In previous studies, baldcypress [Taxodium distichum (L.) Rich.] clones were selected for tolerance to high pH soils, drought and salt exposures, and ornamental characteristics. The objective of the current research was to determine the treatment combinations that yielded optimum root quantity (percentage) and rooted cutting quality (root number, length, dry mass, and shoot dry mass) on vegetative cuttings for a representative clone. Cuttings were treated with factorial combinations of one of four potassium salt of indole-3-butyric acid (K-IBA) concentrations [0, 5,000, 10,000, 15,000 mgÁL -1 (0, 20.72, 41.44, 62.16 mM, respectively)], wounded or not wounded (1-cm long basal incision), and rooted in one of three substrates (100% perlite, 100% peatmoss, or 50% perlite:50% peatmoss). Data indicated a tradeoff between potential rooting quantity and root quality measurements in response to different substrates. Although rooting percentages were affected by substrates only at P # 0.10 (53% in 100% perlite versus 36% in 100% peatmoss), there were highly significant (P # 0.0001) differences in rooted cutting potential among substrates as measured by the percentage of cuttings with basal callus. Cuttings placed in 100% perlite callused at 85%, whereas cuttings placed in 100% peatmoss callused at ' '53%. The 100% peatmoss treatment, however, yielded cuttings with significantly greater root quality for all measurements, except root number per cutting. Wounding cuttings proved to have deleterious effects on root quality measurements. Total root length was ' '14.5 cm for non-wounded cuttings and ' '10.8 cm for wounded cuttings. Increasing K-IBA concentrations did not significantly (P # 0.05) affect rooting or callus percentages but did significantly affect root dry mass, total root length, and average root length per cutting. Total root length increased from 10.8 cm at 0 mgÁL -1 K-IBA to 16 cm at 15,000 mgÁL -1 K-IBA. Mean root number per cutting increased from ' '1.6 with wounded cuttings planted in 100% peatmoss to ' '3.1 with non-wounded cuttings planted in 100% perlite. Results suggested that high-quality softwood baldcypress cuttings should not be wounded, should be treated with 15,000 mgÁL -1 K-IBA, and grown in a substrate with intermediate water-holding capacity to achieve an acceptable balance between rooting percentage and rooted cutting quality objectives.
With container-grown trees offered to the public in an increasing array of sizes, it is important to determine the effects of different sizes of container stock on transplant establishment. Clonal replicates of Vitex agnus-castus, Acer rubrum var. drummondii, and Taxodium distichum grown under common nursery conditions in five container sizes, 3.5, 11.7, 23.3, 97.8, or 175.0 L (#1, #3, #7, #25, or #45, respectively), were transplanted to a sandy clay loam field. Physiological stress was measured using xylem water potential and photosynthetic gas exchange rates. Height, trunk diameter, and canopy spread were monitored post-transplant for three growing seasons and root growth was sampled for the first two growing seasons. Trees of all three species from smaller-sized containers, 23.3 L (#7) or less, exhibited reduced transplant shock, decreased establishment time and increased growth rates in comparison to larger-sized containers, apart from increased mortality in 3.5 L (#1) A. rubrum and slower growth in 3.5 L (#1) T. distichum compared to those transplanted from 11.7 L (#3) or 23.3 L (#7) containers Reduced stress levels and increased growth rates corresponded in timing with greater change in root extension of smaller container-grown trees. At the end of three growing seasons, no statistical differences in height or trunk diameter were present for V. agnus-castus container sizes. With a modest wait, consumers may find that smaller container-grown trees will overcome transplant stress more quickly and exhibit growth rates that surpass those of larger container-grown trees. Index words: Acer rubrum, Taxodium distichum, Vitex agnus-castus, container-grown trees, transplant shock, transplant establishment, photosynthesis, transpiration, water stress. Species used in this study: Chaste tree (Vitex agnus-castus L. [an unnamed white flowering clone]); red maple (Acer rubrum L. var. dummondii [Hook. & Arn. ex Nutt.] Sarg. ‘Maroon'); bald cypress (Taxodium distichum (L.) Rich. [test clone TX8DD38]).
Two-year-old, field-grown golden kiwifruit (Actinidia chinensis) and fuzzy kiwifruit (Actinidia deliciosa) plants were evaluated for injury following an early freeze event of −4.1 °C on 14 Nov. 2018 in Burleson County, TX. Plant material included seven cultivars: one seed-propagated [Sungold™ (ZESY002)] and three cutting-propagated golden kiwifruit (AU Golden Dragon, AU Golden Sunshine, CK03), and one seed-propagated (Hayward) and two cutting-propagated fuzzy kiwifruit (AU Authur and AU Fitzgerald). Observations were made 5 weeks after the frost event. Base trunk diameter (BD) and maximum trunk diameter damaged (MDD) provided a reference of plant size and crude measurement of damage intensity, as evident by presence of water-soaked necrotic and/or dehydrated tissue following the removal of a thin slice of periderm, vascular cambium, phloem, and xylem. Percent of base diameter damaged (PBDD) was calculated as MDD divided by BD and provided an assessment of damage, unbiased by plant size. Percent of shoot damaged (PSD) was visually evaluated as the percentage of entire shoot system exhibiting damage. In addition, presence of basal damage (DB) and basal cracking (CB) were recorded. A strong cultivar response was observed for BD, MDD, PBDD, and PSD. Mean cultivar values for PSD ranged from 79% and 19% for AU Authur and Sungold™ seedlings, respectively, which represented extremes among cultivars. Fuzzy kiwifruit exhibited greater injury (PBDD, PSD, DB, and CB) as compared with golden kiwifruit cultivars. Basal damage and basal cracking proved unique to fuzzy kiwifruit, as DB ranged from 0% in Sungold™ seedlings to 100% in fuzzy kiwifruit ‘AU Authur’ and ‘AU Fitzgerald’. In spite of having greater vigor, golden kiwifruit plants sustained less injury. Method of propagation had no effect on injury. PBDD and PSD proved to be reliable field assays for documenting injury, based on their strong correlation value (r = 0.92). Greater relative autumn frost tolerance of golden kiwifruit over fuzzy kiwifruit cultivars is previously unreported.
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