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This research aimed to assess how the partial removal of carbon dioxide affects fermentations to provide a better understanding of how the manipulation of carbon dioxide concentration can be used to optimize industrial fermentations. To achieve this, fermentation kinetics, fermentation metabolic products, and yeast stress indicators were analyzed throughout ongoing brewing fermentations conducted under partial vacuum with atmospheric pressure controls. The partial vacuum reduced the solubility of carbon dioxide in the media and decreased the time necessary to reach carbon dioxide saturation. The effect was an increased rate of fermentation, and significantly more viable cells produced under vacuum pressure compared to controls. Ethanol, glycerol, and volatile organic compound concentrations were all significantly increased under partial vacuum, while indicators of yeast stress (trehalose) were reduced. Additionally, as the number of yeast cells was higher under partial vacuum, less sugar was consumed per volume of yeast cell. This study measured fermentation kinetics, metabolic products, and yeast health to holistically assess the effect of partial vacuum during a batch fermentation and found significant differences in each that can be individually exploited by researchers and industry. Summary An exploration of batch yeast fermentation in a low-pressure environment, with a focus on the health and productivity of the yeast cells. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine how topdressing or incorporating fertilizer with stratified or mulched substrates could affect the growth of Hibiscus rosa-sinensis 'Snow Queen', a popular ornamental plant, and the growth of liverwort (Marchantia polymorpha) and bittercress (Cardamine flexuosa), two common nursery weed species. Five different substrate treatments were evaluated, which included three stratified substrates composed of pine bark screened to a small (0.63–1.27 cm), medium (≤1.90 cm), and large (0.96–1.90 cm) particle size and two industry-standard substrates that were either mulched with rice hulls or remained unmulched. All treatments were then fertilized via either topdressing or incorporating a controlled-release fertilizer (CRF). Bittercress control was highest in mulched containers, followed by those stratified using the medium pine bark, and its growth increased overall in topdressed vs. incorporated containers regardless of substrate or mulch treatment. All the stratification treatments resulted in a decrease in liverwort coverage compared to the industry standard treatment, but topdressing generally increased liverwort coverage compared with incorporating fertilizer. In conclusion, both topdressing and incorporation appear to be compatible with fertilizer placement methods with substrate stratification from a crop production standpoint; however, weed growth may increase if fertilizer is topdressed. [ABSTRACT FROM AUTHOR]

Although composed mostly of sand, observations of new urban residential communities in Florida suggested relatively wide ranges in clay content and importation of offsite soils. Often these communities are constructed around surface water where heavy summer rains and intense landscape maintenance present concerns for surface water contamination. Due to land sculpturing, soil compaction and importation; onsite soil physical properties may differ from soil maps developed decades before. How much change and what changes occurred has seldom been quantified. This study examined soil characteristic data from diverse, newly constructed urban soils and examined relationships with soil infiltration rates. Samples were collected from 40 lots in nine newly established urban residential communities within Central Florida to quantify textural composition, bulk density (Db), moisture retention, and pore size distribution. Most lots (90%) contained sandy soil dominated by micropores (58% total mean pore space). Variability of Db was low with most communities exhibiting high soil compaction (>1.7 g cm-3), which may indicate potential plant root penetration concerns. Mean soil infiltration rates among communities were high (11 to 64 cm hr-1), with large variations (2.0 to 111.1 cm hr-1). Correlations between soil moisture retention volumes, Db, and infiltration rate did not occur. However, soil texture was a significant predictor of infiltration rate. Relationships between infiltration rates and soil characteristics were poor (r² = 0.43) and suggest direct measurement of infiltration rate may be necessary. High infiltration rates, despite compaction, indicate reduced potential for surface water contamination if a sufficient natural fetch separates landscapes from water bodies. [ABSTRACT FROM AUTHOR]