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The timing of flowering is central to plant life‐history as it initiates sexual reproduction, thus controlling plant interaction with pollinators and climate factors. A fundamental question is: what are the drivers of flowering time strategy in a species?We assembled mean flowering times for the indigenous dicotyledonous flora of New Zealand (n = 1303 species, including 177 tree species) and used phylogenetic models to determine how climate, plant traits, and evolutionary history (phylogeny) controlled interspecific variation in flowering times across an island flora.Across all species, on average, flowering was 19 days earlier in abiotically pollinated species relative to biotically pollinated species, 23 days earlier in woody species, relative to herbaceous species, 45 days earlier in species with fleshy‐fruits, relative to species with dry fruits and 31 days earlier in gender dimorphic species, relative to cosexual species. Species in warmer and drier climates flowered earlier than those growing under cool, moist climates.When all factors were considered together, the strongest influence on flowering time was sexual system: gender dimorphic species flowered earlier than cosexuals, even after accounting for other factors.Synthesis. We propose that these differences in flowering time arise because of sexual selection for early male flowering and sexual conflict between male and female individuals. As sexual selection and conflict may be stronger in gender dimorphic species than in cosexual species, our study suggests that plant sexual system is an important force structuring the phenology of plant communities, with potential consequences for ecological interactions and ecosystem processes. [ABSTRACT FROM AUTHOR]

New methodologies have enabled viable sap yields from juvenile sugar maple trees. To further improve yields, a better understanding of sap exudation is required. To achieve this, the anatomy of the xylem must first be fully characterised. We examine juvenile maple saplings using light optical microscopy (LOM) and scanning electron microscopy (SEM), looking at sections cut along differing orientations as well as macerations. From this we measure various cell parameters. We find diameter and length of vessel elements to be 28 ± 8 μm and 200 ± 50 μm, for fibre cells 8 ± 3 μm and 400 ± 100 μm, and for ray parenchyma cells 8 ± 2 μm and 50 ± 20 μm. We also examine pitting present on different cell types. On vessel elements we observe elliptical bordered pits connecting to other vessel elements (with major axis of 2.1 ± 0.7 μm and minor 1.3 ± 0.3 μm) and pits connecting to ray parenchyma (with major axis of 4 ± 2 μm and minor 2.0 ± 0.7 μm). We observe two distinct pit sizes on fibres with circular pits 0.7 ± 0.2 μm in diameter and ellipsoidal pits 1.6 ± 0.4 μm by 1.0 ± 0.3 μm. We do not observe distinct pitting patterns on different fibre types. The various cell and pit measurements obtained generally agree with the limited data available for mature trees, with the exception of vessel element and fibre length, both of which were significantly smaller than reported values. [ABSTRACT FROM AUTHOR]

We tested whether selection of ryegrass for reduced root hair length and density would reduce root competition on white clover for phosphate (P). A Rhizosheath Selection Tool was used to select two ryegrass populations with contrasting root hair traits. These were grown at five soil P levels in a glasshouse experiment and rhizosheath trait selection had no effect on growth or shoot P concentrations. The ryegrass populations were also grown with white clover in soils with Olsen P12 or 19 mg L−1. In the Olsen P12 soil, clover grown with the smaller rhizosheath ryegrass had significantly heavier shoots and contained more P than clover grown with the larger rhizosheath ryegrass. In the Olsen P19 soil differences in ryegrass rhizosheath had no effect on clover growth. The results showed that under the experimental conditions, grass-clover competition for soil P could be modified by the rhizosheath traits of ryegrass. [ABSTRACT FROM AUTHOR]

Consumer acceptance of fruit is determined by size, flavour and ripeness. In this study we investigated how altering the carbohydrate supply to Actinidia chinensis var. chinensis 'Zesy002' kiwifruit altered the balance between growth and accumulation of metabolites. Canes were phloem girdled and fruit thinned to a leaf-to-fruit ratio (L:F) of either 2 (Low carbohydrate) or 6 (High carbohydrate) at either 38 (Early) or 86 (Late) days after anthesis (DAA) and compared with ungirdled control canes with a L:F of 3. Fruit growth, metabolite accumulation, cytokinin concentrations and maturation were monitored and the sensory attributes of ripe fruit were assessed. The final weight of Early-High and Late-High carbohydrate fruit was 38% and 16% greater compared with control fruit. High carbohydrate fruit had increased starch, soluble sugar and cytokinin concentrations and fruit began to mature earlier and those with a Low carbohydrate had decreased concentrations and matured later compared with control fruit. Control fruit were described by consumers as more acidic and under-ripe compared with those from Early-High carbohydrate canes, but as sweeter than those from Low carbohydrate canes. This study showed that carbohydrate supply can have a major impact on the growth, sugar accumulation and maturity of 'Zesy002' fruit sinks. [ABSTRACT FROM AUTHOR]

Abstract A high-throughput assay was developed to screen Phytophthora species for fungicide sensitivity using optical density measurements for unbiased, automated measurement of mycelial growth. The efficacy of the optical density assay (OD) to measure phosphite sensitivity in Phytophthora species was compared to two widely used methods, radial growth (RG) and dry weight (DW) assays. Three isolates of each of Phytophthora cinnamomi , P. multivora and P. pluvialis , with known phosphite exposure and three isolates of each species with no prior phosphite exposure, were screened for phosphite sensitivity using the three assays. Mycelial growth measurements were taken after culturing for 6, 14 and 15 days for the OD, DW and RG assays respectively. Mycelial growth inhibition at 15, 80, 200 and 500 μg/mL phosphite relative to growth on control media was used to determine effective concentration values for 50% growth reduction (EC50). The species varied in their tolerance to phosphite with P. cinnamomi being the least sensitive followed by P. multivora and P. pluvialis. No significant differences in tolerance were found between isolates within the same species using any method. The OD assay produced comparable EC50 values to the RG and DW assays. The growth of the three species was more sensitive to phosphite in the DW than the RG and OD assays, however limited sample throughput and greater variation in measuring small amounts of mycelia in the dry weight assessment increase variability and limits throughput. The OD assay offers a fast method to enable an inventory of chemical resistance and is particularly advantageous for slow growing species as it requires less time and offers greater throughput than existing RG and DW methods. Highlights • A high-throughput optical density (OD) assay was developed to screen Phytophthora species for fungicide sensitivity. • Efficacy of the OD assay to measure phosphite sensitivity in Phytophthora species was compared to two widely used methods. • Phytophthora cinnamomi was the least sensitive to phosphite followed by P. multivora and P. pluvialis. • The OD assay produced comparable EC50 values to the radial growth (RG) and dry weight (DW) assays. • The OD assay requires less time and resources and offers greater throughput than existing RG and DW methods. [ABSTRACT FROM AUTHOR]

Sugar maples (Acer saccharum Marshall) develop elevated stem pressures in springtime through the compression and expansion of gas bubbles present within xylem fibres. The stability of this gas within the fibres is hypothesised to be due to the elevated sugar concentration of maple sap and the presence of an osmotic barrier between fibres and vessels. Without this osmotic barrier gas bubbles are predicted to dissolve rapidly. In this work we investigated the existence of this osmotic barrier. We quantified the fraction of the xylem occupied by gas-filled fibres using synchrotron based microCT. After imaging fresh stem segments we perfused them with either a 2% sucrose solution or water, imaging again following perfusion. In this way we directly observed how total gas present in the fibres changed when an osmotic pressure difference should be present, with the 2% sucrose solution, and when it is absent, with the water. Following a first round of perfusion we perfused stem segments with the other perfusate, repeating this multiple times to observe how switching perfusates affected gas-filled fibres. We found that perfusing stem segments with water resulted in a significant reduction in the xylem fibre gas, but perfusing stem segments with a sucrose solution did not significantly reduce the gas in the fibres. These results support the hypothesis that an osmotic barrier exists between fibres and vessels., (© The Author(s) 2024. Published by Oxford University Press.)