Four underutilized small trees, Chilopsis linearis, Rhus lanceolata, Acacia wrightii, ×Chitalpa tashkentensis, and a commercial control Fraxinus velutina, were grown outdoors in 15-L containers. Four media combinations, 3 pine bark: 1 sand, 3 pine bark: 1 coconut coir pith, 3 kenaf stalk core: 1 sphagnum peat, and 3 kenaf stalk core: 1 coconut coir pith (v/v), were amended with Sierrablen 18N–2.6P–10K at three rates, 3.6, 7.1, and 10.7 kg·m-3. Fraxinus velutina and C. linearis seedlings were transplanted to the field to evaluate initial landscape establishment. Growth was typically reduced, in both the field and container, when kenaf media was used during production. EC was greatest early and with higher fertility rates. Leachate pH decreased over time, and was lower at high fertility rates. Soil particle size >6.0 mm decreased substantially in kenaf media over time. Water holding capacity increased, while air space and total root volume decreased in kenaf media. Physical characteristics and growth responses were similar with coconut coir and peat moss.
Mitchell W. Goyne and Michael A. Arnold
Mitchell W. Goyne and Michael A. Arnold
Growth responses during nursery production in 2.2- and 11.4-liter plastic containers to conventional and alternative media of four species of small trees of limited availability for potential use in urban sites in the southwest United States (Acacia wrightii, Chilopsis linearis, × Chitalpa tashkentensis, and Rhus lanceolata) were compared to that of a commercially available small tree (Fraxinus velutina). Four media combinations, at 3:1 (v/v) of bark: sand (conventional), bark: coconut coir pith, kenaf stalk core: peatmoss, and kenaf: coir, with three fertilizer concentrations (3.6, 7.2, and 10.7 kg·m–3 of 18N–2.6P–10K Osmocote) were tested with each species. All species exhibited commercially acceptable growth (80 to 167 cm mean heights in 11.4-liter containers in 240 days) with near 100% survival in most media and fertilizer combinations with the following exceptions: shoot extension of Rhus lanceolata was reduced by 20 to 30 cm and survival by 20% to 50% in kenaf media with high fertility rates; and Acacia wrightii had acceptable shoot extension but exhibited poor trunk diameter growth across media relative to the other species. Slightreductions in growth of some species were noted with kenaf media and slight increases with coconut coir, but differences were not likely of commercial significance. Kenaf media was significantly lighter (20% to 80%) than bark media, but had elevated initial electrical conductivity (EC) and shrank to 60% to 70% of its initial volume after 240 days. Kenaf: peatmoss media had a slightly lower mean pH (6.34) compared to the other media (pH 6.41–6.49).
Allen D. Owings, Edward W. Bush, and Mitchell W. Goyne
Leachates were collected at 3-month intervals over 12 months to determine the influence of bark, controlled-release fertilizer, and dolomitic lime sources and dolomitic lime application rates on pH of nursery media. The randomized complete-block design was arranged as a factorial and included three bark sources (pinebark, hardwood, and pinebark + hardwood), two fertilizer sources (Nutricote 17-7-8 and SierraBlen 18-7-10), and two dolomitic lime sources (microencapsulated granular and pulverized). Dolomitic lime application rates were 0, 5, 10, and 15 pounds per cubic yard. Leachate pH was influenced over the one-year evaluation period by fertilizer source, bark source, and application rate of dolomitic lime. Dolomitic lime source was not a significant factor in adjustment of leachate pH. Pinebark medium had lower leachate pHs than hardwood medium and the medium containing hardwood and pinebark. Dolomitic lime influenced leachate pH of pinebark medium more than the other bark sources. SierraBlen was more acid-forming than Nutricote.
Michael A. Arnold, Larry J. Shoemake, and Mitchell W. Goyne
Transplant studies were conducted on Taxodium distichum L., Platanus occidentalis L., Quercus shumardii Buckl., Fraxinus velutina Torr., and Chilopsis linearis (Cav.) Sweet seedlings grown in 2.2- to 9.1-L black plastic containers. Effects of half-sib family selection on post-transplant root regeneration potential (RRP) and field establishment were investigated with P. occidentalis. Taxodium distichum, Q. shumardii, and P. occidentalis were used to determine seasonal variation in relationships among RRP characteristics and measures of successful transplant establishment. Post-transplant effects of avoidance of circling root development vs. remediation practices were investigated with Q. shumardii. Effects of container media composition on field establishment and RRP of container-grown plants were studied using F. velutina and C. linearis. Impacts of rotation time on RRP and field establishment were investigated with T. distichum. Rates of RRP were the measure most consistently linked to improved post-transplant shoot growth of P. occidentalis. Utilization of locally adapted genotypes and avoidance of summer transplant were important in establishment of P. occidentalis and T. distichum. Increased small diameter root regeneration was linked to reduced water stress during transplanting of Q. shumardii. Physical characteristics of the container media impacted initial post-transplant growth of F. velutina and C. linearis.
Michael A. Arnold, Bruce Lesikar, Ann Kenimer, Don C. Wilkerson, and Mitchell W. Goyne
The nursery/greenhouse industry is the fastest growing segment of U.S. agriculture. Consumer demand for excellent product quality requires luxury applications of water and agricultural chemicals. These cultural practices tend to yield significant volumes of runoff rich in nutrients and pesticides. A capture and recycle system at the Nursery/Floral Crops Research and Education Center at Texas A&M University was fitted with 12 subsurface flow (SSF) and 12 free-surface flow (FSF) wetland cells. Constructed wetland cells provided substantial reduction of runoff nutrient concentrations without increasing electrical conductivity, an indicator of salinity. Growth of Iris pseudacorus L. and Canna ×generalis L.H. Bailey during spring growth was greater in the FSF wetland cells, while that of Colocasia sp. Fabr. was greater in the SSF wetland cells. Equisetum hyemale L. grew equally well in both cell types. Direct reuse of nursery runoff reduced the number of Ilex vomitoria Ait. `Nana' reaching marketable size in 2.3-L containers. Interactions among irrigation water sources and container media types for growth indices occurred for Juniperus procumbens `Green Mound' and I. vomitoria `Nana', but not for Raphiolepis indica L. `Carmelita'.