bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Basis for Productivity in Anthurium andraeanum Hort.
Authors: Elibox Winston , Umaharan Pathmanathan
Published: February 2019

Anthurium andraeanum Hort. is an important tropical ornamental crop regarded as second only to orchids in its commercial importance. The genetic basis for productivity in anthurium was studied using parent–offspring regression analysis. Sixteen parental genotypes (4 years old) and 14 biparental progeny families (60 plants each, 4 years old) derived from the parents were used in the study. Yield expressed as number of cut flowers per plant per year (CFPY) was significant both between parental genotypes (P < 0.001) and between progeny families (P < 0.05). Mean CFPY of the parent genotypes was normally distributed and ranged from 4.8 in ‘Local Mina Red’ to 9.8 in ‘Kalapana’ with a mean of 7.5. CFPY in Year 1 was strongly correlated to that in Year 2 (Pearson’s r = 0.96; Spearman’s r = 0.93) and the broad sense heritability (H2) was high (87.6%) under controlled shadehouse conditions. CFPY in the progeny families varied from four to 14 with progeny means ranging from 5.7 in ‘Honduras/Local Mina Red’ to 7.2 in ‘Mirjam/Kalapana’. Progeny of seven and 10 crosses possessed mean CFPY greater than that of the more productive parent and the midparent values, respectively. The frequency distribution for productivity of the 840 progeny plants was skewed to the right with a modal class of six to seven. The correlation coefficient between progeny CFPY and midparent CFPY was large and significant (r = 0.90, P < 0.001). The regression of mean progeny CFPY on mean midparental CFPY was strong (y = 0.51x + 2.56; R2 = 0.81) with an estimated narrow sense heritability (h2) of 51.0%. A breeding strategy for improving per plant productivity based on the results is discussed.
Cropload Management of ‘Vidal blanc’ Improves Primary Bud Cold Hardiness and Maintains Berry Composition in the Lower Midwestern United States
Authors: Wilson Patsy E. , Archbold Douglas D. , Masabni Joseph G. , Kurtural S. Kaan
Published: February 2019

Canopy architecture, yield components, berry composition, pruning weight, Ravaz Index, and midwinter primary bud cold hardiness of own-rooted ‘Vidal blanc’ (Vitis vinifera × Vitis rupestris) were measured in response to balanced pruning formula treatments of 20, 30, or 40 nodes retained for the first 454 g of dormant pruning weight and an additional 10 nodes for each additional 454 g and three cluster thinning levels of one, two, and two+ clusters per shoot in 2006 and 2007. Although the pruning formula affected the distance between shoots along the canopy, and the number of count shoots per hectare, the canopy leaf layer numbers were unaffected in either year. Application of the pruning formula did not affect components of yield in either year. However, the number of clusters and yield per vine were affected by cluster thinning treatments where they increased linearly with the decrease in its severity, explaining 73% and 77% of total variance in yield in 2006 and 2007, respectively. Pruning formula or cluster thinning did not affect berry composition substantially. Cluster thinning improved the percentage of mature nodes on shoots before a killing frost in both years. Cluster thinning to one or two clusters per shoot also improved the lethal temperature killing 50% of the primary buds compared with no cluster thinning in both years of the study. Mature wood weight and total pruning weight displayed a quadratic response to cluster thinning where two clusters per shoot had the greatest weight for both, whereas pruning formula had no effect on pruning weight. Optimum fruit weight–pruning weight ratio was achieved with the 30 + 10 pruning formula and two clusters per shoot cluster thinning treatments in both years of the study. The results of this study provide valuable information for growers of interspecific hybrids such as ‘Vidal blanc’ in the lower midwestern United States as well as in other regions with long, warm growing seasons. Balanced pruning to 30 nodes per 454 g of dormant prunings and cluster thinning to two clusters per shoots optimized yield, maintained fruit composition, improved primary bud cold hardiness, and achieved an optimum fruit weight-to-pruning weight ratio of 10.0 kg·kg–1. Thus, this approach should be used for ’Vidal blanc’ in the lower midwestern United States to sustain production.
Bell Pepper (Capsicum annum L.) Crop as Affected by Shade Level: Fruit Yield, Quality, and Postharvest Attributes, and Incidence of Phytophthora Blight (caused by Phytophthora capsici Leon.)
Authors: Díaz-Pérez Juan Carlos
Published: February 2019

High temperatures can be detrimental to bell pepper, resulting in reduced fruit yield and increased incidences of fruit disorders such as sunscald and blossom-end rot. Shade nets are used to modify the crop microenvironment to improve plant growth and yield. The objectives were to evaluate effects of shade level on fruit yield, quality, and postharvest attributes and the incidence of Phytophthora blight (caused by Phytophthora capsici Leon.) in bell pepper (Capsicum annum L.). Experiments were conducted in Tifton, GA, in 2008 (with cv. Heritage) and 2009 and 2010 (with cvs. Camelot, Lafayette, Sirius, and Stiletto). Bell pepper plants were grown under shade levels of 0% (unshaded, as a control), 30%, 47%, 63%, and 80%. Shade level affected fruit yield, quality, postharvest attributes, and incidence of Phytophthora blight in plants. Total marketable (Fancy and US1) fruit yield increased with increasing shade level to a maximum at 35% shade and then decreased with further increments in shade level. Relative to unshaded plants, marketable yields were improved by 119% (2008) and 43% (2009 and 2010) at 35% shade level. US2 and cull (sunscald) fruit number declined with increasing shade level. ‘Camelot’ produced among the greatest number and yield of marketable fruit; ‘Sirius’ had the heaviest fruit and greatest number of culls. Fruit nitrogen (N), phosphorus (P), and potassium (K) concentrations increased and aluminum (Al), molybdenum (Mo), and nickel (Ni) decreased with increasing shade level. ‘Lafayette’ had the highest fruit concentration of N, calcium (Ca), sulfur (S), manganese (Mn), and zinc (Zn). Fruit soluble solids and percent of fruit dry weight decreased with increasing shade level; fruit water loss rate and bacterial soft rot incidence were unaffected. Fruit skin a* and b* values decreased in yellow fruit cultivars (‘Lafayette’ and ‘Sirius’) with increased shade level. Incidences of Phytophthora blight in plants and fruit sunscald decreased with shade level. Beneficial effects of shading on bell pepper were associated with a reduction in irradiation, air temperature, and soil temperature under shaded conditions resulting in amelioration of heat stress in the plants. Optimal shade level for maximal fruit yield was that which maximized the cooling effect resulting from reduction of infrared (IR) radiation and minimized the decrease in net photosynthesis resulting from reduction in photosynthetically active radiation (PAR).
Scenario-based Cost Analysis for Vegetable Grafting Nurseries of Different Technologies and Sizes
Authors: Lewis Myles , Kubota Chieri , Tronstad Russell , Son Young-Jun
Published: February 2019

Grafting of fruiting vegetables is a relatively new advent in the United States with promise as a technology to improve both yields and the environment. However, investing in a commercial-sized grafting enterprise requires substantial capital investment and is a risky endeavor. A tool to help evaluate grafting costs for different production technologies and sizes of operation is a useful decision aid for individuals investing in new or modifying existing operations to produce grafted plants. Using a combination of engineering and financial equations, a scenario-based analysis was completed to obtain approximate capital and variable costs per plant for both new and existing production facilities. For exemplary purposes, four scenarios consisting of two different crops (tomato and watermelon) at two production sizes with different technology levels [low-volume manual grafting (one million plants per year) and high-volume fully automated grafting (100 million plants per year)] are presented to compare costs. For simplification purpose, consistent weekly production was assumed in the cost simulation. Total capital costs were $115,127 and $118,974 for low-volume production for grafted tomato and watermelon plants, respectively. They were $21.6 million and $16.7 million under high-volume production for tomato and watermelon, respectively. Among the four scenarios evaluated, variable costs per plant (costs of plants produced) were lowest for watermelons with high-volume production ($0.089 per plant), suggesting that production costs of grafted plants could decrease by scaling up production and introducing automation. Sensitivity analyses for high-volume production of tomato showed that the electricity rate, grafting clip price, and grafting robot speed were factors with the greatest influence on costs of plants. Scenario-based cost analysis was shown to be an effective tool for developing strategies to reduce the price of grafted plants.
Hydrogen Sulfide Acts as a Fungicide to Alleviate Senescence and Decay in Fresh-cut Sweetpotato
Authors: Tang Jun , Hu Kang-Di , Hu Lan-Ying , Li Yan-Hong , Liu Yong-Sheng , Zhang Hua
Published: February 2019

Hydrogen sulfide (H2S) has been shown to be a gaseous molecule in the regulation of many processes in plants such as abiotic stress tolerance, root organogenesis, stomatal movement, and postharvest fruit senescence. We studied the role of H2S in the regulation of senescence and fungal decay in fresh-cut sweetpotato (Ipomoea batatas L., cv. Xushu 18) roots. H2S donor sodium hydrosulfide (NaHS) alleviated senescence in fresh-cut sweetpotato root tissue in a dose-dependent manner with the optimal concentration of 2.0 mmol·L−1 NaHS solution. At the optimal concentration of 2.0 mmol·L−1 NaHS, H2S fumigation maintained higher levels of reducing sugar in sweetpotato fresh-cut root. H2S treatment also significantly increased the activities of guaiacol peroxidase (POD) and decreased those of polyphenol oxidase (PPO) in sweetpotato during storage. Further investigation showed that H2S treatment maintained a lower level of lipoxygenase (LOX) activity compared with water control. Consistently, the accumulation of malondialdehyde (MDA) was reduced in H2S-treated groups. Three fungal pathogens, Rhizopus nigricans, Mucor rouxianus, and Geotrichum candidum, were isolated from sweetpotato tissue infected with black rot or soft rot. H2S fumigation at 1 to 2.5 mmol·L−1 NaHS resulted in effective inhibition of the three fungi when grown on medium. When the three fungi were inoculated on the surface of sweetpotato slices, H2S fumigation greatly reduced the percentage of fungal infection. In conclusion, these data suggest that H2S effectively alleviated the senescence and decay in sweetpotato slices and might be developed into a novel fungicide for reduction of black rot or soft rot in sweetpotato.
A Database for Three Dioscoridean Illustrated Herbals
Authors: Whipkey Anna , Kalbaugh Kirby , Franz Audra , Janick Jules
Published: February 2019

An image database was developed for three illustrated recensions of the non-illustrated manuscript of Dioscorides entitled Πɛρí ύλης ιατρικης (De Materia Medica in Latin; On Medical Matters in English) written in approximately Year 65: Juliana Anicia Codex (JAC) or Codex Vindobonensis produced in Year 512, Codex Neapolitanus (NAP) produced in the late sixth or early seventh century, and Morgan 652 (M652) produced between 927 and 985. The database that brings up images and accompanying records is searchable by herbal, common name in English and Greek (Roman alphabet), binomial (current and in source document), and botanical family. In addition, a Venn diagram of images in the three herbals permits a search for images that are common or unique among the three herbals. The database makes it possible to locate images in herbals written in Greek that are difficult to access and will be useful to horticulturists and herbal scholars. The database can be accessed at .
Freeze Response of Citrus and Citrus-related Genotypes in a Florida Field Planting
Authors: Inch Sharon , Stover Ed , Driggers Randall , Lee Richard F.
Published: February 2019

A test population consisting of progenies of 92 seed-source genotypes (hereafter called “parent genotypes”) of Citrus and Citrus relatives in the field in east–central Florida was assessed after natural freeze events in the winters of 2010 and 2011. Eight seedlings per parent genotype were planted in a randomized complete block design; however, as a result of mortality, the number of plants assessed in some genotype groups was reduced at some or all sampling dates. The citrus diseases huanglongbing and citrus canker were endemic in the planting and may have influenced tree response to cold temperatures. Unusually low temperatures (near –4 °C each winter) for east–central Florida were experienced during the trial period. Defoliation and dieback were significantly greater in the winter of 2011 than in the winter of 2010. The winter in 2011 was preceded by a period of extraordinarily low temperatures in mid-December with no period of cool temperatures to allow trees to acclimate. In 2010 the average defoliation was 53% ± 28% and less than 13% of the trees exhibited any noticeable dieback, whereas in 2011, the average defoliation and dieback were 93% ± 17% and 51% ± 35%, respectively. Within the genus Citrus, several progenies were identified that had 16% to 24% dieback in 2011 and these were from parent genotypes C. reticulata (CRC 2590) (23%), C. sinensis (CRC 3858) (24%), C. maxima (CRC 3945) (16%), C. hassaku (CRC 3907 and 3942) (16% and 17%), C. aurantium (CRC 628 and 2717) (18% and 7%), C. taiwanica (CRC 2588) (21%), and C. neo-aurantium (C. obovoidea + C. unshiu graft chimera) (CRC 3816) (23%). Within other genera in the Aurantiodeae, Poncirus trifoliata (CRCs 301, 3957, 3549, and 4007), Severinia buxifolia (CRC 1497), Bergera koenigii (CRC 3165), and Glycosmis pentaphylla (CRC 3285) had the least amount of dieback, all at less than 23%. The two species within the Toddalioideae subfamily of the Rutaceae (Casimiroa edulis and Zanthoxylum ailanthoides) had among the least amount of dieback (1% and 8%, respectively). When considered by groups, the Citrons and Australian natives had the greatest amount of dieback in 2011, 68% and 65%, respectively. The trifoliates (Poncirus and hybrids) had the least dieback, ranging from 4% to 40%. The information from this study may be useful in germplasm enhancement and Citrus breeding targeting greater cold tolerance.
Suitability of Two Table Olive Cultivars (‘Manzanilla de Sevilla’ and ‘Manzanilla Cacereña’) for Mechanical Harvesting in Superhigh-density Hedgerows
Authors: Morales-Sillero Ana , Rallo Pilar , Jiménez María Rocío , Casanova Laura , Suárez María Paz
Published: February 2019

At a time of increasing demand, the extremely high cost of manual labor required to harvest fruit in table olive groves is limiting the economic survival of the crop in many producing countries. New grove designs and management practices such as superhigh-density (SHD) groves now in use in oil olive production should be explored as an option to facilitate mechanical harvesting in table olives. The feasibility of two table olive cultivars, Manzanilla de Sevilla and Manzanilla Cacereña, to be harvested in a 5-year-old SHD grove (1975 trees/ha) was studied in 2012 when trees of both cultivars formed highly productive continuous hedgerows (≈10,000 and 18,000 kg·ha−1, respectively). The differences between manual and mechanical harvesting using a grape straddle harvester were evaluated taking into consideration harvesting time, efficiency in fruit removal, and fruit quality both before and after processing as Spanish-style green olives. The average harvest time per hectare with a grape straddle harvester was less than 1.7 hours compared with 576 person/hour or more when done manually. Fruit removal efficiency was high in both cases, 98% for mechanical treatment and 100% for hand treatment. Mechanically harvested fruits had a high proportion of bruising damage (greater than 90%) and the severity of the damage was greater in ‘Manzanilla de Sevilla’ than in ‘Manzanilla Cacereña’. After Spanish-style green processing, however, the proportion of bruised fruits was below 3% in each cultivar. The fruit size in both cultivars was suitable for table olive processing and only 7% and 4% of ‘Manzanilla de Sevilla’ and ‘Manzanilla Cacereña’ fruits, respectively, were diverted to oil extraction as a result of insufficient size. Small differences were found between processed ‘Manzanilla Cacereña’ fruits that were manually or mechanically harvested. In contrast, mechanically harvested ‘Manzanilla de Sevilla’ fruits showed a significantly higher proportion of cutting (18%), a type of damage that may take place during harvesting, and lower firmness and texture than those harvested manually.
A Rapid Screening Approach to Identify Resistance to Basil Downy Mildew (Peronospora belbahrii)
Authors: Pyne Robert M. , Koroch Adolfina R. , Wyenandt Christian A. , Simon James E.
Published: February 2019

Sweet basil (Ocimum basilicum L.) is among the most widely popular and economically important culinary herbs. Worldwide production of sweet basil has been threatened by a newly emerging disease, downy mildew (Peronospora belbahrii). Although tolerance and resistance have been identified in other Ocimum species, the traditional sweet basils all have been reported to be highly susceptible. There is an urgent need for evaluation of basil germplasm to identify sources of host resistance to P. belbahrii within Ocimum spp. and especially among O. basilicum species. In searching for genetic resistance, we developed a rapid approach to screen and evaluate downy mildew response at the cotyledon and true leaf growth stages under controlled environmental conditions. To confirm the reliability and reproducibility of this screening method, an experiment was conducted in which three basil species (Ocimum basilicum, sensitive; O. xcitriodorum, tolerant; and O. americanum, resistant to basil downy mildew) were evaluated for response to downy mildew inoculations at three growth stages. Disease incidence (DI) at the cotyledon growth stage was equal to or greater than true leaf growth stages for all species indicating that cotyledon response to downy mildew inoculations is a viable marker for predicting true leaf stage resistance. This approach was then used to screen 36 USDA-NPGS O. basilicum accessions at cotyledon and first true leaf growth stages to identify promising downy mildew-resistant breeding lines. Thirty accessions were susceptible at both growth stages (DI = 1.0). Four accessions exhibited little or no sporulation at either growth stage (DI less than 0.06), three of which showed other symptoms including chlorosis and necrosis. One accession, PI 652053, demonstrated no signs or symptoms but differed greatly from other accessions in regard to leaf morphology and habit. Results show that a resistant, mature plant can be identified at the cotyledon growth stage, providing a robust, low-input approach to identify promising downy mildew-resistant breeding material. Field evaluations of basils under high downy mildew pressure confirmed the applicability of this new screening approach to identify resistance to basil downy mildew.
Root-knot Nematode Resistance, Yield, and Fruit Quality of Specialty Melons Grafted onto Cucumis metulifer
Authors: Guan Wenjing , Zhao Xin , Dickson Donald W. , Mendes Maria L. , Thies Judy
Published: February 2019

Interest in specialty melons (Cucumis melo) with distinctive fruit characteristics has grown in the United States in recent years. However, disease management remains a major challenge in specialty melon production. In this study, grafting experiments were conducted to determine the effectiveness of using Cucumis metulifer, a species known for its genetic resistance to root-knot nematodes (RKNs; Meloidogyne spp.), as a potential rootstock for managing RKNs in susceptible specialty melon cultivars. In the greenhouse experiment, honeydew melon ‘Honey Yellow’ was grafted onto C. metulifer and inoculated with M. incognita race 1. The grafted plants exhibited significantly lower gall and egg mass indices and fewer eggs compared with non- and self-grafted ‘Honey Yellow’. Cucumis metulifer was further tested as a rootstock in conventional and organic field trials using honeydew melon ‘Honey Yellow’ and galia melon ‘Arava’ as scions. ‘Honey Yellow’ and ‘Arava’ grafted onto C. metulifer exhibited significantly lower galling and reduced RKN population densities in the organic field; however, total and marketable fruit yields were not significantly different from non- and self-grafted plants. Although the improvement of RKN resistance did not translate into yield enhancements, incorporating grafted specialty melons with C. metulifer rootstock into double-cropping systems with RKN-susceptible vegetables may benefit the overall crop production by reducing RKN population densities in the soil. At the conventional field site, which was not infested with RKNs, ‘Honey Yellow’ grafted onto C. metulifer rootstock had a significantly lower total fruit yield than non-grafted ‘Honey Yellow’ plants; however, fruit yields were similar for ‘Arava’ grafted onto C. metulifer rootstock and non-grafted ‘Arava’ plants. Although no significant impacts on the fruit quality attributes of ‘Honey Yellow’ were observed, grafting onto C. metulifer decreased the flesh firmness of ‘Arava’ in both field trials and resulted in a reduction in total soluble solids content under conventional production. In summary, grafting RKN-susceptible melons onto C. metulifer rootstock offers promise for growing these specialty melons; however, more studies are needed to elucidate the scion–rootstock interaction effect on fruit yield and quality.
Plant Species for the Removal of Na+ and Cl– from Greenhouse Nutrient Solution
Authors: Rozema Eric R. , Gordon Robert J. , Zheng Youbin
Published: February 2019

Certain ions such as Na+ and Cl– can accumulate in recirculating greenhouse nutrient solutions and can reach levels that are damaging to crops. An option for the treatment of this problem is phytodesalinization with Na+ and Cl– hyperaccumulating plants that could be added to existing water treatment technologies such as constructed wetlands (CWs). Two microcosm experiments were conducted to evaluate eight plant species including Atriplex prostrata L. (triangle orache), Distichlis spicata (L.) Greene (salt grass), Juncus torreyi Coville. (Torrey’s rush), Phragmites australis (Cav.) Trin. ex Steud. (common reed), Spartina alterniflora Loisel. (smooth cordgrass), Schoenoplectus tabernaemontani (C.C. Gmel.) Palla (softstem bulrush), Typha angustifolia L. (narrow leaf cattail), and Typha latifolia L. (broad leaf cattail) for their Na+ and Cl– accumulation potential. An initial (indoor) experiment determined that J. torreyi, S. tabernaemontani, T. angustifolia, and T. latifolia were the best candidates for phytodesalinization because they had the highest Na+ and Cl– tissue contents after exposure to Na+ and Cl–-rich nutrient solutions. A second (outdoor) experiment quantified the Na+ and Cl– ion uptake (grams of each ion accumulated per m2 of microcosm). J. torreyi, S. tabernaemontani, T. angustifolia, and T. latifolia accumulated 5.8, 3.9, 8.3, and 9.2 g·m−2 of Na+ and 25.7, 18.2, 31.6, and 27.2 g·m−2 of Cl–, respectively. Of the eight species, T. latifolia and S. tabernaemontani showed the greatest potential to accumulate Na+ and Cl– in a CW environment, whereas S. alterniflora, D. spicata, and P. australis showed the least potential.
Sweetpotato Grown from Root Pieces Displays a Significant Genotype × Environment Interaction and Yield Instability
Authors: George Nicholas A. , Shankle Mark , Main Jeff , Pecota Kenneth V. , Arellano Consuelo , Yencho G. Craig
Published: February 2019

Various workers have attempted to develop a root piece planting system for sweetpotato, similar to the system used commercially for potato, but attempts to select and breed sweetpotato clones adapted to root piece planting have met with mixed success. It has been hypothesized this is the result of significant genotype × environment effects, which are complicating phenotype screening. The aim of this work was to investigate genotype × environment interactions and yield stability of sweetpotato grown from cut root pieces. Ten sweetpotato clones were grown from cut root pieces in three locations over three seasons at sites in North Carolina and Mississippi. The study found sweetpotato clones grown from root pieces were influenced by both genetic and environmental factors and that the interaction was often complicated and dependent on the trait being measured. A significant genotype × environment interaction and yield instability were found to be present. Further work will be required to understand the nature of the genotype × environment effects; however, the results suggest programs aiming to develop sweetpotato clones adapted to root piece planting will need to use appropriate multienvironment screening so as to account for genotype × environment effects.
Spontaneous Autotetraploidy and Its Impact on Morphological Traits and Pollen Viability in Solanum aethiopicum
Authors: Sakhanokho Hamidou F. , Islam-Faridi M. Nurul
Published: February 2019

We report for the first time the incidence of spontaneous autotetraploidy in Solanum aethiopicum (PI 636107). Stomatal dimensions and frequency, number of chloroplasts per guard cell, flow cytometry, and chromosome counts were used to differentiate the diploid plants from tetraploids. The impact of increased ploidy on pollen viability as assessed by in vitro germination and on selected morphological traits was evaluated. In vitro pollen germination was reduced in tetraploid plants, but no significant differences were found in fruit production per plant between diploid and tetraploid plants. Compared with the diploids, the tetraploid plants were significantly shorter and had wider leaves and smaller fruits; therefore, tetraploid S. aethiopicum plants can be valuable for future breeding programs, particularly those aiming to develop shorter, more compact plants. Moreover, some S. aethiopicum selections are grown for their edible leaves, so tetraploid plants producing large leaves would be desirable. Additionally, the availability of tetraploid S. aethiopicum could remove hybridization barriers caused by ploidy differences with other tetraploid Solanum species.
Host Status of Rubus Species and Hybrids for the Root Lesion Nematode, Pratylenchus penetrans
Authors: Zasada Inga A. , Moore Patrick P.
Published: February 2019

The root lesion nematode, Pratylenchus penetrans, is a production-limiting pest in red raspberry, Rubus idaeus. Genetic resistance, as a tool to manage P. penetrans in raspberries, would reduce the impact of this nematode on raspberry productivity as well as reduce the need for pre- and/or post-plant chemical treatments to keep populations in control. The host status of 11 Rubus species (R. coreanus, R. crataegifolius, R. innominatus, R. leucodermis, R. niveus, R. parviflorus, R. parvifolius, R. pungens, R. spectabilis, R. sumatranus, and R. odoratus) for P. penetrans was evaluated in greenhouse studies. Additionally, hybrids of R. cockburnianus, R. lasiostylus, R. niveus, R. phoenicolasis, and R. sumatranus with R. idaeus ‘Meeker’ or ‘Tulameen’ were evaluated. The industry standard R. idaeus ‘Meeker’ was included in all trials as the control. Across trials, R. niveus and R. leucodermis were identified as poor hosts for P. penetrans. In addition, when another selection of R. niveus was evaluated in the final year of this study, it was also a poor host for P. penetrans. Among the remaining Rubus species materials tested, there were no consistent differences in host status for P. penetrans. It appears that R. niveus and R. leucodermis might be sources of resistance for P. penetrans. However, a hybrid between R. niveus and R. idaeus ‘Tulameen’ did not consistently support fewer P. penetrans than the ‘Meeker’ control. These results indicate that more research is needed to learn about the inheritance of the putative resistance.
Cross-compatibility in Intraspecific and Interspecific Hybridization within Lychnis and Intergeneric Hybridization between Lychnis and Silene
Authors: Jiang Li , Wang Yun-wen , Dunn Bruce L.
Published: February 2019

Hybridization at intraspecific, interspecific, and intergeneric levels is a well-known breeding strategy to create variations with desirable traits for ornamental flowers. A total of 161 crossing combinations were made on three taxonomic levels, including 12 intraspecific crossing combinations within L. chalcedonica and L. ×haageana, 102 interspecific crossing combinations within Lychnis spp., and 47 intergeneric crossing combinations between Lychnis spp. and Silene spp. Intraspecific crosses showed high cross-compatibility, which yielded mature seeds and progeny plants. Most of the interspecific crossings in genus Lychnis produced limited seed set and germination percentages; however, L. cognate, L. ×arkwrightii, and L. ×haageana showed high cross-compatibility and might be more closely related than other species in Lychnis. As a result of cross-incompatibility, crossing combinations between Lychnis spp. and Silene spp. produced few flowers that set seeds. Significant differences occurred in seed set between crossing combinations and their reciprocal crosses for interspecific and intergeneric crosses. For these hybrids with immature seeds, embryo rescue techniques with immature seed culture would be the only way to produce seedlings.
Ambered Kernels in Stenospermocarpic Fruit of Eastern Black Walnut
Authors: Warmund Michele R. , Van Sambeek J.W.
Published: February 2019

“Ambers” is a term used to describe poorly filled, shriveled eastern black walnut (Juglans nigra L.) kernels with a dark brown or black-colored pellicle that are unmarketable. Studies were conducted to determine the incidence of ambered black walnut kernels and to ascertain when symptoms were apparent in specific tissues. The occurrence of ambered kernels was evaluated in fruit harvested from mature ‘Football’ trees growing at three sites within a commercial black walnut orchard in 2008 to 2010. Mature walnut fruit sampled from trees at Site 2 had greater odds for ambered kernels than those on trees at two other sites within the same orchard with 27% of the walnuts sampled exhibiting symptoms when examined in October. Also, black walnut fruit in 2010 had more ambered kernels than those examined in Oct. 2008 or 2009. Cropload, soil type, ambient temperatures, or precipitation was not apparently associated with a high incidence of ambered kernels. When black walnut fruit from trees at Site 2 were examined from 25 June to 6 Oct. 2011, embryos were visible in 50% of the fruit without discoloration on the first date. Stenospermocarpy (e.g., aborted or rudimentary embryos after fertilization) was observed in fruit with discolored or ambered kernels as early as 7 July. Stenospermocarpic fruit with ambered kernels had shorter embryo axis lengths (root apex to shoot apex) than fruit with non-ambered kernels on 7 July and at successive sampling dates. Cotyledon widths of ambered kernels in stenospermocarpic fruit were narrower than those of non-ambered kernels on 21 July, but symptomatic cotyledons continued to enlarge until 15 Sept. All fruit enlarged during the growing season and nut diameters varied by only 3.4 mm at harvest. Thus, visible embryo degeneration, which was associated with ambered kernels in black walnut fruit, was detected in early July when shell hardening occurs and kernel tissues are enlarging.
Potential of Producing Salicornia bigelovii Hydroponically as a Vegetable at Moderate NaCl Salinity
Authors: Kong Yun , Zheng Youbin
Published: February 2019

Salicornia bigelovii is a halophyte that is capable of growing under high salinity. To evaluate the potential of producing S. bigelovii hydroponically as a vegetable at moderate NaCl concentrations, plants were grown in nutrient solutions with 6, 8, and 10 mm NaCl, and with 200 mm NaCl as a control. Results showed that plants had a reduced main stem length, canopy width, stem diameter, and root system length in 6 to 10 mm NaCl compared with those in 200 mm. Also, fresh weight increase, fresh and dry weights of individual plants, marketable yield, and water use efficiency of the plants grown in solutions with 6 to 10 mm NaCl were significantly lower than those grown in 200 mm. Associated with the reduced growth attributes, remarkable decreases in sodium uptake by the plants were also obtained in 6 to 10 vs. 200 mm NaCl. The results suggest that S. bigelovii is not a good candidate for hydroponic production as a vegetable at moderate NaCl salinity resulting from reduced growth attributes, which are possibly associated with decreased sodium uptake.
Shortening the Period for Assessing the Resistance of Olive to Verticillium Wilt Using Continuous Lighting
Authors: García-Ruiz Gloria María , Trapero Carlos , López-Escudero Francisco Javier
Published: February 2019

The use of continuous and natural lighting was studied to assess the resistance of 12 olive cultivars to the defoliating pathotype of Verticillium dahliae. The plants were inoculated by dipping their bare root system in a conidial suspension. ‘Frantoio’ was used as a moderately resistant control cultivar. Several evaluated cultivars were susceptible to the defoliating pathotype of Verticillium dahliae. However, six of these cultivars were moderately resistant. In most of the evaluated cultivars, continuous lighting allowed for the identification of resistant genotypes during a period that was 3 weeks shorter than that which is normally required in these assessments. This reduction was even greater for the resistant cultivars. The use of continuous lighting could thus be an important tool for use in olive breeding programs, where it is necessary to evaluate many genotypes in short durations and, therefore, to optimize time, space, and labor.
Biochar Media Addition Impacts Apple Rootstock Growth and Nutrition
Authors: Street Tom A. , Doyle Richard B. , Close Dugald C.
Published: February 2019

The effects of biochar soil amendment on perennial plant nutrition and growth are poorly understood. We investigated the effects of a green waste biochar on apple rootstock (Malus domestica var. M26) nutrition and growth in a series of pot trials. Apple rootstocks were grown for 5 months in both soil and sand media, with and without biochar, under a range of fertilization, pH, and soil biological regimes. Plant biomass and leaf nutrient concentration of apple rootstocks and substrate-induced respiration (SIR) of the soil were measured. Addition of biochar was associated with significant increases in leaf concentrations of calcium (Ca), boron (B), and sulfur (S) for apple rootstocks grown in sand. Increased uptake of S has not previously been reported and may be the result of the relatively high S content of the biochar used in this trial that resulted from the low temperature used to pyrolize the biomass. Plant dry mass significantly increased by between 75% and 220% where sand was amended with biochar for every fertilization treatment. Small, but statistically significant, increases in soil pH, from pHc (CaCl2 extraction) 4.7 to 4.9, were found after the addition of biochar but no significant effect on soil SIR was detected. Our results indicate that biochar has positive effects on apple rootstock nutrition and growth in a sand but not in a sandy loam soil.
Alkalinity Showed Limited Effect on Turfgrass Germination under Low to Moderate Salinity
Authors: Zhang Qi , Rue Kevin
Published: February 2019

Saline and alkaline conditions often coexist in nature. Unlike salinity that causes osmotic and ionic stresses, alkalinity reflects the impact of high pH on plant growth and development. In this research, seven turfgrass species, tall fescue (Festuca arundinacea Schreb.), kentucky bluegrass (Poa pratensis L.), creeping bentgrass (Agrostis stolonifera L.), perennial ryegrass (Lolium perenne L.), zoysiagrass (Zoysia japonica Steud.), bermudagrass [Cynodon dactylon var. dactylon (L.) Pers.], and alkaligrass [Puccinellia distans (Jacq.) Parl.], were germinated under 10 saline–alkaline conditions [two salinity concentrations (25 and 50 mm) × five alkalinity levels (pH = 7.2, 8.4, 9.1, 10.0, 10.8)] in a controlled environment. Seed germination was evaluated based on final germination percentage and daily germination rate. Alkaligrass and kentucky bluegrass showed the highest and lowest germination under saline conditions, respectively. Limited variations in germination were observed in other species, except bermudagrass, which showed a low germination rate at 50 mm salinity. Alkalinity did not cause a significant effect on seed germination of tested turfgrass species.
Farmers’ Perceptions, Production and Productivity Constraints, Preferences, and Breeding Priorities of Sweetpotato in Rwanda
Authors: Placide Rukundo , Shimelis Hussein , Laing Mark , Gahakwa Daphrose
Published: February 2019

The role of farmers and their production constraints and preferences are important for sweetpotato breeding and adoption of cultivars and agronomic production packages. The objective of this study was to assess farmers’ perception, production constraints, preferences, and breeding priorities of sweetpotato in selected agro-ecologies of Rwanda. A total of 495 farmers were surveyed in 2013 in eight representative districts: Bugesera and Kayonza in the Eastern Province, Gakenke and Rulindo in the Northern Province, and Gisagara, Huye, and Muhanga in the Southern Province. Data were collected through a participatory rural appraisal (PRA) methodology using a semistructured questionnaire and focus group discussions. Pairwise comparison of 16 food crops allocated sweetpotato as one of the five important food crops for food security and income generation. Drought stress, unavailability of improved cultivars and planting material, and pest and disease damage were perceived to be the five main constraints limiting sweetpotato production, contributing to 17.3%, 15.0%, 12.9%, 11.7%, and 11.5%, respectively. The most important sweetpotato cultivar traits had high yield, early maturity, drought tolerance, disease and pest tolerance, and good culinary taste at 22.5%, 18.5%, 15.4%, 12.7%, and 10.1%, respectively. The characteristics of good storage roots identified by farmers included high dry matter content, good culinary taste, good shape, root size, and sweetness representing 27.4%, 18.8%, 16.1%, 11.6%, and 9.4%, respectively. Each agro-ecological zone has its own specific sweetpotato production constraints and farmers’ preferences, necessitating targeted breeding of different sweetpotato cultivars for each agro-ecological zone for enhanced productivity and successful adoption of cultivars.
Amplified Fragment Length Polymorphism Analysis of Genetic Diversity and Relationships of Wild and Cultivated Peach (Prunus persica L.)
Authors: Meng Fanjuan , Peng Mu , Guan Fachun
Published: February 2019

To date, a narrow genetic base is a serious obstacle in peach (Prunus persica L.) production. Wild peach resources are useful germplasms for breeding new cultivars. In this study, amplified fragment length polymorphisms (AFLPs) were used to analyze the genetic diversity and relationships of wild and cultivated peach germplasms. These results showed that AFLP is an efficient technique for identifying the genetic relationships of wild and cultivated peach. Thirteen AFLP primer combinations generated a total of 377 scorable and clear fragments, all of which (100%) were polymorphic. Moreover, the polymorphism information content (PIC) values ranged from 0.91 to 0.96 with a mean of 0.95. The results of the principal component analysis (PCoA) largely corresponded to those obtained using cluster analysis. The three principal axes accounted for 2.6%, 5.79%, and 25.26% of the total variation, respectively. In conclusion, wild peach germplasms should receive special attention to ensure their conservation.
Evaluation of an Organic Nitrogen Source in a Yellow Squash–Collard Rotation
Authors: Ogles Charles Zachry , Kemble Joseph M. , Wright Amy N. , Guertal Elizabeth A.
Published: February 2019

In-season nitrogen (N) management is a common challenge in organic vegetable production. This is especially true when using polyethylene mulch combined with fertigation. Soluble organic N sources suitable for fertigation in organic vegetable production are needed. The objective of this research was to evaluate an organic fish fertilizer in a squash/collard rotation and to compare its effectiveness to inorganic sources. A 2-year crop sequence of yellow squash (Cucurbita pepo) and collards (Brassica oleracea var. acephala) was used. To eliminate the rotation order effect, the crops were switched each year: yellow squash-collard in Year 1 and collard-yellow squash in Year 2. Three N sources were used along with a zero N control: hydrolyzed fish fertilizer (HFF), inorganic N source with secondary and micronutrients (INORGWM), and inorganic N without secondary or micronutrients (INORGWO). Three N rates and a control were also included: 1) N at the recommended rate (152 kg·ha−1 for yellow squash and 110 kg·ha−1 for collards); 2) N at 80% of the recommended rate; 3) N at 60% of the recommended rate; and 4) a zero N control. Year 2012 yellow squash had a 30% higher yield when grown with inorganic N as compared with squash grown in HFF. Year 2012 collards had a 21% higher yield when grown with INORGWM as compared with collards grown in the HFF. In the second year, highest yields of collards were again produced in the INORGWM treatments followed by those grown in the HFF treatments. Second-year squash grown in the inorganic N treatments produced highest yields, and squash grown in the HFF had a 16% lower yield as compared with those grown in the two inorganic N sources. INORGWO produced lower marketable collard yields than INORGWM or HFF as a result of sulfur deficiency. Although yields were reduced in the crops grown in HFF treatments, the premium price and resultant profit associated with organic products were enough to offset the reduced yield. If growers can obtain the price premiums associated with organic produce, the use of HFF could be an economically feasible option in organic vegetable production.
Factors Affecting School Grounds and Athletic Field Quality after Pesticide Bans: The Case of Connecticut
Authors: Bartholomew Candace , Campbell Benjamin L. , Wallace Victoria
Published: February 2019

Pesticide laws focused on school grounds/athletic fields are beginning to take shape around the United States. A body of literature has examined the health implications of pesticides on school children and faculty and staff. However, little research has examined the impact of changing pesticide regulations on grounds/field quality and expenses. Our research indicate that school grounds/field managers have perceived decreased quality after the Connecticut kindergarten to eighth grade pesticide ban went into effect in 2010. Furthermore, we find that educational sessions or increased expenditures on school grounds/fields can increase the probability of maintaining field quality at integrated pest management levels. However, we see that lower income areas are more likely to experience decreased grounds/field quality after the lawn care pesticide ban took effect.
Temperature, Daylength, and Cultivar Interact to Affect the Growth and Yield of Lettuce Grown in High Tunnels in Subtropical Regions
Authors: Lee Ah-Chiou , Liao Fang-Shin , Lo Hsiao-Feng
Published: February 2019

The production of lettuce, a cool-season leafy vegetable, in high tunnels the year around is a challenge for growers in subtropical regions. The aims of this research were to characterize the growth of locally grown lettuce cultivars, develop a new high-yielding cultivar by crossing romaine-type lettuce ‘Jhih Li Wo’ and Batavia type lettuce ‘Fu San’, and determine the relationships between climatic variables, temperature, and daylength, and days to harvest for maximum marketable yield (DMMY) in individual cultivars in high tunnels. Nine cultivars were grown in high tunnels in the spring and winter of 2008 and summer of 2009 to evaluate growth and maximum marketable yield (MMY), the latter being defined as the aboveground fresh weight of 5 ± 0.7 cm of plant stem. Romaine lettuce ‘Jhih Li Wo’ had a higher growth rate during the initiation of plant growth in the spring of 2008. ‘Jhih Li Wo’ and Batavia lettuce ‘Fu San’ also showed higher growth rate before harvest for the MMY (GRBHD) and exhibited higher MMY and DMMY than butterhead lettuce and leaf lettuce cultivars under summer and winter regimes. However, landraces of leaf lettuce are the main lettuces grown in high tunnels in summer rather than ‘Fu San’ and ‘Jhih Li Wo’ due to their needing fewer DMMY and having a more upright growth form. Among nine cultivars studied, Batavia lettuce ‘Fu San’, romaine lettuce ‘Jhih Li Wo’, and landrace ‘Bai Yeh Wo’ were found to be more adaptable to summer weather. Genotypes with superior growth and yield traits are essential for not only production but also breeding. A new cultivar, Taoyuan No.3, was developed by introducing the high growth rate trait during the initial period of plant growth from romaine lettuce ‘Jhih Li Wo’ into high-yielding Batavia lettuce ‘Fu San’. Another experiment was performed over eight successive seasons to analyze the correlation of temperature and daylength on DMMY for each cultivar using multiple regression analysis from 2008 to 2009. This showed that the proposed models expressed as coefficients of multiple determinants (R2) accounted for 72% to 91% of the total variation in DMMY in each cultivar. Temperature affected DMMY the most and the relative contributions of temperature and daylength to DMMY differed with cultivar. These results provide information about production practices for growers in subtropical regions to use in choosing suitable lettuce cultivars.
Identification of South African Bermudagrass Germplasm with Shade Tolerance
Authors: Dunne Jeffrey C. , Reynolds W. Casey , Miller Grady L. , Arellano Consuelo , Brandenburg Rick L. , Schoeman A. , Yelverton Fred H. , Milla-Lewis Susana R.
Published: February 2019

Bermudagrass, Cynodon spp. is one of the most commonly grown turfgrass genera in the southern United States having excellent drought tolerance, but poor tolerance to shade. Developing cultivars tolerant to shade would allow bermudagrass to become more prevalent in home lawns or other recreational areas in the southeast, where trees dominate the landscape. In this field study, nine accessions collected from Pretoria, South Africa were evaluated for their ability to grow under shade with varying fertility treatments. These accessions and cultivars ‘Celebration’, ‘TifGrand’, and ‘Tifway’ were evaluated under 0%, 63%, and 80% continuous shade during 2011–12. For both years, significant differences among shade levels, genotypes, and the interaction of the two were observed. As expected, the progression from 0% to 63% to 80% shade reduced normalized difference vegetation index (NDVI), percent turfgrass cover (TC), and turf quality (TQ) readings for all accessions. Some genotypes, however, were able to maintain adequate quality and aggressiveness under 63% shade. ‘Celebration’, WIN10F, and STIL03 performed better than ‘Tifway’ (P ≤ 0.05), the susceptible control. Overall, our results indicate that there are promising genotypes among the bermudagrass materials collected from South Africa. These accessions represent additional sources of shade hardiness to be used in bermudagrass breeding. Furthermore, higher nitrogen fertility provided increased NDVI and TQ in some instances suggesting an added benefit of fertility under low-light conditions. However, the increased economic value attributed to the added inputs associated with these increases is outweighed by the low impacts offered.