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Open access

John M. Ruter

Carolina laurel cherry (Prunus caroliniana) is native to the U.S. southeastern coastal plain from North Carolina westward to eastern Texas. The species has been planted extensively in the southeast as an ornamental tree or hedge. Unfortunately, carolina laurel cherry naturalizes readily and is now found in a variety of habitats, both natural and disturbed. Flowering occurs in the late winter/early spring before new leaves emerge and fruit ripens in the fall/winter. Fruit is eaten by migratory birds and seed is dispersed. Seedlings readily germinate in the understory of forests and landscapes in the spring. As there are a limited number of cultivars available, selections with improved form and sterility are needed for the landscape trade. In 2008, seed was collected and treated with Cobalt-60 gamma irradiation at rates ranging from 0 to 150 Gy. The lethal dose killing 50% of the seedlings (LD50) was between 50 and 100 Gy. Three sterile plants were selected in 2012 from the M1 (first generation of mutagen-treated seedlings) population totaling 62 seedlings. M2 (second-generation seedlings from M1 parents) seed was collected Fall 2012, and 1509 seedlings were grown to flowering size in containers. In 2014–15, 120 seedlings that showed no fruit production were planted in the field in Watkinsville, GA, for further evaluation. Ratings on field-grown plants in Dec. 2017 and 2018 showed that 73% and 78% of the plants, respectively, produced no fruit, whereas the remaining plants had minimal to heavy fruit set. Because carolina laurel cherry is andromonoecious, production of male and bisexual flowers was evaluated on 17 selections in 2018. Of 500 flowers evaluated per selection, the number of male flowers per plant ranged from 22 to 415 (4.4% to 83%). The number of racemes with all-male flowers on each selection ranged from 1 to 32. There were no significant correlations between the number of male flowers or number of all-male flowered racemes per plant and production of fruit. Approximately 5% of M2 seedlings remain seedless after 6 years of growth.

Open access

Laura Irish, Cynthia Haynes and Denny Schrock

Participation in field days increases adoption of new techniques and fosters learning. Since 1977, the Iowa State University (ISU) Department of Horticulture has hosted several Home Demonstration Garden (HDG) field days at ISU research farms each year to educate consumers on best practices and cultivars for growing annual flowers and vegetables. Gardens are planted at the farms and feature a specific topic or theme. In 2016 and 2017, 12 HDG field days were hosted in July or August. The objective of these field days was to showcase cultivars of vegetables that are in demand at food pantries and that home gardeners could grow easily for donation to these pantries. In addition to showcasing crops, presentations were delivered that focused on food insecurity implications in Iowa and how community members could impact food security locally. Of more than 400 field-day attendees in 2016, 151 (38%) participated in an optional survey at the end of the day. Similarly, in 2017, 140 of 350 (40%) attendees participated in the survey. Participants reflected on their food security knowledge and intentions to donate fresh produce before and after participation in the field day. Slightly more than a third (39.53% and 37.12%, respectively) of attendees reported some increase in food-security knowledge after participation. In addition, 85% and 72.5% of respondents reported that they will or would consider donating fresh produce to a local pantry after participation in this field day in 2016 and 2017, respectively. This was a change of more than 40% from previous donation patterns in both years. Results from this study are being used to focus future programming of the HDG field days and content of the field day surveys.

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W. Garrett Owen

Coral bells (Heuchera sp.) are popular herbaceous perennials grown for their colorful foliage and venation and their aesthetic appeal in mixed containers and landscapes. Commercial coral bell production requires greenhouse or nursery growers to optimize production inputs such as managing mineral nutrition, thereby maximizing plant growth potential and foliage color. The objective of this study was to determine the optimum fertilizer concentrations, identify leaf tissue nutrient sufficiency ranges by chronological age, and to expand leaf tissue nutrient standards of coral bells grown in soilless substrates during container production. Coral bells (H. hybrida ‘Black Beauty’, ‘Cherry Cola’, ‘Marmalade’, and ‘Peppermint Spice’), varying in leaf color, were grown under one of six constant liquid fertilizer concentrations [50, 75, 100, 200, 300, or 400 mg·L−1 nitrogen (N)] with a constant level of water-soluble micronutrient blend in a greenhouse. Fertilizer concentrations for optimal plant growth and development were determined by analyzing plant height, diameter, growth index, and total dry mass, and were found to be 50 to 75 mg·L−1 N after a nine-week crop cycle. Recently mature leaf tissue samples were collected and analyzed for elemental content of 11 nutrients at 3, 6, and 9 weeks after transplant (WAT) from plants fertilized with 50 to 75 mg·L−1 N. The black- (‘Black Beauty’) and red- (‘Cherry Cola’) colored-leaved cultivars contained higher total N, phosphorus (P), potassium (K), calcium (Ca), sulfur (S), zinc (Zn), and boron (B) than the orange- (‘Marmalade’) and green- (‘Peppermint Spice’) colored-leaved cultivars. For instance, in mature growth, total N concentration for ‘Black Beauty’ and ‘Cherry Cola’ ranged between 3.45 to 3.63% and 3.92% to 4.18% N, respectively, whereas for ‘Marmalade’ and ‘Peppermint Spice’, ranges were between 2.98% to 3.25% and 2.78% to 3.23% N, respectively. Optimal leaf tissue concentration sufficiency ranges determined in this scientifically based study were narrower and often times higher than previously reported survey values for coral bells.

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Marie Abbey, Neil O. Anderson, Chengyan Yue, Michele Schermann, Nicholas Phelps, Paul Venturelli and Zata Vickers

Aquaponics, the combination of hydroponics and aquaculture into one growing system, is a controlled environment production system that potentially has increased environmental and consumer benefits over traditional production methods. There are many different ways to configure aquaponics systems that include different fish species, water circulation, lighting, plant species/density, and more. We tested three cultivars of lettuce, a common aquaponically produced crop, for yield in multiple aquaponic systems and conditions over a 13-month period in Minnesota. Four different aquaponic configurations and four types of fish were tested over the course of the experiment. There was no addition of supplemental nutrients to the systems to evaluate the differences between treatments and set a baseline. There was no difference in yield between lettuce produced aquaponically and those grown in soilless medium. However, there was a difference in yield between lettuce grown with different fish treatments. The tilapia treatment produced higher average yield than yellow perch. There was a difference between cultivars, with higher average yield from loose-leaf bunch cultivars (Salanova, Skyphos) than the bibb type (Rex). Average yield for all but one treatment was above that of reported commercial field production, making lettuce a competitive aquaponic crop in most systems.

Open access

Heidi C. Anderson, Mary A. Rogers and Emily E. Hoover

Consumer demand for local and organic strawberries (Fragaria ×ananassa) is increasing. Growers who can meet this demand have a competitive edge in the direct-to-consumer market. Innovations in strawberry production for northern climates offer new opportunities for growers to meet the demand for local organic strawberries. Typically adopted for season extension, the use of poly-covered tunnels for crop protection provides other benefits including protection from adverse weather. Low tunnels are easy to install, low cost, temporary protective structures that are well-adapted for annual day-neutral strawberry production, and they are more space efficient than high tunnels for these low-stature crops. A range of specialty tunnel plastics that modify and diffuse light are available, but there is little information on how these influence strawberry plant growth and performance in the field. Our objectives were to determine the effects of experimental ultraviolet blocking and transmitting plastics on light and microclimate in low tunnel environments and assess differences in fruit yield and quality in the day-neutral strawberry cultivar Albion in an organic production system. This research was conducted on U.S. Department of Agriculture-certified organic land over 2 years, in 2016 and 2017. We found that ultraviolet intensity and daily light integral (DLI) were lower in covered plots than in the open field. Maximum daily temperatures were slightly higher in covered plots. Both ultraviolet-blocking and ultraviolet-transmitting plastics improved marketable fruit yield compared with the open-field control. Strawberries grown in the open-field treatment were lower in chroma than covered plots in 2017, and there was no difference in total soluble solids between treatments in either year. Low tunnel systems allow for increased environmental control and improved fruit quality and are well-adapted for day-neutral organic strawberry production systems.

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Fengxia Shao, Sen Wang, Juan Chen and Rongyan Hong

To investigate whether reproductive disorders exist in the sexual reproduction of Ziziphus jujuba Mill. ‘Zhongqiusucui’ and to understand the reproductive biology of ‘Zhongqiusucui’ and genetic improvements in jujube trees, we used ‘Zhongqiusucui’ flowers at different developmental stages as materials and conducted field and microscopic observations on the developmental pattern of mega- and microsporogenesis, as well as on the development of male and female gametophytes. The results show the following. 1) From the inflorescence development stage to flowering, the grade 0 bud on the inflorescence exhibited an increase in horizontal diameter, longitudinal diameter, peduncle length, and bud weight, but the rates of increase were different. From day 1 to day 5 after the inflorescence had developed, floral buds mostly grew horizontally. Day 5 was the floral bud flattening stage. From day 6 to day 8 after the inflorescence had developed, floral buds mostly grew longitudinally, and day 8 was the floral bud enlarging stage. 2) The stamens of ‘Zhongqiusucui’ had five anthers, and there were four locules per anther. The anther wall consisted of epidermis, endothecium, one- to two-layered middle layer, and a secretory-type tapetum. In addition, the development of the anther wall belonged to the basic type. The cytokinesis of the microsporocytes was synchronous, the tetrads mostly arranged as a tetrahedron, and the mature pollen had three germ pores, three grooves, and was bicellular pollen. During meiosis, the microsporocytes in each locule were at the same phase and therefore exhibited synchrony. Among the different anthers in the same floral bud, as well as the four locules in the same anther, the microsporocytes had asynchronous meiosis. 3) The pistils in the ‘Zhongqiusucui’ had two ovaries, two anatropous ovules, inner and outer integument, crassinucellate tetrads formed by the meiosis of megasporocytes aligned linearly along the nucellus, megaspore at the chalazal end that developed into the functional megaspore, which underwent mitotic division three times and developed into the mature embryo sac containing seven cells and eight nuclei, and embryo sac development of the Polygonum type. 4) The external morphology of the ‘Zhongqiusucui’ floral buds correlated with the internal developmental stage of the male and female gametophyte. Therefore, the internal developmental progress of the stamen and pistil can be determined by the external morphological characteristics of the floral buds.

Open access

Michael A. Schnelle

Five woody species, black locust (Robinia pseudoacacia), yaupon holly (Ilex vomitoria), black cherry (Prunus serotina), snailvine [Cocculus carolinus (formerly Menispermum carolinum or Epibaterium carolinum)], and southern waxmyrtle [Morella cerifera (formerly Myrica cerifera)], are all native to Oklahoma and nearby states. They all have varying levels of use in and importance to the United States nursery industry. Past natural habitats and where these plants have spread to date, either intentionally or naturally, are discussed here. These native plants have migrated to or have become increasingly dominant in regions of the continental United States because of prolific fruit loads dispersed by birds and mammals, anthropogenic disturbances, overgrazing pastures, and certain species’ tolerance of environmental extremes. Potential control measures include chemical applications, timely cultivation, heightened awareness of grazing practices, and prescribed burning.

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Yang Chen, Xianzhi Zhou, Yongsheng Lin and Yucan Zhang

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Adriano dos Santos, Francisco Eduardo Torres, Erina Vitório Rodrigues, Ariane de Andréa Pantaleão, Larissa Pereira Ribeiro Teodoro, Leonardo Lopes Bhering and Paulo Eduardo Teodoro

This study aimed to evaluate the adaptability and phenotypic stability of cowpea genotypes using a nonlinear regression analysis and multivariate analysis. Experiments were performed at four sites in Brazil using a randomized blocks design with 20 treatments and four replications. The adaptability and stability of genotypes were evaluated by Toler nonlinear regression and genotype plus genotype × environment (GGE) biplot methodologies. Most of the genotypes revealed linear response patterns, with no differences regarding the favorable and unfavorable environments. Regarding the genotype classification for stability and adaptability, the Toler and GGE biplot methodologies are congruent. Genotypes MNC99-537F-4, MNC00-561G-6, MNC99542F-5, and Patativa have high overall adaptability and adequate yield. Therefore, they should be recommended for cultivation in the tested environments. Genotypes closer to the ideotype by the GGE biplot method are considered doubly desirable by the nonlinear method.