Growing consumer awareness of the health benefits associated with fruits and vegetables and demand for easy to prepare products has prompted the development of a wide variety of minimally processed fruits and vegetables. Minimally processed fruits and vegetables are often peeled, cut, or diced which compromise the produces’ natural protective barriers, exposing a nutrient rich medium and providing an ideal environment for the growth of microorganisms, including foodborne pathogens. The germination conditions of sprout vegetables consisting of relatively high temperatures and humidity, low light and abundance of nutrients are also conducive to the proliferation of foodborne pathogens. Recent outbreaks and recalls indicate additional measures are needed to improve food safety and maintain the integrity of the food industry. The objective of this research was to evaluate the efficacy of Lactic Acid Bacteria (LAB) against E. coli O157:H7, L. monocytogenes, and Salmonella spp. on apple slices and alfalfa sprouts and it’s influence on product quality. Apple slices inoculated with E. coli O157:H7, L. monocytogenes, and Salmonella spp. (each at 104 CFU/g) were treated with Lb. plantarum alone and in combination with Pediococcus acidophilus and P. pentosaceus (LPP) (107 CFU/g) while alfalfa seeds were inoculated with L. monocytogenes and Salmonella spp. (each at 101 CFU/g and 103 CFU/g) and treated with LPP (107 CFU/g). The growth of the microorganisms on the apple slices was assessed during five and seven days of storage at 4◦C and 20◦C, respectively. Growth on alfalfa seeds was reported during five days of sprouting at 20◦C. Populations of LAB were maintained between 7.0 log CFU/g and 8.0 log CFU/g throughout storage and sprouting on the sliced apples and alfalfa seeds, respectively. Although LAB had no significant effect on pathogen populations on apple slices during storage at 4°C (p > 0.05), populations were significantly different at 20°C (p < 0.05). Populations of L. monocytogenes in the presence of Lb. plantarum and LPP were 1.84 log CFU/g and 2.84 log CFU/g less than the controls after five days of storage at 20°C (p < 0.05). Populations of E. coli O157:H7 in the presence of Lb. plantarum and LPP were 1.83 log CFU/g and 1.86 log CFU/g less than the control after one and three days of storage, respectively. Finally, populations of Salmonella spp. were 0.86 log CFU/g less than populations in the absence of LPP after three days of storage. LPP had a significant effect on the growth of L. monocytogenes and Salmonella spp. on alfalfa seeds (p < 0.05). After five days of sprouting, populations of L. monocytogenes at an initial concentration of 101 CFU/g and 103 CFU/g on seeds treated with LPP were approximately 4.5 log CFU/g and 1.0 log CFU/g less than the untreated seeds, respectively. Populations of Salmonella spp. at an initial concentration of 101 CFU/g and 103 CFU/g were 1.0 log CFU/g less than the control. Overall, on apple slices the combination of Lb. plantarum with P. acidophilum and P. pentosaceus demonstrated greater efficacy than Lb. plantarum alone and reduction of L. monocytogenes by Lb. plantarum and LPP was greater than Salmonella spp. and E. coli O157:H7 on apple slices and alfalfa seeds, alike. LAB had a minimal effect on the quality of the apple slices and alfalfa seeds. LAB could be an effective strategy in reducing pathogen populations at abusive temperatures and germination conditions without influencing the quality of minimally processed fruit and vegetables.

Resprouting is an important means of plant regeneration especially under conditions that do not favour regeneration through seeding such as frequent disturbances, low productivity, unfavourable soil conditions, extreme cold and limited understorey light availability. Sprouts may be advantageous over seedlings because they have higher survival and growth rates than seedlings, since they use resources from parent plants unlike seedlings that have to acquire their own resources. Resprouting is well documented for ecosystems that experience severe disturbances that damage aboveground biomass. For example, resprouting is important for plant persistence against fire in fire-prone savannas and Mediterranean shrub-lands, and hurricanes and cyclones in tropical forests. In these ecosystems, resprouting often results in multi-stemming, because this dilutes the risk of damage among many stems, improving the chances of individual survival. This study was conducted at coastal dune forest at Cape Vidal in north-eastern South Africa, where there is a high incidence of multi-stemmed trees due to resprouting in response to chronic disturbances of low severity. This study examines (1) the importance of resprouting to tree survival and dynamics in an environment where disturbance severity is low but pervasive, and (2) how this resprouting strategy differs from the more familiar sprouting response to severe disturbances such as fire and hurricanes. Analysis of the relationship between multi-stemming and a number of disturbances potentially causing multi-stemming revealed that stem leaning and substrate erosion were the most important disturbances associated with multi-stemming. There were fewer multistemmed trees on dune slacks that had a stable substrate and were protected from sea winds than on dune crests and slopes that had unstable substrate and were exposed to sea winds. Trees resprouted and became multi-stemmed from an early stage to increase their chances of survival against leaning caused by strong sea winds and erosion, and occasional slumping of the unstable dune sand substrate. These low severity disturbances are persistent and are referred to as chronic disturbances in this thesis. As a result of these chronic disturbances, both single and multi-stemmed trees had short stature because taller individuals that emerged above the tree canopy would be exposed to wind damage. Under chronic disturbances plants may manifest a phylogenetically determined sprouting response. However, in this study resprouting and multi-stemming were the results of the tree-disturbance interaction and not a property of a plant or species and were not phylogenetically constrained. Because the disturbances are predominantly of low severity, leaning trees were able to regain the vertical orientation of the growing section by turning upward (a process referred to as ‘turning up’ in this study) and hence survive without resprouting. Species that were prone to turning upward had a low incidence and degree of leaning of their individuals, low frequency of loss of primary stems and high abundance of individuals. Although turning up is less costly to the individual than resprouting, it could only be used by leaning trees that had small angles of inclination and were not eroded. High intensities of the latter require that individuals resprout to survive. The form and function of resprouting varied between seedlings and juvenile and mature trees. Resprouting in seedlings resulted in a single replacement shoot, unlike sprouting in juvenile and mature trees that resulted in multi-stemmed trees. Like sprouting in juvenile and mature trees, sprouting in seedlings was not phylogenetically constrained. Resprouting in seedlings increased seedling persistence; hence species with more sprout seedlings had larger individual seedlings and seedling banks. Resprouting in seedlings increased the chances of seedling recruitment, whereas resprouting in juvenile and mature trees increased the chances of an established plant maintaining its position in the habitat. After disturbances of high severity, which destroy the photosynthesizing parts, plants resprout using carbohydrates stored below- or above ground. In this study, good resprouters stored more carbohydrates both below- and above ground than poor resprouters. The carbohydrates were mobilized for resprouting after disturbance. More carbohydrates were stored in stems than in roots because the prevailing disturbances were mostly of low severity and hence above ground resources were readily available. Similar to storage by plants in severely disturbed habitats, carbohydrates were stored by reserve formation, which competes for carbohydrates with growth and maintenance and forms permanent storage, rather than accumulation, which temporarily stores carbohydrates in excess of demands for growth and maintenance. Stored carbohydrates are not necessary for resprouting of plants after disturbances of low severity because they can resprout using resources remobilized directly from the disturbed photosynthesizing parts. However, in this study, stored carbohydrates served as a bet-hedge against occasional severe disturbances that occurred in addition to chronic disturbances. Allocation of carbohydrates to permanent storage diverts them from growth and reproduction and hence good resprouters had lower growth rates, seed output, seed size and seedling recruitment than poor resprouters. However, the costs of these traits that resulted in low recruitment from seed by good resprouters, were compensated for by high persistence of established individuals of good resprouters through recruitment of sprout stems. This study demonstrates that resprouting is not only advantageous in severely disturbed environments, but also in environments where disturbances are of low severity but nevertheless confer an advantage on individuals that persist. Thus in forest environments where aboveground biomass is seldom destroyed and individuals are relatively long-lived, resprouting can confer significant fitness and selective advantage on individuals. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

The aim of my thesis is to assess the basic yield factors in the studied varieties of spring wheat. In the year 2013, there were in the framework of the test sown eight varieties (Brawura, Corso, Epos, Granny, Scirocco, Septima, Tercie and Vánek) at the land of the Faculty of Agriculture, University of South Bohemia in Ceske Budejovice. During the vegetation the number of plants, the number of sprouts and the number of spikes was recorded using a quarter tape. The data are in the results section and are converted to 1 m2. Additionally, the infestation by diseases, pests and overrunning with weeds was monitored. Before harvesting, the samples were taken for an evaluation of the number of grains per spike and HTZ. In the results section the main factors of the yield are statistically evaluated. These include the number of spikes, the number of grains per spike and HTZ. The study also evaluates the theoretical and the actual yield and the bulk density. The average number of ears in the varieties of spring wheat ranged from 411 (Corso) to 564 (Epos) ears per 1 m2. The number of grains per spike of individual varieties reached higher values, from 39,6 (Scirocco) to 57,8 (Corso). The average HTZ for the individual varieties was between 34,9 and 43,5 g. At finding of the real yield there were observed values from 3,4 t.ha-1 (Septima) to 4,5 t.ha-1 (Scirocco). The difference between the yield elements of were statistically significant all varieties.

Ekträd har en central roll i den biologiska mångfalden, där de utgör både livsrum och födkrok för ett stort antal insekter, lavar, svampar och fåglar under sin långa livstid och därefter i den döda veden. Ek har minskat dramatiskt under de senaste 200 åren, men orsakerna till detta är inte helt klarlagda. I östra Nordamerika har den försämrade föryngringen av ek kopplats till de betydligt färre skogsbränderna och ur detta har den s.k. brand-ek-hypotesen uppstått. Denna säger att branden spelar en viktig roll i ekens föryngring i östra USA och i Nordamerika p.g.a. att eken är bättre anpassad än många andra träd för att klara brand, vilket ger den en konkurrensfördel som gör att den inte bara gynnas av brand, utan också kan vara beroende av den. Jag har studerat hur föryngring av ek påverkats av en naturvårdsbränning som genomförts i Krogölen i Allgunnens naturreservat i sydöstra Sverige. Hypotesen är att brand har en gynnsam effekt på ekföryngring även i Sverige och att brand-ek-hypotesen är tillämpbar också här. Detta kunskapsområde är relevant för naturvården i Sverige när det gäller att planera naturvårdsbränningar i områden med förekomst av ek. Eftersom studien har genomförts som en pilotstudie, där endast ett brandområde studerats, kan inga slutsatser om generella brandfältseffekter dras. Mina resultat talar för att krontäckning har en effekt på tätheten av fröplantor i Krogölen, och att den har större betydelse i brandfältet än i det obrända området, vilket talar emot brand-ek-hypotesen. Effekten av brand och krontäckning förklarar i denna studie 21,8% av variationen i den rottransformerade fröplanttätheten per 12,6 m2. Det går inte att se någon ökning av fröplantor eller rotskott i det brända området jämfört med det obrända. För framtida studier skulle det vara intressant att titta på fröplantors dödlighet i olika livsstadier under varierande ljusförhållanden, effekten av predation i brandfält, hur olika brandintensitet kan inverka på ekens föryngring samt bestående effekter av brand över tid och betydelsen av i vilket utvecklingsstadie branden skett. / Oak trees have a central role in biodiversity, where they serve as both a habitat and a feeding ground for a large number of insects, lichens, fungi and birds during its long life and thereafter in the dead wood. Oak has declined dramatically over the past 200 years, but the reasons for this are not entirely known. In eastern North America, the deteriorating regeneration of oak has been linked to the significantly less forest fires and from this the so-called fire-oak hypothesis have emerged. It states that the fire plays an important role in the regeneration of the oak in the eastern United States and North America due to the oak being better adapted than many other trees to endure fire, which gives it a competitive advantage that makes it not only benefit from fire, but also possibly depend on it. I have studied how the regeneration of oak has been affected by a prescribed fire in Krogölen in the Allgunnen nature reserve in the south-east of Sweden. My hypothesis is that fire has a favorable effect on oak regeneration also in Sweden and that the fire-oak hypothesis is also applicable here. This area of ​​knowledge is relevant for nature conservation in Sweden in planning prescribed fires in oak areas. As the study has been carried out as a pilot study, studying only one burned area compared to a none burned area, no conclusions about general fire effects can be drawn. My results suggest that canopy cover has an effect on the density of seed plants in Krogölen, and that it is more comprehensive in the fire field than in the unburned area, which is not conclusive with the fire-oak hypothesis. The effect of fire and canopy cover in this study explains 21.8% of the variation in the root-transformed seed plant density per 12.6 m2. There is no increase in seed plant density or root sprout density in the burned area compared to the unburned area. For future studies, it would be interesting to look at seed plant mortality in different life stages under varying light conditions, the effect of predation in fire fields, how different fire intensities can affect oak regeneration, lasting effects of fire over time and the significance of the oak developmental stage when the fire occurs.