bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil Texture and Planting Depth Affect Large Crabgrass (Digitaria sanguinalis), Virginia buttonweed (Diodia virginiana), and Cock’s-comb Kyllinga (Kyllinga squamulata) Emergence
Authors: Hoyle Jared A. , McElroy J. Scott , Guertal Elizabeth A.
Published: February 2019

Greenhouse studies were conducted to explore soil texture and planting depth effects on emergence of large crabgrass, Virginia buttonweed, and cock’s-comb kyllinga. Soil textures examined were sand, loamy sand, and clay loam with planting depths of 0, 0.5, 1, 2, 4, 6, and 8 cm. Percent emergence was standardized relative to surface emergence to allow comparisons among tested weed species. The three-way interaction of weed species, planting depth, and soil texture was never significant for emergence. Significant interactions occurred between weed species and soil texture, weed species and planting depth, and soil texture and planting depth. For all weed species and soil textures, emergence decreased as planting depth increased with the greatest percent emergence at the soil surface. The planting depth at which weed emergence was decreased 50% [relative to surface emergence (D50)] was predicted by regression analysis. Large crabgrass emerged from deepest depths (8 cm) followed by Virginia buttonweed (6 cm) and cock’s-comb kyllinga (2 cm). Large crabgrass, Virginia buttonweed, and cock’s-comb kyllinga D50 occurred at 3.9, 1.1, and 0.8 cm, respectively. Sand, loamy sand, and clay loam D50 occurred at 0.9, 2.3, and 1.9 cm, respectively, with D50 higher in the soils with greater water-holding capacity.
Seed Cryostorage and Micropropagation of Georgia Aster, Symphyotrichum georgianum (Alexander) Nesom: A Threatened Species from the Southeastern United States
Authors: Lynch Sullivan , Johnston Rachel K. , Determann Ron O. , Cruse-Sanders Jennifer M. , Pullman Gerald S.
Published: February 2019

Symphyotrichum georgianum (Asteraceae), commonly known as Georgia aster, is a candidate for listing under the Federal Endangered Species Act in the four southeastern U.S. states where it lives. Rarity of this species is thought to be attributable in part to small population sizes and limited seed production. Protocols for in vitro germination, sustainable shoot micropropagation, shoot establishment in soil, and seed cryopreservation are presented that will assist in the safeguarding and augmentation of dwindling natural populations. Germination in vitro on growth regulator-free half-strength Murashige and Skoog (MS) medium after sterilization in H2O2 initiated the development of shoot cultures. Shoot multiplication and elongation occurred on half-strength MS salts containing 0.1 mg·L–l benzylaminopurine and 0.2 mg·L–l gibberellic acid, producing an average of 18 new shoots over a 6- to 8-week subculture cycle. Shoots rooted easily when planted into cutting mix after treatment with rooting powder containing indole-3-butyric acid (IBA) or in vitro rooting in medium with or without N-acetyl-L-aspartic acid (NAA). Plant survival after 1 month was 90% or higher for all treatments. Cryopreservation tests with seeds from three populations averaged 46.7% germination compared with control seed (no cryostorage) germination of 43%; differences were not statistically significant. Fresh seeds and seeds equilibrated for 1 to 4 weeks at room temperature and 12% relative humidity did not differ significantly in germination post-cryopreservation. Initial observations suggest that Georgia aster rapidly loses seed viability over 1 to 2 years when stored at room temperature. The ability to increase seed longevity through cryopreservation storage may be a critical step in the conservation of this species.
Saline Irrigation Effects on Cynara cardunculus L. Plants Grown in Mediterranean Soils
Authors: Lag-Brotons Alfonso José , Soriano-Disla José Martín , Gómez Ignacio , Navarro-Pedreño José
Published: February 2019

Cynara cardunculus L., known as cynara for industrial application, is a versatile plant for Mediterranean regions. Irrigation with non-conventional salty water sources is a common practice in these water-scarce regions. However, the research performed on cynara salt-stress response is limited and solely tested under soilless conditions. Thereby, the aims of the current experiment were to ascertain the effect of saline irrigation on cynara growth and mineral nutrition in Mediterranean soils. The influence of soil was considered using two typical agricultural soils, mainly differing in their salinity status. Plants were grown under controlled conditions from November until July in pots filled with soil amended with sewage sludge compost. Three saline irrigation treatments were applied (0.7, 2, and 3 dS·m−1) with increasing concentrations of NaCl (4, 13, and 23 mM). Saline irrigation started in January and ended in June. Plants growth parameters (height, dry biomass, heads number, seed yield) declined with saline irrigation. Aboveground dry biomass of plants irrigated with 3 dS·m−1 was reduced approximately one-third regarding the control value, whereas seed yield was reduced in 57%. Despite growth reduction induced by salinity, no symptoms of nutritional deficiency were observed in leaves. Saline irrigation was the main driving factor regarding cynara mineral concentration, except for potassium (K) and manganese (Mn), which were related to soil type. Chlorine (Cl) and sodium (Na) concentration increased at the whole-plant level, whereas magnesium (Mg) showed the opposing trend. Similar trends were observed in the mineral content of cynara aboveground biomass. Interaction effects between soil type and saline irrigation were marginal. Cynara exhibited high K selectivity, which might be associated with a mechanism of salt tolerance, whereas Mg is suggested as a potential indicator of salt stress in cynara plants grown in calcareous Mediterranean soils. We concluded that cynara growth and mineral nutrition were mainly affected by saline irrigation, probably as a result of the accumulation of Na and Cl.
Application of Glufosinate on Dormant Zoysiagrass (Zoysia japonica) Turf
Authors: Xiong Xi , Diesburg Ken , Lloyd Daniel T.
Published: February 2019

Winter application of glyphosate on dormant zoysiagrasses (Zoysia spp.) is a common practice for control of fall-emerging weeds in the upper transition zone. However, repeated application can lead to selection of resistant weed populations. This study evaluated glufosinate, another non-selective herbicide, for weed control and safety on dormant zoysiagrass turf. Field plots were established on three sites during two growing seasons. At two application timings, glufosinate at rates of 0.84 or 1.68 kg·ha−1 were compared with glyphosate at 0.56 kg·ha−1 and a nontreated control. Application timings included 2 to 3 weeks or 2 to 3 days before zoysiagrass spring green-up. Regardless of rate, glufosinate was similar in effectiveness to glyphosate for control of annual bluegrass (Poa annua L.) and mouseear chickweed (Cerastium vulgatum L.). Application timing significantly affected phytotoxicity on zoysiagrass turf. For applications at 2 to 3 weeks before initiation of zoysiagrass green-up in spring, no negative impact on zoysiagrass was found. However, when applications were made within days of zoysiagrass resuming growth, both glufosinate and glyphosate reduced turf quality up to 40%. This study suggests that glufosinate can be an alternative to glyphosate for weed management on dormant zoysiagrass turf, but applications should be timed at least 2 weeks before initiation of spring growth.
Potential for Increasing Southern Highbush Blueberry Flavor Acceptance by Breeding for Major Volatile Components
Authors: Gilbert Jessica L. , Schwieterman Michael L. , Colquhoun Thomas A. , Clark David G. , Olmstead James W.
Published: February 2019

Previously, when selecting for flavor in the University of Florida southern highbush blueberry (SHB, Vaccinium corymbosum L. hybrids) breeding program, sugar/acid ratios and breeder preference were the only factors considered. A more precise method of evaluating flavor would include volatile compounds that may also contribute to the flavor experience. Therefore, volatile profiles of five SHB cultivars (Farthing, FL01-173, Scintilla, Star, and Sweetcrisp) were compared using gas chromatography–mass spectrometry. All cultivars were harvested on four separate dates within the harvest season, and fruit from each cultivar were also harvested at four developmental stages on the first harvest date. Among the cultivars, soluble solids content and volatile production tended to increase with fruit maturity, whereas titratable acidity decreased. All volatile components were more variable than measures of sugars and acids during the harvest season. Many of the volatiles present varied significantly between harvest dates, resulting in significant genotype × environment interactions during the harvest season. A closer examination of linalool, trans-2-hexenol, trans-2-hexenal, hexanal, and 1-penten-3-ol, five volatile compounds commonly associated with blueberry flavor, showed cultivar, developmental stage, and harvest date differences for each volatile. ‘Star’ experienced the least variation through the harvest period.
Grafting Improves Tomato Salinity Tolerance through Sodium Partitioning within the Shoot
Authors: Di Gioia Francesco , Signore Angelo , Serio Francesco , Santamaria Pietro
Published: February 2019

Two greenhouse experiments were carried out to analyze the shoot sodium (Na+) partitioning, yield, and fruit quality of ‘Cuore di Bue’, a salt-sensitive heirloom tomato (Solanum lycopersicum L.), ungrafted or grafted onto interspecific tomato hybrid rootstocks (S. lycopersicum × S. habrochaites) ‘Maxifort’ and ‘Arnold’ in 2009, ‘Arnold’ and ‘Armstrong’ in 2010, grown at different salinity stress (SS) levels (0, 20, and 40 mm of NaCl in 2009; 0 and 20 mm of NaCl in 2010). In both experiments, an interaction was observed between grafting combinations and SS levels in terms of fruit yield, and fruit juice Na+ content. Under no SS conditions, plant grafted onto ‘Maxifort’ and ‘Armstrong’ provided the highest yield in 2009 and 2010 experiments, respectively. In the presence of 20 mm of NaCl, plants grafted onto ‘Arnold’ provided a marketable yield 23.5% (on average) higher than plants grafted onto ‘Maxifort’ or ungrafted in 2009 and 33% (on average) higher than plants grafted onto ‘Armstrong’ or ungrafted in 2010. The further increase of SS to 40 mm of NaCl considerably reduced the productivity of all grafting combinations. At 20 mm of NaCl, plants grafted onto ‘Arnold’ showed also a higher capacity to modulate shoot Na+ partitioning with respect to ungrafted plants by increasing Na+ accumulation in older leaves (52%) and reducing Na+ content in younger and most active leaves (24%), thus enabling the maintenance of higher K+/Na+, Ca2+/Na+, and Mg2+/Na+ ratios compared with ungrafted plants. Fruit total soluble solids content, titratable acidity, and dry matter were unaffected by grafting at any SS level, whereas under SS, the fruit juice Na+ content of grafted plants was consistently lower (from 19% up to 68%) than that of ungrafted plants. Under moderate SS conditions (20 mm of NaCl), the use of rootstock genotypes such as ‘Arnold’ having a particular ability to reduce Na+ accumulation in younger and most active leaves may increase tomato yield and enhance tomato nutritional value by reducing the fruit juice Na+ content.
Nitrogen Mineralization from Canola Meal or Cottonseed Meal with or without Soapstock
Authors: Fine Kathryn E. , Cole Janet C. , Penn Chad J.
Published: February 2019

Nitrogen (N) release rate from organic materials through mineralization is affected by the organic material and environmental conditions. Determining rates of mineralization for canola (Brassica rapa L.) meal and cottonseed (Gossypium hirsutum L.) meal with or without soapstock (a waste byproduct of seed oil extraction) will establish appropriate application rates for consumers. Canola meal, cottonseed meal, cottonseed meal with soapstock, or no treatment (control) was incorporated at a rate of 4.9 g·m−2 N into three loam soils. Experimental units were incubated for 0, 3, 7, 14, 30, or 60 days while maintaining moisture at 60% water-holding capacity and then analyzed for NH4-N and NO3-N, then plant available N was calculated as NH4-N+NO3-N. Ammonium increased with each seed meal amendment during the first 14 days of incubation and then decreased. Nitrate increased in seed meal treatments during the first 14 days of incubation and then continued to increase as NH4-N ions declined. Canola meal and cottonseed meal with or without soapstock increase plant-available soil N.
Sweet Cherry Fruit Firmness and Postharvest Quality of Late-maturing Cultivars Are Improved with Low-rate, Single Applications of Gibberellic Acid
Authors: Einhorn Todd C. , Wang Yan , Turner Janet
Published: February 2019

Sweet cherry (Prunus avium L.) producers in the Pacific Northwest have devoted considerable acreage to late-maturing cultivars. By using these cultivars to extend the harvest window, producers avoid lower returns associated with cherries harvested during the peak period (i.e., midseason) when supplies are overly abundant. Over several years, we evaluated preharvest applications of gibberellic acid (GA3) between 10 and 100 ppm (a.i.) on the late-maturing sweet cherry cultivars Lapins, Skeena, Staccato, and Sweetheart. Individual trials examined the timing of GA3 applications and/or rate on fruit quality attributes at harvest and after 4 weeks of cold storage at 0 °C. The influence of GA3 timing and/or rate on sweet cherry skin color and harvest delay was also evaluated. Multiple applications split between the end of Stage II (pit hardening) and mid-Stage III (final fruit swell) of fruit development did not improve fruit quality attributes or delay skin color development of ‘Skeena’ and ‘Sweetheart’ compared with equivalent concentrations applied once at the end of Stage II. Low concentrations (between 10 and 25 ppm) consistently improved fruit firmness (FF) of all cultivars by 10% to 43%. No further improvements in FF were observed when rates exceeded 25 ppm. Skin color development was retarded by GA3 but did not respond in a consistent manner to increasing rate. Fruit size was not uniformly increased by GA3. In trials where GA3 had a positive effect on fruit size, the effect was observed at low concentrations and was not further improved with increasing rate. A cultivar-dependent response to GA3 was observed for return bloom. ‘Skeena’ reproductive buds per fruiting spur and flowers per floral bud in years after treatment were unaffected by GA3 concentration. On the contrary, the number of flowers per bud of ‘Lapins’ was significantly reduced to 79% and 38% of control levels for 50 and 100 ppm GA3, respectively. At 100 ppm, GA3 additionally limited the number of reproductive buds returning on fruiting spurs of ‘Lapins’. GA3 reduced stem browning and surface pitting disorder of ‘Sweetheart’ and ‘Lapins’ after 4 weeks of cold storage at 0 °C; however, these effects were optimized at 25 ppm. Respiration rate and weight loss were unaffected by GA3 at harvest or after 2 and 4 weeks of cold storage. Unidentified endogenous factors that regulate FF and are inducible by GA3 appear to be largely responsible for improved resistance to pitting. Collectively, the results demonstrate high sensitivity of cherry FF and skin color to GA3. Split applications did not provide further harvest delays or affect any of the attributes evaluated, possibly because low rates (20 ppm) applied at the first timing were sufficient to saturate the response. In general, fruit quality of late-maturing cultivars of sweet cherry was improved by low rates of GA3 applied in a single application at the end of pit hardening.
Environmental Modification Inside Photoselective Shadehouses
Authors: Arthurs Steven P. , Stamps Robert H. , Giglia Frank F.
Published: February 2019

Shade nets are widely used to protect floricultural crops from excessive radiation, wind, hail, and birds. Although black nets are most frequently used, growers are experimenting with colored, gray, and white dispersive netting to impact vegetative vigor, dwarfing, branching, leaf variegation, and timing of flowering. We monitored environmental data inside replicated shadehouse structures (10 × 10 × 3 m high) with full covering of red, blue, pearl, and black nets (all 50% nominal shading factor) in central Florida over 12 months. Actual photosynthetically active radiation (PAR, μmol·m−2·s−1) was reduced most by black nets (55% to 60% shading factor depending on the season) and least under red nets (41% to 51%) with blue and pearl nets intermediate. Spectral analysis revealed blue nets had distinctive peaks at the blue (450 to 495 nm) and far-red beyond 750 nm. Red nets had a minor peak ≈400 nm and major transmittance beyond 590 nm. Pearl nets transmitted more light above 400 nm compared with black nets but did not otherwise alter spectral composition in the visible range. No nets had red/far-red (R/FR) ratios (600 to 700/700 to 800 nm) significantly greater than ambient (close to 1), whereas blue nets had a consistently lowest R/FR ratio of ≈0.8. Both ultraviolet-B and ultraviolet-A (280 to 400 nm) were reduced most by pearl nets and least by red nets. We also noted elevated temperatures and wind resistance (but not relative humidity) under colored and pearl nets compared with black, probably as a result of the different net porosities. Our study documents the different environmental modifications inside structures covered with black, colored, and photoneutral translucent nets, which will help predict or interpret specific plant responses.
Evaluation of Lettuce Genotypes for Salinity Tolerance
Authors: Xu Chenping , Mou Beiquan
Published: February 2019

Lettuce is one of the most commonly used salad vegetables and considered to be a relatively salt-sensitive crop. Salinity is a major constraint to crop production in all important lettuce growing regions of the United States, and the water quality problem is exacerbated by climate change. To identify salt-tolerant lettuce genotypes, 178 cultivars and germplasm accessions (56 butterhead, 39 crisphead, 35 romaine, 33 leaf, and 15 wild types) were selected from a preliminary screening of more than 3800 genotypes, and tested for salinity tolerance in sand cultures under greenhouse conditions. Plants were grown in Hoagland nutrient solution, either with or without 30/15 mm NaCl/CaCl2, and leaf fresh and dry mass (FM and DM), chlorophyll index, and maximal photochemical efficiency (Fv/Fm) were measured 4 weeks after plants were transplanted. Generally, salinity decreased lettuce shoot FM and DM, increased DM/FM ratio and chlorophyll index, and had no effect on Fv/Fm. Some lettuce varieties showed salt tolerance (less than 15% reduction in FM), such as PI 342515, PI 358020c, ‘Morgana’, ‘Amerika’ (butterhead), ‘Laura’ (crisphead), PI 289023, PI 273577, PI 278066, PI 177425 (romaine), PI 171676a, PI 177423, PI 342477, and PI 358018b (leaf). The results indicate that lettuce genotypes differ greatly in their salt sensitivity, which could be useful for growers to choose cultivars and for breeders to improve lettuce adaptation to salinity stress.
Development of Powdery Mildew Fungus on Cucumber Leaves Acclimatized to Different CO2 Concentrations
Authors: Itagaki Kaori , Shibuya Toshio , Tojo Motoaki , Endo Ryosuke , Kitaya Yoshiaki
Published: February 2019

The present study evaluated the development of powdery mildew fungus (Podosphaera xanthii) on leaves of cucumber (Cucumis sativus L.) acclimatized to different CO2 concentrations ([CO2]) to examine plant–pathogen interactions under the wide range of [CO2] that can occur in greenhouse cultivation. Seedlings of resistant and nonresistant cultivars were acclimatized to reduced (200 µmol·mol−1), ambient (400 µmol·mol−1), or elevated (1000 µmol·mol−1) [CO2]. Powdery mildew spores were inoculated onto the adaxial surface of cotyledons or first true leaves, and colonization was measured after 7 days. Colony density decreased as acclimatization [CO2] increased at the cotyledon stage but increased at the first-true-leaf stage in both cultivars. This result implies that when the effects of [CO2] on plant–pathogen interactions are described, growing stage must be specified. The acclimatization [CO2] was correlated positively with leaf mass per area, dry matter content, and carbon (C) content and negatively with nitrogen (N) content at both stages. Therefore, these leaf properties could not explain the changes in host-plant susceptibility between stages. The effect of acclimatization [CO2] was greater on the resistant cultivar than on the nonresistant cultivar, indicating that the resistant cultivar was more responsive.
Phytosanitary Irradiation Preserves the Quality of Fresh Blueberries and Grapes during Storage
Authors: Tong Jonathan , Rakovski Cyril , Prakash Anuradha
Published: February 2019

The objective of this study was to monitor the effects of irradiation on the quality of blueberries and grapes treated at phytosanitary dose levels. Blueberry varieties ‘Star’, ‘Jewel’, and ‘Snowchaser’ and grape varieties ‘Sugraone’ and ‘Crimson Seedless’ were irradiated at a target dose of 400 Gy (range of 400–590 Gy for blueberries and 400–500 Gy for grapes) and stored for 3 and 18 days under refrigeration, plus 3 days at ambient temperatures and evaluated for quality. Storage affected quality of both fruit more than irradiation treatment and there were significant differences among varieties. Irradiated ‘Star’ blueberries maintained their firmness and sensory scores and resisted decay. Alternatively, irradiated ‘Jewel’ blueberries decreased in firmness but sensory scores for overall liking were higher than the control following 3 weeks of storage. ‘Snowchaser’ blueberries were harvested late in the blueberry season and were not as affected by treatment or time due to their initial compromised nature. Firmness was the primary attribute affected by irradiation for both varieties of grapes, but sensory testing showed that consumers did not have a preference for control or irradiated fruit. With respect to other attributes such as color, weight loss, and soluble solids concentration (SSC)/titratable acidity (TA), there were differences among fruit varieties but treatment effects were not significant. Our results show that both, blueberries and grapes, have a high tolerance for phytosanitary irradiation and that storage affects their quality more than irradiation treatment.
Phenotypic and Genetic Diversity in Pumpkin Accessions with Mutated Seed Coats
Authors: Murovec Jana
Published: February 2019

The increasing importance of pumpkin (Cucurbita pepo L.) cultivars for seed production has led to considerable breeding efforts for novel high-yielding and disease-resistant cultivars lacking seedcoats. Because it is very important to use genetically diverse genotypes for the development of cultivars with a broad genetic and phenotypic base, this study focused on phenotypic and genetic diversity within and among available pumpkin accessions with mutated seedcoat phenotypes. Fifty-one accessions were collected from various sources and countries, which showed a wide variety of seedcoat types. Genetic analysis with 18 simple sequence repeat (SSR) markers revealed that 37.59% of the total genetic diversity was attributable to interpopulation differentiation and 62.41% to individual differentiation within populations. The average genetic differentiation between accessions (FST) was from 0.030 to 0.760, whereas expected heterozygosity (He) was between 0.048 and 0.491 and observed heterozygosity (Ho) between 0.056 and 0.522. Based on unweighted pair group method with arithmetic mean (UPGMA) analysis, the genetic relationship among accessions reflects the primary geographical origin of accessions. Marker amplification yielded a total of 109 alleles with an average number of alleles per locus of 6.06. Gene diversity per locus varied between 0.027 and 0.879, whereas the polymorphism information content (PIC) varied between 0.027 and 0.867. This is the first report about intra-accession phenotypic and genotypic variability of pumpkins with mutated seedcoats cultivated for their seeds, which are today used in the baking industry, seed oil production, and in traditional and modern medicine.
Challenges of Strawberry Production in High-pH Soil at High Elevation in the Southwestern United States
Authors: Yao Shengrui , Guldan Steve , Flynn Robert , Ochoa Carlos
Published: February 2019

In 2011, 16 strawberry cultivars were planted with two planting systems—a black-plastic-covered perennial system (BP) and a matted-row system (MR)—arranged in a split-block design with four replications at the New Mexico State University (NMSU) Sustainable Agriculture Science Center, Alcalde, NM. Cultivars varied greatly in their yield and tolerance to high-pH soil. ‘Allstar’, ‘Chandler’, and ‘Darselect’ were the three most sensitive cultivars to high soil pH among the 16 cultivars tested, whereas ‘Wendy’, ‘Brunswick’, ‘Honeoye’, and ‘Clancy’ were the four most tolerant cultivars by the end of July 2011. Two to three applications of 0.67 g·m–1 (linear row) FeEDDHA were used per year through fertigation to effectively treat leaf chlorosis resulting from high soil pH. After averaging the yields of 2012 and 2013, ‘Mesabi’ and ‘Kent’ had greater yield than others and twice the yield of ‘Jewel’. Early cultivars Earliglow and Annapolis and late cultivars L’Amour and Ovation all had low yields in both years. In Jan. 2013, the minimum temperature reached –21.7 °C, which caused crown damage to some cold-tender cultivars, especially in the black-plastic-covered system. ‘Wendy’, ‘Chandler’, ‘Clancy’, and ‘Jewel’ were the cold-tender cultivars, whereas ‘Mesabi’, ‘Kent’, ‘Cavendish’, and ‘Honeoye’ were the hardiest among those tested. Despite repeated late frosts from 19 Apr. to 4 May 2013 and a delayed harvest season, most cultivars produced greater yield than in 2012 with ‘Mesabi’ and ‘Kent’ being the greatest. There were no significant differences in yields in 2012 and 2013 between BP and MR treatments, but yield in BP was significantly lower than in MR in 2014. With appropriate cultivar selection and management, growers can produce strawberries in high-pH soil at high elevation with a short growing season in the Southwest.
Substrate Moisture Content Effects on Growth and Shelf Life of Angelonia angustifolia
Authors: Jacobson Alison Bingham , Starman Terri W. , Lombardini Leonardo
Published: February 2019

Wilting during shelf life is a major cause of postharvest shrink for bedding plants shipped long distances from production greenhouses to retail outlets. The objective of this research was to determine if irrigation at lower, constant substrate moisture content (SMC) during greenhouse production would be a feasible way to acclimate plants for reduced shrinkage during shelf life while potentially conserving irrigation water. In two separate experiments conducted in the fall and spring seasons, rooted plugs of Angelonia angustifolia ‘Angelface Blue’ (angelonia) were grown in greenhouse production until a marketable stage in substrates irrigated at SMC levels of 10%, 20%, 30%, and 40% using a controlled irrigation system. At the end of the greenhouse production stage, plants were irrigated to container capacity and subjected to a simulated shipping environment in shipping boxes in the dark for 2 days. After shipping, plants were placed back in the greenhouse and watered minimally to simulate a retail environment. Data were taken at the end of each stage, i.e., greenhouse production, simulated shipping, and simulated retail. Results indicated that as SMC decreased from 40% to 10%, plants were shorter in height but had proportional and more compact flowering sections. The volume of water received by the 40% SMC plants was three times greater (fall) and 12 times greater (spring) than the 20% SMC plants during greenhouse production and two times greater (fall) and nine time greater (spring) during simulated retail. During production, midday water potentials decreased as the SMC levels decreased, but at the end of the simulated retail, the midday water potentials were the same, suggesting that plants that were drought-stressed during production were acclimated to lower water levels experienced in retail settings. Overall, the 20% SMC treatment produced the best postharvest quality plant resulting from reduced plant height without detrimental effects on flowering. The results demonstrate that while conserving water, controlled irrigation at a lower SMC can produce high-quality plants that have equal shelf life to those that are irrigated at high levels.
Fertilization of Landscape Palms to Reduce Nitrogen and Phosphate Impacts on the Environment
Authors: Broschat Timothy K.
Published: February 2019

Palms are an increasingly important element in landscapes in the subtropical and warm temperate regions of the United States. Unfortunately, palms have very high nutritional requirements and rarely can be found without at least one nutrient deficiency, especially on the sandy and calcareous soils of the southeastern United States. These deficiencies are conspicuous and unsightly, reduce canopy size and vigor, and can become fatal. Current maintenance fertilizer recommendations for landscape palms in Florida growing in these soils entail four applications per year of an 8N–0.9P–10K–4Mg plus micronutrients palm fertilizer. However, because phosphorus (P) and nitrogen (N) are considered pollutants of ground and inland and coastal surface waters, it is important to apply only as much of these elements as necessary for palm health. This study showed that areca palms (Dypsis lutescens) can be grown in a native sand soil or in a calcareous fill soil without supplemental P and with no N applied during the rainy summer months of June through September when application of these elements may be legally restricted. It also demonstrated that the negative effects caused by high N:potassium (K) ratio turf fertilizers can be mitigated by adding a controlled release palm fertilizer that contains no N or P. Because of strong dilution effects in this study, leaf nutrient concentrations were found to be poor indicators of palm quality and nutritional status.
Turf Performance of Bahiagrass, Centipedegrass, and St. Augustinegrass Cultivars under a Linear Gradient Irrigation System
Authors: Zhang Jing , Unruh J. Bryan , Kenworthy Kevin
Published: February 2019

Periodic drought, irrigation requirements, and the enforcement of mandatory watering restrictions have posed a challenge for homeowners and landscape managers to maintain acceptable turf quality during dry periods. Information regarding irrigation requirements and performance of common turfgrass species used for residential and commercial landscapes in the southeastern United States would be valuable. A Linear Gradient Irrigation System (LGIS) provides an efficient way to measure cultivar responses to variable moisture regimes. Nine commercially available cultivars from three turfgrass species: ‘Argentine’ bahiagrass (BH) (Paspalum notatum Flügge); ‘Common’ and ‘TifBlair’ centipedegrass (CP) [Eremochloa ophiruoides (Munro) Hack.]; ‘Captiva’, ‘Classic’, ‘Floratam’, ‘Palmetto’, ‘Raleigh’, and ‘Sapphire’ st. augustinegrass (STA) [Stenotaphrum secundatum (Walt.) Kuntze.] were evaluated during naturally occurring dry periods in 2010 and 2011 for visual quality, color, and density and chlorophyll index. An irrigation gradient ranging from 0% to 120% of reference evapotranspiration (ETo) was provided by LGIS. Centipedegrass and BH had less demands on supplemental irrigation to maintain acceptable quality during periodic drought compared with STA. ‘Argentine’ BH performed similar to ‘Common’ CP for its visual quality except at the irrigation level of 40% ETo. Among STA cultivars, ‘Palmetto’ performed poorest in its relative drought response than other cultivars. ‘Sapphire’ STA needs further study to better characterize its drought response. The irrigation level of 120% ETo decreased turf quality except for ‘Argentine’ BH, and the irrigation replacement at 40% to 80% ETo, depending on turfgrass species and cultivar, may provide enough supplemental moisture to maintain acceptable turf quality during short-duration drought (≈2 weeks) in north Florida regions.
Development of a New Hybrid Between Prunus tomentosa Thunb. and Prunus salicina Lindl.
Authors: Zhang Qijing , Gu Dajun
Published: February 2019

An interspecific hybrid between Prunus tomentosa and P. salicina was produced through controlled pollination and confirmed by comparison of morphological characters and DNA markers. Morphological traits were intermediate between the two parents and fruit are much larger than that of P. tomentosa. Trees grafted on P. tomentosa rootstock are compact, cold hardy, precocious, and productive. It is new and potentially useful stone fruit germplasm for commercial production and further breeding in Prunus.
Involvement of the Redox System in Chilling Injury and Its Alleviation by 1-Methylcyclopropene in ‘Rojo Brillante’ Persimmon
Authors: Novillo Pedro , Salvador Alejandra , Navarro Pilar , Besada Cristina
Published: February 2019

A treatment with 1-methylcyclopropene (1-MCP) is known to reduce softening to the flesh of ‘Rojo Brillante’ persimmon, which is the main chilling injury (CI) symptom that occurs after storage at low temperature. However, very little is known about the mechanism by which 1-MCP confers persimmon tolerance to chilling. The aim of this study was to investigate the changes in the redox system associated with CI and its reduction by 1-MCP during storage at 1 °C and after shelf life period. Our results showed that during cold store, both control and 1-MCP treated fruit underwent gradual oxidative stress (accumulation of H2O2, increment in APX, CAT, LOX, and slight increase in SOD activity) but no CI was manifested. During shelf life conditions, ethylene production was slightly higher in control than in 1-MCP treated fruit. Besides, the CI manifestation of control fruit was associated with oxidative burst [major H2O2 accumulation and sharp increase in catalase (CAT), peroxidase (POD), and lipoxygenase (LOX) activity], while 1-MCP treatment greatly reduced the CI symptoms. The 1-MCP treated fruit showed down-regulated POD activity and up-regulated CAT activity, which resulted in slower H2O2 accumulation. The reduction of the flesh softening as the main manifestation of CI in ‘Rojo Brillante’ persimmon by 1-MCP was associated with the modulation of the redox state of the fruit during the shelf life period that follows low-temperature storage.
Substrate Water Content and Fertilizer Rate Affect Growth and Flowering of Potted Petunia
Authors: Alem Peter , Thomas Paul A. , van Iersel Marc W.
Published: February 2019

Rising concerns over environmental impacts of excessive water and fertilizer use in the horticultural industry necessitate more efficient use of water and nutrients. Both substrate volumetric water content (θ) and fertilizer affect plant growth, but their interactive effect is poorly understood. The objective of this study was to determine the optimal fertilizer rates for petunia (Petunia ×hybrida) ‘Dreams White’ grown at different θ levels. Petunia seedlings were grown at four levels of θ (0.10, 0.20, 0.30, and 0.40 m3·m−3) with eight different rates of controlled-release fertilizer (CRF) (Osmocote 14-14-14; 14N–6.1P–11.6K; rates of 0 to 2.5 g/plant, equivalent to 0 to 6.25 kg·m−3 substrate). Shoot dry weight increased as the CRF rate increased from 0 to 1.67 g/plant but decreased again at even higher CRF rates. The effect of CRF rate on growth was more pronounced at higher θ. Leaf size doubled as the θ thresholds increased from 0.10 to 0.40 m3·m−3. Flowering was reduced by a combination of high CRF rates (greater than 0.63 g/plant) and high θ (0.30 and 0.40 m3·m−3), indicating that optimal conditions for vegetative growth are different from those for maximal flowering. These results suggest that without leaching, high-quality petunias can be grown with lower CRF rates than commercially recommended rates.
Root Growth, Free Amino Acids, and Carbohydrates of Tall Fescue in Response to Soil Salinity
Authors: Yang Yong , Liu Xueyong , Jiang Yuanli , Xiang Zuoxiang , Xu Qingguo , Zhao Na , Shu Bichao
Published: February 2019

Salt-affected soils may retard plant growth and cause metabolic alterations. The objective of this study was to investigate the effect of salinity in deep soil on root growth and metabolic changes of tall fescue (Festuca arundinacea). Tall fescue seeds (cv. Houndog V) were planted in polyvinylchloride (PVC) tubes (9 cm diameter × 45 cm long) for 2 months with three treatments of growth substances: (1) control, filled with peat-sand mixtures for full tubes (40 cm height, sand:organic fertilizers = 7:3, w/w); (2) T20, 20 cm saline soil covered with 20 cm organic fertilizers and sand; (3) T30, 30 cm saline soil covered with 10 cm organic fertilizers and sand. Turf quality and vertical shoot growth rate (VSGR) significantly decreased in T30, but not for T20, when compared with the control. Salinity in deep soil obviously inhibited the root growth as indicated by the lower root length, root projected area, root diameter, root fresh, and dry weight, but increased the level of amino acids (Asp, Glu, Ser, Gly, etc.) and soluble sugars (glucose, fructose, sucrose). Root activity in top layer (0–10 cm) of saline soil increased while decreased in deeper layer (20–40 cm) when compared with the control. The increase of root activity and free amino acids in roots from upper layer and the accumulation of soluble sugars in roots from deeper soil layer under salinity conditions were the adaptive responses and regulative mechanisms that for supporting the above-ground plant growth in tall fescue when exposed to deep soil salinity conditions. These results also suggested that a 20 cm of improved mixture of organic fertilizers with sand on the top of saline soil could be sufficient to supply basic space for the normal growth of turfgrass with regular spray irrigation.
Induction of Anthocyanin Accumulation in Crabapple (Malus cv.) Leaves by Low Temperatures
Authors: Tian Ji , Han Zhen-yun , Zhang Li-ru , Song Ting-Ting , Zhang Jie , Li Jin-Yan , Yao Yuncong
Published: February 2019

Anthocyanins are protective pigments that accumulate in plant organs such as fruits and leaves, and are nutritionally valuable components of the human diet. There is thus considerable interest in the factors that regulate synthesis. Malus crabapple leaves are rich sources of these compounds, and in this study we analyzed leaf coloration, anthocyanin levels, and the expression levels of anthocyanin biosynthetic and regulatory genes in three crabapple cultivars (Royalty, Prairifire, and Flame) following various temperature treatments. We found that low temperatures (LTs) promoted anthocyanin accumulation in ‘Royalty’ and ‘Prairifire’, leading to red leaves, but not in ‘Flame’, which accumulated abundant colorless flavonols and retained green colored leaves. Quantitative reverse transcript PCR (RT-PCR) analyses indicated that the expression of several anthocyanin biosynthetic genes was induced by LTs, as were members of the R2R3-MYB, basic helix–loop–helix (bHLH) and WD40 transcription factor families that are thought to act in a complex. We propose that anthocyanin biosynthesis is differentially regulated in the three cultivars by LTs via the expression of members of this anthocyanin regulatory complex.
Vavilovian Centers of Plant Diversity: Implications and Impacts
Authors: Hummer Kim E. , Hancock Jim F.
Published: February 2019

N.I. Vavilov, Academician of the V.I. Lenin All-Union Academy of Agricultural Sciences, takes his place as a founding pillar of knowledge in the cathedral of the origin and development of cultivated plants. Relying on the theories of his revered predecessors, Charles Darwin and Alphonse de Candolle, Vavilov developed the concept of centers of origin for agronomic crops. Vavilov’s astute hypotheses set the stage for the modern use of exotic germplasm in plant breeding. Vavilov, a devoted scientist, continued to revise and refine his theory of the centers of origin throughout his lifetime based on additional plant collections and data evaluation. Though he initially proposed three in 1924, and eight in 1935, his final papers of 1940, discussed seven major centers with some minor additions. His concept of specific centers of origin for crop plants was not an isolated aphorism but has directed breeders, on their study and reflection, to the continued improvement and economic development of plants for humanity. Inherent genetic plant variability is the basis of domestication and breeding into crops of economic importance with food, fuel, fiber, and industrial uses. The objective of this article is to present a summary of Vavilov’s plant explorations. His collection trips led to the development of his theory of the centers of origin of cultivated crops, the law of homologous variation, as well as his concept of genetic erosion. Further modification of his theories by other scientists and the impact of his ideas are mentioned. His influence on present day conservation of genetic resources are presented.
Genetic Diversity of Carpetgrass Germplasm Based on Simple Sequence Repeat Markers
Authors: Wang Xiaoli , Wang Zhiyong , Liao Li , Zhang Xinyi , Bai Changjun
Published: February 2019

Carpetgrass [Axonopus compressus (Sw.) Beauv.] is an important warm-season perennial turfgrass that is widely used in tropical and subtropical areas. The genetic diversity of 63 carpetgrass accessions in China was studied using simple sequence repeat (SSR) markers. Fourteen SSR primer combinations generated a total of 49 distinct bands, 48 (97.96%) of which were polymorphic. The number of observed alleles ranged from 2 to 6, with an average of 3.5. Coefficients of genetic similarity among the accessions ranged from 0.24 to 0.98. Unweighted pair-group method with arithmetic means (UPGMA) clustered the 63 accessions into three groups, and not all samples from the same region belonged to the same group. SSR markers will promote marker-assisted breeding and the assessment of genetic diversity in wild germplasm resources of carpetgrass.
Effects of Fertigation Duration on the Pollution, Water Consumption, and Productivity of Soilless Vegetable Cultures
Authors: Urrestarazu Miguel , Morales Isidro , La Malfa Tommaso , Checa Ruben , Wamser Anderson F. , Álvaro Juan E.
Published: February 2019

The management of water and nutrient ions, such as nitrate, has been studied extensively in recent decades. Increasingly efficient models have been developed for the use of water and nutrients through the automation of fertigation techniques. The application of a fertigation volume for a duration four times longer than applied on the control was evaluated. In Almería (Spain), one pepper crop and two tomato crops—with and without grafting—were grown between Oct. 2013 and June 2014 in a soilless system with a coir substrate. The effects on root growth, plant growth, production, and quality were measured. The following parameters for the fertigation of the nutrient solution and drainage were recorded: % drainage volume, electrical conductivity (EC) of the nutrient solution, pH, and concentration of nitrates and potassium. The absorption of potassium and nitrate, and the nitrate emissions of the drainage were estimated. The results showed an increase in the root volume and an improved distribution in the cultivation unit for the treatment application in the pepper crop. Slowing the applied fertigation improved the absorption of water and nitrates, and the production in the ungrafted tomato and pepper crops, while the grafted tomato crop was unaffected. Nitrate emissions were lower in the evaluated treatment of the pepper and ungrafted tomato crops. The fruit quality parameters were unaffected.
Propagation Methods Affect Fruit Morphology and Antioxidant Properties but Maintain Clonal Fidelity in Lowbush Blueberry
Authors: Goyali Juran C. , Igamberdiev Abir U. , Debnath Samir C.
Published: February 2019

The berry morphology (size and weight), phytochemical content (polyphenols, flavonoids, anthocyanins, and proanthocyanidins), and antioxidant activity of lowbush blueberry (Vaccinium angustifolium Ait.) wild clone QB 9C and cultivar Fundy, propagated by tissue culture (TC) and softwood cutting (SC), were studied over two growing seasons to evaluate the effect of propagation methods on fruit yield and the content of antioxidant metabolites. Number of flower clusters, number of berries and berry weight per plant, diameter and weight of individual berry were higher in SC plants than those of TC plants. Significant interaction between genotypes and propagation methods were observed for total phenolic and flavonoid content of fruits. Berries from TC plants contained more polyphenols and flavonoids than those of SC plants. Twenty microsatellite markers were used to assess the clonal fidelity of TC regenerants and SC plants. The identical monomorphic amplification profiles within the TC plants of each genotype confirmed the clonal fidelity of micropropagated blueberry plants. These results indicate that propagation methods affected the morphology and antioxidant metabolites but maintained trueness-to-type genetic makeup in blueberry.
Feasibility of Direct Seeding for Stand Establishment of Field-grown Basil
Authors: Kahn Brian A. , Maness Niels O. , Chrz Donna R. , Carrier Lynda K.
Published: February 2019

Six experiments were conducted on ‘Genovese’ basil (Ocimum basilicum L.) in Oklahoma to study the feasibility of establishing basil in the field by direct seeding. Variables examined included use of raw seed or pelleted seed, seeding depth, seeding rate, and comparison with transplanting. Direct seeding was done using a hand-pushed planter (first four experiments), a tractor-drawn planter (fifth experiment), or both types of planter (sixth experiment). Plants were destructively harvested by machine. Stands were established successfully using transplants or using raw or pelleted seed with a hand-pushed planter. Planting at a depth of ≈10 mm resulted in lower yields than planting at a depth where seeds barely were covered with soil (≈5 mm). Seeding rates of ≈80 seeds/m led to higher final stands and higher yields than those obtained with seeding rates of ≈30 seeds/m. These studies were not designed to test effects of plant population on basil yield, but data suggest that final stands above the common recommendation of one plant per 30.5 cm in rows spaced 90 cm apart may result in yield increases. Plots direct-seeded with the tractor-drawn planter failed to establish in the fifth experiment. Plants established using pelleted seed with the hand-pushed planter did not differ from plants established by transplanting in cumulative yields in the sixth experiment, even though the transplanting treatment allowed one additional harvest. The lowest cumulative yields in the sixth experiment came from plants established using pelleted seed with the tractor-drawn planter. Thus, direct seeding of basil was successful only with a hand-pushed planter. While direct seeding is a potentially viable alternative to transplanting for basil stand establishment, there is a need to identify a tractor-drawn seeder that can plant basil at the required shallow depth. In the interim, large-scale producers of basil should continue to use transplants to obtain reliable stand establishment.