Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Abstract   The aim of this study was to increase knowledge of how plants as a whole respond to targeted fertilization and to refine the method of foliar nutrition fertilization. The experiment also aimed to test how herbivores respond when presented with a choice between fertilized and unfertilized Salix leaves in a feeding trial experiment. One major problem that arises when trying to alter the nutrient levels within a specific part of a plant is that adding fertilizer directly to the soil in which the plants grow will have a systemic effect on the plant, causing the plant physiology as a whole to change instead of just changing the properties of the plant part which the study focuses on. The approach chosen for this experiment is to target the leaves directly when applying the fertilizer and therefore try to avoid altering the rest of the plant. Fertilizer in the form of NH3NO4 was added to Salix leaves using a pipette and a brush at two different concentrations. When the leaves had been fertilized they were analyzed and used in a feeding trial experiment to study herbivore response to targeted fertilization. Once all data was analyzed statistically it became clear that both concentrations of the treatment had altered the nitrogen content within the leaves, however only the lower concentration had done so without altering the characteristics of the leaf. The data collected from the feeding trial displayed no statistical evidence for preference between the treated and control leaves in regard to amount consumed by the Phratora beetles, on the other hand when testing for egg laying preference 8/8 of egg clutches were laid on treated leaves.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 4 uppsatser.

The presence of competitors and predators as well as plant quality affect which plants an insect feed from. These factors affect food choice through the entire insect life cycle, and is especially important when it comes to nurturing larvae. Females oviposition choice sets the initial stage for larval growth and survival, and it is therefore predicted that there is a strong selection pressure to make them oviposit on the best plants possible. This study looks into the behavior of nutrient driven ovipositing and food choice in the beetles Phratora vitellinae and Lochmaea caprea by offering individuals ten leaves of Salix viminalis, one treated with extra nitrogen in order to increase the nutritional value, and four treated with extra carbon, which should lower the nutritional value. During the choice experiment, only two females of Phratora vitellinae oviposited, making it impossible to draw any conclusion regarding nutrient driven oviposition choice. However, data showed a preference for nitrogen treated leaves and an avoidance of untreated control leaves in almost every case when looking into the largest loss of area for leaves of each treatment. When analyzing the number of leaves of each treatment that is eaten per individual there was a slight preference for nitrogen treated leaves, even though the probability of nitrogen being ranked as most preferred in this case was almost zero. Carbon treated leaves and acetone treated control leaves were equally avoided. For Lochmaea caprea, females fed from a significantly larger numer of leaves than males did (t-test, t=1.86, p=0.0003). An ANOVA showed no significant difference in C:N ratio among leaf treatments (ANOVA, F=9.28E-07, p=0.99). Since plant C:N ratio most likely will increase continuously due to CO2 emissions, the effects an increased carbon concentration in plant tissues has on oviposition and food choice in herbivorous insects is something to look further into. More studies on this subject are therefore needed.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2004. / Härtill 5 uppsatser.

Lic.-avh. Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 2 uppsatser. Felaktigt institutionsnamn i publikationen. Rätt namn: Department of Entomology.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 5 uppsatser.

Le phénomène naturel d’érosion des berges peut menacer des infrastructures humaines. Des protections végétales peuvent être installées afin de mimer les dynamiques de végétation et armer la berge grâce aux racines. Cependant, les changements climatiques globaux sont susceptibles d’entraîner et d’aggraver les sécheresses, ce qui va stresser les végétaux présents et compromettre la bonne réussite des ouvrages de génie végétal. La principale question est donc « Quelles sont les caractéristiques biotechniques et les facultés d’acclimatation à la sécheresse de boutures de Salicaceae et Tamaricaceae, espèces utilisées ou potentiellement utilisables en génie végétal ? ». L’étude de différentes populations d’espèces classiquement utilisées que sont les saules démontre une résistance à la sécheresse plus efficace des populations méridionales tandis que les productions de biomasses restent plus élevées chez les populations septentrionales. L’étude des traits biotechniques et du comportement racinaire d’espèces potentielles appartenant aux Tamaricaceae (Tamarix gallica et Myricaria germanica) montre un taux élevé de reprise au bouturage, une forte production de biomasses et une stratégie de prospection racinaire différente des saules, ce qui leur confère une résistance à la sécheresse accrue. Ceci confirme une utilisation possible de ces espèces dans des ouvrages de génie végétal soumis à sécheresse. / The natural phenomenon of riverbank erosion can threaten human stakes. Vegetative bioengineering protections can be installed to imitate the vegetation dynamics and anchor the soil bank thanks to roots. However, global climate change could induce and increase droughts, what is going to stress plants and to compromise the bioengineering works success. The main question is thus " what are the biotechnical capabilities and the drought acclimatization faculties of cuttings of Salicaceae and Tamaricaceae, species used or potentially useful in bioengineering? ". The study of different populations of species such as willows demonstrates a more effective drought resistance of the Southern populations whereas the biomass productions remain higher with the Northern populations. The study of the biotechnical traits and the root behavior potentially useful species such as Tamaricaceae (Tamarix gallica and Myricaria germanica) show a high resprouting rate, a high biomass production and a prospecting root strategy different from willows. This results confer them a better drought resistance. This confirms a possible use of these species in vegetative bioengineering works subjected to drought.