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- Author or Editor: D. Joseph Eakes x
Two 8- to 9- month [Nutricote 20-7-10 (Type 270) and Osmocote 18-6-121 and two 12- to 14- month [Nutricote 20-7-10 (Type 360) and Osmocote 17-7-121 controlled release fertilizers were preplant incorporated into a 3:1 pine bark:peat moss medium during two potting dates (April 12 and June 6, 1991) at the rate of 1.5 kg N/m. Plant growth of two woody ornamentals, 'Green Luster' Japanese holly and 'Fashion' azalea, and monthly medium solution electrical conductivity (EC) were determined. Growth index [GI = (height + width at widest point + width perpendicular to widest point)/3] response to fertilizer treatment was species specific. Nutricote 20-7-10 (type 360) produced the largest GIs for holly, while GIs for azalea were not affected 420 days after initiation (DAI) of the test. Plants potted in April had greater GIs than those potted in June for the two plant species 420 DAI, regardless of fertilizer type. Osmocote 18-6-12 and 17-7-12 controlled release fertilizers had the greatest medium solution ECs from 90 to 180 DAI.
The influence of K nutrition (25, 75, 150, 300, 450, and 600 mg K/liter) and moisture stress conditioning (MSC) (exposing plants to four sublethal dry-down cycles) on leaf water relations, evapotranspiration, growth, and nutrient content was determined for salvia (Salvia splendens F. Sellow `Bonfire'). Potassium concentration and MSC had an interactive influence on osmotic potential at full (π100) and zero (π0) turgor. Differences in osmotic potential between MSC and non-MSC plants for π100 and π0 increased with increasing K concentration. Increasing K concentration and MSC resulted in active osmotic adjustment and, consequently, increased cellular turgor potentials. Foliar K content increased with increasing K concentration and MSC. High K concentrations and MSC both reduced plant evapotranspiration on a per-plant and per-unit-leaf-area basis. Greatest shoot dry weight occurred for plants grown with 300 mg K/liter and non-MSC. Total leaf area increased with increasing K concentration, but MSC had little effect.
We determined the influence of moisture stress conditioning (MSC) (exposing plants to four nonlethal dry-down cycles) on gas exchange and water loss of Salvia splendens F. Sellow `Bonfire'. During day 1 following final irrigation, no differences in leaf water potentials (ψL) were observed due to MSC. However, MSC plants had lower midday net photosynthesis (Pn), transpiration (E), and leaf conductance (gL) than controls. Stomatal inhibition of photosynthesis (SI) of MSC plants was greater than that of controls. Further, the lack of differences in mesophyll resistance to CO2(rm due to MSC indicate gas exchange differences during day 1 were stomatal in nature. During day 2, MSC plants exhibited greater Pn, E, and gL, while SI and rm were greater for controls. MSC plants maintained positive Pn rates and .turgor and lower ψL than control plants during day 2. Higher water-use efficiency estimates were observed for MSC plants than for controls.
Strong academic abilities and practical work experience are important to employers of horticulture graduates. In greatest demand are students with competent personal and leadership abilities and technical skills. Increased class size and increased university core curriculum requirements hinder our capacity to develop these added skills within our curriculum. However, through extracurricular offerings we can offer students ways to develop skills that are not fully expressed in the academic arena. Student interaction in the traditional horticulture club requires practicing interpersonal relation and often conflict resolution skills. Students learn to work as a team to accomplish goals that they have set for themselves as a group. The Associate¥ Landscape Contractors of America (ALCA) Student Career Days experience offers a highly effective means for reinforcing cognitive skills gained in the classroom and laboratory, as well as supplementing academic learning opportunities with technical activities beyond those offered in the curriculum.
Traditional propagation courses seldom allow extensive evaluation of the variables required for successful propagation. A series of experiments were designed to give an individual student practical experience in woody plant propagation. Softwood terminal cuttings were taken on five shrub or tree species, dividing each species into separate experiments comparing talc vs. liquid auxin formulations. Selections evaluated included luster leaf holly with treatments of 3000, 8000, and 16,000 ppm K-IBA; hetz holly, crape myrtle, and anise tree with treatments of 1000, 3000, and 8000 ppm K-IBA; and sugar maple with 8000 and 16,000 ppm K-IBA. Budding and seed propagation also were evaluated in sugar maple. In each species, except sugar maple, liquid quick-dip at the highest K-IBA concentration produced the best rooting. The student gained many educational benefits in basic experimental design, evaluation of data collected, and drawing conclusions to findings significant by industry standards. The student also learned and how production cycles have an impact on various methods, development stages of cutting material, and wounding techniques. The practical propagation experience gained was of primary importance thereby further preparing the student for employment in the industry.
The objective of this study was to determine differences in the bulk anthocyanin content of bark tissue of container-grown red maple (Acer rubrum L. and Acer ×freemanii E. Murray) at two Georgia locations with different environmental conditions. Rooted cuttings and tissue-cultured plantlets of eight cultivars were grown in either Blairsville or Tifton, Ga. [U.S. Dept. of Agriculture (USDA) Hardiness Zones 6b and 8a; American Horticultural Society (AHS) Heat Zones 5 and 8, respectively], from June 1995 until Dec. 1996. Bark tissue from twigs of trees grown in Blairsville was visually redder and contained more total anthocyanin than did that of trees grown in Tifton. Levels of total anthocyanins were higher (P = 0.0007) at Blairsville (0.087 mg·g-1, N = 48) than at Tifton (0.068 mg·g-1, N = 47). At both locations the levels were highest in `Landsburg' (`Firedance'™), followed by `Franksred' (`Red Sunset'™) and `October Glory'. This is the first report to quantify anthocyanin differences in bark tissue of container-grown trees. Cooler nights in Blairsville might have contributed to increased coloration by reducing respiratory losses, thus leaving more carbohydrates available for pigment production.
Acer rubrum `October Glory' has grown well in field studies across the southeastern United States. However, there is limited information on container production for this cultivar. Our objective was to evaluate first-year growth of container-grown `October Glory' at three locations with dissimilar climates in Georgia and Alabama. Rooted cuttings were planted in no. 3 containers at one location in Apr. 1995. Trees were transported the second week of June to Blairsville, Ga.; Auburn, Ala.; and Tifton, Ga. Trees were grown for 6 months until dormant and were harvested at the end of December. Location had no impact on final plant height increase (Blairsville, Auburn, and Tifton, 59.8, 53.0, and 60.2 cm, respectively). Increases in stem diameter and shoot dry mass were greatest at Tifton (8.4 mm, 17.5 g) and least at Blairsville (6.3 mm, 9.2 g), with Auburn similar to both locations (6.8 mm, 12.2 g). Root dry masses and root: shoot ratios were greatest in Tifton (17.2 g, 0.967), with no differences between Blairsville (4.9 g, 0.508) and Auburn (7.0 g, 0.641). Despite climatic dissimilarities, among locations, producers of container-grown `October Glory' could expect similar growth during the first year throughout Georgia and Alabama.
Two inch caliper Acer rubrum, Quercus phellos, and Platanus occidentalis were planted March 26, 1990, into 8' × 8' planting holes that were lined with either Typar Biobarrier, Dewitt Pro-5 Weed Barrier or left unlined as a control. There has been little or no root penetration beyond the Biobarrier for the 3 tree species during the first 3 years of this study. At the end of 1990, the control and the Dewitt Pro-5 had similar root penetration numbers. By the end of 1991, the Dewitt Pro-5 had greater root penetration than did the control for A. rubrun. Root penetration of Dewitt Pro-5 and the control treatment was similar for Q. phellos and P. occidentalis. There were no differences in root penetration for Dewitt Pro-5 and the control in 1992 for any species. There were no differences in height for any tree species following the 1990 or 1991 growing seasons and no difference following the 1992 growing season for A. rubrum and Q. phellos. The control treatment had the grearest height for P. occidentalis in 1992. There were no differences in caliper due to root control treatment for the 3 species during the first 3 years of this study.
Leaf water relations and gravimetric water loss as influenced by K rate (25, 75, 150, 300, 450 and 600 ppm) and moisture stress conditioning (MSC - exposing plants to 4 sub-lethal dry down cycles) were determined for salvia (Salvia splendens `Bonfire'). K rate and MSC had a synergistic effect on leaf osmotic potentials. Osmotic potentials at both full and zero turgor decreased with increasing K rate and MSC. Differences between MSC and no-MSC plant osmotic potentials increased as K rate increased. Active osmotic adjustment with increasing K rate and MSC resulted in increased cellular turgor potentials. Both high K rates and MSC reduced plant gravimetric water loss on a unit leaf area basis.