Thesis (Ph. D.)--University of Adelaide, Dept. of Plant Science, 1996. / Includes bibliographical references (leaves 209-254).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 99-103). Also available via the Internet.

No description available.

Light is one of the environmental signals that regulate axillary shoot development. However, little is known about molecular and physiological mechanisms regulating the development of the axillary shoot in response to light signals. Molecular events associated with the enhanced apical dominance of phytochrome B mutant sorghum (Sorghum bicolor) were analyzed to reveal processes mediating axillary shoot development in response to light. The enhanced apical dominance of phyB-1 mutant sorghum is due to inhibition of bud outgrowth and is accompanied by upregulation of the dormancy-associated gene (SbDRM1) in the buds. Increased expression of the Teosinte Branched1 (SbTB1) gene (encoding a putative transcription factor that represses bud outgrowth) suggests that the inhibition of bud outgrowth in phyB-1 sorghum is due to the absence of active phyB to repress SbTB1. The results were confirmed by growing wild type seedlings at high plant density or with supplemental farred (FR) light that induces enhanced apical dominance. However, the SbTB1 gene is not involved in the inhibition of bud outgrowth induced by defoliation in wild type seedlings. The results indicate variations in molecular mechanisms among different signals inhibiting branching. Increased expression of SbMAX2 (which encodes an F-box protein that represses bud outgrowth) in buds repressed by light and defoliation suggests common mechanisms at the downstream end of pathways inhibiting branching. The expression levels of several cell cycle-related genes including SbPCNA, SbHis4, SbCycD2, SbCycB and SbCDKB were down-regulated in the repressed buds of FRtreated and defoliated seedlings indicating the suspension of cell division in those buds. However, these cell cycle-related genes were continuously expressed in the repressed buds of phyB-1, suggesting that inhibition of bud outgrowth in phyB-1 is not associated with down-regulation of cell cycle-related gene expression. The down-regulation of cell cycle-related genes in the buds of FR-treated wild type seedlings indicates that other sensors, in addition to phyB, regulate bud outgrowth in response to FR enrichment. The approaches used and results achieved will provide direction for future research on this important topic.

Thesis (Ph. D.)--University of Adelaide, Dept. of Soil Science, 1997. / Includes bibliographical references (leaves 164-193).

Thesis (M. Ag. Sci.)--University of Adelaide, 1956. / Typewritten copy. Includes bibliographical references.

Thesis (Ph.D.)--University of Alberta, 2010. / Title from PDF file main screen (viewed on July 13, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Soil Science, Department of Renewable Resources, University of Alberta. Includes bibliographical references.

Foliage feeding insects like fall armyworm (FAW) [Spodoptera frugiperda (J. E. Smith)], granulate cutworm (GCW) [Feltia subterranean (F.)], velvetbean caterpillar (VBC) [Anticarsia gemmatalis (Hübner)] and corn earworm (CEW) [Helicoverpa zea (Boddie)] in peanut (Arachis hypogaea (L.)) and their effects on canopy defoliation and the resultant yield loss is outdated and essentially non-existent in Mississippi. With the expansion of peanuts throughout the state since 2012, growers struggle to manage foliageeeding pests in peanut. The lack of current information regarding insect pressure and economic injury levels is troublesome; especially with newer, high yielding, disease resistant cultivars. Research was required to understand how peanuts respond to complete canopy removal at different times during the growing season. Consequently, we evaluated the severity of canopy defoliation causing significant levels of yield loss during key physiological growth periods. This information will assist growers and extension personnel streamline management decisions for canopy defoliation in peanut throughout Mississippi.

No description available.

Peanut, Arachis hypogaea (L.), provides good rotational benefits for subsequent crops. During 2017, 2018, and 2019, research was conducted to determine the defoliating caterpillar complex in peanut in Mississippi, create a sweep net threshold for the complex, and determine yield losses associated with defoliation. The complex is comprised of yellow-striped armyworm, Spodoptera ornithogalli (Guenée); soybean looper, Chrysodeixis includens (Walker); corn earworm, Helicoverpa zea (Boddie); fall armyworm, S. frugiperda (Coquillet); southern armyworm, S. eridania (Stoll); beet armyworm, S. exigua (Hübner); green cloverworm, Hypena scabra (Fabricius); velvetbean caterpillar, Anticarsia gemmatalis (Hübner); and granulate cutworm, Feltia subterranea (F.). There was a significant relationship between the number of caterpillars on a drop cloth and the number per 25 sweeps. Defoliation during vegetative and early reproductive stage peanut caused a delay in canopy closure for all levels of defoliation although yield losses of 11.2% only occurred when defoliation reached 100%. During late season, peanut yield was reduced by 13% when defoliation reached 50%. With these data, a sweep net sampling and defoliation threshold can be derived. Managing caterpillar pests all season is necessary to reduce chances of yield loss due to defoliation.