the determination of irrigation depth and time. The spreadsheet enables the grower to make reading and to know in a fast way how much water to apply into the soil. The test of the spreadsheet was performed in an irrigated orchard of grapevines in Petrolina, State of Pernambuco, Brazil. Soil water retention curves and tensiometer readings from the effective rooting depth were used as a basis for obtaining the soil water matric potential, soil water content, water availability, soil water content to be replaced, net and gross irrigation depth and irrigation time. The analysis of the use of the irrigation scheduling spreadsheet resulted in a shorter time for irrigation in relation to the irrigation scheduling based only on the crop evapotranspiration. The spreadsheet can be helpful to growers adjust irrigation depth when irrigation scheduling is based only on crop evapotranspiration. Source

Sousa A.E.C.,Campus Universitario | Gheyi H.R.,NEAS | Correia K.G.,Federal University of Pernambuco | Soares F.A.L.,Instituto Federal Of Educacao Goiano | Nobre R.G.,Federal University of Campina Grande
Revista Ciencia Agronomica

Soil salinity reduces the absorption of water by plants, consequently their growth and production. Aiming to evaluate the growth of the physic nut as a function of irrigation with saline water during the third year of growth, an experiment was conducted in a protected environment, adopting a randomized block with a 5 x 2 factorial design consisting of five levels of electrical conductivity of the water used for irrigation - ECw (0.6; 1.2; 1.8; 2.4 and 3.0 dS m-1) and two levels of P2O5 per year (135 and 200 g per plant) and four replications. Plants were cultivated in pots of 200 L and irrigated at intervals of three days. The increase of ECw, starting from the 30th day after pruning (DAP), caused significant reduction in the variables: stem diameter, leaf number and leaf area. The leaf area and number were most affected and therefore are the best indicators to express the effects of water salinity on the physic nut. The salinity of the irrigation water interferes negatively in dry-matter accumulation in the leaves, and the mean water consumption of the physic nut is reduced by about 60% when irrigated with water with the highest ECw in relation to the lowest. Leaf area was the only growth variable influenced by phosphorus levels in the three evaluations, where leaf number was influenced at 30 DAP. This physic nut crop demonstrates sensitivity at water salinity levels above 1.6 dS m-1. Source

de Paula L.,Federal Rural University of Pernambuco | Rolim M.M.,Federal Rural University of Pernambuco | Neto E.B.,Federal Rural University of Pernambuco | Soares T.M.,NEAS | And 2 more authors.
Revista Brasileira de Engenharia Agricola e Ambiental

This research was accomplished with the objective of evaluating the nutritional efficiency of the use of serum of cow milk in substitution to the nutrient solution in hydroponic cultivation of forage corn. The experiment was carried out under greenhouse conditions in a completely randomized design with six treatments and five replications. The conventional nutrient solution was used as the control. The other treatments were distributed in different levels (20, 40, 60, 80 and 100%) of milk serum dilution in drinking water. Corn plants were harvested 15 days after the germination, separating biomass of shoots from biomass of the substrate with the roots. The mass of fresh and dry matter, the macro (N, P, K, Ca, Mg and S) and micronutrient (Fe, Cu, Zn and Mn) contents were evaluated, besides the elements in toxic levels (Na and Cl), in both shoots and substrate plus roots masses. Increase in milk serum concentration promoted reduction of hydroponic forage yield, increment in N, S and Zn, stability of K, reduction of Ca and Mg, and no effect on P, Fe and Cu contents in shoots. In root there was increase in P, K, Ca, Mg, S and Cu. Source

Bione M.A.A.,NEAS | Paz V.P.S.,NEAS | da Silva F.,CCAAB | Ribas R.F.,CCAAB | Soares T.M.,NEAS
Revista Brasileira de Engenharia Agricola e Ambiental

The scarcity of good quality water in the Brazilian semiarid region has justified the growth of scientific researches on the use of brackish water. In the present study the effects of brackish water on growth and production of basil plants were evaluated in hydroponic system during October-November 2012. The treatments consisted of four levels of salinity (1.45, 3.80; 6.08 and 8.48 dS m-1) obtained by adding NaCl to the local fresh water, a control prepared with the fresh water (EC=0.29 dS m-1) and a reverse osmosis reject (EC=8.39 dS m-1) of a municipality in the semiarid region. Thirty six plots were randomized into six blocks. Data were analysed by analysis of variance and regression. There was a linear reduction in the production of fresh and dry matter of shoots (FMS and DMS) with increase in salinity, corresponding to respectively, 7.86 and 6.76% with per unit increase in electrical conductivity (dS m-1); there was no difference between NaCl and isosmotic water of desalination reject in reference to the production of FMS. The plant height and growth rate did not indicate the influence of salinity on basil. The brackish waters produced no damage symptoms in plants. © 2014, Departamento de Engenharia Agricola - UFCG/Cnpq. All rights reserved. Source

Discover hidden collaborations