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Landscape mulches are widely promoted to improve soil moisture retention, suppress weeds, and improve the growth of landscape plants. The objective of this project was to determine the effect of common landscape mulches (pine bark, hardwood fines, cypress mulch, color-enhanced ground pallets) on soil moisture, soil pH, weed control, and physiology and growth of landscape shrubs. Two additional treatments were not mulched: no mulch + no weed control and no mulch + weed control. Growth was measured on eight taxa (Euonymus alatus ‘Compactus’, Spiraea ×bumalda ‘Goldflame’, Weigela florida ‘Java red’, Taxus ×media ‘Runyan’, Thuja occidentalis ‘Golden Globe’, Hydrangea paniculata ‘Tardiva’, Viburnum dentatum ‘Synnestvedt’, Viburnum trilobum ‘Compactum’). Leaf gas exchange [net photosynthesis and stomatal conductance (g s)] were measured on Hydrangea paniculata, V. dentatum, and V. trilobum only. All mulches increased soil moisture compared with no mulch + weed control. There was no difference in soil pH or foliar nitrogen among treatments. All mulches, except cypress mulch, increased plant growth of most shrub taxa compared with no mulch without weed control. Mulches increased g S relative to no mulch without weed control. Photosynthetic rates of plants mulched with cypress mulch were less than the other mulches and not different from no mulch. Overall, the result suggests that, except for cypress mulch, the organic mulches tested are equally effective in improving growth of landscape plants. Reduced photosynthetic efficiency and growth of shrubs with cypress mulch suggest potential allelopathic effects.
Michigan State Univ. (MSU) offers 10 certificate programs through the Institute of Agricultural Technology. These programs are campus based, approximately three semesters in length, and include a professional internship. Efforts were made in horticulture to expand programs into major population centers through joint programs with community colleges. Cooperative agreements were developed with Grand Rapids Community College and with Northwestern Michigan College in Traverse City. Issues addressed in the agreements include recruiting, admissions, advising, financial aid, integration of curriculum from both institutions, distance-learning delivery through the CODEC system, instructional commitments from campus-based and adjunct faculty, procedures for transfer to bachelor's degree program at MSU, and graduation. The symbiotic relationship between the institutions has expanded curriculum opportunities in the local areas, increased accessibility to MSU Horticulture programs, and better serves the nontraditional student. Outreach efforts for academic programs complement the traditional outreach that has occurred through the Cooperative Extension Service.
Starch gel electrophoresis and principal component (PC) analysis were used to determine the levels of genetic variation and the relationship between morphology and geographic origin for Cornus florida (flowering dogwood) populations in a Michigan provenance plantation. The populations are representative of the species' geographic distribution, ranging from Texas to Georgia and north to Connecticut and Michigan. Allelic variation at 11 loci encoded by 5 enzymes was very low in comparison to other plant species. On average, populations displayed 1.16 alleles per locus, 9.89% of loci polymorphic, with an observed heterozygosity value of 0.048. Genetic identify values ranged from 0.961 to 1.00 and displayed no relationship with geographic origin. While the isozyme analysis revealed little genetic variation, the PC analysis revealed a considerable amount of morphological variation. Most variation (83.3%) in leaf and flower bud morphology was explained by three PCs. Leaf characters revealed no relationship with geographic origin. However, flower bud size and number of florets decreased with changes in latitude from northern, central, and southern populations, respectively. The relationship between flower bud size and latitude suggests an adaptive response to photoperiod throughout the species' geographic range.
Responses of Magnolia ×soulangiana (Soul.-Bod.) `Jane' (`Jane' saucer magnolia) to consecutive short term pretransplant drought stresses and recovery after transplanting were evaluated beginning October 1997 and June 1998. Plants were subjected to one (mild) or two (moderate) 3-day drought stress periods or a two 3-day and one 4-day (severe) drought stress period, each separated by two rewatering periods over 24 hours. One day after each stress period, plants were transplanted into the field and well watered to monitor recovery from stress. Plant response was determined by measuring whole-plant CO2 assimilation, leaf gas exchange (CO2 assimilation, transpiration, stomatal conductance) and canopy growth throughout stress and recovery periods. Whole-plant and leaf CO2 assimilation were lower for the stressed treatments for most of the measurements taken during stress in the fall and spring. After release from stress and transplanting, leaf CO2 assimilation returned to control levels for mild and moderate fall stresses within 2 to 3 d by the next measurement, while it was over 3 weeks until recovery from the severe stress. There was no difference in leaf gas exchange following release from stress and transplanting during the spring stress. More rapid defoliation occurred for the severe fall-stressed plants compared to the controls after release from stress in the fall. Flower number was reduced in spring for the fall-stressed plants. At termination of the experiment, the growth index was lower for severe fall-stressed plants but there were no differences for other fall stress treatments. There was no increase in growth for control or stressed plants for the spring experiment.
Several plant species that are not consumed by animals were collected, extracted with organic solvents, and tested at different venues for their effectiveness as animal feeding repellents. Species with the most repellent activity were daffodil (Narcissus pseudo narcissus), bearded iris (Iris sp.), hot pepper (Capsicum frutescens), catnip (Nepeta cataria) and peppermint (Mentha piperita). Considerable effort was expended to isolate and identify compounds from these species responsible for repellent activity. Eight chemicals have been isolated and purified, and four of them have been identified. Both daffodil and catnip contain more than one repellent, but none of the four compounds identified were common to both species. Combinations of extracts from more than one plant species proved to have more repellent activity than extracts from individual species used alone. In several tests these plant extracts proved to be as effective or better than available commercial repellents. A plethora of additives and surfactants were tested to increase repellent activity by enhancing the spreading, penetration or persistence of the extracts.
Consumers face risks each time they purchase and consume products. Guarantees provide a means of potentially decreasing risk for products that cannot be evaluated until consumption has begun, as with ornamental plants. Despite the potential risk reduction, the effect of guarantees on consumer purchases has been a source of debate for many retailers. Research conducted at Michigan State Univ. examined the effects of guarantees on consumer satisfaction and regret of three horticultural products: hanging baskets, potted roses, and perennials. Over half (56%) of respondents stated the retail outlet provided a guarantee. Twenty-six percent stated the guarantee was a deciding factor in choosing that particular plant while 27% stated it was the deciding factor in shopping at that particular retail location. Results show that guarantees reduce risk for consumers, reducing the incidence of regret but have no effect on customer satisfaction.
For most residential home improvements, excluding landscapes, professionals can document return on investment. Our objective was to compare costs of installing landscapes with perceived home value, and determine return on investment. We administered surveys in eight selected U.S. cities in 1999. Self-selected participants from home and garden shows were asked to examine a photograph of a home without landscaping (base home), and were given its value estimated by local realtors. Participants were asked to view 16 additional photographs of the base home with different landscapes. Cost estimates for landscape materials and installation were calculated. Results showed that a sophisticated landscape with large and diverse plant material added up to 13% to the perceived value of a new $200,000 home. On average, any level of landscaping added value to the home. The increase in perceived value as a percentage of project cost was greatest for simple designs with small evergreen plant material. Complicated designs that included hardscapes and large, diverse plant material returned the least. In general, we found that return on investment for landscaping is comparable to the returns gained on several major home improvements, yet differed with respect to geographic region. We found that colored hardscape, developed from a red brick paver walkway, returned less than color from flowering annuals. Return on investment was greatest for annual plants added for color.
A consumer research study was conducted examining effects of plant guarantees on satisfaction and regret in the purchase of three horticultural products: hanging baskets, potted roses, and container perennials. Five hundred and seventeen respondents were divided into two groups: those who were offered a guarantee and those who were not offered a guarantee. The effects of satisfaction and regret on repurchase intentions were recorded on multi-item seven-point Likert scales. A structural equation model was used to examine simultaneous relationships between regret, satisfaction, and intention to repurchase. Survey results indicated guarantees would increase satisfaction and decrease regret for hanging baskets, but not for container perennials and potted roses. Five of six models showed regret and/or satisfaction directly impacted intention to repurchase. Both satisfaction and regret had a direct influence on repurchase intentions for the hanging baskets model regardless of the presence or absence of guarantees. When guarantees were absent, satisfaction and regret had direct effects on intention to repurchase for the perennial model. Regret was the only construct to directly impact intention to repurchase in the potted rose model. Guarantees appear to lower the risks of buying some products and may improve the perception of quality of the offering.