bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance of Zoysia matrella ‘Zeon’ in Shallow Green Roof Substrates under Moisture Deficit Conditions
Authors: Ntoulas Nikolaos , Nektarios Panayiotis A. , Nydrioti Efthimia
Published: February 2019

The use of turfgrasses might provide an additional solution for establishing green roofs in urban environments. The aim of the present study was to determine Manilagrass [Zoysia matrella (L.) Merr. ‘Zeon’] drought tolerance when grown under green roof conditions and under two different irrigation regimes. Treatments included: 1) two extensive green roof substrates {locally produced substrate [3 sandy loam soil:8 pumice:4 perlite:4 compost:1 zeolite (by volume)] and a commercially available substrate based on crushed tiles}; 2) two substrate depths (7.5 cm or 15 cm); and 3) two irrigation regimes (3 mm or 6 mm of irrigation every 3 days). Substrate characteristics (particle size distribution, saturated and dry bulk density, total porosity, water potential curves, in situ substrate moisture, pH, electrical conductivity, and nutrient analysis), turfgrass growth, and physiological status [green turf cover (GTC), normalized difference vegetation index (NDVI), and leaf relative water content (RWC)] were determined. During moisture deficit periods, GTC, NDVI, and RWC were most affected by substrate depth; moderately affected by irrigation regime; and, to a lesser extent, by substrate type. Turfgrass growth and physiological status were best during moisture deficit conditions in the deeper profile (15 cm) using the higher amount of irrigation (6 mm) and the locally mixed substrate.
Organic Fertilization, Green Manure, and Vetch Mulch to Improve Organic Zucchini Yield and Quality
Authors: Montemurro Francesco , Fiore Angelo , Campanelli Gabriele , Tittarelli Fabio , Ledda Luigi , Canali Stefano
Published: February 2019

A 2-year field experiment was carried out in a Mediterranean environment to study the effects of vetch (Vicia sativa L.) residue management strategies incorporating green manure (GM) using a roller-crimper (RC) and different organic fertilizers (municipal solid waste compost, anaerobic digestate, and a commercial organic fertilizer) on organic zucchini (Cucurbita pepo L.) yield and quality. Zucchini yield was influenced positively by the vetch residue management strategy, although the response was significantly different between years. The vetch cover crop increased marketable zucchini yield in the first year by 46.6% compared with the fallow (FA) treatment, indicating that this fertility-building crop could reduce off-farm nitrogen (N) fertilizer input for subsequent crops. Averaging over 2 years of the experiment, marketable zucchini yield increased by 15.2% and 38% with the RC mulch and GM plow-down, respectively, compared with the FA treatment, although differences were significant in the first year only. The application of organic fertilizers in vetch management plots increased marketable zucchini yield by 21.8% in the first year compared with the unfertilized control. This result is particularly relevant, because organic fertilizers were applied at ≈50% of the normal application rate for zucchini after taking into account biological N fixation attributable to the vetch. The concentrations of soil mineral N at harvest were 19, 27, and 28 mg·kg−1 for the RC, FA, and GM treatments, respectively. These mineral N concentrations indicated that a portion of applied organic fertilizer N, and N attributable to vetch (GM and RC), remained in the soil at harvest, suggesting the potential for leaching, which should be taken into account in the overall fertilization program. These research findings suggest that effective vetch cover crop management and the application of organic fertilizers can improve yield and quality of organically managed zucchini.
Genetic Mapping of Seed Traits Correlated with Seed Oil Percentage in Watermelon
Authors: Meru Geoffrey , McGregor Cecilia
Published: February 2019

Egusi watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai subsp. mucosospermus var. egusi (C. Jeffrey) Mansf.] is known for its distinctive fleshy-pericarp seed phenotype and high seed oil percentage (SOP). The seed is part of the daily diet in West Africa where it is used in soups and stews or processed for cooking oil. Genetic mapping studies have revealed that most of the variation in SOP between egusi and normal, non-egusi seed is explained by the egusi (eg) locus, which is also associated with the unique seed phenotype. However, variation in SOP is also observed within egusi and normal seed types although the basis of this variation remains to be elucidated. A high correlation between kernel percentage (KP) and SOP has been observed in watermelon and other crops, and recent data also suggest an association between seed size and SOP in watermelon. The aim of this study was to elucidate the relationship among SOP, KP, and seed size traits in watermelon and to identify quantitative trait loci (QTL) associated with the latter traits to facilitate marker-assisted selection (MAS) for traits correlated with SOP. KP showed a significant (α = 0.05) positive correlation with SOP in both egusi and normal seed types, whereas seed size traits showed significant negative correlations with SOP. QTL associated with KP and seed size traits in normal seed were colocalized with a previously mapped locus for SOP on linkage group (LG) 2, but in egusi seed, a QTL explaining 33% of phenotypic variation in KP was localized on LG 7. The results of this study show that SOP in watermelon is correlated with KP and seed size, but KP is associated with different loci in normal and egusi seed phenotypes.
Dryocosmus kuriphilus-induced Chestnut Galls and Their Inhabitants
Authors: Warmund Michele R.
Published: February 2019

Studies were conducted to characterize altered tissues of larvae-infested buds and stem and leaf galls induced by Dryocosmus kuriphilus Yasumatsu on Chinese chestnut trees (Castanea mollissima Blume) and to describe gall inhabitants. Bud and gall samples were collected from chestnut trees growing in Mantua, OH, on 2 Mar. and 3 May 2012, respectively, and prepared for microscopy. Uni- and multilocular larval chambers containing one D. kuriphilus larva per chamber were observed in buds and stem galls. Evidence of insect-modified Castanea cells was present as a two-layer zone of hypertrophied plant cells adjacent to the larval chambers before budbreak on 2 Mar. By 3 May, stem and leaf galls were in the growth and differentiation stage of development. Within galls, torn cell walls and disorganized organelles were visible in the protoplasm of cells surrounding ovoid-shaped larval chambers. A continuous layer of nutritive cells with large nuclei and nucleoli, abundant lipid bodies and mitochondria, and fragmented vacuoles was contiguous to larval chambers. At the outermost region of the nutritive tissue, cells had recently divided. Larger vacuolated cells, with slightly thickened walls, were observed surrounding recently divided cells. Thin-walled parenchyma cells in the chestnut gall cortex had large vacuoles with fewer organelles than those of the nutritive layer. Vascular tissue within the gall was connected with that of the plant host tissue outside the gall. In some chestnut galls, a single parasitoid larva was found attached to a D. kuriphilus larva. Each parasitoid larva had six pairs of setae on its head capsule, a pair of clypeal setae, a notched labrum, a semicircular lobed labium, 13 post-cephalic body segments, and rows of long, erect setae on all body segments.
Water Use and Growth of Hibiscus acetosella ‘Panama Red’ Grown with a Soil Moisture Sensor-controlled Irrigation System
Authors: Bayer Amanda , Mahbub Imran , Chappell Matthew , Ruter John , van Iersel Marc W.
Published: February 2019

Efficient water use is becoming increasingly important for horticultural operations to satisfy regulations regarding runoff along with adapting to the decreasing availability of water to agriculture. Generally, best management practices (BMPs) are used to conserve water. However, BMPs do not account for water requirements of plants. Soil moisture sensors can be used along with an automated irrigation system to irrigate when substrate volumetric water content (θ) drops below a set threshold, allowing for precise irrigation control and improved water conservation compared with traditional irrigation practices. The objective of this research was to quantify growth of Hibiscus acetosella ‘Panama Red’ (PP#20,121) in response to various θ thresholds. Experiments were performed in a greenhouse in Athens, GA, and on outdoor nursery pads in Watkinsville and Tifton, GA. Soil moisture sensors were used to maintain θ above specific thresholds (0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, and 0.45 m3·m−3). Shoot dry weight increased from 7.3 to 58.8 g, 8.0 to 50.6 g, and from 3.9 to 35.9 g with increasing θ thresholds from 0.10 to 0.45 m3·m−3 in the greenhouse, Watkinsville, and Tifton studies, respectively. Plant height also increased with increasing θ threshold in all studies. Total irrigation volume increased with increasing θ threshold from 1.9 to 41.6 L/plant, 0.06 to 23.0 L/plant, and 0.24 to 33.6 L/plant for the greenhouse, Watkinsville, and Tifton studies, respectively. Daily light integral (DLI) was found to be the most important factor influencing daily water use (DWU) in the greenhouse study; DWU was also found to be low on days with low DLI in nursery studies. In all studies, increased irrigation volume led to increased growth; however, water use efficiency (grams of shoot dry weight produced per liters of water used) decreased for θ thresholds above 0.35 m3·m−3. Results from the greenhouse and nursery studies indicate that sensor-controlled irrigation is feasible and that θ thresholds can be adjusted to control plant growth.
Russeting in Apple Seems Unrelated to the Mechanical Properties of the Cuticle at Maturity
Authors: Khanal Bishnu P. , Shrestha Rejina , Hückstädt Leonie , Knoche Moritz
Published: February 2019

Russeting is a commercially important disorder of the fruit skin of apples (Malus ×domestica Borkh.). It is thought to result from microscopic cracking of the cuticle on the fruit surface and the subsequent formation of a periderm just below. The study investigates 22 apples cultivars having widely different russeting susceptibilities to determine if susceptibility could be related to the mechanical characteristics of the cuticles at maturity. The mass per unit area of the cuticular membrane (CM), the dewaxed cuticular membrane (DCM), and the cuticle’s wax content all varied significantly among the cultivars examined but no simple correlative relationships with russeting susceptibility could be found. Across all cultivars, the mass of wax per unit area was linearly related to CM mass per unit area (R = 0.77, P < 0.0001). The cuticle of all cultivars was markedly strained as indexed by the release of biaxial strain in the CM on extraction of the wax. The release of biaxial strain was linearly and positively related to wax mass per unit area. Maximum force () in uniaxial tensile tests, strain at maximum force (), and the stiffness (S) differed widely among the cultivars tested, but, again, there were no relationships between these mechanical properties and russeting susceptibility. Wax extraction from the CM decreased the in uniaxial tensile tests, increased , and decreased the S. Our results show that none of the cuticle variables measured at maturity nor any of the isolated-cuticle mechanical properties contributes significantly to russeting susceptibility.
Improving Conservation through Cultivation: Nine Container Substrates Influence Growth of a Rare Cycad, Zamia pumila L.
Authors: Murphy Vickie , Moore Kimberly , Griffith M. Patrick , Husby Chad
Published: February 2019

Cycads comprise the most threatened major group of plants on earth and many species require horticultural assistance to ensure their survival. Appropriate container substrate properties, especially relatively high air space content, are crucial to successful cultivation of most cycads from seed. Cycad substrates in common use include substantial portions of organic materials that will decompose over time, reducing aeration. At Montgomery Botanical Center, novel inorganic substrates have improved survival and growth of several very rare and challenging Zamia species, suggesting the need for a rigorous evaluation of different inorganic container substrates. Effects of 1) coarse silica sand (6/20 grade); 2) Fafard (a peat/perlite mix); 3) perlite (expanded volcanic glass); 4) pumice (volcanic rock); 5) Turface (calcined clay); 6) Profile (calcined clay); 7) a 50% sand (6/20): 50% Profile mix; 8) Permatil (calcined slate); or 9) Axis (calcined diatomaceous earth) on growth of Zamia pumila L. seedlings (grown from seed of Dominican Republic provenance) were evaluated. Growth parameters were measured after 18 months. Sand produced significantly higher total dry weight and leaf area than all other substrates. A combination of at least 18% air space combined with little coarse material (sand) or with some coarse material combined with enough smaller particles to fill part of the large pores created by coarse material (Fafard) likely contributed to better growth in these compared with the other seven substrates. The other substrates may have been either too coarse, leading to excessively large pores, which are known to inhibit growth in some plants if the pores are much larger than fine root diameters, or too fine (i.e., too low of an air space percentage). The fine roots of Zamia can be less than 1 mm in diameter, whereas higher proportions of coarse substrate particles over 4 mm in diameter inhibited growth, possibly by creating excessively large pores. In contrast, higher proportions of fine substrate particles of 0.25 to 0.5 mm were beneficial to growth.
Baby Leaf Lettuce Germplasm Enhancement: Developing Diverse Populations with Resistance to Bacterial Leaf Spot Caused by Xanthomonas campestris pv. vitians
Authors: Hayes Ryan J. , Trent Mark A. , Mou Beiquan , Simko Ivan , Gebben Samantha J. , Bull Carolee T.
Published: February 2019

Baby leaf lettuce cultivars with resistance to bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vitians (Xcv) are needed to reduce crop losses. The objectives of this research were to assess the genetic diversity for BLS resistance in baby leaf lettuce cultivars and to select early generation populations of lettuce with BLS resistance. Greenhouse experiments using artificial Xcv inoculations were conducted to assess BLS resistance in 35 cultivars of 10 lettuce types used in baby leaf production and in F2 through F3:4 progeny from ‘Batavia Reine des Glaces’ (BLS-resistant, green leaf color) × ‘Eruption’ (BLS-susceptible, red leaf color). Higher disease severity was identified in red leaf and red romaine cultivars compared with other types, indicating the need to target these types for resistance breeding. Selection for BLS resistance and red-colored leaves was therefore conducted among 486 F2 plants, 38 F2:3 families, and two populations of F3:4 families from ‘Batavia Reine des Glaces’ × ‘Eruption’. Two populations were identified with uniform levels of BLS resistance equivalent to ‘Batavia Reine des Glaces’ and variable leaf morphology and color. These populations can be used by private and publicly employed lettuce breeders to select for diverse types of lettuce cultivars suitable for baby leaf production and with BLS resistance.
Incidence and Severity of Asiatic Citrus Canker on Diverse Citrus and Citrus-related Germplasm in a Florida Field Planting
Authors: Stover Ed , Driggers Randall , Richardson Matthew L. , Hall David G. , Duan Yongping , Lee Richard F.
Published: February 2019

Xanthomonas citri ssp. citri (Xcc) is the causal agent of Asiatic citrus canker (ACC), a commercially important disease in Florida citrus as well as in many other regions. In this study we evaluated occurrence of foliar lesions from ACC on progenies of 94 seed-source genotypes (hereafter called “parent genotypes”) of Citrus and Citrus relatives in the field in east–central Florida to identify the relative susceptibility to ACC. Eight seedlings per parent genotype were planted in a randomized complete block planting, but the number of plants assessed in some genotype groups was reduced by mortality at some or all sampling dates. Plants experienced ambient exposure to high Xcc inoculum pressure and plants were assessed in Sept. 2010, July 2011, Oct. 2011, May 2012, and Sept. 2012. The incidence and severity of ACC lesions were assessed and evaluated using non-parametric analyses to compare progeny from the 94 parent genotypes. Progeny of 14 parent genotypes did not exhibit ACC symptoms at any date. All were in genera other than Citrus with only Microcitrus and Eremocitrus being cross-compatible with Citrus. The kumquat hybrid C. halimii, two accessions of C. reticulata, C. nobilis, and C. sunki were the only Citrus species in the group that had a low severity (percent total leaf area showing symptoms) on each date of assessment. The aforementioned accessions had an average incidence and severity of ACC lesions of less than 4% in 2011 and 2012, but 26% to 38% in 2010 when no chemical control for ACC was applied in the adjoining citrus groves at our field site. Fourteen of the 16 progeny of C. reticulata and related parent genotypes were in the group with the lowest incidence and severity of ACC on two or more assessment dates. However, for analysis of only the most symptomatic leaves on each plant, 10 C. reticulata parent genotype progenies were in the most resistant category on the Sept. 2012 assessment despite having a low incidence and severity of ACC symptoms overall. Progeny of Poncirus and its hybrids as well as those of C. maxima, C. limon, and related species were the most severely diseased at all assessment dates. There were few instances in which progeny of different accessions of the same species had markedly different responses to ACC: progeny of C. reticulata ‘Fremont’ displayed more severe ACC compared with several other C. reticulata groups and C. aurantium ‘Zhuluan’ displayed much lower incidence and severity of ACC compared with several other accessions designated C. aurantium. Information on ACC susceptibility in diverse Citrus and Citrus relatives may prove useful for breeding programs aimed at reducing ACC susceptibility and will be of value to researchers interested in mechanisms of ACC resistance and susceptibility.
Assessment of Root System Development among Four Ornamental Tree Species through Time via X-ray Computed Tomography
Authors: Bauerle Taryn L. , Centinari Michela
Published: February 2019

Tree root systems are inherently dynamic in their distribution within a soil volume. Analysis of tree root system space occupation through time can improve not only our implicit understanding of a virtually hidden portion of a plant, but influence future management decisions through a more thorough understanding of root placement within a soil volume. We compared root standing crop populations of four ornamental tree species including Acer rubrum L. ‘Franksred’ (Acer), Carpinus betula L. ‘Columnaris’ (Carpinus), Gleditsia tricanthos L. var. inermis ‘Skycole’ (Gleditsia), and Quercus rubra L. ‘Rubrum’ (Quercus) grown in a nursery mix substrate within large 57-L containers using an X-ray computed tomography (CT) approach through time. Individual root identification was performed manually on two-dimensional slices of CT scans. Our data show high variation in species total root number through time with Carpinus exhibiting the largest root population throughout the study period. However, species exhibited differences in root distribution patterns as exemplified by the shallow and horizontally more uniform rooting pattern of Acer in comparison with the highly plastic root distribution in space through time in Gleditsia. Root frequencies within 1-mm root diameter class distributions shifted by species with the most drastic differences found between high frequencies of relatively small diameter roots in Acer vs. pronounced shifts in dominate root diameter size class as found in Gleditsia and lesser so in Carpinus during a growing season. Our findings demonstrate differences in whole tree root systems space occupation non-destructively through time and highlight a disparity in how species fill a container volume during growth.
Prestorage Conditioning and Diphenylamine Improve Resistance to Controlled-atmosphere-related Injury in ‘Honeycrisp’ Apples
Authors: Contreras Carolina , Alsmairat Nihad , Beaudry Randy
Published: February 2019

‘Honeycrisp’ apples were found to be sensitive to injury from O2 and CO2 partial pressures typical of those in controlled-atmosphere (CA) storage. A preliminary study was conducted in 2008 to investigate the effect of the following O2/CO2 partial pressure (kPa) combinations: 1/0, 3/0, 1/3, 3/3, 21/3, 21/0 (air), and 21/0 with 1-methylcyclopropene (1-MCP; 1 μL·L−1) on CA-related injuries of 'Honeycrisp' during storage for 6 months at 3 °C. ‘Honeycrisp’ apples were found to be sensitive to an injury comprised of irregular-edged brown lesions in the cortex occasionally accompanied by the formation of lens-shaped voids. The symptoms are similar to CA-related injuries described for other apple cultivars and often characterized as a “CO2 injury.” Injury severity increased as O2 declined and as CO2 increased and was evident within the first month of storage. During 2009, 2010, and 2011, a study was conducted to evaluate options for avoiding injury during CA storage for this cultivar. Fruit were conditioned at 3, 10, and 20 °C for 5 days and then exposed to the following O2/CO2 partial pressure combinations: 3/0, 3/3, 21/0 (regular air); 3/3 with diphenylamine (DPA) drench (1 g·L−1); and 21/0 with 1-MCP (1 μL·L−1). Injury severity declined as the temperature of the prestorage conditioning period increased; holding fruit for 5 days at 20 °C almost completely eliminated the disorder. The antioxidant DPA also provided nearly complete control of CA injury. 1-MCP, although not studied in conjunction with a modified atmosphere, was found to cause no injury in air storage and may provide an alternative to CA storage and avoid the risk of CA injury for ’Honeycrisp’. The relationship between disorder development and growing degree-days, rainfall, and maturity indexes was studied. Ethylene was the only factor with a significant linkage to the development of CA injury (R2 = 0.35; P = 0.0043). Suggestions for handling of ‘Honeycrisp’ for extended storage are presented.
Daily Photosynthesis, Water Relations, and Ion Concentrations of Euonymus Irrigated with Treated Wastewater
Authors: Gómez-Bellot María José , Nortes Pedro Antonio , Ortuño María Fernanda , Sánchez-Blanco María Jesús , Gonçalves Karoline Santos , Bañón Sebastián
Published: February 2019

Euonymus japonica Thunb. (euonymus) plants were submitted for 9 months to two irrigation treatments using water from different sources: a control (C) water with electrical conductivity (EC) less than 1.2 dS·m−1 and reclaimed wastewater (RW) with EC ≈4 dS·m−1. At the end of the experiment, no differences in the total dry weight were observed between treatments, whereas the leaf dry mass increased (to the detriment of the root part in RW plants). Throughout the day, the stem water potential (Ψstem) of the RW plants was lower than in C, whereas stomatal conductance (gS) was slightly reduced in RW from 0800 hr to 1200 hr, but no significant variation in photosynthesis (Pn) or energy conversion efficiency (F′v/F′m) in photosystem II was detected through the effect of salinity. Gas exchange and fluorescence showed a tendency to increase after midday in plants treated with RW. The photosynthetic behavior and fluorescence of RW plants may have been related to the nitrogen and chlorophyll content of the leaves, confirming the resistance of the photosynthetic mechanism to salinity in this species in these conditions. The toxic effects produced by high concentrations of boron (B), sodium (Na+) and chloride (Cl–) were offset by the effect of other ions like magnesium (Mg2+), potassium (K+), and phosphorus (P) in plants irrigated with RW, thus improving their physiological status without decreasing their ornamental value.
Flurprimidol Performance on Ornamental Species in Relation to Trimming Time and Method of Application
Authors: Smith Hunter C. , Ferrell Jason A. , Koschnick Tyler J.
Published: February 2019

The plant growth regulator flurprimidol (Cutless G) is registered for use on ornamental plants to reduce internode elongation and reduce trimming frequency. It has been hypothesized that timing of the trimming event can be related to the efficacy of the flurprimidol treatment. Granular flurprimidol was applied to well-established plants at a standard rate of 22.5 g/a.i. (15 lbs product)/1000 ft2 on 23 Apr. 2012 and 1 May 2013.Two common Florida landscaping species, Viburnum odoratissimum and V. suspensum, were selected to be trimmed at different times to investigate flurprimidol efficacy by measuring plant regrowth, biomass, and visual appearance. The five trimming treatments occurred at 7 days before (flurprimidol) application (DBA), 0 DBA, 7 days after application (DAA), 14 DAA, and 21 DAA. No significant differences were observed in trimming times for flurprimidol-treated V. odoratissimum or V. suspensum. V. odoratissimum shoot regrowth was significantly reduced in flurprimidol-treated plants compared with the untreated control (UTC). The insufficient growth regulation observed in both Viburnum species is likely the result of species tolerance. Two flurprimidol application methods, granular and drench, were evaluated against an UTC on two landscaping species, Elaeagnus pungens and Loropetalum chinense. This experiment was to determine if a granular or drench application would influence the performance of flurprimidol. Shoot growth of E. pungens was reduced 4.3% and 13.9% by the granular and drench applications, respectively, but was not significantly different from one another or the UTC. The granular application reduced biomass (25.1%) but was not significantly different from the drench (16.9%). L. chinense shoot regrowth was decreased 39.5% and 38.2% by the granular and drench treatments, respectively. Plant biomass was significantly reduced in both treatments compared with the UTC (17.0% by granular and 13.9% by drench), but the biomass and visual assessments between the application methods were not significantly different. Species sensitivity was found to have a substantial influence on the efficacy of a flurprimidol application.
Late-season Surface Water Induces Skin Spot in Apple
Authors: Winkler Andreas , Grimm Eckhard , Knoche Moritz , Lindstaedt Julian , Köpcke Dirk
Published: February 2019

Skin spot is a commercially important disorder of the fruit skin of ‘Elstar’ apples (Malus ×domestica Borkh.). The disorder is characterized by patches of small brownish dots (“skin spots”) that usually appear on the skin after fruit are removed from storage. Water-induced cuticular microcracks are implicated in the etiology of skin spot. The objectives of our study were 1) to establish the effect of surface wetness on the severity of skin spot; and 2) to identify possible relationships between meteorological records of rainfall over a number of seasons and the severity of skin spot in those seasons. Surface wetness treatments were imposed on fruit using overhead sprinklers installed above trees grown under a plastic rain shelter. During early fruit development [14 to 44 days after full bloom (DAFB)], surface wetness did not affect the severity of skin spot. However, during the later part of the growing season (greater than 44 DAFB), increased surface wetness increased the incidence and severity of skin spot and also the severity of cuticular microcracking. Most skin spots and microcracks were already present at harvest before storage, but skin spots and microcracking did increase slightly during subsequent controlled atmosphere (CA) storage. Over a 9-year period, the severity of skin spot in ‘Elstar’ apples grown and stored locally under standard orchard and storage conditions was positively correlated to the number of rainy days. This correlation was greater for the period between 1 Aug. to harvest than for periods 1 June to harvest or 1 July to harvest. Fruit treated with 1-methylcyclopropene (1-MCP) were more susceptible to skin spot than untreated control fruit. Calculating regression equations for the relationship between the severity of skin spot and the number of rainy days (period 1 Aug. and harvest) revealed that the (commercially important) threshold score for skin spot of 2 is predicted to occur after 44 rainy days for control fruit and after 34 rainy days for 1-MCP-treated fruit. Our data demonstrate that skin spot arises from cuticular microcracks, which in turn result from numerous exposures to surface wetness (rain, dew), especially those occurring during later stages of fruit development.
Capsaicinoid and Carotenoid Composition and Genetic Diversity of Kas I and Ccs in New Mexican Capsicum annuum L. Landraces
Authors: Rodriguez-Uribe Laura , Hernandez Luz , Kilcrease James P. , Walker Stephanie , O’Connell Mary A.
Published: February 2019

Two key fruit qualities in Capsicum annuum are fruit pungency and color. We characterize 13 New Mexican landraces for fruit quality traits at both the chemical level measuring the capsaicinoids, dihydrocapsaicin, and capsaicin as well as five carotenoids, β-carotene, β-cryptoxanthin, zeaxanthin, violaxanthin, and capsanthin, and at the genetic level sequencing two genes in these landraces, Kas I, a capsaicinoid pathway gene, and Ccs, a carotenoid pathway gene. All of the landraces had unusually high levels of dihydrocapsaicin in comparison with capsaicin levels. The levels of the most abundant red pigment, capsanthin, ranged between 468 and 1007 μg·g−1 dry weight fruit in field-grown fruit, whereas levels of β-carotene were more similar in the landraces (13 to 22 μg·g−1 dry weight fruit). Twelve different Kas I alleles were found in the landraces, which predicted six novel KAS proteins in these landraces. Seven alleles of Ccs were found, which predicted three novel CCS proteins. These results demonstrate that the landraces under cultivation in small farms and pueblos in northern New Mexico are sources of important genetic diversity for Capsicum crops.
Planting Date Influences Fresh Pod Yield and Seed Chemical Compositions of Vegetable Soybean
Authors: Li Yansheng , Du Ming , Zhang Qiuying , Wang Guanghua , Jin Jian , Herbert Stephen , Liu Xiaobing
Published: February 2019

Planting date influences grain soybean yield and quality, but no information is available regarding the responses of seed chemical compositions to delayed planting date in vegetable soybean [Glycine max (L.) Merr.]. Three vegetable soybean cultivars, CAS No.1, Tai 292, and 121, were planted on 3 May, 15 May, 27 May, and 8 June in the field during the 2010 and 2011 growing seasons. The experiment was a randomized complete block design with three replications on a typical Mollisol (black soil). We found that late planting reduced fresh pod yield in all cultivars and years. The reduction in fresh pod yield to delayed planting was significantly correlated with the reduction in the number of two-seed pods per plant. Cultivars with strong capacity in retaining more two-seed pods may possess an advantage if planting is delayed. Planting after 15 May increased seed protein content by 4.1% to 7.5% and reduced oil content by 2.4% to 26.3% for different cultivars. The contents of free amino acid, sum of fructose and glucose, raffinose, and stachyose in seed were also increased by late planting. By contrast, late planting reduced the seed sucrose content ranging from 7.6% to 45.5% for the different cultivars. Planting on 3 May usually produced the greatest fresh pod yield and highest seed sucrose content. These results demonstrated that late planting after early May might have a negative impact on the eating quality of vegetable soybean.
Carbohydrate Accumulation and Flowering-related Gene Expression Levels at Different Developmental Stages of Terminal Shoots in Litchi chinensis
Authors: Yang Hai-Fang , Kim Hye-Ji , Chen Hou-Bin , Rahman Jillur , Lu Xing-Yu , Zhou Bi-Yan
Published: February 2019

Litchi trees flower at the apex of terminal shoots. Flowering is affected by the maturity of terminal shoots before growth cessation occurs during the winter. In this study, we focused on changes of flowering in three important cultivars, Guiwei, Feizixiao, and Huaizhi, from Dec. 2012 to Mar. 2013 under natural winter conditions. Flowering rate, carbohydrate accumulation, and expression of the flowering-related genes were determined at three different developmental stages of terminal shoots with dark green, yellowish green and yellowish red leaves, respectively. The results showed that the total soluble sugar and starch contents in the dark green leaves were the highest, whereas those in the yellowish red leaves were the lowest. Trees with dark green terminal shoots had the highest flowering rates, whereas those with yellowish green or yellowish red shoots had relatively lower flowering rates. SPAD was highest in dark green leaves and lowest in yellowish red leaves at the start of the trial. The SPAD value of yellowish red leaves slightly increased but did not reach the levels of the dark green leaves, whereas levels of the other leaf stages remained fairly constant. Expression level of the litchi homolog FLOWERING LOCUS C (LcFLC), the floral inhibitor in yellowish red leaves, increased from 16 Jan., whereas that in dark green leaves declined to a level lower than the yellowish red leaves on 4 Feb. Expression level of the litchi homolog CONSTANTS (LcCO), the floral promoter in dark green leaves, was higher than that of yellowish red leaves before 26 Jan. Expression level of the litchi homolog FLOWERING LOCUS T 2 (LcFT2), encoding florigen, was higher in dark green leaves than in the other two leaf types. Our results suggest that terminal shoots should be matured and leaves should turn green for successful flowering. Mature leaves had higher expression levels of the floral promoter and florigen. In litchi production, leaves of the terminal shoots (potential flowering branches) should be dark green during floral induction and differentiation stages, and winter flushes should be removed or killed.
Exogenous Foliar and Root Applications of Abscisic Acid Increase the Influx of Calcium into Tomato Fruit Tissue and Decrease the Incidence of Blossom-end Rot
Authors: Barickman T. Casey , Kopsell Dean A. , Sams Carl E.
Published: February 2019

Plants encounter various environmental stress factors that can potentially impact nutritional requirements and fruit quality. Adequate levels of calcium (Ca) in tomato (Solanum lycopersicum) fruit have positive effects on fruit quality, specifically firmness. One of the results of insufficient Ca uptake and movement in tomato is the physiological disorder blossom-end rot (BER), which is associated with a Ca deficiency in the distal fruit tissue. Previous research has demonstrated that foliar abscisic acid (ABA) applications decreased the incidence of BER and increased the uptake of Ca into fruit tissue. This study examined how root and foliar spray ABA applications, individually and in combination, affect the partitioning of Ca between the leaves and fruit of tomato plants, especially in the distal tissue, and how ABA affects the incidence of BER in the distal tissue of tomato fruit. ‘Mt. Fresh Plus’ tomato were grown in the greenhouse at 25/20 °C (day/night) under a 16-hour photoperiod. Plants were treated with different Ca concentrations in the fertilizer solution. Plants were also treated with foliar spray ABA applications weekly. Calcium was applied through the irrigation lines at 60, 90, or 180 mg·L−1. ABA treatments were applied as a combination of foliar sprays and root applications. Foliar ABA applications, treatments consisted of deionized (DI) water control (0.0 mg ABA/L) or 500 mg ABA/L. For ABA root applications, treatments consisted of a DI water control (0.0 mg ABA/L) or 50 mg ABA/L applied through the irrigation lines. ABA spray treatments were applied once weekly until dripping from the foliage (tops of pots were covered to prevent spray drip into the pot), whereas root applications were applied four times per day through the irrigation system. Fruit tissues were harvested 84 to 90 days after seeding. Fruit tissue was harvested at red ripe maturity and evaluated for yield, BER, and Ca concentrations. Leaves were harvested at the time of fruit and were analyzed for Ca concentrations. The results indicate that a combination of the spray and root applications of ABA resulted in the greatest decrease in BER. The foliar spray application of ABA combined with the Ca treatment of 180 mg·L−1 decreased the incidence of BER. Results also demonstrate that ABA treatments are effective in increasing fruit Ca and preventing BER in the early stages of plant development but are less effective in preventing Ca deficiency in the later stages of growth.
Mini-Horhizotron: An Apparatus for Observing and Measuring Root Growth of Container-grown Plant Material In Situ
Authors: Judd Lesley A. , Jackson Brian E. , Yap Ted C. , Fonteno William C.
Published: February 2019

An apparatus was developed that allows for a range of non-destructive measurements on root growth in containers (pot culture). The mini-Horhizotron was designed to measure root growth of small plant material such as seedlings, herbaceous plugs, or woody plant liners normally grown in containers less than 3.8 L. The mini-Horhizotron design has three chambers extending away from the center that could be filled with the same substrate or filled separately with different substrates/treatments to observe root growth response from a single plant. The objectives were: 1) to test the suitability of the mini-Horhizotron’s design and its effects on plant growth with several different species; 2) to test two different experimental designs on the mini-Horhizotrons for research purposes; and 3) to test the effect of wood-amended substrates on root length of a single species. Measurement included quantification of the longest roots growing away from the center (where the plug was transplanted). Herbaceous and woody plants grown in the mini-Horhizotrons included: Echinacea purpurea (L.) Moench ‘Prairie Splendor’, Chrysanthemum L. ‘Garden Alcala Red’, Rudbeckia hirta L. ‘Becky Yellow’, and Ilex crenata Thunb. ‘Steeds’. These plants produced root and shoot growth similar to plants grown in traditional greenhouse containers with approximately equal heights and volumes, allowing for root observations in the mini-Horhizotrons to be considered simulations of traditional container-grown crop production. Results from the initial root growth measurements provide evidence that the mini-Horhizotron may be used with a different substrate in each chamber, effectively altering a portion of the rhizosphere of one plant and reducing the number of mini-Horhizotrons needed for replications during scientific studies. Root growth was measured in three substrates containing by volume 70:30 peat:perlite (control), peat:pine-wood chips, or peat:shredded pine wood. For the species grown in pine-wood chips or shredded pine wood-amended substrates, root growth equaled or exceeded that observed in the control substrate at all time periods. The mini-Horhizotron was used to non-destructively measure treatment/substrate effects on root growth while providing full visual access to the root zone and developing root system.
The Effect of Glycinebetaine Priming on Seed Germination of Six Turfgrass Species under Drought, Salinity, or Temperature Stress
Authors: Zhang Qi , Rue Kevin , Mueller Jeanna
Published: February 2019

Glycinebetaine (GB) seed priming enhances stress tolerance in various plants during the germination and seedling growth stage; however, information regarding turfgrass is limited. In this study, GB at 5 to 50 mm was used to prime seeds of six turfgrass species to evaluate the potential of GB priming in enhancing tolerance to drought, salinity, and sub-optimal temperature during germination. Stress tolerance was determined as relative final germination percentage (FGP) and daily germination percentage (DGP), expressed as percentage of germination under stress conditions compared with the control treatment (i.e., unprimed seeds germinated under non-stress condition) for each species. Daily germination percentage was more sensitive to stress than FGP. Perennial ryegrass (Lolium perenne L.) showed high tolerance to drought, salinity, and chilling temperatures (5 and 10 °C below optimal germination temperature) followed by tall fescue (Festuca arundinacea Schreb.) and creeping bentgrass (Agrostis palustris L.), whereas kentucky bluegrass (Poa pratensis L.), bermudagrass [Cynodon dactylon var. dactylon (L.) Pers.], and zoysiagrass (Zoysia japonica Steud.) were stress-sensitive. Kentucky bluegrass and bermudagrass showed higher germination at 10 mm GB under temperature stress and drought and temperature stresses, respectively; however, other grasses showed limited responses to seed priming. Our results showed that the efficacy of GB priming is plant-, GB concentration-, and stressor-dependent.
Effect of Plant Population and Breeding Lines on Fresh-market, Compact Growth Habit Tomatoes Growth, Flowering Pattern, Yield, and Postharvest Quality
Authors: Frasca Aline Coelho , Ozores-Hampton Monica , Scott John , McAvoy Eugene
Published: February 2019

Compact growth habit (CGH) tomatoes (Solanum lycopersicum) are determinate plants with shortened internodes and strong side branching due to the brachytic gene (br) that grow either prostrate or upright as a result of unidentified gene(s). Compact growth habit tomatoes do not require staking, tying, or pruning and can potentially be mechanically harvested, lowering Florida fresh-market tomato production costs. Therefore, the objective of this study was to evaluate the effects of two planting configurations (single and double row) and breeding lines (BLs) on CGH tomato plant growth, flowering pattern, yield, and postharvest fruit quality. Two experiments were conducted in Immokalee, FL, during Spring 2013 and 2014 in a split-plot design with four replications. Planting configurations affected CGH tomato growth at midseason in 2013 but not in 2014; however, in 2014, CGH tomato vines grew outside the beds into the row middles, which is uncommon for this tomato type and undesirable. Plants of CGH tomatoes had a similar flowering pattern to a conventional upright tomato cultivar, which was unexpected. Planting configurations did not affect marketable yields in 2013, but single-row plots produced higher extra-large and total marketable yields at first and total season harvests in 2014. Total season marketable harvests ranged from 26.1 to 53.6 and 29.3 to 45.6 Mg·ha−1 in 2013 and 2014, respectively. Fla 8916 was among the highest yielding BLs, maximizing extra-large and total season marketable yields. Unmarketable fruit ranged from 22% to 31% and 25% to 52% of the total season harvest in 2013 and 2014, respectively, and the most common defects were sunscald, off-shape, catface, and graywall. All CGH evaluated may be suitable for mature-green harvest regarding postharvest fruit quality, although fruit ripening uniformity was of concern in 2014. Average CGH total season marketable yields harvested twice were lower than expected yields of staked-upright tomato cultivars that may be harvested three times, but higher than Florida average yields. However, CGH tomato total production cost can potentially be lower than staked-upright cultivars making CGH tomatoes a viable alternative for the Florida mature-green fresh-market industry to remain sustainable.
Incorporating Eye Tracking Technology and Conjoint Analysis to Better Understand the Green Industry Consumer
Authors: Behe Bridget K. , Campbell Benjamin L. , Khachatryan Hayk , Hall Charles R. , Dennis Jennifer H. , Huddleston Patricia T. , Fernandez R. Thomas
Published: February 2019

Plants are often merchandised with minimal packaging; thus, consumers have only the plant (intrinsic cue) or information signs (extrinsic cues) on which to assess the product and base their purchase decision. Our objective was to segment consumers based on their preferences for certain plant display attributes and compare their gaze behavior when viewing plant displays. Using conjoint analysis, we identified three distinct consumer segments: plant-oriented (73%), production method-oriented (11%), and price-oriented (16%) consumers. Using eye tracking technology, we show that subjects spent more visual attention to cues in the horticultural retail displays that were relatively more important to them. For example, plant-oriented consumers were the fastest segment to fixate on the plants and looked at the plants for longer amounts of time compared with the other segments. Production method-oriented consumers looked at the labeling related to production method for a longer duration, whereas the price-oriented consumer looked at the price sign the longest. Findings suggest that retailers should carefully consider the type of information included on retail signage and the visual impact it has on different consumers.
Efficient Somatic Embryogenesis and Plant Regeneration from Immature Embryos of Tapiscia sinensis Oliv., an Endemic and Endangered Species in China
Authors: Wang Yuyu , Chen Faju , Wang Yubing , Li Xiaoling , Liang Hongwei
Published: February 2019

High-frequency somatic embryogenesis and plant regeneration were achieved from immature cotyledonary-stage embryos in the endangered plant, Tapiscia sinensis Oliv. Plant growth regulators with different concentrations and combinations on embryogenesis capacity were studied. The optimal explants for in vitro somatic embryogenesis were immature embryos in T. sinensis. A high callus induction rate of 100% was achieved on Murashige and Skoog (MS) basal medium supplemented with 1.0 mg·Ll−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5% (w/v) activated charcoal. Alternatively, a high induction rate (96.16%) of somatic embryogenesis was obtained on MS basal medium supplemented with the combination of 0.05 mg·L−1 α-naphthaleneacetic acid (NAA) and 0.2 mg·L−1 6-benzylaminopurine (6-BA), and somatic embryos proliferated fastest on the mentioned medium supplemented with 0.5% (w/v) activated charcoal and 3% (w/v) sucrose, inoculation of explants proliferating 21 times in the 23-day subculture. Of the 100 plantlets transferred to field after the acclimation, 95 (95%) survived. Based on the histocytological observations, the development of somatic embryos was similar to that of zygotic embryos. There were two accumulation peaks of starch grains in the embryogenic calli and in the globular-stage embryos, both closely related to the energy supply, and the embryoids were of multicelluar origin.