• An unusual postharvest spotting disease of the comercial mushroom, Agaricus bisporus, caused by a novel pathovar of Pseudomonas tolaasii

      Dobbin, Christine L.; Department of Biological Sciences (Brock University, 2001-11-04)
      An unusual postharvest spotting disease of the commercial mushroom, Agaricus bisporus, which was observed on a commercial mushroom farm in Ontario, was found to be caused by a novel pathovar of Pseudomonas tolaasii. Isolations from the discoloured lesions, on the mushroom pilei, revealed the presence of several different bacterial and fungal genera. The most frequently isolated genus being Pseudomonas bacteria. The most frequently isolated fungal genus was Penicillium. Of the bacteria and fungi assayed for pathogenicity to mushrooms, only Pseudomonas tolaasii was able to reproduce the postharvest spotting symptom. This symptom was typically reproduced 1 to 7 days postharvest, when mushroom pilei were inoculated with 101 to 105 cfu. Of the fungi tested for pathogenicity only a Penicillium sp. and Verticillium fungicola were shown to be pathogenic, however, neither produced the postharvest spotting symptom. The Pseudomonas tolaasii strain isolated from the postharvest lesions differed from a type culture (Pseudomonas tolaasii ATCC 33618) in the symptoms it produced on Agaricus bisporus pilei under the same conditions and at the same inoculum concentration. It was therefore designated a pathovar. This strain also differed from the type culture in its cellular protein profile. Neither the type culture, nor the mushroom pathogen was found to contain plasmid DNA. The presence of plasmid DNA is therefore not responsible for the difference in pathogenicity between the two strains.
    • Using GPS, GIS & remote sensing to understand Niagara Terroir

      Marciniak, Matthieu; Department of Biological Sciences (2012-03-30)
      The focus of this study was to detennine whether soil texture and composition variables were related to vine water status and both yield components and grape composition, and whether multispectral high definition airborne imagery could be used to segregate zones in vineyards to target fruit of highest quality for premium winemaking. The study took place on a 10-ha commercial Riesling vineyard at Thirty Bench Winemakers, in Beamsville (Ontario). Results showed that Soil moisture and leaf'l' were temporally stable and related to berry composition and remotely-sensed data. Remote-sensing, through the calculation of vegetation indices, was particularly useful to predict vine vigor, yield, fruit maturity as well as berry monoterpene concentration; it could also clearly assist in making wines that are more representative ofthe cultivar used, and also wines that are a reflection of a specific terroir, since calculated vegetation indices were highly correlated to typical Riesling.
    • Using GPS, GIS & remote sensing to understand Niagara Terroir : Pinot noir in the Four Mile Creek & St. David's Bench sub-appellations

      Ledderhof, David; Department of Biological Sciences (2012-03-30)
      The relationships between vine water status, soil texture, and vine size were observed in four Niagara, Ontario Pinot noir vineyards in 2008 and 2009. The vineyards were divided into water status zones using geographic information systems (GIS) software to map the seasonal mean midday leaf water potential (,P), and dormant pruning shoot weights following the 2008 season. Fruit was harvested from all sentinel vines, bulked by water status zones and made into wine. Sensory analysis included a multidimensional sorting (MDS) task and descriptive analysis (DA) of the 2008 wines. Airborne multispectral images, with a spatial resolution of 38 cm, were captured four times in 2008 and three times in 2009, with the final flights around veraison. A semi-automatic process was developed to extract NDVI from the images, and a masking procedure was identified to create a vine-only NDVI image. 2008 and 2009 were cooler and wetter than mean years, and the range of water status zones was narrow. Yield per vine, vine size, anthocyanins and phenols were the least consistent variables. Divided by water status or vine size, there were no variables with differences between zones in all four vineyards in either year. Wines were not different between water status zones in any chemical analysis, and HPLC revealed that there were no differences in individual anthocyanins or phenolic compounds between water status zones within the vineyard sites. There were some notable correlations between vineyard and grape composition variables, and spatial trends were observed to be qualitatively related for many of the variables. The MDS task revealed that wines from each vineyard were more affected by random fermentation effects than water status effects. This was confirmed by the DA; there were no differences between wines from the water status zones within vineyard sites for any attribute. Remotely sensed NDVI (normalized difference vegetation index) correlated reasonably well with a number of grape composition variables, as well as soil type. Resampling to a lower spatial resolution did not appreciably affect the strength of correlations, and corresponded to the information contained in the masked images, while maintaining the range of values of NDVI. This study showed that in cool climates, there is the potential for using precision viticulture techniques to understand the variability in vineyards, but the variable weather presents a challenge for understanding the driving forces of that variability.
    • Utilisation of Proximal Sensing Technology to Map Variability in Ontario Vineyards

      Kotsaki, Eleni; Department of Biological Sciences
      Precision agriculture is a term used to refer to a suite of technologies used for the optimisation of production in agronomic crops. The overall goal of this study was to determine whether high resolution proximally sensed observations acquired by the GreenSeeker™ technology could be correlated with soil moisture, vine water status, yield components and grape composition, and whether temporally consistent relationships could be established. The research was carried out on three experimental sites involving two Riesling, two Cabernet franc and two Pinot noir blocks throughout the Niagara Region of Ontario (Canada). A grid of geolocated sentinel vines was chosen for each vineyard block. Data were collected three times during the growing season between fruit set and veraison [soil moisture, leaf water potential (ψ)], at harvest (yield components, berry composition) and in winter [vine size, winter hardiness (LT50)]. GreenSeeker™ observations were likewise collected from lag phase to just prior to harvest, through the calculation of Normalized Difference Vegetation Index (NDVI). Thereafter, relationships between vine water status, yield components and berry composition variables as well as data from the GreenSeeker™ were validated. Overall, higher NDVI values were associated with yield components and vine size, while lower NDVI values were correlated with better berry composition, suggesting that GreenSeeker™ is a practical tool for vineyard vegetative growth surveys, and for grape composition inferences. Clustering associations were made through k-means statistical analysis in conjunction with Moran's I spatial autocorrelation index; soil moisture followed by the NDVI had the strongest clustering patterns. The outcomes from proximal sensing technology allow opportunities to stream and compliment present agricultural practices towards higher accuracy and efficacy by means of exploiting the observed variation.
    • The utility of sedimentary diatoms as a measure of historical lake ph

      Dixit, Sushil Sharan.; Department of Biological Sciences (Brock University, 1983-07-09)
      As a result of increased acid precipitation, the pH of a large number of Canadian Shield lakes has been falling. Prior to this study there was no documentation available to explain the history of lake acidification for the Algoma area lakes. In order to obtain this information the diatom inferred pH technique was developed in this study. During two field seasons, July 1981 and July 1982, short sediment cores (circa 25-30 cm) were collected from 28 study lakes located north of Lake Superior, District Algoma, Ontario. The surface sediment diatoms (0-1 cm) from each of these lakes were carefully identified, enumerated, and classified in terms of their pH indicator status. The surface sediment diatom analysis indicated that lake pH is one of the most important factors affecting the species composition and relative abundance of diatom populations. Thus diatom assemblages can be sensitive indicators of lake acidification. When Nygaard's index alpha was plotted against observed lake pH, a statistically significant relationship resulted (r=-0.89; p=<O.OI). The index alpha regression equation was used to construct the pH histories of 4 lakes (lakes X4, CS, U3, and WI). The repeatability of this technique was confirmed by comparing two downcore paleo-pH profiles of Lake WI. These two paleo-pH profiles represented almost identical paleo-pH patterns for Lake WI. The paleo-pH study of Lake X4 revealed that the lake has been rather acidic (pH <5.6) for the last 200 years. It appears that the recent increase in acid precipitation 3 over the last 30 years has not altered the water pH compared to the lake's pH history. However, the paleo-pH study of another acidic lake (Lake CS) indicated that its pH has significantl}* dropped over the last 30 years . During this time the Lake CS pH has dropped almost 2 pH units (7.1 to 5.2). The other two lakes studied for downcore pH were circumneutral in nature . One of these lakes (Lake U3) displayed a relatively stable pH history while the other lake (Lake WI) displayed significant pH fluctuations over post-Ambrosia time. The variable pH history of Lake WI was probably associated with the Algoma sintering plant plume and forest fires. A significant relationship between surface sediment diatoms and observed lake pH and secondly a statistically significant relationship between index alpha and observed pH suggested that diatoms are one of the best indicators of lake pH. Thus diatom inferred pH technique has great potential in explaining the rate of lake acidification.
    • Utilization of unmanned aerial vehicles and proximal sensing to detect Riesling vineyard variability

      Dorin, Briann; Department of Biological Sciences
      A single vineyard block can consist of significant spatial variability for several grape-growing attributes. The ability to detect and subsequently respond to this variation can lead to improved vineyard management, a growing practice termed precision viticulture. The overall goal of this research study was to determine if remote-sensing technologies could be used to detect Riesling vineyard variability, thus enhancing precision viticulture implementation. Approximately 80 grapevines in a grid pattern were geo-located within each of six commercial Riesling vineyards across the Niagara Peninsula in Ontario. From these grapevines the following variables were measured to determine their vineyard variation: soil and vine water status, vine size/vigor, winter hardiness, virus titer, yield components, and berry composition. Subsequently, remote-sensing technologies collected thermal [by unmanned aerial vehicle (UAV)] and multispectral (by UAV and ground-based proximal sensing technology GreenSeeker™) data from each block. Multispectral data were transformed into the Normalized Difference Vegetation Index (NDVI). Vineyard UAV NDVI maps were further used for selective harvesting of areas corresponding to low vs. high NDVI and wines made from these two zones were compared chemically and sensorially. The hypothesis was that remote and proximal sensing technologies could accurately detect vineyard variation for manually collected variables and further implicate differences in wine attributes upon zonal harvesting. Direct positive correlations were observed between remotely and proximally sensed NDVI vs. vine size, leaf stomatal conductance, leaf water potential, virus infection, yield, berry weight, and titratable acidity and inverse correlations with Brix and potentially-volatile terpene concentration. Maps created from remotely and proximally sensed data demonstrated similar spatial configurations to interpolated maps of these variables. In general, GreenSeeker NDVI demonstrated the most significant relationships with measured variables compared to UAV NDVI and UAV thermal data. Wines created from areas of low vs high NDVI differed inconsistently in their wine pH. Sensorially, in certain sites and vintages, panelists were able to distinguish between wines made from low vs high NDVI zones. Overall, remote sensing demonstrates the ability to detect vineyard areas differing in measures of vine health, size, yield, berry composition, and wine attributes, though more research is needed to understand the inconsistent results observed between vineyard sites and vintages.
    • Viability interactions between the left and right arms of the second chromosome of Drosophila melanogaster

      Pechan, Peter Alexander.; Department of Biological Sciences (Brock University, 1977-07-09)
      Inter and intrachromosomal viability interactions have been detected in a few experimental studies. Computer simulations and analytical models have led to postulation of nonadditivity of gene action. This study reports evidence of strong nonadditive interactions between the arms of the metacentric second chromosome of Drosophila melanogaster. Mean viability for 40 homozygous lines of the second chromosomes was 0.720+0.265 • Mean viability for 40 half homozygous second chromosomes was 0.928!O.)10 • Significant heterogeneity among and within lines was found in both groups of chromosomes, as well as a highly significant viability difference between the two groups. Comparison of observed viabilities with the expected values, according to the theories of additive and multi - plicative gene action. was made for both groups. Highly significant departures from the expected values were found for over 90% of the lines in both groups of chromosomes, for both additive and multiplicative models of gene action.
    • Water and electrolyte content and distribution in tissues of thermally-acclimated rainbow trout, Salmo gairdneri

      Mearow, Karen M.; Department of Biological Sciences (Brock University, 1978-07-09)
      The primary objective of this investigation was that of providing a comprehensive tissue-by-tissue assessment of water-electrolyte status in thermally-acclimated rainbow trout, Salmo gairdneri. To this end levels of water and the major ions, sodium, chloride and potassium were evaluated in the plasma, at three skeletal muscle sites, and in cardiac muscle, liver, spleen, gut and brain of animals acclimated to 2°, 10° and 18°C. The occurrence of possible seasonal variations in water-electrolyte balance was evaluated by sampling sununer and late fall-early winter populations of trout. On the basis of values for water and electrolyte content, estimates of extracellular and cellular phase volumes, cellular electrolyte concentrations and Nernst equilibrium potentials were made. Since accurate assessment of the extracellular phase volume is critical in the estimation of cellular electrolyte concentrations and parameters based on assumed cellular ion levels, [14 C]-polyethylene glycol-4000, which is assumed to be confined to the extracellular space, was employed to provide comparisons with various ion-defined spaces (H20~~s, H20~~/K and H20~~s). Subsequently, the ion-defined space yielding the most realistic estimate of extracellular phase volume for each tissue was used in cellular electrolyte calculations. Water and electrolyte content and distribution varied with temperature. Tissues, such as liver, spleen and brain appeared to be the most thermosensitive, whereas skeletal and cardiac muscle and gut tissue were less influenced. 'Summer' series trout appeared to be more capable of maintaining their water- electrolyte balance than the ~fall-winter' series animals. i The data are discussed in terms of their possible effect on maintenance of appropriate cellular metabolic and electrophysiological functions.
    • Water quality and fish populations of the Welland River, Ontario /

      Steele, Peter Owen.; Department of Biological Sciences (Brock University, 1981-06-15)
      The water quality and fish populations of the Welland River were observed to decline with distance downstream. This coincided with increased agricultural , domestic and industrial waste loadings. The river upstream of the City of Welland received considerable loadings from agricultural sources. Centrarchids, sciaenids, ictalurids, cyprinids and esocids characterized this upper section of the river. Most of these species were tolerant of low dissolved oxygen concentrations and the high turbidity which prevailed there . The river near Port Robinson receives many industrial and domestic wastes as evidenced by the water quality data. The fish in this section were less abundant and the observed population was comprised almost solely of cyprinids. Further downstream, near Montrose, the Welland River received shock loads of chemical wastes that exceeded a specific conductance of ISiOOO ;umhos/cm. Few fish were captured at this site and those that were captured were considered to be transients. A review of the literature revealed that none of the common indices of water quality in use today could adequately predict the observed distributions. In addition to the above, the long-term trend (l3 yrs) of water quality of the lower Welland River revealed a gradual improvement. The major factor thought to be responsible for this improvement was the operation of the Welland Sewage Treatment Plant. The construction of the New Welland Ship Canal coincided with large fluctuations of the total solids and other parameters downstream. These conditions prevailed for a maximum of three years (1972- 1975)' Furthermore, spawning times and temperatures, geographic distributions, length-weight regressions and many other descriptive aspects of the ecology of some 26 species/ taxa of fish were obtained. Several of these species are rare or new to southern Ontario.
    • X-ray diffraction studies of muscle : observations on the anterior byssus retractor muscle of Mytilus edulis and the insect flight muscle from Sarcophaga bullata

      Cottrell, Alan Philip.; Department of Biological Sciences (Brock University, 1977-07-09)
      The interfilament spacing of the anterior byssus retractor muscle from Mytilus edulis was studied as the muscle was extended. It was found that variations in this spacing were very small and consistent with the hypothesis that the interfilament spacing was independent of the extension of the muscle. It was observed that the interfilament spacing was dependent on the osmolarity of the bathing medium. In concentrated solutions of the artificial seawater, the interfilament spacing decreased; while in dilute solutions of artificial seawater, it was observed that the interfilament spacing was increasing. X-ray diffraction patterns were obtained from fresh, and glutaraldehyde fixed, specimens of insect flight muscle from Sarcophaga bullata. There patterns were in general agreement with previous X-ray diffraction studies of insect flight muscle. A reflexion G at 93A was observed and interpreted as arising from diffraction in the mitochondria. Specimens of dried insect flight muscle produced a diffraction pattern consisting of arc and ring reflexions. This was interpreted as suggesting an ordered arrangement of cristae, in the mitochondria from these muscles.