MORPHOPHYSIOLOGICAL AND NUTRITIONAL BEHAVIOR OF Hymenaea stigonocarpa Mart. ex Hayne (FABACEAE) SEEDLINGS SUBMITTED TO LIMING

ABSTRACT Liming is beneficial for plants as it promotes pH elevation, neutralization of toxic aluminum, increase in calcium (Ca²+) and magnesium (Mg²+) supply, and provides greater root systems. However, it is known that different species, mainly those native to the Cerrado, respond in different ways to this technique. Given the above, the objective of this study was to determine how Hymenaea stigonocarpa (“Jatobá-do-Cerrado”) seedlings respond to liming in Dystrophic Red Latosol. The plants were cultivated in four-liter pots, submitted to different base saturation (natural soil, 30, 45, 60 and 75% V) and maintained in a greenhouse. Biometrics, biomass, nutritional content and physiological parameters were evaluated. A difference in Ca²+ and Mg²+ contents between leaves and stems was observed, leading to significant reductions in stomatal conductance, transpiration, internal CO2 concentration and internal and external CO2 concentration ratios, resulting in a reduction of the investment in growth and biomass. Given these results, there is no need for liming in the production of H. stigonocarpa seedlings in a Dystrophic Red Latosol.

Abnormal pH elevation in the Chaobai River, a reclaimed water intake area

Understanding the main reasons causing pH elevation in river water has important implications for river ecosystem management and improvement of water quality and can provide a theoretical basis for the direction of water quality improvement.

Effects of Acetic Acid and Arginine on pH Elevation and Growth of Bacillus licheniformis in an Acidified Cucumber Juice Medium†

Bacillus licheniformis has been shown to cause pH elevation in tomato products having an initial pH below 4.6 and metabiotic effects that can lead to the growth of pathogenic bacteria. Because of this, the organism poses a potential risk to acidified vegetable products; however, little is known about the growth and metabolism of this organism in these products. To clarify the mechanisms of pH change and growth of B. licheniformis in vegetable broth under acidic conditions, a cucumber juice medium representative of a noninhibitory vegetable broth was used to monitor changes in pH, cell growth, and catabolism of sugars and amino acids. For initial pH values between pH 4.1 to 6.0, pH changes resulted from both fermentation of sugar (lowering pH) and ammonia production (raising pH). An initial pH elevation occurred, with starting pH values of pH 4.1 to 4.9 under both aerobic and anaerobic conditions, and was apparently mediated by the arginine deiminase reaction of B. licheniformis. This initial pH elevation was prevented if 5 mM or greater acetic acid was present in the brine at the same pH. In laboratory media, under favorable conditions for growth, data indicated that growth of the organism was inhibited at pH 4.6 with protonated acetic acid concentrations of 10 to 20 mM, corresponding to 25 to 50 mM total acetic acid; however, growth inhibition required greater than 300 mM citric acid (10-fold excess of the amount in processed tomato products) products under similar conditions. The data indicate that growth and pH increase by B. licheniformis may be inhibited by the acetic acid present in most commercial acidified vegetable products but not by the citric acid in many tomato products.

Copper Deposition in Stator Cooling Water Systems

Water cooled steam turbine-generator stator systems are subject to flow restrictions and pluggage by copper that originates from within the stators. Deposition may occur within hollow stator bars or coils, or in filters or screens in the water flow circuit. In extreme cases of deposition, flow restriction can cause the generator to overheat due to reduction of cooling flow, resulting in unit outages and potentially serious equipment damage. Chemistry programs to minimize corrosion and transport of copper within the system include high oxygen, low oxygen, and alkaline (pH elevation). In all cases high purity water is required for the application. Examination of copper deposits can provide clues to the adequacy of the chemistry treatment program for minimizing system corrosion.