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Articles 1 - 13 of 13
Full-Text Articles in Life Sciences
Climate Interactions Drive Tree Physiology And Growth In A Northeastern Forest Ecotone, Alexandra M. Barry
Climate Interactions Drive Tree Physiology And Growth In A Northeastern Forest Ecotone, Alexandra M. Barry
Electronic Theses and Dissertations
Climate change is a threat to global forest ecosystems. In the northeastern United States, forest trees are facing rising temperatures and increasingly inconsistent moisture regimes. In addition to long-term changes in climate conditions, there is concern about the potential for more frequent and intense climate extremes, which can have severe and rapid negative effects on tree physiology and growth. Further, climate extremes may co-occur to produce a greater magnitude of effect than the sum of their parts, with a prominent example being hot droughts, which are increasing in occurrence and severity. The impact of these and other extreme climate interactions …
Influence Of Biochar As A Soil Amendment On Soil Water Content And Wild Blueberry Physiology, Abigayl Novak
Influence Of Biochar As A Soil Amendment On Soil Water Content And Wild Blueberry Physiology, Abigayl Novak
Electronic Theses and Dissertations
Maine wild (or lowbush) blueberries (Vaccinium angustifolium Ait.) continue to face challenges imposed by climate change. Reduced frequency of precipitation and increased drought conditions have negatively impacted this crop since it resides in sandy soils with limited retention of water and nutrients. The wild blueberry plants growing in water- and nutrient-poor sandy soils are likely to have poor resilience to drought, resulting in a decline in berry yield during drought years. Thus, there is an urgent need to find a drought management solution for wild blueberries. Compared with other drought management practices, such as irrigation systems, mulching, and adopting drought-resistant …
Genetic Characterization Of Centromere-Mediated Uniparental Genome Elimination In Arabidopsis, Diana Spencer
Genetic Characterization Of Centromere-Mediated Uniparental Genome Elimination In Arabidopsis, Diana Spencer
Electronic Theses and Dissertations
The production of haploids through crossing was first discovered from instances of interspecies crosses in Nicotiana spp. in 1924. Since then, haploid induction crosses has been used to improve plant breeding programs and commercially utilized in a number of crop industries. The generation of doubled haploid instantaneously creates a pure homozygous line, therefore eliminating the need for several generations of inbreeding. There are several pathways to induce haploids in plants: of these methods, centromere-mediated genome elimination pathway engenders the highest haploid induction rate (HIR) with up to 45% in Arabidopsis compared to 15% through phospholipase-mediated haploid induction in maize. Centromere-mediated …
Functional Diversity In Blueberries And Their Responses To Extreme Drought, Pratima Pahadi
Functional Diversity In Blueberries And Their Responses To Extreme Drought, Pratima Pahadi
Electronic Theses and Dissertations
Climate change is expected to lead to novel climate conditions with an increase in frequency and severity of drought across many places around the globe including the north-eastern (NE) United States. Therefore, experimental studies that test the impacts of changing environmental conditions over long time scales or experimental studies that mimic these conditions are crucial to understand the potential impact on crops in this region. Wild lowbush blueberries and highbush blueberries are two important crops in NE USA. In this study, the leaf functional, structural, nutrient traits across genotypes of wild blueberries (Vaccinium angustifolium and V. myrtilloides) at …
Tree Responses To Moderate And Extreme Drought In The Northeastern United States, Ruth A. Van Kampen
Tree Responses To Moderate And Extreme Drought In The Northeastern United States, Ruth A. Van Kampen
Electronic Theses and Dissertations
Climate change is expected to lead to novel drought conditions in the Northeastern United States. Therefore, experimental studies that mimic these conditions are crucial to understand the potential impact on forests. Further, recent large scale dendrochronological studies suggest that spring and summer droughts may immediately impact tree growth while fall droughts may cause delayed impacts on growth the following growing season. Therefore, in this study, we investigated the impacts of six-week-long spring, summer, and fall droughts on the physiology and intra-annual growth on 288 saplings of six tree species native to the Northeastern United States. These species (deciduous broadleaf angiosperms, …
Characterization Of Dickeya Dianthicola And Pectobacterium Parmentieri Causing Blackleg And Soft Rot On Potato, Tongling Ge
Characterization Of Dickeya Dianthicola And Pectobacterium Parmentieri Causing Blackleg And Soft Rot On Potato, Tongling Ge
Electronic Theses and Dissertations
Potato blackleg and soft rot (PBSR), which can be caused by Dickeya spp. and Pectobacterium spp., is a serious problem worldwide. The recent outbreak of PBSR in the Northeastern USA, caused primarily by D. dianthicola, has resulted in significant economic losses since 2015. This seedborne disease is highly associated with and therefore spread by seed tuber distribution. To understand how the outbreak occurred and where the pathogen originated, a total of 1204 potato samples were collected from 11 northeastern states from 2015 to 2020. All the samples were processed for bacterial isolation and DNA extraction. Dickeya dianthicola and P. …
Microsite Requirements For Successful Regeneration In Lowland Northern White-Cedar (Thuja Occidentalis) Forests, Jeanette Allogio
Microsite Requirements For Successful Regeneration In Lowland Northern White-Cedar (Thuja Occidentalis) Forests, Jeanette Allogio
Electronic Theses and Dissertations
Declines in stands of northern white-cedar (Thuja occidentalis L., hereafter cedar) have been observed as both shifts in species composition and reductions in cedar densities, particularly those stands in lowland sites (Curtis 1946, Boulfroy 2012). While several factors inhibiting cedar regeneration have been identified, a thorough understanding of the conditions that best promote regeneration is lacking. Our objectives for the first chapter were to characterize the site conditions associated with successful regeneration in lowland cedar stands and to describe how spatial patterns of various cedar size classes relate to site preference and to regeneration dynamics. These objectives were achieved …
The Dispersal Pattern Of Thekopsora Minima In Wild Blueberry Determined By A Molecular Detection Method, Nghi Nguyen
The Dispersal Pattern Of Thekopsora Minima In Wild Blueberry Determined By A Molecular Detection Method, Nghi Nguyen
Electronic Theses and Dissertations
Blueberry rust caused by Thekopsora minima is a common disease in wild blueberry (Vaccinium angustifolium) and other Vaccinium genera. Understanding the spore dispersal pattern and disease cycle of fungal pathogens in wild blueberry is crucial for the development of a more efficient disease management program. Molecular assays for rapid detection and quantification of Thekopsora minima were developed to be incorporated with a spore trap sampling method and weather data collection to examine spore dispersal pattern and production in three different fields: Blueberry Hill Farm in Jonesboro, East Machias, and Spring Pond in Deblois, Maine, in three years 2014, …
Flower Visitation In Relation To Pollen And Nectar Nutrition: Implications For Pollinator Habitat And Conservation, Megan E. Leach
Flower Visitation In Relation To Pollen And Nectar Nutrition: Implications For Pollinator Habitat And Conservation, Megan E. Leach
Electronic Theses and Dissertations
Pollination of both wild and crop plants is at a crossroads; honey bee populations are experiencing losses at a higher rate than ever before, and some native bee species are declining in abundance to the point of being listed as endangered species. A few examples of these threats include pesticide exposure, habitat loss, and climate change. In response to bee population declines, conservation efforts have been initiated to increase habitat quality for bees by planting pollinator reservoirs or gardens. Plants provide nutrition to bees in the form of pollen and nectar. Several studies have shown links between higher nutritional quality …
Propagation And Container Production Of The Amelanchier Spicata Complex, Gregory J. Melcher
Propagation And Container Production Of The Amelanchier Spicata Complex, Gregory J. Melcher
Electronic Theses and Dissertations
Amelanchier is a genus in the Rosaceae containing shrubs and trees indigenous to North America that possess traits valued by the horticulture industry. Amelanchier spicata (dwarf serviceberry), a heterogeneous complex of hybrids indigenous to eastern North America, has agricultural and ornamental merit with notable characteristics. White blossoms emerge in early spring, edible pomes ripen in the summer, and vibrant, orange foliage occurs in the fall. I investigated phenological and physiological factors influencing adventitious rooting of stem cuttings, the effects of nitrogen source on the development of seedlings grown in container culture, and phenotypic variation among seedlings of A. spicata from …
Assessing The Biological Condition Of Maine Streams And Rivers Using Benthic Algal Communities, Thomas John Danielson
Assessing The Biological Condition Of Maine Streams And Rivers Using Benthic Algal Communities, Thomas John Danielson
Electronic Theses and Dissertations
The purpose of this study was to test and develop algal methods of evaluating the condition of Maine streams and rivers. The primary objective was to develop a statistical model to predict attainment of Maine's aquatic life criteria for water quality classes A, B, and C. I collected 298 samples of algae on rocks from 193 locations across the state. The major pattern in species composition related to conversion of forests to urban, residential, and agricultural land uses. I calculated preferred environmental conditions of 236 algal taxa for 1) concentrations of nitrogen, phosphorus, and dissolved ions in the water, 2) …
Localization Of Expansin Expression During Adventitious And Lateral Rooting In Response To Auxin In Loblolly Pine, Fuyu Xu
Electronic Theses and Dissertations
Loblolly Pine is the most important and widely cultivated timber species in the southern United States. Due to its fast growth, it is extensively planted for lumber and pulpwood. Vegetative propagation will enhance gains from genetic improvement of tree species. Rooted-cutting is at present the most reliable non-somatic embryogenesis method for cloning specific genotypes. However, an abrupt decline of adventitious rooting capacity has hindered the application of vegetative propagation in loblolly pine. Unraveling the rooting mechanism may facilitate a way to overcome this barrier. Regulation of lateral and adventitious root formation by auxin has been demonstrated through the application of …
Characterization Of Biochelators, Membrane Redox Systems, And Quinone Reductases From Wood Degrading Basidiomycetes, Weihong Qi
Electronic Theses and Dissertations
Biodegradation of wood by brown rot fungi is dependent upon a non-enzymatic system involving Fenton chemistry. Iron biochelators with molecular weights lower than 1kD are important components in this process. Phenolate biochelators drive a hydroxyl radical generating Fenton reaction by reducing ferric iron. Biochelators may be mineralized or alternately, in some cases oxidized biochelators may be regenerated via a quinone redox cycle. Electron donors for this postulated regeneration have not been identified. Extracellular cellobiose dehydrogenase has also been found to drive the Fenton reaction by generating ferrous iron and hydrogen peroxide. This research compared the production of biochelators and the …