Calibração da Reflectometria no Domínio do Tempo (TDR) para a estimativa da concentração da solução no solo

Time Domain Reflectometry (TDR) is a reliable method for in-situ measurements of the humidity and the solution concentration at the same soil volume. Accurate interpretation of electrical conductivity (and soil humidity) measurements may require a specific calibration curve. The primary goal of this work was to establish a calibration procedure for using TDR to estimate potassium nitrate concentrations (KNO3) in soil solution. An equation relating the electrical conductivity measured by TDR and KNO3 concentration was established enabling the use of TDR technique to estimate soil water content and nitrate concentration for efficient fertigation management.

Ambiência aérea em alojamento de frangos de corte: poeira e gases

Air quality in animal production environment has been refereed as an interesting point for studies in environmental control systems with the focus both to the animal health which live in total confinement, as to the workers. The objective of this research was to determine the variation on the aerial environmental quality in two types of broiler housing: conventional (Gc) and tunnel type (Gt). The total dust values in both houses offered adequate rearing conditions to the birds; however, regarding the inhale dust in the air was above the limits recommended for humans. Carbon monoxide concentration in the heating phase during the evaluated period was above the 10 ppm maximum recommended, and it was higher during the cold season in Gt house (30 ppm) when compared to the Gc house (18 ppm). Ammonia concentration peaks in the air were above the 20 ppm recommended from the 20th day of production in both houses and in daily average, for a period higher in Gt (4h30) when compared to Gt (2h45). Only traces of nitrate oxide and methane were found while carbonic dioxide gas concentration evaluated during daytime met the limits allowed for both birds and labor.

Antioxidative responses of cell suspension cultures of two Coffea arabica varieties to low aluminum levels at pH 5.8

The effects of aluminum (Al) on the activities of antioxidant enzymes and ferritin expression were studied in cell suspension cultures of two varieties of Coffea arabica, Mundo Novo and Icatu, in medium with pH at 5.8. The cells were incubated with 300 µM Al3+, and the Al speciation as Al3+ was 1.45% of the mole fraction. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) were increased in Mundo Novo, whereas glutathione reductase (GR) and guaiacol peroxidase (GPOX) activities remained unchanged. SOD, GR, and GST activities were increased in Icatu, while CAT activity was not changed, and GPOX activity decreased. The expression of two ferritin genes (CaFer1 and CaFer2) were analyzed by Real-Time PCR. Al caused a downregulation of CaFER1 expression and no changes of CaFER2 expression in both varieties. The Western blot showed no alteration in ferritin protein levels in Mundo Novo and a decrease in Icatu. The differential enzymes responses indicate that the response to Al is variety-dependent.