Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Analysis and evaluation of the simultaneous growth and yield equations presented by Beck and Della-Bianca (1972) for predicting basal area growth and cubic-foot volume growth and yield in yellow-poplar stands after a single thinning indicated that a separate set of coefficients was required for stands thinned twice. A joint loss function involving both volume and basal area was used to estimate the coefficients in the system of equations. The estimates obtained were analytically compatible, invariant for projection length, and numerically equivalent with alternative applications of the equations. Given estimates of basal area and cubic-foot volume from these equations, board-foot volumes can also be calculated. As an adjunct to the stand level equations, compatible stand tables were derived by solving for the parameters of the Weibull distribution from attributes predicted with the stand-level equations. This procedure for estimating the parameters of the diameter distributions of the stands before thinning gave reasonable estimates of number of trees, basal area, and cubic-foot volume per acre by diameter class. The thinning algorithm removes a proportion of the basal area from each diameter class and produces stand and stock tables after thinning from below that are consistent with those generated before thinning. Finally, volume ratio equations were fitted to provide estimates of merchantable volume, i.b. or o.b., to either a specified diameter or height limit, where volume between any two diameter or height limits can be obtained through subtraction. Through rearrangement of the ratio equations, implicit taper functions were specified to predict height at a given diameter and diameter at a given height. / Master of Science

Willow and poplar are the main trees used for soil erosion control in New Zealand (NZ) with successful establishment critical to greater use of this technology. Five experiments were conducted at the Pasture and Crop Research Unit, Massey University Palmerston North, NZ to examine the ability of willow and poplar to establish as a willow/poplar pasture system in NZ over a period of 3 years from December 2002 to April 2005. With an objective to select the best size for low cost planting, stem diameters (10 mm, 25 mm and 35 mm) were planted vertically and stem lengths (50 mm, 200 mm and 600 mm) were planted horizontally to determine their growth, establishment, biomass production and regrowth after browsing. From December 2002 to March 2003, three management treatments, mowing, herbicide and control (no weed control) treatments, were designed and applied to determine their effects on growth and shoot biomass production. From September 2004 to April 2005, mowing was replaced by sheep browsing and the effect of browsing, herbicide and control treatments on soil and tree water status (soil water content, soil water loss and deficit, and stem water potential) were examined. Longer (600 mm) and thicker stem diameters (35 mm) produced the greatest shoot biomass (edible biomass, total biomass and root biomass) compared to the thin stem cuttings (50 mm length and 10 mm diameter). Higher tree survival was also found for longer (600 mm) and thicker stems diameter (35 mm). The mown treatment produced significantly more edible and total shoot dry matter (DM) than the herbicide and control treatments, with willow clone 'Kinuyanagi' producing higher total shoot DM than 'Tangoio'. Pasture management had no significant effect on soil water content during spring 2004 and late summer/autumn 2005, however, it was significant during early and mid summer. Strong relationships between (i) soil water content and stem water potential (SWP), and (ii) SWP and soil water deficit were found and could help growers to predict the amount of water required during the growing season. The results clearly demonstrated that sheep grazing had negligible damaging effect on willow and poplar (main stem, branch breakage and tree leaning) and tree mortality, and that young trees can be browsed during pasture shortages in summer drought. Cutting size and understorey control for establishing willow and poplar into pasture have been better defined by this research. It is recommended that farmers establishing willow and poplar for fodder plant thick (vertical planting) and long stems (horizontal planting) for higher growth and biomass production.

Vegetative propagation allows the amplification of selected genotypes for research, breeding, and commercial planting. However, efficient in vitro regeneration and genetic transformation remains a major obstacle to research and commercial application in many plant species. Our aims are to improve knowledge of gene regulatory circuits important to meristem organization, and to identify genes that might be useful for improving the efficiency of in vitro regeneration. In this thesis, we have approached these goals in two ways. First, we analyzed gene expression during poplar (Populus) regeneration using an AffymetrixGeneChip® array representing over 56,000 poplar transcripts. We have produced a catalog of regulated genes that can be used to inform studies of gene function and biotechnology. Second, we developed a GUS reporter system for monitoring meristem initiation using promoters of poplar homologs to the meristem-active regulatory genes WUSCHEL (WUS) and SHOOTMERISTEMLESS (STM). This provides plant materials whose developmental state can be assayed with improved speed and sensitivity. For the microarray study, we hybridized cDNAs derived from tissues of a female hybrid poplar clone (INRA 717-1 B4, Populus tremula x P. alba) at five sequential time points during organogenesis. Samples were taken from stems prior to callus induction, at 3 days and 5 days after callus induction, and at 3 and 8 days after the start of shoot induction. Approximately 15% of the monitored genes were significantly up-or down-regulated based on both Extraction and Analysis of Differentially Expressed Gene Expression (EDGE) and Linear Models for Microarray Data (LIMMA, FDR<0.01). Of these, over 3,000 genes had a 5-fold or greater change in expression. We found a very strong and rapid change in gene expression at the first time point after callus induction, prior to detectable morphological changes. Subsequent changes in gene expression at later regeneration stages were more than an order of magnitude smaller. A total of 588 transcription factors that were distributed in 45 gene families were differentially regulated. Genes that showed strong differential expression encoded proteins active in auxin and cytokinin signaling, cell division, and plastid development. When compared with data on in vitro callogenesis from root explants in Arabidopsis, 25% (1,260) of up-regulated and 22% (748) of down- regulated genes were in common with the genes that we found regulated in poplar during callus induction. When ~3kb of the 5' flanking regions of close homologs were used to drive expression of the GUSPlus gene, 50 to 60% of the transgenic events showed expression in apical and axillary meristems. However, expression was also common in other organs, including in leaf veins (40% and 46% of WUS and STM transgenic events, respectively) and hydathodes (56% of WUS transgenic events). Histochemical GUS staining of explants during callogenesis and shoot regeneration using in vitro stems as explants showed that expression was detectable prior to visible shoot development, starting 3 to 15 days after explants were placed onto callus inducing medium. Based on microarray gene expression data, a paralog of poplar WUS was detectably up-regulated during shoot initiation, but the other paralog was not. Surprisingly, both paralogs of poplar STM were down-regulated 3- to 6-fold during early callus initiation, a possible consequence of its stronger expression in the secondary meristem (cambium) than in shoot tissues. We identified 15 to 35 copies of cytokinin response regulator binding motifs (ARR1AT) and one copy of the auxin response element (AuxRE) in both promoters. Several of the WUS and STM transgenic events produced should be useful for monitoring the timing and location of meristem development during natural and in vitro shoot regeneration. / Graduation date: 2008