bluuebunny/crossref_metadata_2025 huggingface dataset:
Fruit Trait Variation in a Caribbean Germplasm Collection of Aromatic Hot Peppers (Capsicum chinense Jacq.)
Authors: Bharath Sarah M. , Cilas Christian , Umaharan Pathmanathan
Published: February 2019

Aromatic hot peppers (Capsicum chinense Jacq.) are an important agricultural commodity for many small-scale farmers in the Caribbean because it is a commercially viable crop and one that is integral to the cuisines of the region. The large variation in fruit shape, size, color, pungency, and aroma of this species facilitates a diverse range of uses. Using 264 accessions from a Caribbean germplasm collection (representing primarily the Caribbean Basin, Central and South America), this study investigated 1) morphological variation in 13 fruit descriptors of agro-economic importance; and 2) morphological groups based on geographic origin. All 13 fruit descriptors showed significant variation. Fruit color [immature (six states) and mature (12 states)] was the most diverse qualitative fruit trait. Among the quantitative traits, fruit weight and fruit width showed the highest broad-sense heritability (0.81), and fruit weight was highly correlated with fruit width and placenta size. Cluster analysis revealed four main clusters, which did not show a clear separation of accessions based on major geographic regions, but there was a highly significant association (P < 0.0001) between geographic subgroups and the clusters to which they were assigned. Most accessions of the Northern Caribbean (particularly the Bahamas and Puerto Rico) separated quite distinctly from most accessions of the Southern Caribbean and clustered with most accessions of Central and South America. Accessions of the Southern Caribbean (Lesser Antilles, Trinidad & Tobago) were substantially more similar to each other than they were to most accessions of Central and South America, thereby suggesting genetic differences between accessions of the Southern Caribbean islands and the mainland populations. Collectively, the results show that this germplasm collection contains useful accessions with desired fruit quality traits and a level of genetic variation that can be used to encourage its active conservation and use for further evaluation trials and crop improvement as well as guide ongoing complementary germplasm introductions to augment the collection’s diversity.
Training System Affects Sweet Cherry Harvest Efficiency
Authors: Ampatzidis Yiannis G. , Whiting Matthew D.
Published: February 2019

Intuitively, tree architecture will affect harvest efficiency of tree fruit crops, yet there are no empirical studies that document this. The objective of the current research was to investigate the role of training system on harvest rate of individual pickers in commercial sweet cherry (Prunus avium L.) orchards. We used a real-time labor monitoring system (LMS) with the ability to track and record individual picker efficiency in 11 orchards throughout the Pacific Northwest. Trees were trained to one of five different architectures: 1) upright fruiting offshoots (UFO), a planar architecture comprised of unbranched vertical fruiting wood; 2) Y-trellised, an angled dual planar architecture; 3) Kym Green Bush (KGB), a multileader bush; 4) central leader (CL); and 5) traditional multileader open center (MLOC), trees comprised of three to five main leaders. A consistent picking crew was used to facilitate comparisons among systems and eliminate variability in skill among pickers. The LMS calculated harvest rate, picking cost, weight of harvested fruit, number of harvested buckets, range in fruit weight per bucket/bin, and mean fruit weight per bucket/bin for individual pickers. Tests revealed a significant effect of canopy architecture on labor efficiency. The highest mean (± se) harvest rates (0.94 ± 0.02 kg·min−1 and 0.78 ± 0.03 kg·min−1) were recorded in ‘Cowiche’/‘Gisela®5’ and ‘Tieton’/‘Gisela®5’ orchards trained to the UFO system, respectively. High harvest efficiency in these orchards was likely the result of the planar, simplified architecture and that most fruit were accessible from the ground. The third highest picking rate was recorded in the KGB system (0.73 ± 0.04 kg·min−1), a fully pedestrian orchard. Interestingly, harvest rate of slower pickers was improved to a greater extent (+132%) than skilled pickers (+83%) when comparing pedestrian and planar systems (e.g., UFO and KGB) with traditional architecture (MLOC). Furthermore, picking rate of individual pickers varied within 1 day by more than 100%, likely as a result of variability in fruit density within trees, tree size as well as fruit accessibility. We documented variability of more than 35 kg in final bin weight across all orchards and a range in bucket weight between ≈7 and 13 kg. These results suggest that architecture has a major effect on harvest efficiency and that current systems of piece-rate picker reimbursement are beset with inaccuracy.
Effects of Fertilization, Arbuscular Mycorrhiza, and Salinity on Growth, Yield, and Bioactive Compounds of Two Aloe Species
Authors: Cardarelli Mariateresa , Rouphael Youssef , Rea Elvira , Lucini Luigi , Pellizzoni Marco , Colla Giuseppe
Published: February 2019

Three greenhouse experiments were carried out to compare the responses of Aloe arborescens and Aloe barbadensis with organic fertilization (standard or reduced fertilization level), arbuscular mycorrhiza [with AM (+AM) or without AM (–AM)], and salinity (1 or 80 mm NaCl) in terms of plant growth, leaf yield, mineral composition, and nutraceutical value. In all experiments, the yield of fresh leaves was significantly higher by 320%, 252%, and 72%, respectively, in A. barbadensis in comparison with A. arborescens. Doubling the fertilizer dose, plant growth parameters increased, but the bioactive compounds were negatively affected. The highest antioxidant activity was recorded with A. barbadensis using both fertilization regimes, whereas the highest values of anthraquinones aloin were observed in A. barbadensis using a reduced fertilization regime and when plants were inoculated with AM fungi. β-polysaccharide concentration was significantly higher in A. barbadensis in comparison with A. arborescens and was increased by 33% when plants were inoculated with AM fungi. In both Aloe species, increasing the salinity decreased the leaf fresh weight and total dry biomass but increased the aloin and β-polysaccharides content by 66% and 21%, respectively. The results suggest that cultural practices such as organic fertilization, inoculation with AM fungi, and irrigation with saline water can represent effective tools to achieve a more favorable phytochemical profile.
Uptake Efficiency of Phosphorus in Different Light Environments by Zinnia (Zinnia elegans) and Vinca (Catharanthus roseus)
Authors: Frantz Jonathan M.
Published: February 2019

Two warm-season bedding plant species, zinnia (Zinnia elegans) and vinca (Catharanthus roseus), were used to determine if phosphorus (P) supply should be adjusted with light supply, and if deficiency and/or oversupply symptoms were apparent at different P rates when growth rates were altered by light levels. An additional goal was to determine the influence of P and light on overall P uptake efficiencies and water use efficiencies. Plants were grown in a greenhouse with or without shade over portions of the bench and supplied 0.1, 0.2, 0.5, 1, 2, or 4 mm P along with complete nutrient solution as needed with no leaching fraction. Optimum plant growth and flower development rate occurred at a P supply of 0.5 mm regardless of the light supply. Plant growth was greatly reduced by P supply below 0.5 mm regardless of shade conditions. Tissue P concentration was not influenced by light, but overall P content (mg P per plant) was higher when plants were grown without shading as a result of larger plants in higher light environments. The appearance or severity of deficiency symptoms also was not influenced by light. Water use efficiency was maximized when growth was not limited by P supply (at or above 0.5 mm). One hundred percent recovery of applied P was obtained at the 0.5 mm P supply in vinca, whereas recovery was less at the same P supply in zinnia. These results indicate no benefit for plant growth and flowering to P supply above 0.5 mm and illustrate how P content is demand-driven. However, there was no induction or delay of nutrient stress symptoms as a result of different plant growth rates in the different light differences environments.
Composted Dairy Manure and Alfalfa Hay Mulch Affect Soil Ecology and Early Production of ‘Braeburn’ Apple on M.9 Rootstock
Authors: Forge Tom , Neilsen Gerry , Neilsen Denise , Hogue Eugene , Faubion Dana
Published: February 2019

A variety of organic mulches and amendments have been observed to improve soil quality and productivity of apple orchards. Alfalfa hay and composted dairy manure solids (CDS) are readily available in the apple-growing region of the Pacific Northwest and British Columbia and could be used to improve orchard performance. The objective of this research was to determine the influences of CDS amendment and alfalfa hay mulch on populations of soil microfauna, soil chemical properties, and early growth; nutrient uptake; and yield of apple planted into a fumigated coarse-textured soil in central Washington State. Alfalfa mulch significantly improved tree vigor and fruit yield with minimal adverse effects on fruit quality, whereas the CDS amendment had minor effects on vigor and yield. Both alfalfa mulch and CDS amendment increased availability and uptake into leaves and fruit of most key nutrients but plant nutrient concentrations were not deficient in control plots, suggesting that increased nutrient availability was probably not the primary reason for the increased vigor attributed to alfalfa mulch at this site. The alfalfa mulch resulted in elevated populations of microbivorous nematodes and protozoa that persisted through later years of the experiment, indicating greater overall microbial activity, mineralization of nutrients, and possible direct stimulation of root growth under mulch; the CDS amendment did not consistently enhance populations of microbivorous nematodes. The alfalfa mulch, but not CDS amendment, suppressed the buildup of populations of root-lesion nematodes, which are important components of the replant disease complex that was suppressing tree growth at the site despite the preplant fumigation. Accordingly, we speculate that the reduced impacts of root-lesion nematodes contributed to the improved vigor and fruit yield of trees grown with alfalfa hay mulch.
Ethephon Improved Pigmentation but Had No Effect on Cayenne Pepper Fruit Yield in Southern New Mexico
Authors: Uchanski Mark E. , Blalock Adam
Published: February 2019

In the desert southwest of the United States, cayenne pepper (Capsicum annuum L.) is an important crop. It is used in the production of hot sauce mash, the precursor to many hot sauces. Because hand harvest is currently required to accommodate staggered crop development, more uniform maturity is desired to facilitate mechanical harvest to decrease labor costs. This study was performed over 3 years (2009–11) and in two locations in southern New Mexico, resulting in five unique year/location scenarios (environments). Four timings of ethephon (0.56 kg a.i./ha) spray applications were evaluated for their potential to increase red cayenne cv. Mesilla yields and percentage of red pods. If yield increases and pigmentation improvements occur, ethephon may facilitate a once-over mechanical harvest. Ethephon was applied once at four key cayenne growth stages based on heat units accumulated after planting (HUAP): 1400 HUAP (late June to early July), 1800 HUAP (mid-July), 2800 HUAP (late August to early September), and 3100 HUAP (mid- to late September). Application timings corresponded to early bloom, peak bloom, late physiological maturity of plants, and preharvest, respectively. A non-sprayed control was also included. Fresh red, green, and non-marketable pod weights were recorded for each treatment in a once-over simulated machine harvest in October and analyzed for statistical differences. Mid- to late-season (2800–3100 HUAP) ethephon treatments significantly decreased undesirable green pod yield and, therefore, increased red pod percentage in four of five environments. Although a red pod yield increase was only observed in one environment (a drip-irrigated plot in 2010), there were no negative impacts on red pod yield in any environment resulting from ethephon application. In addition, pepper quality (yield of unmarketable pods) was not significantly reduced by ethephon. Previous work has focused on increasing red pod yields with mixed results. The results show that ethephon may synchronize cayenne pepper red fruit maturity necessary for mechanical harvest and reduce the labor involved in removing green pods before processing.
In Vitro Culture and Rooting of Diospyros virginiana L.
Authors: Palla Kaitlin J. , Beasley Rochelle R. , Pijut Paula M.
Published: February 2019

The hard, strong, very close-grained wood of common persimmon (Diospyros virginiana L.; Ebenaceae) is desirable for specialty products such as golf club heads, percussion sticks, billiard cues, and for wood turnery. The edible fruit of cultivated varieties is sold as pulp for use in puddings, cookies, cakes, and custards. Persimmon is usually propagated by grafting. Own-rooted clonal persimmon could offer several advantages to specialty fruit growers such as elimination of grafting, graft incompatibility issues, and improved rootstocks for variety testing. Four mature, grafted (male and female) persimmon genotypes and one hybrid were used for nodal explant culture. Nodal stem explants were cultured on Murashige and Skoog (MS) medium containing 10 μM zeatin, 3% (w/v) sucrose, and 0.7% (w/v) Bacto agar. Explants were routinely transferred to fresh medium every 3 weeks until shoot cultures were established. All nodal explants excised from grafted greenhouse plants produced at least one viable shoot. For in vitro rooting of microshoots, half-strength MS medium with 0, 5, 10, or 15 μM indole-3-butyric acid (IBA), 0.1 g·L−1 phloroglucinol, 3% (w/v) sucrose, and 0.7% (w/v) Bacto agar were tested with a 10-day dark culture treatment followed by culture in the light. Best rooting (14% to 87%) was achieved on medium containing 5 μM IBA for the common persimmon genotypes with means averaging from 0.5 to 3.9 roots per shoot. Ninety-one percent rooting with 5.3 ± 2.6 roots per shoot was achieved for the hybrid persimmon. Rooted plants were successfully acclimatized to the greenhouse.
Responses of Growth and Mineral Nutrition of Garden Roses to Saline Water Irrigation
Authors: Niu Genhua , Starman Terri , Byrne David
Published: February 2019

The responses of garden roses to irrigation water with elevated salts are unknown. Two experiments were conducted to evaluate the relative salt tolerance of 13 self-rooted rose cultivars by irrigating the plants with nutrient solutions at an electrical conductivity (EC) of 1.4 dS·m−1 (control) or nutrient saline solutions at EC of 3.1, 4.4, or 6.4 dS·m−1. In Expt. 1, ‘Belinda’s Dream’, ‘Caldwell Pink’, ‘Carefree Beauty’, ‘Folksinger’, ‘Quietness’, and ‘Winter Sunset’ plants were grown in a greenhouse from 13 Aug. to 21 Oct. (10 weeks). Shoot dry weight of all cultivars decreased as EC of irrigation water increased. ‘Winter Sunset’ was most sensitive among these cultivars to salt stress followed by ‘Carefree Beauty’ and ‘Folksinger’ with severe leaf injury at EC of 3.1 dS·m−1 or higher or death at EC of 6.4 dS·m−1. No visual damage was observed in ‘Belinda’s Dream’ or ‘Caldwell Pink’, regardless of the salinity level. In Expt. 2, ‘Basye’s Blueberry’, ‘Iceberg’, ‘Little Buckaroo’, ‘The Fairy’, ‘Marie Pavie’, ‘Rise N Shine’, and ‘Sea Foam’ plants were grown in the greenhouse from 29 Sept. to 16 Nov. (7 weeks) and irrigated with the same nutrient or nutrient saline solutions. Salinity treatment did not affect shoot dry weight of ‘Basye’s Blueberry’, ‘Little Buckaroo’, ‘Sea Foam’, and ‘Rise N Shine’. Shoot dry weight of ‘Iceberg’, ‘The Fairy’, and ‘Marie Pavie’ decreased as EC of irrigation water increased. No or little visual damage was observed in ‘Little Buckaroo’, ‘Sea Foam’, and ‘Rise N Shine’. Leaf tip burns were seen in ‘Iceberg’, ‘Marie Pavie’, ‘Basye’s Blueberry’, and ‘The Fairy’ at EC 6.4 of dS·m−1. Generally, these symptoms were less severe than those observed in Expt. 1, probably attributable partially to the shorter treatment period. Whereas shoot Na+ and Cl– varied greatly among the rose cultivars, the shoot concentrations of Ca2+, K+, and Mg2+ did not. Generally, salinity-tolerant cultivars had higher shoot Na+ and Cl– concentrations. In summary, in Expt. 1, ‘Belinda’s Dream’ was the most tolerant cultivar, whereas ‘Winter Sunset’ was the least tolerant followed by ‘Carefree Beauty’. In Expt. 2, ‘Iceberg’, ‘Marie Pavie’, and ‘The Fairy’ were less tolerant to salinity as compared with other cultivars, although the differences were small.
Stolons Reserves and Spring Green-up of Seeded Bermudagrass Cultivars in a Transition Zone Environment
Authors: Giolo Maurizio , Macolino Stefano , Barolo Erica , Rimi Filippo
Published: February 2019

Bermudagrass is the most widely used warm-season turf species in the transition zones of Europe. The Venetian valley (northeastern Italy) is a typical transitional zone, characterized by cold winters and hot summers, where the performance of bermudagrass mostly depends on cold tolerance and duration of winter dormancy. A 2-year field study was conducted from May 2009 to July 2011 at the agricultural experimental farm of Padova University. The objective of this study was to assess the relationships occurring between spring green-up of seeded bermudagrasses and their nonstructural carbohydrates and crude protein (CP) content in stolons during late winter. The cultivars used were ‘Caribe’, ‘Mohawk’, ‘Princess-77’, ‘Sultan’, ‘SWI 1012’, and ‘Jackpot’. The plots were seeded in May 2009 and turf samples were collected in Mar. 2010 and 2011 for determination of stolons dry weight, diameter, and content of carbohydrates and CP. ‘Princess-77’ had lower content of starch in stolons compared with the other cultivars and was characterized by late spring green-up. The cultivars tested showed wide differences in stolons morphology (dry weight and diameter), whereas there were poor diversity for CP and water-soluble carbohydrates (WSC) in both years of research. Correlation analyses indicated a negative relationship between the days of the year necessary for spring green-up and stolons starch content and also between CP and starch. Moreover, there was a positive correlation between stolons starch and diameter, suggesting that spring green-up may be enhanced by selection of high starch-accumulating cultivars having coarse stolons.
Year-round Variations in Essential Oil Content and Composition of Male and Female Juniper
Authors: Zheljazkov Valtcho D. , Astatkie Tess , Jeliazkova Ekaterina
Published: February 2019

Rocky Mountain juniper (Juniperus scopulorum Sarg.) is an evergreen dioecious tree (produces male and female plants). The pleasant aroma and the medicinal value of this species are the result of the essential oil. The hypothesis of this study was that the essential oil content and composition may be different in male and in female trees and also may be affected with seasonal changes throughout the year. The objective was to evaluate year-round variations in essential oil composition of Rocky Mountain juniper within single male and female trees. The concentration of essential oil in fresh leaves varied from 0.335% to 0.799%, and at most sampling points, the oil content in the biomass of the male tree was greater than that in the biomass of the female tree. There was a trend toward increased essential oil content in male juniper in 220 to 342 days after the first sampling (DAFS), compared with the one in 35 to 184 DAFS. The concentrations of the oil constituents alpha-pinene, alpha-terpinene, gamma-terpinene, terpinolene, pregeijerene B, elemol, beta-eudesmol/alpha-eudesmol, and 8-alpha-acetoxyelemol were greater in the oil of the female tree than in the oil of the male tree. Conversely, the concentrations of alpha thujene, sabinene, myrcene, limonene, and delta-cadinene were greater in the oil of the male tree than in the oil of the female tree. However, the concentration gradient trends for both female and male trees were similar for myrcene and sabinene, for alpha-terpinene and terpinolene, for pereijerene B and elemol, and for beta-eudesmol/alpha-eudesmol and 8-alpha-acetoxyelemol. Overall, lower concentrations in the oils at 101 to 132 or 163 DAFS were found for myrcene and alpha-pinene sabinene, whereas the concentrations of gamma-terpinene, elemol (female tree), beta-eudesmol/alpha-eudesmol (female tree), and 8-alpha-acetoxyelemol (female tree) were greater during this period. This study demonstrated that the content and composition of the essential oil from Rocky Mountain juniper are subject to seasonal changes and also depend on the sex of the tree.
Direct Shoot Organogenesis in Murraya paniculata (L.) Jack: A Prerequisite for Genetic Transformation
Authors: Shen Xiuli , Orbović Vladimir , Dutt Manjul , Castle William S. , Gmitter Frederick G.
Published: February 2019

An efficient in vitro regeneration system through direct shoot organogenesis was established for Murraya paniculata (L.) Jack (Orange Jessamine). Epicotyls, leaves, roots, and cotyledons from in vitro-germinated seedlings and several plant growth regulators (PGRs) were evaluated for their effects on plant regeneration. Longitudinally cut epicotyl segments were observed to be the optimal explants followed by uncut epicotyls (not longitudinally cut). Roots, leaves, and cotyledons were not suitable as explants as a result of little or no shoot induction. Adventitious shoot induction was enhanced by the addition of 6-benzyladenine (BA). The highest percentage of shoot induction (87%) and the greatest number of shoots per explant (12.7) occurred on Murashige and Skoog (MS) medium supplemented with 15 μM BA from longitudinally cut epicotyls followed by 5.2 shoots per explant from uncut epicotyls. Optimal concentration of gibberellic acid (GA3) for shoot elongation was observed to be 15 μM. Eighty-five percent of the regenerated shoots produced roots with an average of three roots per shoot on MS medium supplemented with 5 μM indole-3-butyric acid (IBA). Our protocol for direct shoot organogenesis can potentially lead to the development of a robust method for production of transgenic plants of M. paniculata through Agrobacterium-mediated genetic transformation.
Environmental Stress and Methyl Jasmonate-mediated Changes in Flavonoid Concentrations and Antioxidant Activity in Broccoli Florets and Kale Leaf Tissues
Authors: Ku Kang Mo , Juvik John A.
Published: February 2019

Aqueous solutions of 250 μM methyl jasmonate (MeJA) were sprayed on aerial plant surfaces 4 days before harvest at commercial maturity of five commercial broccoli (Brassica oleracea L. var. italica) hybrids, ‘Pirate’, ‘Expo’, ‘Imperial’, ‘Gypsy’, and ‘Green Magic’, and two kale cultivars, Red Winter (Brassica napus ssp. pabularia) and Dwarf Blue Curled Vates (Brassica oleracea L. var. acephala DC.) in replicated field trials over 2 years. While having no effect on broccoli floret concentrations, MeJA treatments significantly increased total phenolics in kale cultivars over two seasons by 27% and extract antioxidant activity by 31% using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Partitioning experiment-wide trait variances indicated that the variability in broccoli floret concentrations of total phenolics (74%), quercetin (24%), kaempferol (34%), and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) (66%) and DPPH (62%) antioxidant activity was largely influenced by year-associated environmental factors. In broccoli, the differential accumulation of solar radiation among cultivars resulting from the variation in days to maturity was significantly correlated with total phenolics, ABTS, and DPPH antioxidant activity. Broccoli floret and kale total phenolic, quercetin, and kaempferol concentrations significantly correlated with DPPH and ABTS antioxidant activity. To summarize, total phenolic and flavonoid concentrations and their associated antioxidant activity in broccoli florets were unaffected by MeJA but varied significantly among cultivars and over growing seasons. Apical, compared with basal, leaves in kale were more responsive to MeJA-mediated increases in total phenolics and ABTS and DPPH antioxidant activity.
Wetland Technologies for Nursery and Greenhouse Compliance with Nutrient Regulations
Authors: White Sarah A.
Published: February 2019

The need to protect our water resources and increasing public awareness of the importance of cleaner water for ecological and human health reasons are driving regulations limiting nutrient release from traditionally exempt, non-point source agricultural contributors. Modification of production practices alone may not be adequate to meet regulated nutrient criterion limits for irrigation and stormwater runoff entering surface waters. Three constructed wetland technologies are well suited to help agricultural producers meet current and future regulations. The first two technologies, surface- and subsurface-flow constructed wetlands, have been in use for over 40 years to cleanse various types of wastewater, whereas floating treatment wetlands are an emerging remediation technology with potential for both stormwater and agricultural runoff treatment applications. The mechanisms driving removal of both nitrogen (N) and phosphorus (P) in constructed wetland systems are discussed. Surface-flow constructed wetlands remediate N contaminants from both container nursery and greenhouse production wastewater, whereas P remediation is variable and tied most closely to active plant growth as the constructed wetland ages. Subsurface-flow constructed wetlands effectively remediate N from production wastewater and can be tailored to increase consistency of P remediation through selection of P-sorbing root-bed substrates. Floating treatment wetlands effectively remediate both N and P with a designed surface area of a pond covered depending on the target effluent concentration or regulated total maximum daily load. The choice of treatment technology applied by growers to meet regulated water quality targets should be based on both economic and site-specific considerations.
Watermelon Quality Traits as Affected by Ploidy
Authors: Davis Angela R. , Webber Charles L. , Liu Wenge , Perkins-Veazie Penelope , Levi Amnon , King Stephen
Published: February 2019

High-quality, high-phytonutrient watermelons [Citrullus lanatus (Thumb.), Matsum & Nakai] have strong market opportunities. To produce highly nutritious fruit in a seedless triploid market, the nature of phytonutrient accumulation as affected by ploidy must be understood. The present study performed on six field-grown watermelon diploid (2n) inbred lines, their induced autotetraploids (4n), and autotriploids (3n) determined the importance of ploidy on quality and nutritional content. Lycopene, total soluble solids (TSS), L-citrulline (hereafter referred to as citrulline), glutathione (GSH), weight, width, and length were measured in ripe fruit from one location. Our findings contradict some previous manuscripts, which did not use diploid inbred lines and their induced autoploidy relatives. Of the traits we analyzed that did not have a family-by-ploidy interaction (citrulline, GSH, weight, and width), we determined citrulline levels were not significantly affected by ploidy in five of six families nor was there a significant correlation when all family’s citrulline values were averaged. Previous studies on field-grown fruit that did not use autoploidy lines suggested triploid fruit had more citrulline than diploid fruit. GSH was higher in autotriploid than in diploid or autotetraploid (95.0 vs. 66.9 or 66.7 μg·g−1 GSH, respectively). Additionally, we found an association with higher GSH in larger fruit. Autotriploid fruit were, in general, heavier and wider than diploid and autotetraploid fruit, and autotetraploid fruit were generally smaller than diploid fruit. Of the traits we analyzed that had a family by ploidy interaction (lycopene, TSS, and length), we determined within four families, ploidy affected lycopene concentration, but whether this interaction is positive or negative was family-dependent. These data suggest the triploid state alone does not give fruit higher lycopene concentrations. The mean TSS was higher in autotetraploid than in autotriploid, which was again higher than in diploid fruit averaged across families (10.5%, 10.2%, and 9.5% TSS, respectively); there was a family × ploidy interaction so the significance of this increase is affected by the triploid’s parents. Lycopene and TSS had a slight positive correlation. Four of six families showed no statistical correlation between ploidy and length, and although mean length across family demonstrated smaller tetraploid fruit, the family-by-ploidy interaction demonstrates that this observation is family-dependent. Length and width correlate well with weight when combining data for all ploidy levels and when analyzing each ploidy separately. Length correlates more closely with width in autotriploid fruit than in diploid or autotetraploid fruit.
Branching and Blind Node Incidence in Interspecific Backcross Families of Peach
Authors: Carrillo-Mendoza Omar , Chaparro José X. , Williamson Jeffrey
Published: February 2019

Tree size and branching control has gained importance as labor and pruning costs have increased. In addition, the occurrence of blind nodes is a critical factor that affects peach tree architecture and productivity in subtropical climates. Seven backcross families segregating for branching and blind nodes were developed using ‘Flordaguard’ peach × P. kansuensis or ‘Tardy Nonpareil’ almond F1s backcrossed to ‘AP00-30WBS’, ‘UFSharp’, or ‘UF97-47’ peach selections and evaluated for branching index and blind node frequency during the winters of 2010 and 2011. P. kansuensis backcrosses presented increased branching and lower blind node incidence, whereas almond backcrosses presented less branching and higher blind node incidence, resembling the P. kansuensis and almond F1 parents, respectively. There was also broad variability for branching and blind nodes within the P. kansuensis and ‘Tardy Nonpareil’ almond backcross families influenced by the peach parents that were used to generate the backcross populations. The moderate heritability and year-to-year correlation for these traits indicate that they are affected by the environment, but selection for reduced branching and lower blind node incidence is feasible.
Instrumental Textural Analysis of Muscadine Grape Germplasm
Authors: Conner Patrick J.
Published: February 2019

Twenty-six muscadine grape (Vitis rotundifolia Michx.) cultivars and selections were evaluated for a range of skin and flesh texture attributes. Two Vitis vinifera L. and one Vitis labruscana Bailey table grape cultivars were included for comparison. Penetration tests using a flat cylindrical probe were used to assess whole berry texture. Ideal whole berry texture is firm and easily broken down during mastication, which was measured as small berry deformation at first peak and berry maximum force, respectively. Muscadine berry deformation at first peak ranged from 4.35 to 7.82 mm and berry maximum force ranged from 5.7 to 13.9 N. V. vinifera table grape berries were firmer (3.14 to 3.19 mm berry deformation at first peak) and more tender (4.0 to 4.9 N berry maximum force) than muscadine berries. Berry penetration work was strongly correlated with both berry deformation at first peak and berry maximum force and ranged from 13.0 to 54.1 mJ in the muscadine germplasm. Penetration tests of muscadine berry flesh revealed a range of flesh firmness from very soft (0.65 N) to firm (3.06 N) but none was as firm as the V. vinifera berry flesh (3.9 N). Penetration tests of muscadine berry skins revealed newer selections bred for table use had relatively tender skins with a skin break force of 12.1 N, which was not different from V. vinifera samples. Berry penetration work and flesh maximum force were determined to be the most useful characteristics for routine screening of breeding program material.
Weed Management Practices for Organic Production of Trailing Blackberry: I. Plant Growth and Early Fruit Production
Authors: Harkins Renee H. , Strik Bernadine C. , Bryla David R.
Published: February 2019

Weed management practices were evaluated in a new field of trailing blackberry (Rubus L. subgenus Rubus Watson) established in western Oregon. The field was planted in May 2010 and certified organic in May 2012. Treatments included two cultivars, Marion and Black Diamond, grown in 1) non-weeded plots, where weeds were cut to the ground just before harvest; 2) hand-weeded plots, hoed two to three times per year; and 3) weed mat plots, covered with black landscape fabric. Each treatment was fertilized with fish emulsion and irrigated by drip. Weeds increased from 2010 through 2012 in both non-weeded and hand-weeded plots and required 38 and 90 h·ha−1 of labor to remove the weeds in the latter treatment in 2011 and 2012, respectively. Weeds in weed mat plots, in comparison, were confined primarily to the planting holes in the fabric and required only 1 h·ha−1 of labor for weed removal each year. Blackberry growth, in terms of number and dry weight of the primocanes, was similar among treatments during the first year after planting but differed with cultivar and weed management the next season. In 2011, ‘Black Diamond’ produced shorter but an average of three more primocanes per plant than ‘Marion’, whereas plants in hand-weeded and weed mat plots produced nearly twice as many primocanes as non-weeded plots. Hence, when fruit were produced on floricanes (the previous year’s primocanes) for the first time in 2012, ‘Black Diamond’ had 15% more yield than ‘Marion’, and weed control increased yield by 67% with hand-weeding and 100% with weed mat, on average. ‘Black Diamond’ and weed control also produced larger berries (measured as average individual fruit weight) with a greater water content but a lower soluble solids concentration. So far, of the three practices studied, weed mat was best suited to organic production of blackberries. The initial cost of the weed mat was far less than the cost of hand-weeding during the first 3 years after planting, and after only one season of fruit production, the yield benefit of weed mat provided enough profit to warrant its use over no weeding or hand-weeding.
Plant Nutrition Requirements for an Installed Sedum-Vegetated Green Roof Module System: Effects of Fertilizer Rate and Type on Plant Growth and Leachate Nutrient Content
Authors: Clark Mary Jane , Zheng Youbin
Published: February 2019

The objectives of this study were to compare fertilizer rates and types to identify an optimum rate to maintain green roof vegetative coverage and encourage plant growth (i.e., plant performance) while minimizing the amount and concentration of nutrients leached from a green roof module system. Sedum-vegetated modules with no added fertilizer (control) were compared with modules fertilized with 5, 7.5, 10, 15, 20, 30, and 60 g·m−2 nitrogen (N) of 16N–2.6P–10K POLYON® Homogenous NPK plus Minors, 5–6 month controlled-release fertilizer (CRF), 5 g·m−2 N of a 2.9N–2.2P–2.3K fly-larvae processed chicken manure fertilizer (5-Sus), or 5 g·m−2 N of 4N–4P–4K Gaia Green All Purpose organic fertilizer (5-OR). The total amount and concentration of aluminum (Al), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), potassium (K), magnesium (Mg), sodium (Na), NH4+, nickel (Ni), NO3–, phosphorus (P), lead (Pb), sulfur (S), and zinc (Zn) in leachate as well as plant overall appearance, winter injury, vegetative coverage, shoot height, bloom duration, and leaf color of green roof modules were evaluated between July 2011 and Aug. 2012. A CRF fertilizer rate of 15 g·m−2 N maximized vegetative coverage and overall plant appearance while maintaining leachate quality within Ontario and Canadian guidelines for most of the measured elements. The amount of Zn in the CRF appeared to be higher than plant demand and the high amount and concentration of P in leachate was likely the result of release from the growing substrate. The 5-Sus fertilizer resulted in increased coverage the first spring and increased greenness soon after application compared with the same rate of CRF. Overall, 15 g·m−2 N of CRF was the best treatment based on vegetative coverage and plant growth in sedum-vegetated green roof modules.
Evaluation of the Germination Potential of Citrus Seeds during the Harvesting Season
Authors: Orbović Vladimir , Dutt Manjul , Grosser Jude W.
Published: February 2019

The effects of fruit age on the seed quality and germination percentage of ‘Duncan’ and ‘Flame’ grapefruit and ‘Hamlin’ sweet orange were investigated. Our results suggested that seed germination varied from 98% to 100% for the two grapefruit cultivars and 85% to 100% for ‘Hamlin’ regardless of time of harvest. Within the first 5 months of the harvest season, chilling of ‘Duncan’ and ‘Hamlin’ seeds at 4 °C for 7 days after fruit sampling resulted in a lower germination percentage only with the ‘Hamlin’ seeds. Seed moisture content of all three cultivars varied slightly through the season and remained steady at 60% and 70% for batches of fresh seeds stored at room temperature or at 4 °C. Our results suggest that high seed viability and germination percentage can allow the use of these seeds for experimentation regardless of the time the fruit were picked during the harvest season.
Optimum Plot Size and Number of Replications for Determining Watermelon Yield, Fruit Size, Fruit Firmness, and Soluble Solids
Authors: Boyhan George E.
Published: February 2019

Plot size and number of replications were evaluated for watermelon [Citrullus lanatus (Thunb.)] over a 3-year period. Four different methods were used, including plotting basic unit plots against changes in cvs, Hatheway’s method for detecting a true difference as a percent of the mean with a 20% threshold, Bartlett’s homogeneity of variance test, and computed least significant differences (lsds). An initial evaluation was done in a trial with several varieties. Plotting cv against number of basic units using plots with different watermelon varieties suggests a plot size of ≈7 basic units (1 basic unit = 3.34 m2). With a single variety and basic units of 6.69 m2 for inside rows, the plot size was ≈4 basic units and for the outside row 5 basic units. With plot sizes of 2.23 m2, the number of basic units per plot was estimated at ≈5 basic units. Bartlett’s test suggests larger basic unit plot sizes of 14 to 20 with a 3.34-m2 basic unit size with multiple varieties. With a single variety, 4 to 8 basic unit plot sizes are required with 6.69-m2 basic unit size. Results were unreliable with 2.23-m2 plot sizes using Bartlett’s test. Computed lsds, which were 5% of the mean or less, could be achieved with plots sizes of 10 basic units and five replications with 3.34-m2 basic unit plots and using multiple varieties. Other combinations meeting these criteria included 14 basic unit plots and two or three replications. With a 6.69-m2 basic unit size, plots of 6 basic units and four replications would meet the 5% criteria. Finally, with the 2.23-m2 basic unit size, a plot size of 8 basic units and three replications would result in an lsd of 5% of the mean. Results with Hatheway’s method were similar to plots of basic units against cv. Hatheway’s method also has an estimate of number of replications and with 3.34-m2 basic unit, the 20% threshold of detecting true differences occurred with 10 to 14 basic units and four replications. For fruit size, firmness, and soluble solids, the basic unit plot sizes ranged from 5 to 7. Plot size estimates were larger with 6.69 m2 compared with 2.23 m2 for fruit characteristics.
Evaluation of Physicochemical and Storability Attributes of Muscadine Grapes (Vitis rotundifolia Michx.)
Authors: Barchenger Derek W. , Clark John R. , Threlfall Renee T. , Howard Luke R. , Brownmiller Cindi R.
Published: February 2019

Muscadine grapes (Vitis rotundifolia Michx.) are native to the southeastern United States and have potential for greater fresh-market sales if postharvest storage can be improved, but limited information is available on postharvest storability. In 2012 and 2013, physiochemical and storability attributes were measured in 17 muscadine genotypes (selections and cultivars) from the muscadine breeding program at the University of Arkansas or commercial cultivars. The postharvest and physiochemical attributes of the muscadines were measured at harvest and during storage for 3 weeks at 2 °C. Nutraceutical compounds were measured initially after harvest. As a result of extreme differences in weather in 2012 and 2013, the data were analyzed by year. Genotypes significantly affected storage attributes [weight loss (%), and unmarketable berries (%)] and physiochemical attributes such as penetration force (force to penetrate berry skin), titratable acidity (TA), pH, soluble solids (%), berry color (L*, chroma, and hue) as well as the nutraceutical compounds. The postharvest attributes of weight loss and unmarketable berries and the physiochemical attribute of penetration force were significantly affected by postharvest storage, but berry composition attributes remained fairly constant during storage. Overall, University of Arkansas selections AM 04, AM 26, AM 28, and the cultivar Southern Jewel had the highest potential for postharvest storage, whereas the genotypes AM 01, AM 15, AM 18, and ‘Nesbitt’ had the least potential. Genotypes AM 03, AM 04, AM 27, and ‘Ison’ had the highest nutraceutical contents [total anthocyanins, total phenolics, total flavonols, resveratrol, and oxygen radical absorbance capacity (ORAC)], whereas AM 18, AM 28, ‘Supreme’, and ‘Tara’ had the lowest contents. Postharvest storage potential, berry composition, berry color, and nutraceutical content were genotype-specific, but commercially viable genotypes were identified that can provide genetic material for breeding programs and postharvest evaluation protocol for commercial use.
Cellular Mechanisms of Reproductive Barriers in Some Crosses of Water Lily (Nymphaea spp.) Cultivars
Authors: Sun Chun-Qing , Ma Zhi-Hu , Sun Guo-Sheng , Dai Zhong-Liang , Teng Nian-jun , Pan Yue-Ping
Published: February 2019

Reproductive barriers exist in some water lily crosses that result in low seed set and low breeding efficiency. We investigated pollen morphology, pollen viability, microspore development, pistil receptivity, and embryo and endosperm development in six water lily crosses using paraffin section as well as light and scanning electron microscopy (SEM) techniques. The results indicated that the percentage of pollen with normal morphology ranged from 8.9% to 55.2%. The pollen viabilities of ‘Fen Zhuang’, ‘Bai Lu’, and ‘Hong Ying’ were 33.9%, 3.3%, and 20.7%, respectively. Stigmatic pollen germination peaked at 12 h after pollination and varied from 0.3 to 65.7 grains per stigma among the crosses. The production of embryos with normal morphology ranged from 0% to 43.6% at 5 days after pollination, from 0% to 31.4% at 15 days after pollination, and from 0% to 19.7% by 20 days after pollination. The seed sets of the six crosses were from 0% to 10.9%. Our results suggest that the low seed set in some crosses is the result of low pollen viability, low pistil receptivity, and embryo abortion.
Accessions of Citrullus lanatus var. citroides Are Valuable Rootstocks for Grafted Watermelon in Fields Infested with Root-knot Nematodes
Authors: Thies Judy A. , Ariss Jennifer J. , Hassell Richard L. , Buckner Sharon , Levi Amnon
Published: February 2019

Root-knot nematode-resistant rootstock lines (designated RKVL for Root-Knot Vegetable Laboratory) derived from wild watermelon (Citrullus lanatus var. citroides) were compared with wild tinda (Praecitrullus fistulosus) lines and commercial cucurbit rootstock cultivars for grafting of seedless triploid watermelon ‘Tri-X 313’ (C. lanatus var. lanatus) in a field infested with the southern root-knot nematode (RKN) (Meloidogyne incognita) in Charleston, SC, during 2009 and 2010. In both years, RKN infection was severe in ‘Emphasis’ bottle gourd, ‘Strong Tosa’ hybrid squash, and wild tinda rootstocks with galling of the root system ranging from 86% to 100%. In 2009, the RKVL wild watermelon rootstocks exhibited lower (P < 0.05) percentages of root galling (range 9% to 16%) than non-grafted ‘Tri-X 313’ (41%), ‘Emphasis’, ‘Strong Tosa’, and the wild tinda rootstocks. The grafted wild watermelon rootstock RKVL 318 produced more (P ≤ 0.05) fruit (12 per plot) than all other entries (mean = five per plot), and it produced a heavier (P ≤ 0.05) fruit yield (29.5 kg per plot) than all entries except self-grafted ‘Tri-X 313’ (21.5 kg per plot). In 2010, soil in half of the plots was treated with methyl bromide (50%):chloropicrin (50%) (392 kg·ha–1) before planting. The RKVL wild watermelon rootstocks exhibited resistance to RKN with percentages of root system galled ranging from 11% for RKVL 316 to 56% for RKVL 301 in the untreated control plots. Fruit yields in the untreated plots were 21.9, 25.6, and 19.9 kg/plot for RKVL 301, RKVL 316, and RKVL 318, respectively. Yields were greater (P ≤ 0.05) for the three RKVL rootstocks than for ‘Strong Tosa’ (3.0 kg) and ‘Ojakkyo’ wild watermelon rootstock (2.8 kg) in the untreated plots. Yields of watermelon grafted on ‘Strong Tosa’ were nearly seven times greater (P ≤ 0.05) in the methyl bromide-treated plots than in the untreated plots. In contrast, yields of RKVL 316 and RKVL 318 were similar in both treatments and the yield of RKVL 301 was less (P ≤ 0.05) in the methyl bromide-treated plots than in the untreated plots. The three RKVL wild watermelon rootstock lines exhibited resistance to RKN. RKVL 316 had low root galling and produced the heaviest fruit yield and greatest numbers of fruit of any rootstock evaluated in 2010. The RKVL lines should be useful sources of RKN resistance for rootstocks for grafted watermelon.
Leaf and Soil Nutrient Relations of Elaeocarpus joga Merr. in Oceanic Island Calcareous Soils
Authors: Marler Thomas E. , Lawrence John H.
Published: February 2019

The leaf nutrient status and stoichiometry of nitrogen (N), phosphorus (P), and potassium (K) were determined for Elaeocarpus joga trees in Guam’s dominant calcareous soils to understand nutrient limitations in limestone soils of Oceania and contribute to global databases on leaf economic spectrum studies. Supplemental N, P, or K was added to soils to determine plant growth and nutrient concentration responses. Leaf and soil quantifications of nutrients enabled multiple trait comparisons. Supplemental N stimulated growth of young cultivated plants without affecting leaf N concentrations. Supplemental K increased leaf K concentration but did not generate a growth response. Supplemental P did not affect growth or leaf P concentration. N:P, N:K, and K:P were most influenced by K additions. Leaf N and P concentrations of mature trees in unmanaged settings were similar to unfertilized young plants in the controlled study, but leaf K concentration was greater in the mature trees. Leaf nutrient relations were not overtly related to soil nutrient relations for mature trees. Results indicate that N and K are the limiting factors in calcareous soils of the Mariana Islands for this endemic tree species, age and size of trees do not greatly influence leaf nutrient content, and leaf stoichiometry is constrained and less variable than soil stoichiometry.