Tree growth relationships and silvicultural tools to assist stand management in private native spotted gum dominant forests in Queensland and northern New South Wales.

Spotted gum dominant forests occur from Cooktown in northern Queensland (Qld) to Orbost in Victoria (Boland et al. 2006) and these forests are commercially very important with spotted gum the most commonly harvested hardwood timber in Qld and one of the most important in New South Wales (NSW). Spotted gum has a wide range of end uses from solid wood products through to power transmission poles and generally has excellent sawing and timber qualities (Hopewell 2004). The private native forest resource in southern Qld and northern NSW is a critical component of the hardwood timber industry (Anon 2005, Timber Qld 2006) and currently half or more of the native forest timber resource harvested in northern NSW and Qld is sourced from private land. However, in many cases productivity on private lands is well below what could be achieved with appropriate silvicultural management. This project provides silvicultural management tools to assist extension staff, land owners and managers in the south east Qld and north eastern NSW regions. The intent was that this would lead to improvement of the productivity of the private estate through implementation of appropriate management. The other intention of this project was to implement a number of silvicultural experiments and demonstration sites to provide data on growth rates of managed and unmanaged forests so that landholders can make informed decisions on the future management of their forests. To assist forest managers and improve the ability to predict forest productivity in the private resource, the project has developed: • A set of spotted gum specific silvicultural guidelines for timber production on private land that cover both silvicultural treatment and harvesting. The guidelines were developed for extension officers and property owners. • A simple decision support tool, referred to as the spotted gum productivity assessment tool (SPAT), that allows an estimation of: 1. Tree growth productivity on specific sites. Estimation is based on the analysis of site and growth data collected from a large number of yield and experimental plots on Crown land across a wide range of spotted gum forest types. Growth algorithms were developed using tree growth and site data and the algorithms were used to formulate basic economic predictors. 2. Pasture development under a range of tree stockings and the expected livestock carrying capacity at nominated tree stockings for a particular area. 3. Above-ground tree biomass and carbon stored in trees. •A series of experiments in spotted gum forests on private lands across the study area to quantify growth and to provide measures of the effect of silvicultural thinning and different agro-forestry regimes. The adoption and use of these tools by farm forestry extension officers and private land holders in both field operations and in training exercises will, over time, improve the commercial management of spotted gum forests for both timber and grazing. Future measurement of the experimental sites at ages five, 10 and 15 years will provide longer term data on the effects of various stocking rates and thinning regimes and facilitate modification and improvement of these silvicultural prescriptions.

Nutritional constraints on displacement of Fusarium pseudograminearum from cereal straw by antagonists.

Displacement of the fungus Fusarium pseudograminearum from stubble by antagonists is a potential means of biocontrol of crown rot in cereals. The role of carbon and nitrogen nutrition in interactions between the pathogen and the antagonists Fusarium equiseti, Fusarium nygamai, Trichoderma harzianum and the non-antagonistic straw fungus Alternaria infectoria was investigated. Sole carbon source utilization patterns on Biolog plates were similar among the three Fusarium species, suggesting a possible role for competition. However, carbon niche overlap was unlikely to be important in antagonism by T. harzianum. Straw medium supplemented with sugars generally reduced the inhibitory effect of antagonists on growth of F. pseudograminearum in dual culture, indicating that availability of simple carbon sources does not limit antagonism. Adding nitrogen as urea, nitrate or ammonium to straw medium had little effect on antagonism by F. equiseti and F. nygamai, but ammonium addition removed the inhibitory effect of T. harzianum on growth of F. pseudograminearum. Displacement of F. pseudograminearum from straw by all fungi in a Petri dish assay was greater when urea or nitrate was used as a nitrogen source than with ammonium. All forms of nitrogen significantly increased displacement of F. pseudograminearum from straw under simulated field conditions when straws were either inoculated with T. harzianum or exposed to resident soil microbes. However, in 2 out of 3 experiments urea and nitrate were more effective than ammonium. The results suggest that availability of nitrogen, but not carbon, is limiting the activities of antagonists of F. pseudograminearum in straw, and the way nitrogen is applied can influence the rate of displacement and mortality of the pathogen in host residues.

DAQ566 Genetic approaches to resist to Fusarium and Bipolaris in wheat/barley

Genetic approaches to resistance of bread wheat to crown rot and common root rot.

Genetic approaches to resistance to Fusarium and Bipolaris in wheat and barley

This project provided information on the genetics of crown rot (CR) resistance to help breeding work, located new parent lines in wheat and barley, and provided an insight into yield losses that occur in commercial varieties with increasing levels of CR for risk management. Genetic experiments found some highly resistant lines were poor parents, and CR resistance was complex. Best parent lines and many specific crosses were identified for further work. New potential parent lines were identified in wheat and barley, some now used in breeding programs. Yield loss can be severe even with low levels of CR when combined with drought stress. CR can reduce yield even with a wet finish.

The structure of Norway spruce (Picea abies [L.] Karst.) stems in relation to wood properties of sawn timber

An important challenge in forest industry is to get the appropriate raw material out from the forests to the wood processing industry. Growth and stem reconstruction simulators are therefore increasingly integrated in industrial conversion simulators, for linking the properties of wooden products to the three-dimensional structure of stems and their growing conditions. Static simulators predict the wood properties from stem dimensions at the end of a growth simulation period, whereas in dynamic approaches, the structural components, e.g. branches, are incremented along with the growth processes. The dynamic approach can be applied to stem reconstruction by predicting the three-dimensional stem structure from external tree variables (i.e. age, height) as a result of growth to the current state. In this study, a dynamic growth simulator, PipeQual, and a stem reconstruction simulator, RetroSTEM, are adapted to Norway spruce (Picea abies [L.] Karst.) to predict the three-dimensional structure of stems (tapers, branchiness, wood basic density) over time such that both simulators can be integrated in a sawing simulator. The parameterisation of the PipeQual and RetroSTEM simulators for Norway spruce relied on the theoretically based description of tree structure developing in the growth process and following certain conservative structural regularities while allowing for plasticity in the crown development. The crown expressed both regularity and plasticity in its development, as the vertical foliage density peaked regularly at about 5 m from the stem apex, varying below that with tree age and dominance position (Study I). Conservative stem structure was characterized in terms of (1) the pipe ratios between foliage mass and branch and stem cross-sectional areas at crown base, (2) the allometric relationship between foliage mass and crown length, (3) mean branch length relative to crown length and (4) form coefficients in branches and stem (Study II). The pipe ratio between branch and stem cross-sectional area at crown base, and mean branch length relative to the crown length may differ in trees before and after canopy closure, but the variation should be further analysed in stands of different ages and densities with varying site fertilities and climates. The predictions of the PipeQual and RetroSTEM simulators were evaluated by comparing the simulated values to measured ones (Study III, IV). Both simulators predicted stem taper and branch diameter at the individual tree level with a small bias. RetroSTEM predictions of wood density were accurate. For focusing on even more accurate predictions of stem diameters and branchiness along the stem, both simulators should be further improved by revising the following aspects in the simulators: the relationship between foliage and stem sapwood area in the upper stem, the error source in branch sizes, the crown base development and the height growth models in RetroSTEM. In Study V, the RetroSTEM simulator was integrated in the InnoSIM sawing simulator, and according to the pilot simulations, this turned out to be an efficient tool for readily producing stand scale information about stem sizes and structure when approximating the available assortments of wood products.

Management objectives of Queensland fisheries: Putting the horse before the cart

A review of future management arrangements for the Queensland East Coast Trawl fishery was undertaken in 2010 to develop a management plan for the next 10 years. A key question raised at the start of the review process was: what should the management plan achieve? As with fisheries management in most countries, multiple management objectives were implicit in policy statements, but were poorly specified in some areas (particularly social objectives) and strongly identified in others (e.g., an objective of sustainability). As a start to the management review process, an analysis of what objectives the management system should aim to achieve was undertaken. A review of natural resource management objectives employed internationally was used to develop a candidate list, and the objectives most relevant to the fishery were short-listed by a scientific advisory group. Additional objectives specific to Queensland fisheries management, but not identified in the international review, were also identified and incorporated into the objective set. The relative importance of the different objectives to different stakeholder groups was assessed using the Analytic Hierarchy Process. As with other studies, the relative importance of the different objectives varied both within and between the different stakeholder groups, although general trends in preferences were observed.

What was behind the bark? : An assessment of decay among urban Tilia, Betula and Acer trees felled as hazardous in the Helsinki City area

Old trees growing in urban environments are often felled due to symptoms of mechanical defects that could be hazardous to people and property. The decisions concerning these removals are justified by risk assessments carried out by tree care professionals. The major motivation for this study was to determine the most common profiles of potential hazard characteristics for the three most common urban tree genera in Helsinki City: Tilia, Betula and Acer, and in this way improve management practices and protection of old amenity trees. For this research, material from approximately 250 urban trees was collected in cooperation with the City of Helsinki Public Works Department during 2001 - 2004. From the total number of trees sampled, approximately 70% were defined as hazardous. The tree species had characteristic features as potential hazard profiles. For Tilia trees, hollowed heartwood with low fungal activity and advanced decay caused by Ganoderma lipsiense were the two most common profiles. In Betula spp., the primary reason for tree removal was usually lowered amenity value in terms of decline of the crown. Internal cracks, most often due to weak fork formation, were common causes of potential failure in Acer spp. Decay caused by Rigidoporus populinus often increased the risk of stem breakage in these Acer trees. Of the decay fungi observed, G. lipsiense was most often the reason for the increased risk of stem collapse. Other fungi that also caused extensive decay were R. populinus, Inonotus obliquus, Kretzschmaria deusta and Phellinus igniarius. The most common decay fungi in terms of incidence were Pholiota spp., but decay caused by these species did not have a high potential for causing stem breakage, because it rarely extended to the cambium. The various evaluations used in the study suggested contradictions in felling decisions based on trees displaying different stages of decay. For protection of old urban trees, it is crucial to develop monitoring methods so that tree care professionals could better analyse the rate of decay progression towards the sapwood and separate those trees with decreasing amounts of sound wood from those with decay that is restricted to the heartwood area.

Tropical dryland agroforestry on clay soils: : Analysis of systems based on Acacia senegal in the Blue Nile region, Sudan

Acacia senegal, the gum arabic producing tree, is the most important component in traditional dryland agroforestry systems in the Blue Nile region, Sudan. The aim of the present study was to provide new knowledge on the potential use of A. senegal in dryland agroforestry systems on clay soils, as well as information on tree/crop interaction, and on silvicultural and management tools, with consideration on system productivity, nutrient cycling and sustainability. Moreover, the aim was also to clarify the intra-specific variation in the performance of A. senegal and, specifically, the adaptation of trees of different origin to the clay soils of the Blue Nile region. In agroforestry systems established at the beginning of the study, tree and crop growth, water use, gum and crop yields, nutrient cycling and system performance were investigated for a period of four years (1999 to 2002). Trees were grown at 5 x 5 m and 10 x 10 m spacing alone or in mixture with sorghum or sesame; crops were also grown in sole culture. The symbiotic biological N2 fixation by A. senegal was estimated using the 15N natural abundance (δ15N) procedure in eight provenances collected from different environments and soil types of the gum arabic belt and grown in clay soil in the Blue Nile region. Balanites aegyptiaca (a non-legume) was used as a non-N-fixing reference tree species, so as to allow 15N-based estimates of the proportion of the nitrogen in trees derived from the atmosphere. In the planted acacia trees, measurements were made on shoot growth, water-use efficiency (as assessed by the δ13C method) and (starting from the third year) gum production. Carbon isotope ratios were obtained from the leaves and branch wood samples. The agroforestry system design caused no statistically significant variation in water use, but the variation was highly significant between years, and the highest water use occurred in the years with high rainfall. No statistically significant differences were found in sorghum or sesame yields when intercropping and sole crop systems were compared (yield averages were 1.54 and 1.54 ha-1 for sorghum and 0.36 and 0.42 t ha-1 for sesame in the intercropped and mono-crop plots, respectively). Thus, at an early stage of agroforestry system management, A. senegal had no detrimental effect on crop yield, but the pattern of resource capture by trees and crops may change as the system matures. Intercropping resulted in taller trees and larger basal and crown diameters as compared to the development of sole trees. It also resulted in a higher land equivalent ratio. When gum yields were analysed it was found that a significant positive relationship existed between the second gum picking and the total gum yield. The second gum picking seems to be a decisive factor in gum production and could be used as an indicator for the total gum yield in a particular year. In trees, the concentrations of N and P were higher in leaves and roots, whereas the levels of K were higher in stems, branches and roots. Soil organic matter, N, P and K contents were highest in the upper soil stratum. There was some indication that the P content slightly increased in the topsoil as the agroforestry plantations aged. At a stocking of 400 trees ha-1 (5 x 5 m spacing), A. senegal accumulated in the biomass a total of 18, 1.21, 7.8 and 972 kg ha-1of N, P, K and OC, respectively. Trees contributed ca. 217 and 1500 kg ha-1 of K and OC, respectively, to the top 25-cm of soil over the first four years of intercropping. Acacia provenances of clay plain origin showed considerable variation in seed weight. They also had the lowest average seed weight as compared to the sandy soil (western) provenances. At the experimental site in the clay soil region, the clay provenances were distinctly superior to the sand provenances in all traits studied but especially in basal diameter and crown width, thus reflecting their adaptation to the environment. Values of δ13C, indicating water use efficiency, were higher in the sand soil group as compared to the clay one, both in leaves and in branch wood. This suggests that the sand provenances (with an average value of -28.07 ) displayed conservative water use and high drought tolerance. Of the clay provenances, the local one (Bout) displayed a highly negative (-29.31 ) value, which indicates less conservative water use that resulted in high productivity at this particular clay-soil site. Water use thus appeared to correspond to the environmental conditions prevailing at the original locations for these provenances. Results suggest that A. senegal provenances from the clay part of the gum belt are adapted for a faster growth rate and higher biomass and gum productivity as compared to provenances from sand regions. A strong negative relationship was found between the per-tree gum yield and water use efficiency, as indicated by δ13C. The differences in water use and gum production were greater among provenance groups than within them, suggesting that selection among rather than within provenances would result in distinct genetic gain in gum yield. The relative δ15N values ( ) were higher in B. aegyptiaca than in the N2-fixing acacia provenances. The amount of Ndfa increased significantly with age in all provenances, indicating that A. senegal is a potentially efficient nitrogen fixer and has an important role in t agroforestry development. The total above-ground contribution of fixed N to foliage growth in 4-year-old A. senegal trees was highest in the Rahad sand-soil provenance (46.7 kg N ha-1) and lowest in the Mazmoom clay-soil provenance (28.7 kg N ha-1). This study represents the first use of the δ15N method for estimating the N input by A. senegal in the gum belt of Sudan. Key words: Acacia senegal, agroforestry, clay plain, δ13C, δ15N, gum arabic, nutrient cycling, Ndfa, Sorghum bicolor, Sesamum indicum

Impact of a biological control agent, Chiasmia assimilis, on prickly acacia (Acacia nilotica ssp. indica) seedlings

A leaf-feeding geometrid, Chiasmia assimilis (Warren), was introduced into northern Queensland from South Africa in 2002 as a biological control agent for the invasive woody weed, prickly acacia, Acacia nilotica subsp. indica (Bentham) Brenan. The insect established in infestations in coastal areas between the townships of Ayr and Bowen where the larvae periodically cause extensive defoliation at some localities during summer and autumn. The impact of this herbivory on a number of plant parameters, including shoot length, basal stem diameter, root length, number of leaves, number of branches, and above and below ground biomass was investigated at one coastal site through an insect exclusion trial using potted seedlings and regular spray applications of a systemic insecticide to exclude the biological control agent. Half the seedlings, both sprayed and unsprayed, were placed beneath the prickly acacia canopy, the other half were placed in full sunlight. Larvae of C. assimilis were found on unsprayed seedlings in both situations. The effects of herbivory, however, were significant only for seedlings grown beneath the canopy. At the end of the five-month trial period, shoot length of these seedlings was reduced by 30%, basal stem diameter by 44%, root length by 15%, number of leaves by 97%, above ground biomass by 87%, and below ground biomass by 77% when compared to sprayed seedlings. Implications are that the insect, where established, may reduce seedling growth beneath existing canopies and in turn may help limit the formation of dense infestations. Crown Copyright (C) 2012 Published by Elsevier Inc. All rights reserved.

Bovine cysticercosis-Development of a real-time PCR to enhance classification of suspect cysts identified at meat inspection

Laboratory confirmation methods are important in bovine cysticerosis diagnosis as other pathologies can result in morphologically similar lesions resulting in false identifications. We developed a probe-based real-time PCR assay to identify Taenia saginata in suspect cysts encountered at meat inspection and compared its use with the traditional method of identification, histology, as well as a published nested PCR. The assay simultaneously detects T. saginata DNA and a bovine internal control using the cytochrome c oxidase subunit 1 gene of each species and shows specificity against parasites causing lesions morphologically similar to those of T. saginata. The assay was sufficiently sensitive to detect 1 fg (Ct 35.09 +/- 0.95) of target DNA using serially-diluted plasmid DNA in reactions spiked with bovine DNA as well as in all viable and caseated positive control cysts. A loss in PCR sensitivity was observed with increasing cyst degeneration as seen in other molecular methods. In comparison to histology, the assay offered greater sensitivity and accuracy with 10/19 (53%) T. saginata positives detected by real-time PCR and none by histology. When the results were compared with the reference PCR, the assay was less sensitive but offered advantages of faster turnaround times and reduced contamination risk. Estimates of the assay's repeatability and reproducibility showed the assay is highly reliable with reliability coefficients greater than 0.94. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.

Patterns of seed bank and size asymmetry of plant growth across varying sites in the invasive Lantana camara L. (Verbenaceae)

Lantana camara L. (Verbenaceae) is a weed of great significance in Australia and worldwide, but little is known about connections among components of its life history. We document over a 3-year period, the links between L. camara seed-bank dynamics and its above-ground growth, including size asymmetry in four land-use types (a farm, a hoop pine plantation and two open eucalypt forests) invaded by the weed near Brisbane, Queensland Australia. Seed-bank populations varied appreciably across sites and in response to rainfall and control measures, and they were higher (~1,000 seeds/m2) when annual rainfall was 15-30 % below the long-term yearly average. Fire reduced seed-bank populations but not the proportion germinating (6-8 %). Nearly a quarter of fresh seeds remain germinable after 3 years of soil burial. For small seedlings (<10 cm high), the expected trade-offs in two life-history traits-survival and growth-did not apply; rather the observed positive association between these two traits, coupled with a persistent seed-bank population could contribute to the invasiveness of the plant. Relationships between absolute growth rate and initial plant size (crown volume) were positively linear, suggesting that most populations are still at varying stages of the exponential phase of the sigmoid growth; this trend also suggests that at most sites and despite increasing stand density and limiting environmental resources of light and soil moisture, lantana growth is inversely size asymmetric. From the observed changes in measures of plant size inequality, asymmetric competition appeared limited in all the infestations surveyed. © 2013 Crown Copyright as represented by: Department of Agriculture, Fisheries and Forestry, Australia.

Fusarium graminearum and Fusarium pseudograminearum caused the 2010 head blight epidemics in Australia

Wheat crops in southeast Queensland (Qld) and northern New South Wales (NSW) were infected with fusarium head blight (FHB)-like symptoms during the 201011 wheat growing season. Wheat crops in this region were surveyed at soft dough or early maturity stage to determine the distribution, severity, aetiology and toxigenicity of FHB. FHB was widespread on bread wheat and durum, and Fusarium graminearum and/or F.pseudograminearum were diagnosed from 42 of the 44 sites using species-specific PCR primers directly on spikelets or from monoconidial cultures obtained from spikelets. Stem base browning due to crown rot (CR) was also evident in some samples from both states. The overall FHB and CR severity was higher for NSW than Qld. Deoxynivalenol (DON) concentration of immature grains was more than 1 mg kg-1 in samples from 11 Qld and 14 NSW sites, but only 13 of 498 mature grain samples sourced from the affected areas had more than 1 mg kg-1 DON. DON concentration in straw also exceeded 1 mg kg-1 in eight Qld and all but one NSW sites but this was not linked to DON concentration of immature grains. The proportion of spikelets with positive diagnosis for F.graminearum and/or F.pseudograminearum and weather-related factors influenced DON levels in immature grains. The average monthly rainfall for AugustNovember during crop anthesis and maturation exceeded the long-term monthly average by 10150%. Weather played a critical role in FHB epidemics for Qld sites but this was not apparent for the NSW sites, as weather was generally favourable at all sites.

Impact of low temperature storage on active and storage forms of folate in choy sum (Brassica rapa subsp parachinensis)

Choy sum (Brassica rapa subsp. parachinensis) is a dark green leafy vegetable that contains high folate (vitamin B9) levels comparable to spinach. Folate is essential for the maintenance of human health and is obtained solely through dietary means. Analysis of the edible portion of choy sum by both microbiological assay and LC-MS/MS indicated that total folate activity remained significantly unchanged over 3 weeks storage at 4 degrees C. Inedible fractions consisted primarily of outer leaves, which showed signs of rotting after 14d, and a combination of rotting and yellowing after 21 d, contributing to 20% and 40% of product removal, respectively. Following deconjugation of the folate present in choy sum to monoglutamate and diglutamate derivatives, the principal forms (vitamers) of folate detected in choy sum were 5-methyltetrahydrofolate and 5-formyl tetrahydrofolate, followed by tetrahydrofolate (THF), 5,10-methenyl-THF, and 10-formyl folic acid. During storage, a significant decline in 5-formyl-THF was observed, with a slight but not significant increase in the combined 5-methyl-THF derivatives. The decline in 5-formyl-THF in relation to the other folate vitamers present may indicate that 5-formyl-THF is being utilised as a folate storage reserve, being interconverted to more metabolically active forms of folate, such as 5-methyl-THF. Although folate vitamer profile changed over the storage period, total folate activity did not significantly change. From a human nutritional perspective this is important, as while particular folate vitamers (e.g. 5-methyl-THF) are necessary for maintaining vital aspects of plant metabolism, it is less important to the human diet, as humans can absorb and interconvert multiple forms of folate. The current trial indicates that it is possible to store choy sum for up to 3 weeks at 4 degrees C without significantly affecting total folate concentration of the edible portion. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.

Effects of seasonal variability on FT-NIR prediction of dry matter content for whole Hass avocado fruit

Fourier Transform (FT)-near infra-red spectroscopy (NIRS) was investigated as a non-invasive technique for estimating percentage (%) dry matter of whole intact 'Hass' avocado fruit. Partial least squares (PLS) calibration models were developed from the diffuse reflectance spectra to predict % dry matter, taking into account effects of seasonal variation. It is found that seasonal variability has a significant effect on model predictive performance for dry matter in avocados. The robustness of the calibration model, which in general limits the application for the technique, was found to increase across years (seasons) when more seasonal variability was included in the calibration set. The R-v(2) and RMSEP for the single season prediction models predicting on an independent season ranged from 0.09 to 0.61 and 2.63 to 5.00, respectively, while for the two season models predicting on the third independent season, they ranged from 0.34 to 0.79 and 2.18 to 2.50, respectively. The bias for single season models predicting an independent season was as high as 4.429 but <= 1.417 for the two season combined models. The calibration model encompassing fruit from three consecutive years yielded predictive statistics of R-v(2) = 0.89, RMSEP = 1.43% dry matter with a bias of -0.021 in the range 16.1-39.7% dry matter for the validation population encompassing independent fruit from the three consecutive years. Relevant spectral information for all calibration models was obtained primarily from oil, carbohydrate and water absorbance bands clustered in the 890-980, 1005-1050, 1330-1380 and 1700-1790 nm regions. These results indicate the potential of FT-NIRS, in diffuse reflectance mode, to non-invasively predict the % dry matter of whole 'Hass' avocado fruit and the importance of the development of a calibration model that incorporates seasonal variation. Crown Copyright (c) 2012 Published by Elsevier B.V. All rights reserved.

Regulation of strawberry growth and development

Strawberries (Fragaria sp.) are adapted to diverse environmental conditions from the tropics to about 70ºN, so different responses to environmental conditions can be found. Most genotypes of garden strawberry (F. x ananassa Duch.) and woodland strawberry (F. vesca L.) are short-day (SD) plants that are induced to flowering by photoperiods under a critical limit, but also various photoperiod x temperature interactions can be found. In addition, continuously flowering everbearing (EB) genotypes are found. In addition to flowering, axillary bud differentiation in strawberry is regulated by photoperiod. In SD conditions, axillary buds differentiate to rosette-like structures called "branch crowns", whereas in long-day conditions (LD) they form runners, branches with 2 long internodes followed by a daughter plant (leaf rosette). The number of crown branches determines the yield of the plant, since inflorescences are formed from the apical meristems of the crown. Although axillary bud differentiation is an important developmental process in strawberries, its environmental and hormonal regulation has not been characterized in detail. Moreover, the genetic mechanisms underlying axillary bud differentiation and regulation of flowering time in these species are almost completely unresolved. These topics have been studied in this thesis in order to enhance strawberry research, cultivation and breeding. The results showed that 8-12 SD cycles suppressed runner initiation from the axillary buds of the garden strawberry cv. Korona with the concomitant induction of crown branching, and 3 weeks of SD was sufficient for the induction of flowering in the main crown. Furthermore, a second SD treatment given a few weeks after the first SD period can be used to induce flowering in the primary branch crowns and to induce the formation of secondary branches. Thus, artificial SD treatments effectively stimulate crown branching, providing one means for the increase of cropping (yield) potential in strawberry. It was also shown by growth regulation applications, quantitave hormone analysis and gene expression analysis that gibberellin (GA) is one of the key signals involved in the photoperiod control of shoot differentiation. The results indicate that photoperiod controls GA activity specifically in axillary buds, thereby determining bud fate. It was further shown that chemical control of GA biosynthesis by prohexadione-calcium can be utilized to prevent excessive runner formation and induce crown branching in strawberry fields. Moreover, ProCa increased berry yield up to 50%, showing that it is an easier and more applicable alternative to artificial SD treatments for controlling strawberry crown development and yield. Finally, flowering gene pathways in Fragaria were explored by searching for homologs of 118 Arabidopsis thaliana flowering-time genes. In total, 66 gene homologs were identified, and they distributed to all known flowering pathways, suggesting the presence of these pathways also in strawberry. Expression analysis of selected genes revealed that the mRNA of putative floral identity gene APETALA1 accumulated in the shoot apex of the EB genotype after the induction of flowering, whereas it was absent in vegetative SD genotype, indicating the usefulness of this gene product as the marker of floral initiation. The present data enables the further exploration of strawberry flowering pathways with genetic transformation, gene mapping and transcriptomics methods.