Arboriculture & Urban Forestry 36(6): November 2010 Arboriculture & Urban Forestry 2010. 36(6): 275-280 275 Humectants as Post-Plant Soil Amendments: Effects on the Wilting Cycle of Drought-Stressed, Container-Grown Tree Seedlings Bruce R. Roberts and R. Scott Linder Abstract. To test the potential effectiveness of humectant-containing compounds for improving soil moisture availability in the rhizosphere of newly transplanted trees, one-year-old Jiffy Plug™ bare-root seedlings of yellow-poplar (Liriodendron tulipifera L.) were treated with Hydretain ES™ and bare-root seedlings of red maple (Acer rubrum L.) and red oak (Quercus rubra L.) and one-year-old (HydES) and EcoSential™ (EcoS) in greenhouse stud- ies. Both products were applied as a root drench to seedlings in 3.8 L plastic pots containing soilless substrate. Following treatment, water was withheld and days to wilt (DTW) recorded for each seedling. For red maple, HydES at the recommended rate (16 mL/L, X), as well as at 0.75X and 0.5X, was effective in increasing DTW, as was EcoS at 16 mL/L (the recommended rate, X) and at 0.75X. For red oak, the lowest concentration of HydES (0.5X) was ineffective, but the two higher levels (X and 0.75X) increased DTW significantly when compared to untreated controls. For yellow-poplar, DTW was consistently greater in treated than in untreated seedlings, but the differences were not always statistically significant. The data also indicate that for certain species (e.g. red maple), production type (Jiffy Plug or bare root) may influence the degree to which seedlings respond to humectant treatment. Key Words. Organic Amendments; Production Type: Red Maple; Red Oak; Root Zone Moisture Management; Yellow-Poplar. The successful establishment of trees after transplanting (post- plant) is a major problem facing all segments of the arboricul- tural industry. Root regeneration is a key factor in determining whether or not a transplant will survive and become established. For root regeneration to be successful, soil moisture in the rhizo- sphere must be adequate to support new growth. In this regard, post-plant growth and development is likely influenced more by plant-soil-moisture relationships than by any other single factor (Roberts 1986). These relationships are especially criti- cal for trees planted in urban areas where the demand for wa- ter resources may exceed existing municipal water supplies, thereby limiting the volume of water available for irrigating newly planted landscape vegetation (St. Hilaire et al. 2008). To help ameliorate transplant shock and to stimulate post- plant growth and development, nontraditional soil additives [defined here as nonfertilizer materials applied to the soil to improve production, vigor, or growth (NCR-103 Commit- tee Report 2004)], have received widespread interest over the past 15–20 years. Included among the numerous backfill soil amendments that have been studied are: composted waste prod- ucts, humic acid-based root stimulants, hydrophylic gels and mycorrhizal-containing substrates (Kelting et al. 1998; Fer- rini and Nicese 2002; Fraser and Percival 2003; Gilman 2004; Abbey and Rathier 2005; Ferrini et al. 2005; Roberts 2006; Chalker-Scott 2007; Scharenbroch 2009). Unfortunately, these amendments are often ineffective, in part because they don’t address the issue of post-plant root zone soil moisture stress. More recent technology has resulted in the development of organic products containing polyhydric alcohols that func- tion as humectants. Humectants are hygroscopic substances containing several hydrophilic groups, often hydroxyl groups, which have a strong affinity to form hydrogen bonds with molecules of water. Aqueous solutions of these organic sub- stances have specific humidity equilibrium points that inhibit evaporation to, and absorb moisture from, the atmosphere at relative humidities above their equilibrium point. Thus, when applied to the growing media around plant material, humec- tant compounds have the potential of improving the propor- tion of water available for plant growth by extracting moisture from air spaces within the soil matrix and, in certain instances, by preventing evaporative loss of water out of porous soils. While humectant-containing compounds have gained wide- spread acceptance in pharmaceutical formulations, food, and personal care products, their use in agriculture is less well doc- umented. A review of the literature suggests the primary use of humectant materials in agriculture has been as carriers for water-soluble herbicides (Matsumoto et al. 1992; Marzouk et al. 1998; Ramsey et al. 2005; Ramsey et al. 2006). Proprietary products containing humectants also have been used to im- prove the drought-resistance of bedding plants (Barrett 1991), and to identify transplant production methods that increase es- tablishment rates and yield in tomato (Ciardi et al. 1998). With the exception of an agricultural extension report from Clem- son University (Arena 2001), no scientific studies could be found that involve the use of humectant-containing compounds for increasing the drought tolerance of woody plant material. The objectives of the present project were to determine wheth- er commercially-available humectant-containing products could ©2010 International Society of Arboriculture
November 2010
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
