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New shoot growth of Carpinus betulus `fastigiata' was treated with stockplant etiolation and stem banding treatments and sampled for anatomical study at intervals over a 16-week period of greening following etiolation. Shading effects on the anatomy of the stem were also investigated. Numerous anatomical changes were noted with stem age and stockplant treatment. Among these were etiolation effects on the lignification of the secondary xylem, thickness of the periderm, and an increase in the percentage of sclereid-free gaps in the perivascular sclerenchyma, Stem banding increased the widths of the cortex and pith. Concomitant propagation studies revealed significant etiolation, shading, and banding effects on rooting percentages and root numbers. Using multiple linear regression methods rooting capacity was modelled best by linear combinations of the widths of the pith, non-lignified secondary xylem, cortical parenchyma and periderm, as well as the percentage of gaps in the sclerenchymatic sheath remaining non-sclerified. It is proposed that the development of sclereids in potential rooting sites reduces rooting potential. The exclusion of light during initial shoot development retards sclereid development by up to 3 months following treatment, which correlates well with observed increases in the rooting potential of etiolated and/or banded stems.
Three experiments were undertaken to examine the effect of stockplant etiolation, shading, and stem banding, prior to cutting propagation, on the auxin dose-response of rooting in stem cuttings of Carpinus betulus `fastigiata'. A 2 × 2 factorial of etiolation and banding utilized stockplants forced in a greenhouse, etiolated for 1 week and banded with Velcro™ for 1 month. In a separate study shading was applied up the time of harvesting cuttings. IBA was applied to cuttings as an aqueous ethanol quick dip in concentrations ranging from 0 to 80 mM. Rooting percentage and number were best described, up to a peak response, by a linear function proportional to the logarithm of applied IBA. The inhibition of rooting by supra-optimal IBA was directly proportional to IBA concentration. Cuttings prepared from shoots which had been etiolated or banded rooted better at low IBA and at their respective optimal IBA levels. Cuttings from shoots receiving both etiolation and banding yielded higher rooting percentages and more roots per rooted cutting on average. Etiolation and banding served to increase both initial and maximum rooting capacities, and to reduce the sensitivity of cuttings to supraoptimal auxin-induced inhibition of adventitious root initiation. The auxin dose-response interacted with shading to yield the best rooting at 95% shade and 3.7 mM IBA.
Four techniques for compaction amelioration were studied: 1) Vertical drainage panels; 2) vertical gravel-filled sump drains; 3) soil trenches filled with sandy loam; and 4) peat amended back fill. The control was backfilled with existing soil on the site. Vertical drainage mats and vertical gravel-filled sump drains were shown to increase O2% in surrounding soil; however, all O2 levels regardless of treatment were above what is considered limiting. Shoot and root growth of Pyrus calleryana `Redspire' was greatest for treatments that alleviated mechanical impedance (soil trenches and amended back fill) and least for treatments that did not (controls and vertical drains). Vertical drainage mats which alleviated mechanical impedance to a lesser degree showed intermediate growth.
The development of a rapid, accurate, yet nondestructive technique for expressing whole-tree leaf area would be extremely useful in studying various growth phenomena in trees. The objective of this research was to evaluate the accuracy of an image analysis process adapted for estimating the leaf surface area of four broad-leafed tree species (Amelanchier L. `Robin Hill Pink', Tilia americana L. `Redmond', Sophora japonica L. `Regent', Fraxinus americana L. `Autumn Purple' and Fraxinus pennsylvanica Marsh.). Video images of photographs taken of each tree canopy were quantified by an image analyzer into unitless surface area values or silhouette areas. The relationship between estimated leaf area as calculated from silhouette area and actual leaf area of these trees as determined by a leaf area meter was highly correlated. Use of this technique would enable a researcher, simply from serial photographs of the canopy, to retroactively estimate leaf or canopy area at crucial interim periods.
An investigation was undertaken to determine whether various light reduction and shoot banding treatments could increase rooting on stem cuttings of Lindera benzoin [(L.) Blume] (northern spicebush), a difficult-to-root woody plant. Stock plants were grown under one of three light conditions (light, shade, or etiolation). Emerging shoots received either no treatment or a banding treatment that involved adhering a hook-and-loop fastener coated with varying concentrations of indole-3-butyric acid (IBA) around the shoot base to create a localized etiolated zone before taking cuttings. Data on rooting percentage and number of roots per cutting were analyzed using logistic and Quasi-Poisson regression, respectively. Etiolated cuttings treated with a band without IBA had the highest rooting probability and number of roots; however, etiolated cuttings across all banding treatments had similarly successful results. Additionally, there were several significant differences in rooting probabilities and root numbers between banding treatments within the shade- and light-grown groups. This research evaluated asexual propagation approaches for use with northern spicebush and provides a framework for the adoption and development of this taxon as a nursery crop.
A tissue culture system was developed to clonally propagate a series of hybrid white oaks (Quercus L.) at the plant breeding program of the Urban Horticulture Institute (UHI), Cornell University. From 2014 through 2018, 34 genotypes and 1966 individual explants of UHI hybrid white oaks were trialed to determine their capacity to establish, multiply, and root in a tissue culture environment. UHI hybrid oak genotypes were selected based on their known tolerance to stresses common in the urban environment (drought, alkaline soils, pests, and diseases) and their ornamental qualities. Individual genotype was the single largest factor affecting successful establishment, multiplication, stabilization, and rooting of hybrid oaks in vitro. Thirteen clones of hybrid oaks were identified as having the capacity to stabilize and grow continuously in the multiplication phase. Multiplication efficiency rates were dependent on individual genotype. Stabilized genotypes showed the capacity to be re-established during successive years. The tissue culture process was simplified and refined to make the protocols less labor intensive for laboratory technicians using these methods. This study presents a preliminary and promising method for the clonal propagation of oak species and provides a path for cultivar development for plants belonging to the genus Quercus.
Growth and physiological characteristics were evaluated in autografted and reciprocally grafted plants of Prunus avium L. ×pseudocerasus Lindl. `Colt' and Prunus cerasus L. `Meteor'. Containerized plants were grown for 150 days in a greenhouse under either well-watered or water-stressed conditions. Both the scion and rootstock influenced growth (relative growth rate, R̄), morphological [leaf area : root surface area (LARSA) and specific leaf area (SLA)], and physiological (mean net assimilation rate, Ē) characteristics of grafted plants. Regardless of the watering regime, plants with `Meteor' scions and `Colt' rootstocks maintained higher R̄ than plants with `Colt' scions and `Meteor' rootstocks. This enhanced growth occurred as a result of higher Ē. Measurements on water-stressed plants also showed that the graft combination of `Meteor' on `Colt' had the lowest LARSA, while the reciprocal combination of `Colt' on `Meteor' had the highest. Differences in LARSA among water-stressed plants primarily reflected changes in SLA, as influenced by both rootstock and scion, and not in partitioning of dry weight between these organs.
Two experiments were conducted to determine the relative resistance of 33 selected cultivars of English ivy (Hedera helix L.) to soil- and shoot-applied NaCl. In the soil-applied NaCl experiment, ramets of the 33 cultivars were irrigated with a fertilizer + 0.25-N NaCl solution for 55 days. `Harrison', `Hibernica', `Thorndale', Wilson', and Woerner' exhibited the least amount of visible shoot damage. Dry weights of all cultivars were much lower in the salt treatment. In the shoot-applied NaCl experiment, plants were sprayed daily with a 0.25-n NaCl solution for 48 days. The young leaves and stems of all cultivars were severely injured by the salt spray, while the mature leaves and stems and the dormant buds were only slightly injured. Reduction in dry weight varied between cultivars. Two subsequent experiments focused on resistance to soil-applied NaCl. Ramets of the NaCl-resistant `Harrison', `Hibernica', and `Thorndale', and the NaCl-sensitive `Baltica', `Cathedral Wall', and Wingertsberg' were irrigated with a fertilizer + 0.25-N NaCl solution for 48 days. Whole-plant Cl content for all six cultivars was in the range of 30,000 ppm. Ramets of `Thorndale' and `Cathedral Wall' were irrigated with a fertilizer + 0.25-N NaCl solution for 30 days with replicate plants harvested at S-day intervals. `Cathedral Wall' accumulated more Cl at a faster rate than `Thorndale'. Mean whole-plant Cl concentration peaked at 97,000 ppm for `Cathedral Wall' and 40,000 ppm for `Thorndale'. Salt resistance may be partly based on slower uptake of Cl.
Tissue osmotic potential(Ψπ) and solute constituents were evaluated in leaves and roots of well-watered and water-stressed Prunus avium L. × pseudocerasus Lindl. `Colt' and Prunus cerasus L. `Meteor'. Osmotic potential at full turgorΨπ,sat decreased in response to water stress for leaves and roots of both cultivars. For `Colt', a cultivar with an indeterminate growth habit,Ψπ,sat decreased by 0.56 MPa and 0.38 MPa for terminal expanding leaves and older expanded leaves, respectively. For `Meteor', a cultivar with a determinate growth habit,Ψπ,sat decreased by ≈0.47 MPa in both terminal and older leaves. RootΨπ,sat was alike for both cultivars and showed a similar decrease of 0.20 MPa in response to water stress. Roots had considerably higherΨπ,sat than did leaves in both cultivars, irrespective of irrigation treatment. Soluble carbohydrates and potassium (K+) were the major solute constituents in both cultivars. Of the soluble carbohydrates, sorbitol was found in the greatest concentration and accounted for the bulk of water stress-induced solute accumulation in both cultivars. Regardless of the irrigation treatment, mature leaves of `Meteor' consistently had lowerΨπ,sat (typically 0.4 MPa) than `Colt'. This variation in Ψπ,sat between Prunus cultivars suggests the potential for selection of cultivars with low Ψπ,sat and possibly superior drought resistance.
Four each of landscape-sized Fraxinus Pennsylvania Marsh. (green ash), Quercus coccinea Muenchh. (scarlet oak), Corylus colurna L. (Turkish hazelnut) and Syringa reticulata Hara `Ivory Silk' (tree lilac) were established on a rhizotron in Ithaca, New York, and root and shoot growth characteristics were observed throughout 1992. Root growth did not begin on any species before bud break. Green ash, scarlet oak and Turkish hazelnut exhibited recurrent shoot growth. Most root growth occurred during periods of bud rest, although no marked antagonism between shoot and root growth was evident. Green ash root growth was synchronous with shoot growth. The root harvest zone of green ash and tree lilac contained higher root length densities, and roots contained within appeared less suberized than that of Turkish hazelnut or scarlet oak. Root spread: crown spread ratio was greatest for Turkish hazelnut. Little root growth occurred on any species after fall leaf drop or when soil temperatures were below 5C. Implications for transplanting are discussed.