Global ETD Search

1	Effect of nitrogen on the photosynthesis and productivity of Zea mays L. seedlings : with particular reference to intraspecific variation Perez-Leroux, Huberto Amiro Jose January 1990 (has links) No description available. 580 Nitrogen/plant productivity
2	Design of digital controller for multivariable plants with actuator failures Fripp, R. N. January 1988 (has links) No description available. 629.8
3	Physiological and Metabolic Responses of Thellungiella salsuginea to Osmotic Stress Guevara, David 02 1900 (has links) <p> Abiotic stresses such as extreme temperatures, drought and high salinity severely compromise plant productivity, and have placed selective pressure for the acquisition of traits enabling plants to adjust to and recover from these unfavorable environmental conditions. Thellungiella salsuginea is a plant that is native to highly saline and semiarid environments and exhibits an exceptional ability to tolerate abiotic stress. In this thesis, I report on laboratory and field studies aimed at identifying traits that allow Thellungiella to tolerate harsh environmental conditions. It was found that Thellungiella accumulates organic solutes in response to abiotic stress. Transcript and metabolite profiling approaches were used to identify metabolic pathways important for the accumulation of compatible organic solutes in Thellungiella in response to sub-optimal environmental conditions. The relative abundance of transcripts encoding enzymes associated with the biosynthesis of compatible organic solutes such as proline or galactinol showed stress-responsive increases in cabinet-grown material and these metabolites were accumulated in salt or drought treated plants, respectively. However, proline and galactinol were found to be of low relative abundance in leaves of field plants. In contrast, several carbohydrates including sucrose, glucose, and fructose made a greater relative contribution to the field plant profiles suggesting that carbohydrates play an important role in plant abiotic stress tolerance during growth under field conditions. The identification of stress-specific metabolic changes can be used to identify important biochemical traits underlying environmental stress tolerance in Thellungiella. This information can be used to improve the tolerance of stress -sensitive crops (including a related crucifer species, canola) that are grown in areas where persistent droughts, saline soils and early or late frosts frequently occur. </p> / Thesis / Doctor of Philosophy (PhD) thellungiella salsuginea osmotic stress abiotic stress plant productivity
4	Impact d’une formulation minérale sur les composantes biologiques des sols agricoles / Impact of mineral fertilzer on the biological componants of Agricultural soil Sultan, Gehan 29 November 2011 (has links) Des études récentes ont permis de constater qu'une part de plus en plus importante des sols agricoles présente des déficiences en micronutriments. Ces carences posent donc de graves problèmes en terme de productivité. Il existe de nombreuses études sur le rôle des micronutriments dans le métabolisme des plantes et des microorganismes. Cependant aucune étude basée sur une approche holistique visant à prendre en considération l'ensemble des trois composantes biologiques du sol (plante, faune, microorganismes) par rapport à l'apport de micronutriments n'a été entreprise à ce jour. L'objectif de cette étude était de préciser l'impact des micronutriments sur les trois composantes biologiques d'un sol en étudiant différents paramètres tels que la production de biomasse végétale, les communautés bactériennes et les aspects fonctionnels à travers l'analyse de l'activité des enzymes du sol.Une expérimentation menée en champ a été réalisée sur une culture de colza. Une comparaison entre blocs parcellaires traités et non traité a été réalisé en analysant le nombre et le poids de siliques ; la teneur en chlorophylle des feuilles, le poids et la densité des vers de terre, les activités enzymatiques, la structure des communautés microbiennes et l'activité microbienne globale. L'apport de micronutriments induit des changements de tous les paramètres biologiques étudiés en fonction du stade de développement de la plante. Parmi les enzymes étudiées (phosphatases alcaline et acide, beta-glucosidase, alpha-glucosidase, beta xylosidase), une augmentation significative de la phosphatase alcaline et de l'alpha-glucosidase a été mesurée mais seulement lorsque la plante est au stade de grenaison. A ce stade, on constate également une augmentation de l'activité microbienne totale ainsi qu'une plus forte densité de vers de terre dans les blocs parcellaires traités. De plus, l'apport de micronutriments affecte de manière significative les communautés de bactéries nitrifiantes mais ce phénomène ne s'observe qu'au stade de la floraison. L'ensemble des ces résultats suggère donc que les micronutriments agissent comme des catalyseurs de l'activité biologique des différents acteurs du sol (plante, microorganismes et macrofaune). Ils sont à l'origine d'une succession d'inter action complexes et modifient alors les processus biologiques qui s'opèrent dans le sol.Le deuxième objectif de cette étude était de comparer l'impact de micronutriments sur les communautés microbiennes en présence /absence de plantes ou de vers de terre. Une expérimentation conduite en microcosme a été entreprise. Compte- tenu que les paramètres physico –chimiques du sol influent la biodisponibilité des micronutriments, l'expérience a été réalisée avec trois types de sols (sols limoneux, argileux et sableux). Les résultats obtenus mettent en évidence que l'impacte des micronutriments sur les communautés bactériennes est subordonné à la présence et le type d'organismes (vers de terre/plante) ainsi qu'à la nature du sol.Finalement, les micronutriments ne doivent plus être perçus en terme de productivité à travers une simple relation avec la plante mais au contraire comme des agents agissant comme catalyseur de l'activité biologique des principaux acteurs du sol. Une telle vision holistique constitue les premières données pour établir les bases de l'agroécologie. / Numerous arable lands in the world have a low availability of micronutrients. This lack of micronutrients has a serious impact on crop production. To increase plant productivity more attention must be paid to micronutrients. A number of studies have focused on the effect of micronutrients on plant and bacterial metabolism. However, studies on the impact of these micronutrients, when all living organisms (plant, macrofauna and microorganism) present in a field are taken into account, are scarce..The aim of the present study was to investigate the effects of these micronutrients on the three soil components. Different parameters were chosen such as plant productivity, bacterial community, soil enzyme and fauna to determine the impact of micronutrients on these organisms.A field experimental approach consisted of micronutrient treatments during oilseed rape cultivation in the Aisne Department (France) was carried out. In comparison to control plots, the weight and number of siliques (seed pods), the chlorophyll content of leaves, the weight and density of earthworms, soil enzyme activities, bacterial communities and total microbial activity were analysed. The addition of micronutrients caused changes to all the biological parameters studied in relation to the plant growth stage. Among the enzymes tested (alkaline and acid phosphatase, beta-glucosidase, alpha-glucosidase, beta xylosidase), a significant increase in alkaline phosphatase and alpha-glucosidase was measured at the 3rd stage of oilseed rape development with the addition of micronutrients. At this stage of oilseed rape development, total microbial activity and the weight and density of earthworms were higher in plots under micronutrient treatment. On the other hand, micronutrients had a significant impact on the nitrifying bacterial community and the total bacterial community only at the 2nd stage of oilseed rape development. All these results suggest that micronutrients act as a catalyst by stimulating plants, soil fauna and microorganisms directly or indirectly. Thus micronutrients can modify biological processes in all living organisms through successive complex interactions.The second objective of this study was to compare the impact of micronutrients on bacterial communities in presence/absence of plants or earthworms. An in vitro experimental approach using microcosms has been conducted to study different parameters (bacterial community, soil enzyme activity, total microbial activity). Because characteristics of soil contents are important in determining the availability of micronutrients in soils the experiment was conducted on three type of soil: sandy; loamy and clay soil. Our results bring to light that the application of micronutrients affected the bacterial communities. However the nature and the importance of this impact varies according to the organisms presents (plant or earthworms) and the nature of the soil.The results of this study provide a scientific basis for fertilizing and utilizing soil, protecting microbial diversity, and accomplishing the sustainable development of agroecology. Biodiversité microbienne Enzymes Activité microbienne Faune de sol Oligoelements Micronutriment Microbial biodiversite Enzymes Microbial activity Oligoelements Micronutrient Plant productivity
5	Sustainable mangement of natural rangeland ecosystems Montenegro-Ballestero, Johnny Unknown Date No description available. Grassland ecosystems Topography Grazing Litter decomposition Plant productivity Modelling Ecosys Soil carbon Carbon budget Climate change Net ecosystem productivity
6	Leaf Rubisco turnover variation in a perennial ryegrass (Lolium perenne L.) population : analysis of quantitative trait loci, implications for productivity, and potential for manipulation : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science, Massey University, Institute of Natural Resources, College of Sciences, Palmerston North, New Zealand Khaembah, Edith Nanjala January 2009 (has links) The Grasslands II perennial ryegrass (Lolium perenne L.) mapping population comprising F1 progeny with the two parents (one plant each from the cultivars Samson and Impact) (Crush et al., 2007) was used to detect putative quantitative trait loci (QTL) for leaf Rubisco turnover and herbage yield traits. Rubisco turnover was described by three mathematical parameters: d (maximum Rubisco content), g (time of d) and f (a measure of curve width). All three parameters exhibited continuous variation among the F1 progeny. Sixteen QTL were detected, seven for Rubisco turnover and nine for herbage yield traits. Support interval overlap on linkage group (LG) 1 and close location on LG2 for plant dry weight (DW) QTL in this study and in a previous analysis (Sartie, 2007) of the same mapping population suggests DW QTL stability across environments. Some QTL identified by Sartie (2007) were not re-confirmed in this study, but new QTL were identified. This suggests genotype x environment interaction generated by variable expression of genes in different environments. Clusters of QTL with overlapping support intervals were found on LG2 and LG5. The cluster on LG2 included QTL for herbage yield traits leaf lamina length (LL), tiller number (TN), productivity index (PI) and DW. The cluster on LG5 included QTL for DW, PI, TN, and d. These two regions offer potential for plant breeding applications. Apart from the QTL for d on LG5, there was no co-location of Rubisco turnover and herbage yield QTL. However, principal component analysis indicated plants with lower d tended to have higher DW; thus Rubisco turnover effects on plant productivity may relate to energy cost of Rubisco synthesis rather than photosynthetic capacity. DW was generally unrelated to f and g; therefore, hypothesised nitrogen use inefficiencies arising from premature Rubisco degradation, or retention of Rubisco at leaf senescence, were not confirmed. LG5 and LG7 on which QTL for d were located have conserved syntenic regions with rice chromosomes 8 and 9 where QTL for Rubisco content at different stages during heading were mapped by Ishimaru et al (2001a). Lolium perenne L. Rubisco turnover Plant productivity
7	Effects of humic acids and soil symbionts on growth, physiology, and productivity of two crop species Peterson, Kendra Leigh 01 August 2017 (has links) No description available. Agriculture Botany Humic acids green peppers kidney beans agriculture farming crops plant productivity plant growth mycorrhizal fungi Rhizobium
8	Birds, bats and arthropods in tropical agroforestry landscapes: Functional diversity, multitrophic interactions and crop yield Maas, Bea 20 November 2013 (has links) No description available. 630 birds bats arthropods multitrophic interactions agroforestry tropical landscape forest margin landscape functional diversity crop yield exclosure experiments experimental exclusion arthropod suppression avian predation ecosystem services mist netting point counts artificial plasticine caterpillar dummy experiment biological control monitoring mapping Lemon-bellied White-eye Grosbeak Starling Zosterops chloris Scissiostrum dubium Theobroma cacao cacao agroforestry cacao diseases cacao harvest cacao pests flying vertebrates aerial insectivores volant vertebrates logging breeding colony flower herbivory mesopredator release predatory insects ants spiders aphids Lepidoptera Coleoptera Lepidopteran larvae sustainable agriculture sustainable agroforestry management implications management recommendations applied managament extensive land use management landscape management conservation biodiversity-friendly dbh distance to forest forest proximity habitat conversion herbivory Indonesia insectivorous bats insectivorous birds invertebrates Central Sulawesi Napu valley leaf gleaning leaf herbivory pests insects phytophagous insects plant productivity remnant forest trees shade tree managament South-east Asia Paleotropics tropical landscape tree height landscape gradient local shade management Cacao Pod Borer Cherelle Wilt fruit abortion Helopeltis sulawesi deforestation habitat fragmentation land use intensification forest margin species critical decline predation experiment species-specific functions Southeast Asia biodiversity conservation mesopredators food security human welfare human well-being poverty alleviation poverty reduction smallholder cacao smallholder plantation cacao farmers sustainable cacao management landscape perspective landscape scale large scale field experiment long term field experiment human wellbeing economic importance economic value valuation ecosystem services landscape matrix yield quality yield quantity fruit productivity species identity species diversity species richness ecosystem functioning pesticide use chemical compounds complex food web tritrophic interactions wildlife-friendly rural livelihoods endangered bird species endangered bat species endemic endemic birds endemic bats beneficial impact IUCN Lore Lindu National Park bioindicator indicator species forest margin agricultural habitat agroforestry systems population density predation activity species activity cacao flower cacao pod Orthoptera linear mixed effect models Tukey Post Hoc Test AICc model selection generalized least squares restricted maximum likelihood model simplification species richness estimator species accumulation linear mixed-effects models Likelihood Ratio Test Maximum Likelihood nocturnal insects diurnal arthropods nocturnal arthropods diurnal insects landscape context Land- und Forstwirtschaft (PPN621302791)

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