William Graves

William Graves
Iowa State University | ISU · Graduate College

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208
Publications
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Publications

Publications (208)
Article
Full-text available
A reputation for coarse root systems with dominant taproots, and for slow shoot development among seedlings, limits use of hickory species ( Carya Nutt.) that could increase diversity in managed landscapes. We examined effects of root pruning and application of auxin on root and shoot development of seedlings of several species of hickory. Our hypo...
Article
Full-text available
We evaluated emerging biopolymer horticultural products that provide fertilizer nutrients to plants (fertilizing biocontainers, pelletized biopolymer fertilizer, and biopolymer fertilizer spikes) for their effectiveness during greenhouse production and garden growth of floriculture crops, and during postproduction culture of container ornamentals....
Article
We evaluated the effects of seven types of 4.5-inch top-diameter biocontainers and five rates of paclobutrazol drench on the growth and development of angelonia ( Angelonia angustifolia ‘Serena White’) and petunia ( Petunia × hybrida ‘Wave ® Purple Improved Prostrate’) during greenhouse production. The container types included were biopolyurethane-...
Article
Full-text available
Various types of emerging bioplastic containers present a range of physical and chemical properties and can perform differently from one another in production environments. Container performance may be affected by substrate moisture content. We quantified the effects of bioplastic container type and substrate volumetric water content (VWC) on the a...
Article
We quantified the growth and quality of ‘Arizona Sun’ blanket flower (Gaillardia × grandiflora) grown in different bioplastic containers and characterized the interest of commercial perennial producers in using bioplastic-based biocontainers in their herbaceous perennial production schemes. Plants were grown in three types of #1 trade gallon (0.75...
Article
Drawbacks of traditional synthetic fertilizer led us to explore a biologically based (bio-based) alternative. Our objective was to quantify the efficacy of wastewatergrown algae pellets and pastes harvested from rotating algal biofilm systems as fertilizers for three crops, ‘Honeycomb’ marigold (Tagetes patula L.), ‘Beefsteak’ tomato (Solanum lycop...
Poster
Full-text available
Carya cordiformis K. Koch (bitternut hickory) offers traits favored for trees used in managed landscapes, where it could replace Fraxinus L. (ash). Hickories often are overlooked due to claims of resistance to transplanting, a supposed result of dominant taproots and minimal development of lateral roots. Root pruning is used to modify coarse root s...
Article
Full-text available
Our objectives were to quantify the growth and quality of herbaceous annuals grown in different types of bioplastic-based biocontainers in commercial greenhouses and quantify producer interest in using these types of biocontainers in their production systems. Seedlings of ‘Serena White’ angelonia (Angelonia angustifolia) and ‘Maverick Red’ zonal ge...
Article
Full-text available
Research examining biocontainers for container-crop production has demonstrated that bioplastics made from soybean [Glycine max (L.) Merr.] can supply mineral nutrients to plants. Using soybean-based bioplastics and biochar (BC), we created pelletized fertilizer designed to be incorporated into soilless substrate. We evaluated the growth of ‘Honeyc...
Book
Full-text available
The variety and number of plants grown in pots (containers) is astonishing. In the United States alone, more than 4.5 billion containerized plants are produced per year by the horticulture specialty-crops industries, and nearly all of them are grown in single-use, petroleum-based plastic containers. Efforts are made by a few to re-use or recycle so...
Poster
Full-text available
Diversification of taxa is an important goal of those who manage urban landscapes. Some otherwise desirable species have not been promoted for use due to reports of challenges associated with their production or establishment. A reputation for being difficult to transplant due to coarse root systems with dominant tap roots, and for slow shoot devel...
Article
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Bioplastics and bioplastic composites are a group of emerging sustainable materials that exhibit favorable characteristics for use in horticulture-production containers. Biocontainers made from composite materials of soy [Glycine max (L.) Merr.] bioplastic and poly(lactic) acid (PLA) have been shown to release nitrogen (N) at a rate suitable for su...
Article
The genus Nyssa L. includes several woody species with traits valued by horticulturists, but only black gum (Nyssa sylvatica Marsh.) is prevalent in the nursery trade. A congener, swamp tupelo (Nyssa biflora Walt.), might be a marketable shade tree, but little is known about propagating it from seeds. Because cold, moist stratification overcomes em...
Article
Full-text available
Over 750,000 metric tons of petroleum-based plastics are consumed per year by the greenhouse and nursery industries in the United States for single-use plant containers. Approximately 98% of this non-renewable, non-biodegradable material is disposed of in the nation’s landfills and represents an obstacle to long-term sustainability. Bioplastics sho...
Article
AimLittle is known about the distribution of temperate forest shrubs in eastern North America during the Last Glacial Maximum (LGM), and how far they subsequently migrated to occupy previously glaciated landscapes. We assessed whether populations of Dirca palustris L. persisted near the glacial margin during the LGM. Such populations might explain...
Article
Tall oil-based polyamide (PA) was blended with lignin-cellulose fiber (LCF), an inexpensive, highly abundant byproduct of the pulp and paper industries, to produce environmental-friendly thermoplastic biocomposites. The effects of the concentration of LCF on the thermal, rheological, and mechanical properties of the composites were studied using di...
Article
Full-text available
One of the most significant limitations to widespread industrial implementation of emerging bioplastics such as poly(lactic acid) and poly(hydroxyalkanoate) (PHA) is that they do not match the flexibility and impact resistance of petroleum-based plastics like poly(propylene) or high-density poly(ethylene). The basic goal of this research is to iden...
Article
Full-text available
The container-crops industry relies heavily on single-use plant containers made from petroleum-based plastics, most of which contribute to the solid waste stream in landfills. Plant containers made from biorenewable materials have potential to be more sustainable, but most commercially available biocontainers are either not durable enough for commo...
Article
Full-text available
The use of petroleum-based plastic containers for the culture of greenhouse crops has become standard practice worldwide. Although the effectiveness and versatility of plastic containers is unquestionable, the heavy utilization of non-degradable, single-use containers made of fossil materials is unsustainable and contributes heavily to the environm...
Article
Poly(lactic acid) (PLA) and distiller’s dried grains with solubles (DDGS) are biobased materials with strong potential for industrial applications. This paper reports the biodegradation behavior of PLA/DDGS (80/20 by weight), a composite material developed for use in high-quality, economical, biodegradable, crop containers for the horticulture indu...
Article
Adipic anhydride-plasticized soy protein (SP.A) was blended with poly(lactic acid) (PLA) at two concentrations (50/50 and 33/67) and was evaluated for use as a sustainable replacement for petroleum plastic in horticulture crop containers. Following the discovery that SP.A/PLA blends provide additional functions above that of petroleum plastic for t...
Article
Full-text available
PHA/DDGS composite is a promising low-cost, bio-based material for use in crop containers for the horticulture industry. This research effort has quantified the effects on mechanical and thermal properties of adding different amounts of DDGS to a PHA matrix. PHA and DDGS were mixed using a twin-screw microcompounder. Fracture surface morphology and...
Article
Full-text available
Biocontainers made of coconut coir, paper, peat, wood, or other natural fibers are considered sustainable alternatives to containers made of petroleum-based plastics, but growers' acceptance and use of fiber containers have been limited by their comparatively high cost, low strength and durability, and poor water-use efficiency (WUE). We hypothesiz...
Conference Paper
Full-text available
More than 750,000 metric tons of petroleum-based plastics are consumed annually by the greenhouse and nursery industries in the United States for single-use plant containers. This extensive use of petroleum-based materials is an obstacle to sustainability because they are non-renewable, non-biodegradable, and about 98% of used containers are dispos...
Conference Paper
In previous research with soy-based bioplastic containers, we found that nitrogen (N), phosphorous (P), and potassium (K) are liberated from the container material during plant production and become available for uptake and assimilation. Therefore, if greenhouse crops are produced in soy-based biocontainers, fertilizer-application strategies may ne...
Conference Paper
Researchers with limited budgets and expertise may find it challenging to isolate and genotype microsatellite loci from plants, especially plants for which no prior genomic information is available. Next-generation sequencing promises to be a rapid, economical approach to microsatellite isolation from plants, although enrichment of genomic DNA for...
Conference Paper
Iowa State University’s campus landscape has attracted students, faculty, alumni, and visitors, since the university was founded in 1858. The 490-acre central campus features historical trees that either predate the institution or were planted as the campus was established. Many historical specimens of trees are approaching the end of their life sp...
Conference Paper
The genus Nyssa Gronov. ex L. includes several woody species with traits valued by horticulturists, but only Nyssa sylvatica Marsh. (black gum) is prevalent in the nursery trade. Although we hypothesize that a closely related species, Nyssa biflora Walt. (swamp tupelo), can be a useful tree for managed landscapes, little is known about propagating...
Article
The extensive use of plastics in agriculture has increased the need for development and implementation of polymer materials that can degrade in soils under natural conditions. The biodegradation behavior in soil of polyhydroxyalkanoate (PHA) composites with 10 wt% distiller's dried grains with solubles (DDGS) was characterized and compared to pure...
Conference Paper
Background/Question/Methods We are studying Dirca palustris L. to address the paucity of data on the phylogeography of shrubs in forests of eastern North America. An interesting case study, D. palustris is distributed broadly but is relatively uncommon; is without obvious vectors for long-distance dispersal of seeds; and has an obscure historical...
Conference Paper
Sustainability and environmental impacts of container-crop production are important to producers and consumers. While the performance, productivity, and low cost of petroleum-plastic containers have led horticultural industries to rely heavily on containers made of these unsustainable materials, emerging bioplastics technologies provide alternative...
Conference Paper
Biocontainers made of coconut coir, paper, peat, wood, or other natural fibers are considered sustainable alternatives to containers made of petroleum-based plastics. Feedstocks for fiber containers are biorenewable and biodegradable, and therefore more ecofriendly than petroleum-based plastics, but growers’ acceptance and use of fiber containers h...
Conference Paper
We sought to document genetic and phenotypic diversity within eastern leatherwood (Dirca palustris), a North American shrub that is rare in horticulture despite its yellow flowers and autumnal leaves, arborescent form, disease resistance, and shade tolerance. Strength of the genetic structure among 92 populations of D. palustris throughout its dist...
Article
Full-text available
As part of a project to develop and assess bio-based, biodegradable plastics for their potential to replace petroleum-based plastics in specialty-crop containers, we evaluated prototype containers made of protein-based polymers from soybean [Glycine max (L.) Merr.] for their effectiveness during production of plants in greenhouses and subsequent es...
Article
Full-text available
Numerous genera of plants are distributed in both eastern North America and in portions of California with the dry summers of Mediterranean climates. We compared effects of flooding and drought on relative growth rate (RGR), photosynthesis, and biomass of seedlings of two genera, Sambucus L. and Ptelea L., with congeners in both regions. Ptelea cre...
Conference Paper
Full-text available
Bioplastic materials were compounded utilizing soy, poly- lactic acid (PLA), and poly-hydroxyalkanoate (PHA) biopolymers along with ethanol industry co-products and biomass additives to manufacture horticultural plant containers. Various formulations and processing conditions were studied to improve mechanical properties of the plastics. These mate...
Article
Full-text available
Shrubs in the genus Dirca are rarely used in landscaping despite their shade tolerance and aesthetic qualities. A trial of 81 plants, 27 of each of three species, was established in 2007 in USDA hardiness zone 5a to evaluate survival and growth. After four winters, survival of Dirca mexicana (89%) was greater than survival of Dirca palustris from F...
Conference Paper
Background/Question/Methods Dirca palustris L. (eastern leatherwood) represents a fascinating case study in plant persistence and colonization in eastern North America since the last glacial maximum ~18,000 years ago. It occurs sporadically from Nova Scotia, west to North Dakota, and south to Louisiana and Florida as a deciduous understory shrub o...
Conference Paper
Background/Question/Methods Species occupying narrow and specialized habitats often have specific physiological, morphological, and genetic traits that allow their persistence in their niches. Dirca L. is a genus of uncommon, deciduous shrubs that are distributed in disparate regions of North America. While the most abundant species, Dirca palust...
Conference Paper
Shrubs in the genus Dirca are rarely used despite their shade tolerance and beauty. A trial of 81 plants, 27 of each of three species, was established in 2007 near the border of USDA hardiness zones 5a and 4b to evaluate survival and growth. After four winters, survival of Dirca mexicana (89%) was greater than survival of Dirca palustris indigenous...
Conference Paper
Numerous woody genera are distributed in both eastern North America and in portions of California characterized by the dry summers of Mediterranean climates. As part of a broader survey of how these taxa have evolved under conditions of disparate moisture availability, our objective was to compare the effects of flooding and drought on relative gro...
Conference Paper
An obstacle to sustainability in the container-crops industry is the nearly universal reliance on containers made from non-renewable, petroleum-based plastics. As part of a project to develop and assess biodegradable plastics for their potential to replace petroleum-based plastics in specialty-crop containers, we evaluated prototype plastic contain...
Conference Paper
A popular graduate course at Iowa State University improves students’ skills associated with the preparation of manuscripts for refereed journals in horticultural science and related disciplines. The class, Publishing in Biological Sciences Journals, has been offered for nearly two decades in a face-to-face, classroom format. The objectives of this...
Chapter
Definition and NeedKey ElementsOther Helpful ElementsIssues to be AvoidedRelationship with the Introduction SectionStructural Method for Building the DiscussionThe Conclude–Expand Method Additional Suggestions to Help you Get Started
Chapter
NeedFinal Checklist of Items to be Included in Initial Manuscript SubmissionInitial Submission and Postsubmission Events
Conference Paper
Full-text available
Plants of the genus Leitneria (corkwood) are shrubs that thrive in shade or sun and grow well in either saturated or drained soils. Although large leaves and upright, thicket-forming stems distinguish this taxon in the landscape, Leitneria is rarely available in nurseries but might be marketed as a stress-resistant specialty plant to those particul...
Conference Paper
Actinorhizal and rhizobiarhizal plants can form mutualistic symbioses with soil-borne bacteria housed in root nodules, a relationship in which the plant receives fixed atmospheric nitrogen while providing energy and a controlled environment for the microsymbiont. Actinorhizal plants form N2-fixing symbioses with actinomycetes from the genus Frankia...
Article
A new species, Leitneria pilosa, and a new subspecies, L. pilosa subsp. ozarkana, are described based on leaf morphology, ISSR polymorphisms, ITS sequence character, and geographical isolation. Our infrageneric assessment of populations of Leitneria showed that L. pilosa, which occurs as western disjunct populations in Missouri, Arkansas, and Texas...
Article
Prevalence of sexual and asexual reproduction by plants influences genetic and spatial structure of populations. We investigated reproduction in five populations of Dirca palustris that span its distribution from Florida to North Dakota, and identified the contributions of sexual and asexual reproduction to the clustering of individuals that is cha...
Conference Paper
Background/Question/Methods Prevalence of sexual and asexual reproduction by plants influences genetic and spatial structure of populations. We investigated reproduction in five populations of Dirca palustris that span the distribution of the species from Florida to North Dakota, and identified the contributions of sexual and asexual reproduction...
Article
Our objective was to determine whether provenance of origin and use of organic mulch influence survival, vegetative growth, and the number and size of fruit of Callicarpa americana L. (American beautyberry) planted north of its natural distribution in the central United States. Forty-eight plants were established in 2006 at each of four locations n...
Article
Knowledge of variation among populations is important for making decisions about conservation of rare, threatened or endangered taxa. We investigated variation within and among five populations of Dirca palustris L. an understory shrub with a sporadic distribution and life-history traits that led us to predict strong phenotypic and genetic differen...
Article
Styrax americanus Lam. (American snowbell) is a shrub or small tree (up to 4 meters) that is underutilized in the nursery industry. Patchy populations of this North American species are most common in the southeastern United States, where winters are mild. We are studying a disjunct population of 15 or fewer individuals indigenous to the harsher cl...
Article
Horticultural use of uncommon trees and shrubs in managed landscapes represents a conservation tool for species that are rare and/or threatened in their natural habitats. Researchers in North America with dual interests in horticultural science and ecology have focused on indigenous species that meet several aesthetic, physiological, and ecological...
Article
Styrax americanus Lam. (American snowbell) is a deciduous shrub or small tree seldom produced in nurseries. This species is distributed in patchy populations found mainly from Florida to southern Illinois, although a small, disjunct population exists in northern Illinois. The winter-hardiness and loss of hardiness during a period of increased tempe...
Article
Bioplastic containers made from zein, a protein from corn (Zea mays L.), have been developed but not evaluated as alternatives to conventional, petroleum-based plastics. We tested the hypothesis that biodegradation of zein containers provides nitrogen (N) that promotes growth of plants and examined whether plants grown in zein containers could be t...
Article
Little is known about the single reported population of Dirca mexicana. I monitored air temperature from mid-2005 through mid-2007, analyzed pH of soil, used the global positioning system (GPS) to define geographical boundaries of the population, explored for additional populations, and studied aspects of sexual and asexual reproduction in situ and...
Article
We conducted two experiments to determine whether Nyssa aquatica and Nyssa ogeche could be propagated from softwood cuttings. In the first experiment, two commercial auxin formulations were used, each at two concentrations. In the second study, we compared root formation among cuttings treated with 3000-ppm indole-3-butyric acid (IBA) in liquid or...
Conference Paper
Background/Question/Methods Styrax americanus Lam. (American Snowbell) is a deciduous, woody plant distributed in patchy populations that are restricted to floodplains and swamp margins. The species occurs primarily from Florida to southern Illinois, but we are studying a disjunct population of 15 or fewer individuals indigenous to a wetland in no...
Conference Paper
Background/Question/Methods Although divergence in floral traits within a species may be constrained by pollinator-mediated stabilizing selection, floral characters also can vary intraspecifically. Such variation may be due to directional selection or to phenotypic plasticity; local resource availability may influence floral size and abundance, for...
Article
Full-text available
Horticulturists have not promoted use of Dirca palustris L. (eastern leatherwood) despite its suite of traits valued by gardeners and landscapers. Horticultural production of D. palustris may be hindered by slow shoot growth and sensitivity of plants to edaphic conditions. Because of discrepancies in reported tolerances of D. palustris to root-zone...
Article
Environmental problems caused by petroleum-based plastics have led to interest in alternatives made from biodegradable polymers (bioplastics), but little effort has been made to evaluate horticultural containers made from these materials. We hypothesized the stability and longevity of containers made from polymers of the hydrophobic corn (Zea mays...
Article
We tested host plant suitability of 10 taxa in the Rhamnaceae for successful preoverwintering development of soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae). In the laboratory, we offered each gynopara and ovipara a single member of each putative host plant and measured survivorship and fecundity. Rhamnus cathartica L. and Rhamnus al...
Article
Eleven species from the family Rhamnaceae, including both species exotic and native to North America, were tested for their acceptability to the fall migrants of the soybean aphid, Aphis glycines Matsumura. Two species, Rhamnus cathartica L. and Rhamnus alnifolia L’Héritier were accepted and had overwintering eggs deposited on them. Eggs survived t...
Article
Full-text available
Species and cultivars of the genus Rhamnus and related genera in the Rhamnaceae were tested for their suitability as overwintering hosts of the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae). The tests were carried out in outdoor cages during the fall through spring of 2002–2003 and 2003–2004. Response of the aphid to the hosts vari...
Article
Leitneria floridana is a rare woody species with a disjunct distribution in the southeastern and south-central United States. Although the distribution of L. floridana is well established, little is known about the comparative biology of its disjunct populations or the factors contributing to its rarity. We studied populations of L. floridana in Mi...
Article
Full-text available
Dirca occidentalis is a rare shrub indigenous to only six counties near the San Francisco Bay in California, United States. We used intersimple sequence repeat (ISSR) markers and automated genotyping to probe 29 colonies of D. occidentalis from four geographically disjunct populations (East Bay, North Bay, Salmon Creek, and Peninsula) and used meth...
Article
Full-text available
Actinorhizal plants form N2-fixing symbioses with soil-borne bacteria of the genus Frankia. Potential exists for development of sustainable, actinorhizal nursery crops that obtain most of their required N through N2 fixation, but information on host-symbiont specificity, presence of compatible Frankia in soils, and techniques to inoculate during pl...
Article
This paper reviews an investigation of the processability and properties of commercially available corn and soy protein polymers for various products. Different formulations of protein substrates were characterized for their mechanical and chemical properties. In this study it was seen that zein plastic sheets could be cast with tensile strengths a...
Article
Full-text available
Maackia amurensis Rupr. & Maxim (Amur maackia) is a leguminous Asian tree capable of forming N2-fixing symbioses with soil- borne Bradyrhizobium spp. This trait sets Amur maackia apart from many legumes now produced in North American nurseries. Two determinants of N2-fixing capacity in legumes are the compatibility of the host plant and its bacteri...
Article
Rhamnus cathartica is an invasive shrub capable of high fecundity in North America. The physiology of R. cathartica has received little attention, but more is needed to understand traits that enhance its success in disturbed environments. Such data may help to predict invasiveness of closely related species such as Frangula caroliniana. We hypothes...
Article
Full-text available
Alnus maritima and Alnus serrulata are riparian shrubs that occur in similar habitats in the southern and eastern United States. Alnus serrulata is abundant throughout this range, but A. maritima is rare, occurring only in small populations in Oklahoma and Georgia and on the Delmarva Peninsula. Alnus maritima is more resistant than A. serrulata to...
Article
Full-text available
We determined the cold hardiness of Dirca occidentalis (western leatherwood) within its restricted natural distribution in northern California and made comparisons to Dirca palustris (eastern leatherwood) from northern (Iowa) and southern (Florida) provenances. Stems of western leatherwood were sampled twice while all or some plants were dormant (O...
Article
Carolina buckthorn [Rhamnus caroliniana Walt, or Frangula caroliniana (Walt.) Gray] is an attractive and water-stress-resistant shrub or small tree distributed extensively in the southeastern United States that merits use in managed landscapes. Due to substantial climatic differences within its distribution (30-year normal midwinter minima range fr...
Article
Full-text available
The newly invasive soybean aphid, Aphis glycines Matsumura, has seriously threatened soybean