bluuebunny/crossref_metadata_2025 huggingface dataset:
Evapotranspiration-based Irrigation Scheduling for Container-grown Viburnum odoratissimum (L.) Ker Gawl.
Authors: Million Jeff B. , Yeager Thomas H. , Albano Joseph P.
Published: February 2019

The capacity for evapotranspiration (ET)-based irrigation scheduling to reduce runoff volume and nutrient leaching was tested in Fall 2004 and Spring 2005. Runoff (container leachate plus unintercepted irrigation and precipitation) was collected continuously for 17 weeks during production of sweet viburnum [Viburnum odoratissimum (L.) Ker Gawl.] in 2.4-L (16-cm top diameter) containers fertilized with an 18N–2.6P–10K polymer-coated, controlled-release fertilizer. Treatments were a factorial arrangement of two irrigation rates (fixed rate of 1 cm·d−1 or a variable, ET-based rate) and two fertilizer rates (15 or 30 g/container in 2004 and 10 or 15 g/container in 2005). Averaged over the two experiments and compared with the 1-cm·d−1 rate, ET-based irrigation reduced the amount of irrigation water applied (L/container) by 39% and runoff volume (L/container) by 42% with greatest reductions observed during the second half of the 2004 experiment and the first half of the 2005 experiment. Compared with 1-cm·d−1 rate, ET-based irrigation reduced runoff nitrogen (N), phosphorus (P), and potassium (K) (mg/container) by 16%, 25%, and 22%, respectively, in 2004 and runoff K 15% in 2005 with irrigation effects varying on a weekly basis. Irrigation treatments did not affect the response of plants to fertilizer rate. Because shoot dry weight was unaffected by irrigation treatments, results indicate that compared with a fixed irrigation rate, ET-based irrigation can reduce irrigation and runoff volumes and to a lesser extent nutrient loss while providing adequate water for plant growth.
Carpological Variability of Almond [Prunus dulcis (Mill.) D.A. Webb cv. Nonpareil] in a Single Orchard during Seven Consecutive Harvests
Authors: Ledbetter Craig A. , Sisterson Mark S.
Published: February 2019

A multiyear study was conducted in California's San Joaquin Valley to examine variability of carpological characteristics of the popular Nonpareil almond cultivar. Samples of ‘Nonpareil’ almond fruit were collected from a single orchard during seven consecutive harvests and evaluated for 19 specific carpological characters. Harvest year significantly affected all measured variables. Of the evaluated characters, fruit weight was the most variable between years, whereas kernel percentage was one of the least variable characters. As a result of year-to-year variability in carpological characters, the relationship between kernel weight and all other measured variables was investigated to determine if regression models could better describe kernels. Kernel weight best explained variability in kernel surface area (R2 = 0.943) with year-to-year variability having only a minor affect on the relationship. The results indicate that ‘Nonpareil’ almonds cannot be described using simple metrics and that definitive metrics must be able to account for differences among years.
How Salinity Affects Co2 Fixation by Horticultural Crops
Authors: Mota-Cadenas César , Alcaraz-López Carlos , Martínez-Ballesta M. Carmen , Carvajal Micaela
Published: February 2019

It has been recognized widely that sequestration of atmospheric CO2 by terrestrial ecosystems can contribute significantly to the stabilization of atmospheric CO2. The carbon sequestration potential of crop lands should be considered as a modest but non-negligible contribution to climate change mitigation. Salinity is one of the most important environmental factors limiting crop production of marginal agricultural soils in many parts of the world. In our research, several physiological analyses were performed in atmospheric CO2, in daylight, both in normal conditions and with salinity (40 mm NaCl). Crops like melon or pepper showed significantly lower photosynthetic rates when they were grown in saline conditions. Also, the total chlorophyll content and carbon percentage were lower in the salinity-treated plants of these species. For lettuce, treated plants showed a significant decrease in photosynthetic rates and chlorophyll content, but there were no differences in carbon content. On the other hand, there were no significant differences in the values of total chlorophyll content, photosynthetic rate, or carbon content for tomato and watermelon plants when control and NaCl-treated plants were compared. The mineral composition data showed greater increases of sodium in both roots and leaves of melon and pepper when plants were treated with NaCl compared with the rest of the species. In conclusion, tomato and watermelon seem to be more efficient in CO2 fixation than the other crops of this experiment and this seems to be related to their greater salinity tolerance.
Cold-hardiness and Deacclimation of Styrax americanus from Three Provenances
Authors: Lenahan Olivia M. , Graves William R. , Arora Rajeev
Published: February 2019

Styrax americanus Lam. (American snowbell) is a deciduous shrub or small tree seldom produced in nurseries. This species is distributed in patchy populations found mainly from Florida to southern Illinois, although a small, disjunct population exists in northern Illinois. The winter-hardiness and loss of hardiness during a period of increased temperature (deacclimation) of plants from this disjunct population may differ from those of S. americanus elsewhere. We examined cold-hardiness and deacclimation of stems of plants from the disjunct population, from southern Illinois, and from Florida. Segments of stems removed from plants grown outdoors in Ames, IA, were exposed to low-temperature ramping, and the temperature at which stems showed 50% damage (LT50) was determined by using the tissue-discoloration method. To assess deacclimation, stem segments were collected from cold-acclimated plants during winter in a minimally heated greenhouse and exposed to controlled warm temperatures for various time intervals followed by low-temperature ramping. Plants from Illinois were ≈15 °C more cold-hardy than plants from Florida in Feb. 2008. Plants from the disjunct population in northern Illinois showed less stem tip injury than did plants from southern Illinois. Deacclimation patterns were similar between plants from both Illinois populations. Plants sampled in Apr. 2009 from Florida deacclimated more rapidly than corresponding samples from Illinois, and the chilling required to overcome endodormancy increased with increasing latitude of plant origin. This research suggests that germplasm from the Illinois populations should be used in regions where the poorer hardiness and deacclimation resistance of most S. americanus would not permit survival.
Effect of Container Design on Plant Growth and Root Deformation of Littleleaf Linden and Field Elm
Authors: Amoroso Gabriele , Frangi Piero , Piatti Riccardo , Ferrini Francesco , Fini Alessio , Faoro Marco
Published: February 2019

This experiment investigated the effect of different container design on growth and root deformation of littleleaf linden (Tilia cordata Mill.) and field elm (Ulmus minor Mill.). The trial was carried out over two growing seasons (2008 to 2009). In April 2008, 1-year-old bare-root seedlings of the two species were potted in three types of 1-L containers: Superoots® Air-Cell™ (The Caledonian Tree Company, Pathhead, UK), Quadro fondo rete (Bamaplast, Massa e Cozzile, Italy), and smooth-sided containers. At the beginning of the second growing season, the same plants were repotted in the following 3-L containers: Superoots® Air-Pot™ (The Caledonian Tree Company), Quadro antispiralizzante (Bamaplast), and smooth-sided containers. At the end of each growing season, a subset of the plants from each container type was harvested to determine shoot and root dry mass and root deformation (by dry weight of root deformed mass relative to the whole root mass). Chlorophyll fluorescence and leaf chlorophyll content were measured during the second growing season. For both species, at the end of first growing season, the poorest root architecture was observed in the smooth-sided containers, whereas Superoots® Air-Cell™ and Quadro fondo rete both reduced the percentage of deformed root mass. At the end of the second growing season, plants of both species grown in Superoots® Air-Pot™ showed less deformed root mass, whereas Quadro antispiralizzante provided good results only in littleleaf linden. A reduction of field elm root biomass and littleleaf linden shoot biomass was observed at the end of the trial in plants grown in Superoots® Air-Pot®. Plants grown in these containers showed less leaf chlorophyll content compared with plants grown in smooth-sided containers at the end of the second year.
Comparison of Kasugamycin to Traditional Bactericides for the Management of Bacterial Spot on Tomato
Authors: Vallad Gary E. , Pernezny Kenneth L. , Balogh Botond , Wen Aimin , L. Figueiredo Jose Francisco , Jones Jeffrey B. , Momol Timur , Muchovej Rosa M. , Havranek Nikol , Abdallah Nadia , Olson Steve , Roberts Pamela D.
Published: February 2019

Studies were conducted at three locations in Florida to evaluate the effects of kasugamycin alone, in alternation, or as a tank-mix partner with copper bactericides and other fungicides against bacterial spot of tomato. In greenhouse trials, kasugamycin, formulated as Kasumin® 2L, reduced bacterial spot severity by up to 37.5% compared with a non-treated control. Little advantage in disease control was observed by mixing kasugamycin with other fungicides. Kasugamycin was assessed in six field trials. In the four field trials that tested kasugamycin alone, it was as effective as the standard copper + mancozeb treatment for the control of bacterial spot. In four trials, no benefit was observed in applying kasugamycin as a mixture with copper + mancozeb, and only one of three trials did alternating kasugamycin with copper + mancozeb improve bacterial spot control over either the copper + mancozeb standard or kasugamycin alone. Although kasugamycin was effective for the control of bacterial spot in greenhouse and field trials, rapid development of resistance in field populations of X. perforans may shorten the effective use of this antibiotic.
Plant Growth Is Stimulated by Tea-seed Extract: A New Natural Growth Regulator?
Authors: Andresen Marianne , Cedergreen Nina
Published: February 2019

Various plant extracts are being marketed claiming to enhance both crop yield and quality and being environmentally friendly. However, these claims are rarely documented by scientific data. In this study, we investigate the growth regulatory effect of Tea Seed Powder (TSP), a saponin-rich waste product from tea seed (Camellia sp.) oil production. The product was tested in various concentrations on Lemna growth and as a soil and spray application on growth of pot grown beet, mustard, oat, and barley. Finally, two treatments, 0.2 g TSP/L dry soil and weekly sprays with TSP solutions corresponding to 1.5 g TSP/m2, were tested for effects on strawberry yield. The results showed significant growth-enhancing effects on the sterile Lemna of ≈20% above control, demonstrating that the growth increase was a plant physiological response to TSP rather than an indirect effect of TSP affecting pests and diseases or improving nutrient uptake. Soil-treated, pot-grown beet, oat, and barley plants showed significant biomass increases in the range of 27% to 41% above control at concentrations of ≈0.3 g TSP/L dry soil, whereas increases of 14% to 26% were observed in plants sprayed with 0.15 to 1.5 g TSP/m2. Sprayed strawberries had a 38% higher berry yield compared with control plants in 2008, whereas no difference in leaf number and area, number of runners, and inflorescences were detected. In 2009, there were no significant observable differences between sprayed plants and controls. Soil-treated strawberry plants, however, showed a decrease in leaf number in 2008 and in strawberry yield in 2009. The study concludes that TSP has pronounced and direct physiological effects on plants, which can both increase and decrease growth and yield depending on the applied dose. The growth-enhancing effect could be used commercially to improve crop yield; however, because TSP is also known to be very harmful to earthworms, possible environmental effects of the use of TSP in agriculture and horticulture must be considered before use.
The Gastrodia Antifungal Protein (GAFP-1) and Its Transcript Are Absent from Scions of Chimeric-grafted Plum
Authors: Nagel Alexis K. , Kalariya Hetal , Schnabel Guido
Published: February 2019

The Gastrodia antifungal protein (GAFP-1) is a monocot mannose-binding lectin found in the Asiatic orchid Gastrodia elata. Transgenic plum (Prunus domestica var. ‘Stanley’) lines (4J and 4I) expressing GAFP-1 exhibit enhanced disease resistance to the stramenopile pathogen Phytophthora cinnamomi and the root-knot nematode Meloidogyne incognita. Rootstocks created from such transgenic lines might be more readily accepted by consumers if it can be shown that foreign gene products are not migrating into a grafted, nontransgenic scion on which fruit is produced. In this study, wild-type (WT) plum tissue was budded onto transgenic plum lines 4J and 4I to create chimeric-grafted trees. Tissues from chimeric-grafted trees were analyzed for gafp-1 transcripts (leaf and root) and protein (leaf, soft shoot, and root) by reverse transcription–polymerase chain reaction and immunodetection, respectively. Transcripts of gafp-1 were detected consistently in the root tissues but not within the leaves of the grafted, WT scions. Similarly, the GAFP-1 lectin was identified within the roots, but not in the soft shoot or leaf tissues of the grafted, WT scions. These results suggest that gafp-1 mRNA and protein are not moving into the WT scion tissues of chimeric-grafted plum trees.
Resistance to Phytophthora cactorum in Diploid Fragaria Species
Authors: Eikemo Hävard , Brurberg May B. , Davik Jahn
Published: February 2019

Sixty accessions/genotypes (entries) of diploid Fragaria sp. were tested for susceptibility to Phytophthora cactorum in greenhouse tests. Four experiments, each with four to 35 entries, were conducted, and each entry was represented by 36 to 45 plants per experiment. The plants were graded according to the number of weeks of survival during the first 4 weeks and for plants surviving more than the first 4 weeks, scoring was based on amount of necrosis in the crown. Statistical analysis showed no significant difference among the four experiments. A majority of the accessions (48) were categorized as being resistant or moderately resistant to Phytophthora cactorum. The disease score for this group varied from 1.06 to 3.09. Five accessions with disease scores ranging from 6.25 to 7.43 were considered highly susceptible. Within F. vesca, a highly significant proportion of the total variation in disease scores (57.6%) was attributable to the differences between accessions and, hence, of genetic nature. There was no indication of any Fragaria species being more resistant or susceptible than others and no systematic differences resulting from geographic origin.
Characterization of Strains of Xanthomonas axonopodis pv. dieffenbachiae from Bacterial Blight of Caladium and Identification of Sources of Resistance for Breeding Improved Cultivars
Authors: Seijo Teresa E. , Peres Natalia A. , Deng Zhanao
Published: February 2019

Bacterial blight, caused by Xanthomonas axonopodis pv. dieffenbachiae (Xad), is the most common foliar disease of caladium, an ornamental aroid grown for its colorful foliage. The disease can reduce the marketability of caladiums produced as potted plants and lower the yield of caladiums grown for tuber production. Three bacterial strains were isolated from symptomatic caladiums and identified as Xad using fatty acid analysis, carbon source use, and the sequence of the 16S-23S spacer, and tested for virulence against three susceptible cultivars. Two strains were virulent to all of the cultivars; however, one strain was differentially pathogenic, virulent against two cultivars, but not to the usually highly susceptible ‘Candidum’. In greenhouse inoculation tests of 17 cultivars and one breeding line, four cultivars were ranked as highly susceptible, nine as moderately susceptible, and five as resistant. Ten of these cultivars were also evaluated with natural infection in the field with good agreement between the results of the greenhouse and field evaluations. Cultivars White Queen, Florida Red Ruffles, Florida Sweetheart, Candidum Jr., and Mrs. Arno Nehrling have been identified as resistant to bacterial blight in greenhouse or field evaluations and can potentially be used in future breeding efforts to produce improved cultivars.
Screening of Agaricus bisporus (Lange, Imbach) Strains and the Casing Variables for Quality Mushroom Production in Spain
Authors: Pardo Arturo , de Juan Arturo , Alvarez-Ortí Manuel , Pardo José E.
Published: February 2019

Production and quality parameters of three commercial strains of cultivated mushroom Agaricus bisporus (Lange, Imbach) were evaluated. A correlation matrix was made between the main parameters. Blancochamp BL-40, a smooth white hybrid, generally produced the greatest number of mushrooms and provided the highest yield, and its firm mushrooms showed high protein, dry matter, and soluble solid content. Pla. 8.9, a midrange hybrid type, produced mushrooms with a high protein, soluble solid, and ash content. The third strain assayed was Gurelan 45, which produced large, firm off-white mushroom crops. A correlation matrix was made between the main parameters. In regard to the other parameters considered, no strain stood out from the others. The Rioja-type casing produced the greatest number of mushrooms, although these were smaller and harvested earlier than those produced in other casing mixtures. Soil without additives produced the largest mushrooms, which also had a higher dry matter content, were firmer, and contained more soluble solids. The other casing materials, binary mixtures of soil with sphagnum or black peat, produced mushrooms of intermediate values. The correlation matrix showed that the higher the number of mushrooms, the greater the overall yield, the smaller the size, and the earlier the first flush. It was also observed that a higher content in dry matter was correlated with firmer texture, greater contents in soluble solid and protein, and lower pH and ash content.
Adoption of Soilless Cropping Systems in Mediterranean Greenhouses: An Application of Duration Analysis
Authors: Alcon Francisco , García-Martínez Mari Carmen , De-Miguel María Dolores , Fernández-Zamudio María Ángeles
Published: February 2019

The Mediterranean basin holds the greatest area of horticultural crops grown under plastic in the world. Spain houses almost 50,000 ha of greenhouses and is one of the largest suppliers of European Union markets. Soilless cropping systems constitute an efficient production practice used in greenhouses and lessen the limitations arising from the ban of methyl bromide. Soilless cultivation is associated with the use of expensive technology, which makes farmers consider such adoption carefully. The aim of this work is to statistically identify the factors that significantly influence the timing of adopting soilless cultivation by using duration analysis. The study focuses on Mediterranean greenhouses, specifically horticultural producers in the southeast of Spain. The results suggest that certain individual characteristics as well as aspects of a social nature exert a favorable influence by reducing the delay in adopting soilless cultivation. Furthermore, technical complexity, commercial aspects related to price, and the repercussion of policies regulating methyl bromide use are also discussed in this work.
In Vitro Regeneration of Cephalotus follicularis
Authors: Ko Chia-Yun , Lin Tsai-Yun , Ho Chin-Wen , Shaw Jei-Fu
Published: February 2019

To establish a mass micropropagation procedure for Cephalotus follicularis, the effects of varying the strengths of solid Murashige and Skoog (MS) medium were investigated using subcultured shoot explants. After a 60-day primary culture from root mass, the regenerated shoot explants were subcultured every 60 days in solid MS medium. To facilitate shoot proliferation, liquid MS medium was applied with or without exogenous auxin and cytokinin. Our results demonstrate that shoot proliferation and survival of C. follicularis is most effective in modified MS (MMS) medium containing one-fifth or one-tenth strength macronutrients and full-strength micronutrients. Successful shoot proliferation and development of C. follicularis explants were obtained in one-fifth or one-tenth modified liquid MS medium without auxin and cytokinin or with addition of 5 μM indole 3-acetic acid/1 μM N6-benzyladenine for 45 days. The liquid medium consistently produced more explants than the solid medium and shortened the culturing time. Plantlets cultured in hormone-free one-fifth MMS medium developed greater root systems. Using the liquid culture we established, vigorous plants with extensive roots were obtained within 4 months. Plant survival in the greenhouse reached 100%.
Effect of Irrigation Scheduling on Gerbera Flower Yield and Quality
Authors: Tsirogiannis Ioannis , Katsoulas Nikolaos , Kittas Constantinos
Published: February 2019

Better understanding of the effects of irrigation frequency and dose on flower production of gerbera plants (Gerbera jamesonii) can lead to optimal water management and crop yield. Measurements of greenhouse microclimate and production and quality characteristics of a gerbera crop were carried out under two irrigation frequency regimens in soilless cultivation in a greenhouse located in Arta, Greece. Irrigation scheduling was based on solar radiation and performed whenever accumulated solar radiation energy outside the greenhouse reached 1650 kJ·m−2 [high irrigation frequency (HIF)] or 3300 kJ·m−2 [low irrigation frequency (LIF)]. The amount of water applied was 0.125 mm and 0.250 mm for HIF and LIF, respectively. Stem fresh weight, length and thickness, and number of harvested gerbera flowers were measured along with crop evapotranspiration, crop leaf area, and greenhouse microclimate variables. Measurements started 8 months after transplanting and lasted 90 days (May to July). Leaf area, fresh weight, harvested cut flowers, and the main quality characteristics of gerbera flowers (stem length and flower diameter) were unaffected by the irrigation frequency. In the framework of the experiment, simple formulas for calculation of leaf area index were developed. Finally, a first approach study of an alternative remote sensing irrigation control method using a reflectance index was made and the results are presented.
Isolation and Characterization of Microsatellite Loci for the Ornamental Plant Primula obconica Hance (Primulaceae)
Authors: Yan Hai-fei , Ge Xue-jun , Hu Chi-ming , Hao Gang
Published: February 2019

Nine microsatellite loci were isolated from Primula obconica using the FIASCO protocol. We used 30 individuals from three populations for the assessment of microsatellite variation. Seven loci were detected with microsatellite polymorphism. The number of alleles per locus ranged from three to seven. The average observed heterozygosity and expected heterozygosity ranged from 0.167 to 0.6 and from 0.409 to 0.653, respectively. These microsatellite markers will be useful to assess the genetic variation and genetic structure of P. obconica.
Assessment of Resistance in Lettuce (Lactuca sativa L.) to Mycelial and Ascospore Infection by Sclerotinia minor Jagger and S. sclerotiorum (Lib.) de Bary
Authors: Hayes Ryan J. , Wu Bo Ming , Pryor Barry M. , Chitrampalam Periasamy , Subbarao Krishna V.
Published: February 2019

Lettuce drop caused by Sclerotinia spp. is an economically important disease of lettuce (Lactuca sativa L.), and cultivars with resistance to mycelial infection by Sclerotinia sclerotiorum (Lib.) de Bary and S. minor Jagger as well as to S. sclerotiorum ascospores are needed. Assessing resistance in field experiments can be complicated by fast bolting or small stature lettuce lines that may escape rather than resist the pathogens. Therefore, methods to select resistant lines from morphologically variable populations are needed. We used S. sclerotiorum and S. minor-infested field experiments, regression analysis, field experiments with artificially high plant densities, and S. sclerotiorum ascospore inoculations to identify lettuce lines with resistance to both pathogens. Three replicated experiments in S. sclerotiorum-infested fields were conducted in Yuma, AZ, and three replicated experiments in a S. minor-infested field were conducted in Salinas, CA, using diverse populations of iceberg, romaine, leaf, butterhead, Latin, oilseed lettuce, and wild relatives of lettuces; and genetic variation for the incidence of lettuce drop from mycelial infections was identified. In two S. minor field experiments, a quadratic regression model was developed that related rapid bolting with reduced lettuce drop. Regression residuals were calculated, and eight cultivars or PIs had negative residuals in two independent field experiments, indicating higher resistance than predicted by their rate of bolting. Eruption, a small-statured Latin cultivar, had significantly lower disease levels than susceptible cultivars in experiments with high plant densities, indicating that its small size did not facilitate disease escape. Ascospore inoculations confirmed resistance in ‘Eruption’ and L. virosa SAL012, whereas the oilseed lettuce PI 251246 may have partial resistance to infection. These lines will likely be useful for development of Sclerotinia spp.-resistant lettuce cultivars.
Response of Evapotranspiration of Viburnum odoratissimum to Canopy Closure and the Implications for Water Conservation during Production and in Landscapes
Authors: Beeson Richard C.
Published: February 2019

Transpiration of woody shrubs appears to increase with decreases in plant density within production beds as plants are randomly removed for sale. To assess potential impact on irrigation management, this observation was tested with market-sized plants in suspension lysimeters at specific levels of canopy closure. Canopy closure was defined as the percentage of cumulative projected two-dimensional canopy area of individual plants per unit ground area on which they were placed. In 1997, evapotranspiration (ETA) of plants in 26.6-L containers was comparable from isolated plants up to 67% canopy closure. At full canopy closure (100%), ETA was 40% less than 67% closure or lower. When repeated in 2003, results were similar for similar-sized plants and for two sizes smaller (11.4- and 3.8-L containers). ETA response to canopy closure was independent of height from 0.5 to 1.5 m tall. At full canopy closure, whole plant transpiration was equivalent to that measured from only the upper 40% (by height) of the canopy under full sun. This was independent of plant size. Implications for water conservation during production and plants’ irrigation needs in landscapes are discussed.
Effects of Cowpea Leaf Harvesting Initiation Time and Frequency on Tissue Nitrogen Content and Productivity of a Dual-purpose Cowpea–maize Intercrop
Authors: Saidi Mwanarusi , Itulya Francis M. , Aguyoh Joseph N. , Ngouajio Mathieu
Published: February 2019

Cowpea [Vigna unguiculata (L.) Walp.] is an important component of most traditional cropping systems in the semiarid tropics. It provides both leaf vegetable and/or grain. Dual-purpose production of cowpea is most common in subsistence farming systems. Little is, however, known about the effects of cowpea leaf harvesting on tissue nitrogen composition and productivity of most cowpea-based cropping systems. A four-season study was carried out at the National Dry Land Research Center, Katumani, Kenya, to establish the effects of cowpea leaf harvesting initiation time and frequency on 1) tissue nitrogen content of cowpea and maize in a dual-purpose cowpea–maize intercropping systems; and 2) cowpea and maize yield and the overall productivity of a cowpea–maize intercrop measured by land equivalent ratio (LER). Cowpea leaf harvesting was initiated at 2, 3, or 4 weeks after emergence (WAE) and continued at 7- or 14-day intervals until onset of flowering. Cowpea tissue nitrogen content was highest in the control treatment and lowest in cowpea subjected to leaf harvesting from 2 WAE or at 7-day intervals, whereas maize tissue nitrogen content showed the reverse trend. Harvesting cowpea leaves from 3 WAE or at 7-day intervals gave the highest leaf vegetable yield, whereas grain yields were highest when no leaf harvesting was done. Maize yields were significantly improved by harvesting of leaves of the companion cowpea. Harvesting cowpea leaves for use as leaf vegetable increased productivity per unit area of land as measured by LER with the highest productivity achieved when leaf harvesting was initiated at 4 WAE or done at a 14-day interval.
Relative In Vitro Wood Decay Resistance of Sapwood from Landscape Trees of Southern Temperate Regions
Authors: Baietto Manuela , Wilson A. Dan
Published: February 2019

The development of wood decay caused by 12 major root-rot and trunk-rot fungi was investigated in vitro with sapwood extracted from nine ornamental and landscape hardwood and conifer species native to southern temperate regions of North America, Europe, and the lower Mississippi Delta. Wood decay rates based on dry weight loss for 108 host tree–wood decay fungi combinations were compared at 21 °C over 1-year and 2-year incubation periods in the absence of tree-resistance mechanisms. Strains of Armillaria mellea, Ganoderma lucidum, and Heterobasidion annosum exhibited the highest decay potential in most tree species tested. The order of fungi causing the greatest decay varied over time as a result of temporal changes in decay-rate curves. Relative wood durability or resistance to decay generally was greater in gymnosperm than in angiosperm wood types. Quercus nuttallii, Fraxinus pennsylvanica, and Quercus lyrata sustained the highest levels of decay by all fungi. Northern white cedar (Thuja occidentalis) sapwood was most resistant to decay by all rot-fungi tested, sustaining only limited weight loss after 1 and 2 years of decay, although sapwood of Pinus taeda, Liquidambar styraciflua, and Platanus occidentalis had relatively low levels of decay after 2 years. These results in combination with data from portable decay-detection devices provide useful information for the management of tree breakages or failures resulting from wood decay fungi in hazardous landscape trees. Some potential landscaping applications for tree evaluations, risk assessments, and selections for tree-replacement plantings are discussed.
Color Changes and Antioxidant Content of Vine and Postharvest-ripened Tomato Fruits
Authors: Pék Zoltán , Helyes Lajos , Lugasi Andrea
Published: February 2019

Tomato fruit ripening is a complex, genetically programmed process that culminates in dramatic changes in texture, color, flavor, and aroma of the fruit flesh. The characteristic pigmentation of red ripe tomato fruit is the result of the de novo synthesis of carotenoids, mainly lycopene and β-carotene, which are associated with the change in fruit color from green to red as chloroplasts are transformed to chromoplasts. The aim of this study was to examine the effect of ripening conditions on color development and antioxidant content. Detached tomato fruit stored at 15 and 30 °C and vine-ripened fruits were studied to characterize the ripening process by Hue (°) index (CIELab color system), which is strongly influenced by the circumstances of ripening. Total polyphenols, ascorbic acid, and lycopene content of tomato fruits were analyzed at the end of the experiment. Changes in the color of fruit stored at 15 °C and vine-ripened fruit showed significantly higher a* compared with fruit stored at 30 °C. Storage temperature influenced positively ascorbic acid and negatively lycopene content, whereas total polyphenols did not show differences among the different ripening conditions.
Optimizing Early Flowering and Pre-selection for Short Juvenile Period in Olive Seedlings
Authors: Moreno-Alías Inmaculada , Rapoport Hava F. , López Rafael , León Lorenzo , de la Rosa Raúl
Published: February 2019

In recent years, the juvenile period of olive seedlings has been reduced by diverse forcing and pruning-formation techniques, but it is still a major drawback for breeding. Plant height at the time when seedlings are transplanted to the field has been found effective for obtaining earlier flowering, but the value of this parameter varies widely among olive breeding programs. We evaluated different transplant dates, taking into account mean plant height and age, with the aim of determining the optimum parameters for achieving early flowering and easy plant management and, at the same time, for the early elimination of genotypes with a long juvenile period. A mean seedling height of ≈100 cm at the time of planting in the field provided the best results in terms of shortening the juvenile period and facilitating handling of the seedlings. For all dates tested, seedling height at transplanting was effective as a pre-selection criterion for the early elimination of genotypes with long juvenile periods, with slight improvement in effectiveness with advancing transplant date.
Efficient Breeding System for Red-fleshed Apple Based on Linkage with S3-RNase Allele in ‘Pink Pearl’
Authors: Sekido Keiko , Hayashi Yusaku , Yamada Kunio , Shiratake Katsuhiro , Matsumoto Shogo , Maejima Tsutomu , Komatsu Hiromitsu
Published: February 2019

We have used a red-fleshed apple cultivar, Malus ×domestica Pink Pearl, and its progeny, ‘JPP 35’, as paternal parents for producing new red-fleshed cultivars suitable for fresh use or processing such as pie fillings, dried apple, apple juice, or cider. In this process, we found that the S3-RNase allele of ‘Pink Pearl’ was linked to its red flesh trait. It was suggested that this trait might be controlled by a new gene apart from the MYB10 (MdMYB10) gene. Using ‘JPP 35’ (S-RNase allele genotype; S3S7) produced by ‘Jonathan’ (S7S9) × ‘Pink Pearl’ (S3Sx) as a paternal parent, we developed a system for producing red-fleshed progenies suitable for fresh use. That is, 96% and 86% of progenies from ‘Shinano Sweet’ (S1S7) × ‘JPP35’ (S3S7) and ‘Orin’ (S2S7) × ‘JPP35’ (S3S7) containing the S3-RNase allele, respectively, showed the red flesh trait. Similarly, red-fleshed progenies suitable for apple pie or natural red juice could be produced by ‘Jonathan’ (S7S9) × ‘JPP35’ (S3S7).
Use of Commercially Available Pollenizers for Optimizing Triploid Watermelon Production
Authors: Dittmar Peter J. , Monks David W. , Schultheis Jonathan R.
Published: February 2019

An experiment was conducted during 2005 and 2006 in Kinston, NC, with the objective of maximizing triploid watermelon [Citrullus lanatus (Thunb.) Matsum. and Nak.] fruit yield and quality by optimizing the choice and use of pollenizers. Treatments were pollenizer cultivars planted singly [‘Companion’, ‘Super Pollenizer 1’ (‘SP1’), ‘Summer Flavor 800’ (‘SF800’), and ‘Mickylee’] or in pairs (‘Companion’ + ‘SP1’, ‘Companion’ + ‘SF800’, and ‘SP1’ + ‘SF800’). All pollenizers from these seven treatments were interplanted with the triploid cultivar Tri-X-313. Planting arrangement was compared by establishing ‘SF800’ in a hill versus an interplanted field arrangement. Effect of pollenizer establishment timing on triploid fruit yields and quality was evaluated by establishing ‘SP1’ 3 weeks after planting and comparing it with the establishment of ‘SP1’ at the time of triploid plant establishment. Finally, a triploid planting with no pollenizer (control) was included to determine pollen movement. Fruit yield from the control was 22% or less of yield of the other treatments containing a pollenizer and less than 10% in the initial or early harvests. Pollen movement was minimal among plots and differences in yield and fruit quality could be attributed to pollenizer treatment. In 2005, the use of ‘Companion’, ‘SP1’, or ‘Mickylee’ as pollenizers produced similar total yields, whereas ‘SF800’ produced the lowest yield. In 2005, ‘Companion’ produced more large fruit than the other individual pollenizer treatments. Combining the pollenizers generally did not enhance triploid yields or quality. Interplanting of pollenizers consistently resulted in greater yield compared with the hill system. Late planting of ‘SP1’ increased the incidence of hollow heart in the marketable fruit and decreased yield compared with simultaneously planting ‘SP1’ and triploid plants. Thus, selection of pollenizer, planting arrangement, and time of pollenizer establishment are all important considerations to optimizing triploid yield and quality.
Potential Photosynthetic Advantages of Cucumber (Cucumis sativus L.) Seedlings Grown under Fluorescent Lamps with High Red:far-red Light
Authors: Shibuya Toshio , Endo Ryosuke , Kitamura Yuki , Kitaya Yoshiaki , Hayashi Nobuaki
Published: February 2019

To evaluate the effect of fluorescent lamps with a high red:far-red (R:FR) light on the potential photosynthesis of transplants, we investigated the photosynthetic light responses of cucumber (Cucumis sativus L.) seedlings grown under fluorescent lamps with high R:FR light (FLH) and compared them with the responses of the seedlings grown under metal-halide lamps (ML) that provided a spectrum similar to that of natural light and under a fluorescent lamp with low R:FR light (FLL). The seedlings were grown under FLH (R:FR = 7.0), ML (R:FR = 1.2), or FLL (R:FR = 1.1) at a photosynthetic photon flux density (PPFD) of 350 μmol·m−2·s−1. The gross photosynthetic rate (Pg), quantum yield of photosystem II (ΦPSII), and photosynthetic electron transfer rate (ETR) of the foliage leaves were then evaluated at PPFDs ranging from 0 to 1000 μmol·m−2·s−1. The photosynthetic light response of FLH seedlings was similar to those of sun leaves, and the responses of ML and FLL seedlings were similar to those of shade leaves. The Pg, ETR, and ΦPSII of FLH seedlings at PPFD of 1000 μmol·m−2·s−1 was 1.38, 1.32, and 1.28 times, respectively, those of ML seedlings, and was 1.40, 1.23, and 1.22 times, respectively, those of FLL seedlings. The Pg was closely correlated with ETR in each treatment. FLH seedlings had thicker leaf and greater chlorophyll content per leaf area than ML and FLL seedlings. The greater Pg of FLH seedlings than in the other two groups of seedlings at high PPFD was probably the result of the improved ETR resulting from physiological and morphological changes in response to the high R:FR light.
Effects of Pricing Influences and Selling Characteristics on Plant Sales in the Green Industry
Authors: Campbell Benjamin L. , Hall Charles R.
Published: February 2019

Data from the 2004 National Nursery Survey conducted by the USDA-CSREES S-1021 Multistate Research Committee (referred to as the Green Industry Research Consortium) were used to evaluate the effect of pricing influences and selling characteristics on total gross firm sales and gross sales of several plant categories (trees, roses, shrubs/azaleas, herbaceous perennials, bedding plants, foliage, and potted flowering plants) for commercial nurseries and greenhouses. As expected, the firm's selling characteristics play a large role in whether a firm sells a specific plant category. Demand factors also play a role in affecting plant category sales with income, population, and race tending to be the only significant variables, except for the potted flowering plants category. In regard to sales, our results show that certain factors affecting pricing decisions play a critical role in both plant category sales and total sales. Furthermore, demand and business characteristics play a limited role as well, but not as big a role as selling characteristics. Of note is that firms with an increased percentage of sales through wholesale channels (of most plant categories and overall) result in increased sales. By understanding the nursery and greenhouse industry environment and how decisions affect overall and categorical sales, firms can implement strategies that capitalize on factors that have the potential to generate increased sales.
Essential Oils from Six Herbal Plants for Biocontrol of the Maize Weevil
Authors: Kerdchoechuen Orapin , Laohakunjit Natta , Singkornard Sasathorn , Matta Frank B.
Published: February 2019

Essential oils from sweet basil (Ocimum basilicum L.), holy basil (O. americanum L.), hairy basil (O. tenuiflorum L.), lime (Citrus aurantifolia Swingle), kaffir lime (C. hystrix DC.), and clove (Eugenia caryophyllus L.) were isolated by simultaneous distillation extraction. Toxicity assays against the maize weevil (Sitophilus zeamais Motschulsky) using 30 to 120 μL oil extract from the six plants on 70-mm-diameter filter paper discs resulted in 100% weevil mortality within the 5-h assay period. On rice samples, sweet basil oil extract was the most effective, resulting in 96% to 100% mortality regardless of oil extract volume on the first day during the 5-day assay period. Probit analysis showed that sweet basil oil extract applied on grains had four to five times lower LD50 (lethal dose to kill 50% of the weevils) and two to three times lower LD99 values than the remaining oil extracts. Repellency assay using 1 to 8 μL oil extract showed a different trend, because hairy basil was the most effective among treatments. Based on the effective control of the maize weevil by the oil extracted from herbal plants, such oil extracts could be useful in stored agricultural products and plant protection and reduce the risk associated with synthetic insecticides.
Thermotherapy for Control of Fungal Pathogens in Propagative Rootstocks of Horseradish
Authors: Eranthodi Anas , Babadoost Mohammad , Trierweiler Bernhard
Published: February 2019

This study was conducted to develop a reliable method for control of set-borne inoculum of Verticillium and Fusarium species that cause the internal discoloration of horseradish roots. Horseradish propagative root stocks (sets), 0.5 to 3.0 cm in diameter and 20 to 25 cm long, were treated by immersing them into water at 44, 45, 46, 47, 48, 49, and 50 °C for 10, 20, and 30 min. Treated and untreated sets were cultured on acidified potato dextrose agar to determine the presence of the pathogens in the sets. Treatments at temperatures lower than 46 °C did not control the set-borne inoculum of the pathogens. Treated and untreated sets were also planted in the greenhouse and fields to assess the effects of the thermotherapy on germination of the sets and vigor of the plants. Treatments at 48 °C or greater either delayed or reduced set germination and reduced plant vigor. The most effective treatment for control of the set-borne pathogens without adverse effects on set germination or plant vigor was determined to be 47 °C for 20 min.
Grafting Fraser Fir (Abies fraseri): Effect of Grafting Date, Shade, and Irrigation
Authors: Hibbert-Frey Haley , Frampton John , Blazich Frank A. , Hinesley L. Eric
Published: February 2019

Grafting fraser fir [Abies fraseri (Pursh) Poir.] scions onto rootstocks of turkish fir (Abies bornmuelleriana Mattf.) is a strategy used by some Christmas tree growers in the southern Appalachian Mountains of North Carolina to reduce losses by phytophthora root rot caused by Phytophthora cinnamomi Rands. This study compared the traditional time of grafting (April) with eight summer/early fall grafting dates from mid-July through mid-October. Shade and irrigation treatments were also superimposed on the grafting dates. To ensure optimal grafting success, grafting should be performed in the late winter/early spring (April) when scions are dormant and the rootstocks are becoming active. April graft success was 95% but when grafting fresh scions in summer/fall, graft success decreased from 52% in July to 0% in October. Shade improved summer graft success (52% with, 38% without). Irrigation did not significantly affect graft success or subsequent growth. In a supplemental storage study, grafting of stored scion material in summer/early fall was not successful (less than 1%).
Grapevine and Soil Water Relations with Nodding Needlegrass (Nassella cernua), a California Native Grass, as a Cover Crop
Authors: Costello Michael J.
Published: February 2019

Nodding needlegrass [Nassella cernua (Stebbins & R.M. Love) Barkworth], a California native perennial grass, was tested for its effects on grapevine and soil–water relations in a drip-irrigated vineyard in Parlier, CA. Vine water status and in-row and between-row soil moisture (at 0.3 m, 0.6 m, 0.9 m, 1.2 m, and 1.5 m) were monitored semiweekly from June to September. There was no overall significant difference in leaf water potential between treatments. In-row soil moisture was lowest at depths of 0.6 m to 0.9 m within the nodding needlegrass treatment but was lowest from 0.3 m to 0.9 m within the clean cultivation treatment. Compared with clean cultivation, nodding needlegrass in-row soil moisture was significantly higher at depths of 0.3 m and 0.6. m and did not differ at depths of 0.9 m and 1.2 m. In contrast, in-row soil moisture was significantly higher under clean cultivation compared with nodding needlegrass at 1.5 m. Between-row soil moisture was significantly higher under clean cultivation compared with nodding needlegrass at every depth. Combining in-row and between-row data, overall vineyard soil moisture was slightly lower, by 1.2% points, in the nodding needlegrass treatment compared with clean cultivation. There was no interaction between treatment and depth for between-row soil moisture, indicating that the vines used little water from the between-row area. The lack of difference between treatments in the rate of soil moisture depletion over the season indicates that nodding needlegrass used little water during the summer. Based on these results, nodding needlegrass appears to be suitable as a permanent cover crop in California drip-irrigated vineyards where competition for summer water is a concern.
Pigment Concentrations among Heat-tolerant Turfgrasses
Authors: Lefsrud Mark G. , Sorochan John C. , Kopsell Dean A. , McElroy J. Scott
Published: February 2019

Heat-tolerant bluegrass varieties were developed to resist dormancy and retain pigmentation during heat stress events. The objective of this study was to investigate the influence of grass species, nitrogen (N) fertilization, and seasonality on the accumulation patterns of lutein, β-carotene, and chlorophyll a and b in the leaf tissues of turfgrass. The heat-tolerant bluegrass cultivars Dura Blue and Thermal Blue (Poa pratensis L. × Poa arachnifera Torr.), Apollo kentucky bluegrass (Poa pratensis L.), and Kentucky 31 tall fescue (Festuca arundinacea Schreb.) were compared for the accumulation of plant pigments. Evaluations were conducted over 2 consecutive years (Years 4 and 5 after establishment) during two different seasons (spring and summer) and under varying N fertilization. Fertilizer applications of 5, 14, and 27 g N/m2/year resulted in a significant positive correlation for the accumulation of leaf blade lutein and chlorophyll a and b, but not for β-carotene. The accumulation of the four measured plant pigments among the grasses was significantly different with ‘Apollo’ having the largest concentration of pigments followed by ‘Dura Blue’, ‘Thermal Blue’, and finally ‘Kentucky 31’. Specifically, when comparing the cultivars Apollo and Kentucky 31, the pigment levels decreased 27%, 26%, 26%, and 23% for lutein, β-carotene, and chlorophyll a and b, respectively. The interesting observation of the analysis of the grass pigment concentrations was that the least reported heat-tolerant cultivar in our study (‘Apollo’) had the largest measured pigment concentrations.