bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency of Manure Application in Organic versus Annual Application of Synthetic Fertilizer in Conventional Vegetable Production
Authors: Russo Vincent M. , Taylor Merritt
Published: February 2019

The cost of transporting manure can affect profit. Manure was applied either annually or biennially to bell pepper (Capsicum annuum L.), cv. Jupiter, cucumber (Cucumis sativus L.), cv. Earli Pik, and sweet corn (Zea mays var. rugosa Bonaf.), cv. Incredible (se endosperm genotype), produced using organic methods and compared with production of these crops using conventional methods and annually applied synthetic fertilizer. Conventional and organically maintained portions of the field were separated by a 25-m buffer zone planted with sweet corn, which was provided with manure. The experiment was conducted from 2005 to 2008 at Lane, OK. Nutrient contents of soil and edible portions were determined as were yields. Economic analyses comparing costs of production and profit were conducted. There were yield responses resulting from year. Bell pepper yield was little affected by type of fertilizer application. Cucumber and sweet corn benefited from use of manure over conventional fertilizer. There was no pattern of alternating increased or decreased nutrient content in edible portions or in the soil as a result of annual or biennial application of manure. Treatment with manure produced higher returns than did conventional fertilizer. Annual treatment with manure produced higher returns in bell pepper and sweet corn than did treatment with manure in alternate years; the opposite was true for cucumber. Annual application of manure appears to be necessary for most of the vegetable crops tested.
Response of ‘Honeycrisp®’ Apple Trees to Combinations of Pre-plant Fumigation, Deep Ripping, and Hog Manure Compost Incorporation in a Soil with Replant Disease
Authors: Braun P. Gordon , Fuller Keith D. , McRae Kenneth , Fillmore Sherry A.E.
Published: February 2019

This study evaluated the effects of pre-plant treatments: deep ripping (DR), fumigation (F), deep ripping plus fumigation (DRF), deep ripping plus hog manure compost (DRC), and deep ripping plus fumigation plus hog manure compost (DRFC) in comparison with a non-treated control (NTC) on shoot and root performance of ‘Honeycrisp’ apple trees on M.4 rootstocks in an old orchard site with apple replant disease (ARD). Cylindrocarpon spp., Pythium spp., and Pratylenchus penetrans Cobb, all potential agents of ARD, were present in the orchard soil. Fine-root numbers (1 to 2.9 mm diameter) were significantly greater in the DRC and DRFC treatments than the DR treatment. After 6 years, trunk cross-sectional area (TCSA) and yield were largest for the DRFC treatment followed closely by F. The DR treatment had no effect on TCSA, yield, or yield efficiency when applied alone compared with the NTC. Contrast analysis demonstrated that F was significantly better than non-F for yield in all years and TCSA and yield efficiency in 2007. Also, there was a significant interaction between DR and F treatment in 2005 that significantly reduced yield in the DRF treatment. Contrast analysis showed that compost had a significant positive effect on yield in all three production years and TCSA and yield efficiency in 2007. Yield efficiency in the third production year was largest for F, DRC, and the DRFC treatments. Nutrient analysis revealed that soil phosphorus concentrations in compost-treated plots were double those in other treatments. High phosphorus content of compost may have contributed to the amelioration of ARD symptoms. This study found that in 2007, soil fumigation alone, as conventionally used for ARD control, and composted hog manure were equally effective in increasing yield and yield efficiency of apple trees planted in an ARD soil. The DRFC treatment was the overall best treatment in all years.
Propagation of Quercus cerris, Q. petraea, and Q. pubescens Seedlings by Stem Cuttings
Authors: Struve Daniel , Ferrini Francesco , Bellasio Chandra , Fini Alessio
Published: February 2019

Quercus populations are noted for their genetic variability. However, this variability is difficult to manage through sexual propagation. The purpose of this study was to characterize the early height growth and water use of seedlings from six sources of Quercus native to Italy and to explore the rooting potential of semihardwood stem cuttings taken from young stock plants. There was great variability within a seed source for seedling height (a 1.5- to 7.8-fold difference depending on source) and water use seedling/day (a 0.7- to 16.5-fold difference). Stem cuttings rooted in high percentages (greater than 74%) for two sources of Q. petraea (Mattusch) Liebl. and Q. pubescens Willd. and one source of Q. cerris L. A second Q. cerris source had 48% rooting. Q. petraea and Q pubescens cuttings were rooted successfully in mid-June and early August with high survival percentages. Overwinter survival of cuttings from all propagation dates was 96% (303 of 314 rooted cuttings). In general, seedling stock plant height and water use were not significantly correlated with percent rooting suggesting that those characteristics could be selected independently resulting in tall or short clones with a range of water use efficiencies. Additional testing is needed to determine the relationship between the traits measured on young seedlings and those traits in older individuals.
Isolation and Characterization of 88 Polymorphic Microsatellite Markers in Kentucky Bluegrass (Poa pratensis L.)
Authors: Honig Josh A. , Bonos Stacy A. , Meyer William A.
Published: February 2019

Kentucky bluegrass (Poa pratensis L.) is an important facultative apomictic temperate perennial grass species used for both forage and cultivated turf. Through apomixis, this species is able to propagate diverse and odd ploidy levels, resulting in many genetically distinct phenotypes. A wide range of diverse cultivars and accessions of kentucky bluegrass have been previously characterized based on common turf performance or morphological characteristics as well as by random amplified polymorphic DNA (RAPD) markers. Although previous characterization efforts have provided valuable information, the use of both morphological characteristics and RAPD markers for genetic diversity analysis has limitations. In the current report, we developed and characterized 88 novel microsatellite markers for kentucky bluegrass. Polymorphism for each marker was assessed in 265 kentucky bluegrass cultivars, experimental selections, collections, and hybrids. The number of alleles for individual microsatellites ranged from four to 81 with an average of 38.3 alleles per simple sequence repeat. These polymorphic microsatellite markers would be useful tools for investigating genetic diversity, creation of genetic linkage maps, assessment of levels of apomixis in cultivars and experimental varieties, and identification of aberrant progeny in apomictic kentucky bluegrass breeding programs.
Perennial Ryegrass Allelopathic Potential on Bermudagrass Germination and Seedling Growth
Authors: McCarty Lambert B. , McCauley Raymond K. , Liu Haibo , Totten F. Wesley , Toler Joe E.
Published: February 2019

Overseeded perennial ryegrass (Lolium perenne L.) aggressively competes with bermudagrass [Cynodon dactylon (L.) Pers.] for resources and may adversely affect spring transition by releasing allelochemicals into the environment. Growth chamber studies examined germination and growth of ‘Arizona Common’ bermudagrass in soil amended with 0%, 2%, 12%, or 23% perennial ryegrass root or shoot debris or in soil treated with irrigation water in which perennial ryegrass roots at 0, 5, 10, or 20 g·L−1 or shoots at 0, 10, or 20 g·L−1 had been soaked. Inhibitory effects on bermudagrass germination and growth were most extensive when soil was amended with ryegrass shoot debris, because germination, root ash weight, root length density, and root mass density were reduced 33%, 55%, 30%, and 52%, respectively. Soil amended with ryegrass root debris only inhibited bermudagrass-specific root length. Application of irrigation water containing either ryegrass root or shoot extracts only inhibited bermudagrass-specific root length. In conclusion, results obtained when soil was amended with shoot debris demonstrated perennial ryegrass can inhibit bermudagrass germination and growth in controlled environments.
Crapemyrtle Genotype × Environment Interactions, and Trait Stability for Plant Height, Leaf-out, and Flowering
Authors: Pounders Cecil T. , Blythe Eugene K. , Fare Donna C. , Knox Gary W. , Sibley Jeff L.
Published: February 2019

This study reports on the performance of 34 clones of crapemyrtle (Lagerstroemia indica L., L. fauriei Koehne, and L. indica × L. fauriei hybrids) grown in field plots at four locations representative of different environments in the southeastern United States. Traits evaluated were spring leaf-out and initiation of flowering in the second season after field planting and plant height after 3 years of growth. Cluster analysis (Ward's method) was used for grouping and comparison of means across locations for each trait. Best linear unbiased prediction was used for estimating random effects in linear and generalized linear mixed models to better determine the general performance of the clones under a variety of environmental conditions. Each clone's trait stability was quantified using the regression of an individual genotype's performance for each of the three studied traits on an environmental index based on the trait mean for all genotypes grown in an environment. Sequence of clone leaf-out and size rankings were more stable across the environments than the sequence in which the various clones initiated flowering. L. fauriei clones and clones originating from the initial cross between L. indica and L. fauriei were generally later to leaf out, earlier to flower, and more vigorous growers than L. indica or the complex L. indica × L. fauriei clones that were evaluated. First flowering was affected by environmental variation more with interspecific hybrids than with L. fauriei and L. indica clones. Performance, particularly with respect to plant height, of several clones did not agree with previously published classifications. Information generated by this study will allow crapemyrtle breeders, landscape professionals, and consumers to better select the most appropriate crapemyrtle clone for a particular application.
Genetic Diversity among Cucumis metuliferus Populations Revealed by Cucumber Microsatellites
Authors: Weng Yiqun
Published: February 2019

Cucumis metuliferus E. Mey. ex Naud (African horned cucumber, horned melon) is endemic to Africa and is a relative of cultivated cucumber (C. sativus L.) and melon (C. melo L.). In the present study, genetic variation among the USDA C. metuliferus collection was evaluated with microsatellite [simple sequence repeat (SSR)] markers derived from C. sativus genomic DNA sequences. Of 564 cucumber SSRs tested, 51.8% were able to produce polymerase chain reaction amplicons in C. metuliferus suggesting a high degree of DNA sequence homology between the two species. Forty-two cross-species SSRs were used to assess genetic variation among 36 C. metuliferus accessions. Genetic diversity among these accessions was relatively low. Of the 42 SSRs, 12 were monomorphic, and each marker, on average, was able to detect 3.3 alleles among the 36 accessions. Neighbor-joining clustering analysis revealed a positive relationship between genetic divergence and geographic distances among these accessions. Genetic distance of C. metuliferus to melon is smaller than that of C. metuliferus to cucumber.
Screening Capsicum annuum Accessions for Resistance to Six Isolates of Phytophthora capsici
Authors: Candole Byron L. , Conner Patrick J. , Ji Pingsheng
Published: February 2019

Phytophthora blight caused by Phytophthora capsici Leon. is one of the most important diseases of bell peppers (Capsicum annuum L.) in Georgia. The level of resistance in commercial bell pepper cultivars is not effective in managing this disease in moist and humid conditions, and new sources of resistance are needed. A mixture of six Georgia isolates of P. capsici was used for greenhouse mass screening of 2301 accessions of Capsicum annuum. From the initial screening, 77 accessions were identified as resistant to P. capsici-induced root rot. From those 77 accessions, 28 accessions were selected for seed increase and further replicated root inoculation tests. Replicated tests confirmed the resistance of 14 of the 28 accessions, although genetic variability within the accessions hampered the analysis of resistance in some accessions. Two accessions, PI 201237 and PI 640532, demonstrated consistently high levels of resistance to root rot. These two accessions are potential sources of resistance genes that can be incorporated into commercial bell pepper cultivars.
Growing Degree-day Influence on Sprigged Establishment of Two Buffalograss Cultivars
Authors: Peterson Kenton W. , Shearman Robert C. , Gaussoin Roch E. , Horst Garald L. , Schacht Walter H.
Published: February 2019

Attempts to establish buffalograss [Buchloë dactyloides (Nutt.) Engelm.] turfs from sprigs have been limited and successful stand establishment has been inconsistent. This study was conducted to determine whether accumulated growing degree-days (GDD) and cultivar of harvested sprigs have an effect on buffalograss sprig establishment. Two field studies were conducted on a Tomek silty-clay loam (fine smectitic mesic Pachic Agriudolls) in 2007 and again in 2008. The cultivars Legacy, a hexaploid, and Prestige, a tetraploid, were used in this investigation. Sprigs were harvested and planted on 29 June, 17 July, 31 July, and 15 Aug. in 2007 and 15 May, 4 June, 19 June, 2 July, 21 July, 31 July, and 18 Aug. in 2008. The GDDs were back-calculated from these harvest dates. The harvest date of the sprigs represented 1050, 1380, 1670, and 1980 GDD in 2007 and 120, 380, 620, 840, 1200, 1400, and 1720 in 2008. Aboveground buffalograss phytomass and percent buffalograss groundcover data were collected in 2007 and 2008. In 2008, total available sugar and starch content of harvested sprigs were determined for each sprig harvest date. In the 2007 studies, sprigs harvested at 1050 GDDs resulted in the best establishment for both cultivars. In the 2008 studies, ‘Legacy’ established successfully through 840 GDDs, and ‘Prestige’ established through 1200 GDDs. Sugar or starch content did not appear to influence sprigging success. These results support the recommendation to establish buffalograss from sprigs harvested before 1050 GDDs for best results.
Consumer Preferences and Willingness to Pay for Locally Grown Organic Apples: Evidence from a Conjoint Study
Authors: Wang Qingbin , Sun Junjie , Parsons Robert
Published: February 2019

Although organic food has rapidly emerged as an important food industry in the United States and many other countries, farmers and fruit growers need more information on consumer preferences and willingness to pay for locally grown organic food products to make better production and marketing decisions. This article presents the findings from a conjoint study on consumer valuation of major attributes of fresh apples (production method, price, certification, and product origin) and the tradeoffs between price and other attributes. Analysis results based on data from 382 respondents, or 3056 observations, in the state of Vermont suggest that there is likely a significant niche market for locally grown organic apples, and many consumers, especially people who had purchased organic food, are willing to pay significantly more for organic apples produced locally and certified by the Northeast Organic Farming Association. This study also suggests that there are significant differences in preferences between respondents who had purchased organic food and respondents who had not purchased organic food, although both groups showed a strong preference and willingness to pay for locally grown apples as compared with apples from other regions.
Effects of an Indoor Foliage Plant Intervention on Patient Well-being during a Residential Rehabilitation Program
Authors: Raanaas Ruth Kjærsti , Patil Grete Grindal , Hartig Terry
Published: February 2019

Effects of an indoor plant intervention in a Norwegian rehabilitation center were assessed in a quasi-experiment. During a 2-year period, coronary and pulmonary patients (N = 282) completed self-report measures of health, subjective well-being, and emotion on arrival, after 2 weeks, and at the end of a 4-week program. The intervention involved the addition of indoor plants for the second year. On average, patient physical and mental health improved during the program, but the addition of plants did not increase the degree of improvement. Subjective well-being did, however, increase more in patients who went through their program after the addition of plants, although the effect was only apparent in the pulmonary patients. The patients reported more satisfaction with indoor plants and the interior generally after the intervention. Room for the intervention to affect outcomes may have been limited by the well-designed interior and the center's location in a scenic mountain area, but these favorable features of the context apparently did not negate the potential for indoor plants to contribute to patient well-being.
Salinity Tolerance of Sophora secundiflora and Cercis canadensis var. mexicana
Authors: Niu Genhua , Rodriguez Denise S. , Gu Mengmeng
Published: February 2019

Use of reclaimed water to irrigate urban landscapes will likely increase because fresh water supply is diminishing and the population continues to grow in the semiarid southwestern United States. Salt tolerance of two native landscape woody ornamentals, Texas mountain laurel (Sophora secundiflora) and Mexican redbud (Cercis canadensis var. mexicana), was investigated in a greenhouse experiment. Seedlings of the two species were grown in two substrates mixed with composted mulch and a commercial potting mix at two ratios and irrigated with saline solutions at three salinity levels: 1.6 (control, nutrient solution), 3.0, or 6.0 dS·m−1 electrical conductivity (EC). There was no interaction between substrate and EC of irrigation water. Foliar salt damages such as leaf drop, leaf curl, and edge burn were observed in Mexican redbud when the plants were irrigated with solutions at EC of 3.0 and 6.0 dS·m−1. No symptoms were observed on Texas mountain laurel plants, although plants irrigated at EC of 3.0 and 6.0 dS·m−1 were smaller compared with controls. Shoot growth and elongation of both species were reduced by the elevated salinity of irrigation water, and the reduction in Mexican redbud was greater than Texas mountain laurel. Leaf photosynthesis rate and leaf stomatal conductance were also reduced in Texas mountain laurel by the elevated salinity of irrigation water. Tissue Na+ and Cl– concentrations were higher in Texas mountain laurel irrigated with water of elevated salinity.
Longevity of Radiofrequency Identification Device Microchips in Citrus Trees
Authors: Bowman Kim D.
Published: February 2019

Long-term identification of individual plants in the field is an important part of many types of research. In a previous report, we described methods for using implanted radiofrequency identification device (RFID) microchips to tag citrus trees for field research. This report provides an update on the RFID technology for use in plants, the effect of implanted chips on long-term plant growth, and survival of the microchips over time. The microchips were found to have no significant effect on plant health and growth, and most microchips continued to work well through the first 6 years after implantation. Implanted RFID microchips appear useful for long-term tagging of citrus and other woody plant species.
Development and Characterization of 15 Microsatellite Loci for Rhododendron delavayi Franch. (Ericaceae)
Authors: Wang Nian , Chang Qin Zhang , Yang Jun-bo , Zhang Jing-li
Published: February 2019

Rhododendron delavayi Franch. is an important ornamental plant and often plays a role in natural hybridization with other sympatric species in Rhododendron subgenus Hymenanthes. Fifteen microsatellite loci were developed and characterized in this species. The average allele number of these microsatellites was four per locus, ranging from three to six. The ranges of expected (HE) and observed (HO) heterozygosities were 0.0365 to 0.7091 and 0.0263 to 0.9512, respectively. Cross-species amplification in R. agastum and R. decorum showed that a subset of these markers holds promise for congeneric species study. These sets of markers are potentially useful to investigate the genetic structure and gene flow of R. delavayi and other congeneric species.
Measurement of Leaf Vapor Conductance of Cucumber Transplants in the Greenhouse with Minimal Invasion
Authors: Shibuya Toshio , Sugimoto Akihito , Kitaya Yoshiaki , Kiyota Makoto , Nagasaka Yuichiro , Kawaguchi Shinya
Published: February 2019

We estimated leaf vapor conductance (gl) of cucumber grafted transplants under greenhouse growing conditions. Fifty-six transplants were placed on a bench in the greenhouse. The transpiration rate (Tr) of the canopy was estimated by weighing the 16 transplants in the center using an electronic balance. The total vapor diffusion resistance (Rl+b) from inside the leaf to the atmosphere was estimated based on the vapor diffusion model, which incorporates the absolute humidity near the leaf surface and that inside the leaf as well as Tr. Next, gl was estimated from Rl+b and the resistance of leaf boundary layer evaluated with a model leaf. The Tr in the afternoon tended to be larger than that in the morning at the same photosynthetic photon flux (PPF) level. By contrast, the gl in the afternoon tended to be smaller than that in the morning at the same PPF level. The decrease of gl in the afternoon seems to be induced by the excessive transpiration resulting from an increase of vapor pressure deficit at the leaf surface.
Response of Bedding Plants to Saline Water Irrigation
Authors: Niu Genhua , Rodriguez Denise S. , Starman Terri
Published: February 2019

Bedding plants are extensively used in urban landscapes. As high-quality water supply becomes limited in many parts of the world, the use of recycled water with high salt levels for landscape irrigation is being encouraged. Therefore, information on salt tolerance of bedding plants is of increasing importance. Two experiments were conducted, one in a 25% light exclusion shadehouse in summer (Expt. 1) and the other in a greenhouse in winter (Expt. 2). Plants were irrigated with saline solution at electrical conductivities of 0.8, 2.8, 4.0, 5.1, or 7.4 dS·m−1 created by adding NaCl, MgSO4, and CaCl2 to tap water to simulate the composition of local reclaimed water. In Expt. 1, shoot dry weight (DW) at the end of the experiments was reduced in all species at 7.4 dS·m−1 compared with the control (0.8 dS·m−1). The magnitude of reduction varied with species and cultivars. The salinity thresholds of irrigation water in which growth reduction occurred were 4.0 dS·m−1 for angelonia (Angelonia angustifolia) cultivars and ornamental pepper (Capsicum annuum) ‘Calico’ and 4.0 to 5.1 dS·m−1 for helenium (Helenium amarum), licorice plant (Helichrysum petiolatum), and plumbago (Plumbago auriculata). Shoot DW and growth index of ornamental pepper ‘Black Pearl’ and vinca (Catharanthus roseus) ‘Rose’ decreased linearly as salinity increased. All plants survived in Expt. 1 regardless of treatment, except for ornamental pepper ‘Purple Flash’. No visual injuries were observed in Expt. 1 regardless of treatment. Leaf sodium (Na) and chlorine (Cl) concentrations varied with species and treatments. Ornamental pepper ‘Black Pearl’ had the highest leaf Cl concentrations at higher salinities compared with other species and cultivars. Leaf Na concentrations in licorice plant and plumbago were in the range of 10 to 30 g·kg−1 DW, higher than those in other species. In Expt. 2, shoot DW was reduced by salinity treatments in ornamental pepper ‘Black Pearl’, plumbago, and angelonia but not in other species. The three ornamental peppers, ‘Black Pearl’, ‘Calico’, and ‘Purple Flash’, exhibited slight foliar injuries on some plants in Expt. 2 as a result of high salinity in the root zone in the highest salinity treatment. Ornamental pepper ‘Black Pearl’ was most sensitive to salinity stress. In general, the bedding plants tested in this study are moderately tolerant to salt stress and may be irrigated with saline water up to 4.0 dS·m−1 with little reduction in aesthetical appearance.
Isolation and Characterization of Twenty Polymorphic Microsatellite Loci for Moringa oleifera (Moringaceae)
Authors: Wu Jiang-Chong , Yang Jing , Gu Zhi-Jian , Zhang Yan-Ping
Published: February 2019

By using a modified biotin-streptavidin capturing method, a total of 20 polymorphic microsatellite markers were developed from Moringa oleifera Lam. (Moringaceae), a useful multipurpose tree. Twenty-four domesticated individuals, with germplasms of India and Myanmar, were used to screen polymorphism of these 20 microsatellite markers. The number of alleles per locus ranged from two to six. The expected and observed heterozygosity varied from 0.3608 to 0.7606 and from 0.0000 to 0.8750, respectively. Seven loci were significantly deviated from Hardy-Weinberg equilibrium. The availability of these microsatellite primers would provide a powerful tool for aspects of detailed population genetic studies of M. oleifera.
White Oak and Northern Red Oak Leaf Injury from Exposure to Chloroacetanilide Herbicides
Authors: Samtani Jayesh B. , Masiunas John B. , Appleby James E.
Published: February 2019

Previous research by the authors found simulated acetochlor (with atrazine) and s-metolachlor drift to white oak at the leaf unfolding stage caused loss of interveinal tissues (leaf tatters). Reports of leaf tatters in the landscape and nursery settings are more common on white oak (Quercus alba L.) than on northern red oak (Quercus rubra L.). Our objectives were to determine if white and northern red oak differed in susceptibility to chloroacetanilide herbicides, if injury varied between chloroacetanilide herbicides, and if adding atrazine increased leaf injury. Two-year-old seedlings at the leaf unfolding stage were treated with acetochlor, s-metolachlor, and dimethenamid-P alone or combined with atrazine at 1%, 10%, and 25% of the standard field use rate. Within 6 days, all chloroacetanilides at 10% and 25% field use rates, alone or combined with atrazine, caused leaf tatter injury in both species. Acetochlor, s-metolachlor, and dimethenamid-P caused a similar type of leaf injury. Atrazine did not cause loss of leaf tissues or increase injury from chloroacetanilides. At 1% field use rate, only acetochlor, acetochlor + atrazine, and dimethenamid-P caused leaf injury to northern red oaks. The white oaks were not injured by all of the chloroacetanilide treatments at 1% field use rate. The northern red oaks were slightly more susceptible to chloroacetanilides compared with the white oaks. A second study found acetochlor only injured northern red oak when applied at the leaf unfolding stage and only at 25% of field use rate. Acetochlor at 1% field use rate did not injure red oak. Research is needed to explain the greater frequency of leaf tatters on white oaks than on northern red oaks in the landscape and to develop strategies to avoid tree injury.
Anther and Pollen Morphology and Anatomy in Walnut (Juglans regia L.)
Authors: Mert Cevriye
Published: February 2019

The morphology and ultrastructure of anthers and pollen grains were described for eight walnut (Juglans regia L.) cultivars (Şebin, Bilecik, Kaman I, Kaplan 86, Yalova 3, Pedro, Hartley, and Franquette) using light microscopy and scanning and transmission electron microscopy. Anther and pollen dimensions and pollen production capabilities were also determined. The mean number of stamens per staminate flower (14.90 to 20.03) and mean anther dimensions (1412.5 to 2553.5 μm in length and 849.0 to 1145.5 μm in width) differed significantly among the cultivars. The number of pollen grains per anther also varied significantly and ranged from 4720 to 9840 among the cultivars. The pollen grains of walnut plants are spherical in shape (nearly circular) and pantocolporate (with many colporate apertures on the exine). The pollen surface is microechinate with spiniferous projections. The germination pores are circular and nonbordered. Pollen grain length varied from 33.35 to 37.50 μm in the examined cultivars. The ultrastructure of the pollen walls was similar between walnut cultivars. The exine was comprised of nexine and sexine, which was thicker than the underlying nexine. The sexine appeared as a strong tectum that was traversed by thin channels and decorated with spinulose processes. The thicknesses of the various layers of the pollen wall were as follows: intine: 82.1 to 200 nm; exine: 793.1 to 1161.1 nm; and total wall: 954.4 to 1327.8 nm.
Isolation and Characterization of 13 Microsatellite Loci from Luculia pinceana (Rubiaceae), a Typical Distylous Species
Authors: Zhou Wei , Wang Hong , Li De-Zhu , Yang Jun-Bo , Zhou Wei
Published: February 2019

Luculia pinceana Hook. (Rubiaceae) is a typical distylous species with dimorphic and long-styled monomorphic populations. Within this study, we developed 13 microsatellite markers from L. pinceana using a modified biotin–streptavidin capture method. Polymorphism of each locus was assessed in 30 individuals from four dimorphic populations and one monomorphic population. The average allele number of these microsatellites was 4.153 per locus ranging from three to seven. The observed and expected heterozygosities were from 0.040 to 0.840 and from 0.571 to 0.769, respectively. Additionally, all 13 identified microsatellite markers were successfully amplified in its related species, L. yunnanensis, 10 of which showed polymorphism. These microsatellite markers could provide a useful tool for further study of the breeding system and the population genetic structure in this species and within other Luculia species.
Assessment of Freezing Injury in Palm Species by Chlorophyll Fluorescence
Authors: Equiza María A. , Francko David A.
Published: February 2019

Freezing temperatures present major constraints for palm cultivation in temperate regions. As a result of their landscape value, there is a constant need for appropriate species and cultivars for freeze-prone areas. The objective of the present study was to evaluate the suitability of the chlorophyll fluorescence technique for quantitative assessment of freezing injury in palms. Five palm species known to differ in their freezing tolerance were selected: Copernicia alba, Washingtonia filifera, Sabal palmetto, Trachycarpus fortunei, and Rhapidophyllum hystrix. Leaf segments were frozen at –5, –10, –15, and –20 °C for 1 h. Repeated freezing–thawing cycles were additionally performed in young and older leaves of R. hystrix. Depending on the species and temperature, significant differences in the ratio of variable-to-maximal fluorescence (Fv/Fm) were detected 3 h after the freezing treatment, whereas visual symptoms appeared after 24 h. A strong positive correlation (r2 = 0.94) was found between the injury index calculated from Fv/Fm values and the index of injury based on the electrolyte leakage technique. Although both indices provided similar information, the nondestructive chlorophyll fluorescence method allows monitoring the progression of damage as well as the eventual recovery taking place in the leaf tissue after freezing.
Light Intensity Affects Growth, Photosynthetic Capability, and Total Flavonoid Accumulation of Anoectochilus Plants
Authors: Ma Zengqiang , Li Shishang , Zhang Meijun , Jiang Shihao , Xiao Yulan
Published: February 2019

Anoectochilus formosanus, a medicinal plant used to treat hypertension, lung disease, and liver disease, was grown to maximize biomass and secondary metabolite production in a controlled environment under four levels of photosynthetic photon flux (PPF), namely, 10, 30, 60, or 90 μmol·m−2·s−1, that is L10, L30, L60, and L90 treatments, respectively. On Day 45, all growth values were greatest for the L30 plants. Dry weight was lowest for the L10 plants. Leaf area, stem length, and fresh weight were lowest for the L90 plants. The chlorophyll concentration was highest in the L10 treatment and decreased with increasing PPF. Electron transport ratios of leaves were highest in the L30 treatment and lowest in the L90 for the second leaf (counted down from the apex) and in the L10 for the third leaf. An increase in light intensity from 10 to 60 μmol·m−2·s−1 increased the superoxide dismutase activity and was associated with an increase in the total flavonoid concentration. The total flavonoid concentration (mg·g−1 DW) was greatest in the L60 and lowest in the L90. However, the total flavonoid content (mg/plant) was highest in the L30 plants as a result of great biomass. The results indicated that A. formosanus is a typical shade plant suitable to grow under low light intensity at PPF of 30 to 50 μmol·m−2·s−1 for both growth and production of total flavonoid. A light intensity of 90 μmol·m−2·s−1 induced stress on plant growth and reduced photosynthetic capability and the flavonoid accumulation.
Reevaluation of Factors Affecting Bunch Drop in Date Palm
Authors: Cohen Yuval , Freeman Stanley , Zveibil Aida , Ben Zvi Rachel , Nakache Yaakov , Biton Shimon , Soroker Victoria
Published: February 2019

Severe damage has been observed in Israeli date palm (Phoenix dactylifera L.) plantations of the Medjool cultivar as a result of drying and dropping of fruit bunches. Both fractures and rot occurred during peduncle (fruit stalk) development at proximal points located deep within the crown. The phenomenon has been previously described as “cross–cut” or “V-cut.” The present study aimed to characterize the phenomenon and identify the main causal factors. Annual surveys have revealed high levels of fruit bunch drop in all ‘Medjool’ cultivation areas in Israel. Arenipses sabella and other insects were only occasionally detected in the damaged fruit stalks. Similar damage levels observed in insecticide-treated and untreated plots suggested that insects were not directly responsible for this phenomenon. Tissue decay was detected in many of the freshly fallen fruit stalks. The pathogenic fungus, Fusarium proliferatum, was detected in most of the necrotic fruit stalks. Fusarium proliferatum isolates from infected fruit stalks generated necrotic lesions in fruit stalk tissue in vitro. However, fungicide treatments on trees in the orchards were ineffective in reducing bunch drop. On the other hand, restraining the growth rate of the fruit stalk, by reducing irrigation levels (to 20%) during the period of fruit stalk development and growth, significantly reduced bunch drop levels in most of the examined plots. These data suggest that bunch drop in ‘Medjool’ date palm is caused mainly by physiological disorders related to fruit stalk development and growth.
Reconstruction of the Strawberry, Fragaria ×ananassa, Using Genotypes of F. virginiana and F. chiloensis
Authors: Hancock James F. , Finn Chad E. , Luby James J. , Dale Adam , Callow Pete W. , Serçe Sedat
Published: February 2019

The germplasm base of strawberries is restricted. The major cultivated strawberry species, Fragaria ×ananassa, originated ≈250 years ago when South American F. chiloensis subsp. chiloensis forma chiloensis and North American F. virginiana subsp. virginiana accidentally hybridized in European gardens. Since that time, only a handful of native clones have been used by breeders. As a novel way to expand the germplasm base of the strawberry, we preselected native clones of F. virginiana and F. chiloensis for a wide range of horticulturally important characteristics and then reconstructed F. ×ananassa by crossing superior clones of each. Before crossing between species, we undertook one round of selection within species to maximize diversity. Reconstruction appeared to be an effective method of strawberry improvement, because superior families and individuals were identified that had outstanding vigor, high productivity, seed set, fruit color, and firmness. None of the fruit were of commercial size, but one reconstruction family, FVC 11 [(F. virginiana Frederick 9 × LH 50-4) × (F. chiloensis Scotts Creek × 2 MAR 1A)], had individuals with fruit weights of almost 20 g.
Regeneration and Transformation of Taro (Colocasia esculenta) with a Rice Chitinase Gene Enhances Resistance to Sclerotium rolfsii
Authors: He Xiaoling , Miyasaka Susan C. , Zou Yi , Fitch Maureen M.M. , Zhu Yun J.
Published: February 2019

Genetic engineering has the potential to improve disease resistance in taro [Colocasia esculenta (L.) Schott]. To develop a method to produce highly regenerable calluses of taro, more than 40 combinations of Murashige and Skoog (MS) media at full- or half-strength with varying concentrations of auxin [α-naphthaleneacetic acid (NAA) or 2, 4-dichlorophenoxyacetic acid (2, 4-D)], cytokinin [benzyladenine (BA) or kinetin], and taro extract were tested for callus initiation and plant regeneration. The best combination, MS medium with 2 mg·L−1 BA and 1 mg·L−1 NAA (M5 medium), was used to produce regenerable calluses from taro cv. Bun Long initiated from shoot tip explants. After 8 weeks of growth, multiple shoots from these calluses could be induced on MS medium with 4 mg·L−1 BA (M15 medium). The rice chitinase gene (ricchi11) along with the neomycin phosphotransferase (npt II) selectable marker and β-glucuronidase (gus) genes were introduced into these taro calluses through particle bombardment. Transformed calluses were selected on M5 medium containing 50 mg·L−1 geneticin (G418). Histochemical assays for beta-glucuronidase (GUS), polymerase chain reaction (PCR), reverse transcription–PCR, and Southern blot analyses confirmed the presence, integration, and expression of the rice chitinase gene in one transgenic line (efficiency less than 0.1%). Growth and morphology of the transgenic plants appeared normal and similar to non-transformed controls. In pathogenicity tests, the transgenic line exhibited improved resistance to the fungal pathogen, Sclerotium rolfsii, but not to the oomycete pathogen, Phytophthora colocasiae.
Row Arrangements, Seeding Rates, and Gibberellic Acid Treatments to Improve Yield of Machine-harvested Cilantro
Authors: Kahn Brian A. , Maness Niels O.
Published: February 2019

Factorial combinations of two row arrangements on 1.8-m-wide beds (either four rows, each 30 cm apart, or eight rows, each 15 cm apart) and two in-row seeding rates (either 48 or 96 seeds per 30 cm of row) were compared on ‘Santo’ cilantro (Coriandrum sativum L.) in five experiments at Bixby, OK. Plots were harvested once per experiment by cutting at a height of ≈7 cm with a small-plot greens harvester, and fresh weight yields were taken. Treatments minimally affected canopy height at harvest. Eight rows resulted in higher yields than four rows in three of five experiments. Main effects of seeding rate or interactions of row number and seeding rate on yield were rare. Of the four combinations tested, the eight-row arrangement sown at 48 seeds per 30 cm would be recommended. This arrangement was used in three other experiments to test effects of a single preharvest spray application of gibberellic acid (GA). Treatments were a water control and GA at either 10 or 20 g·ha−1. Treatment with GA increased bolting in a 17 Apr. planting and increased canopy height at harvest in two of three experiments. However, GA treatments did not affect yield. Treatment with GA would not be recommended for a spring cilantro crop and may have limited impact on increasing machine recovery of raw product in a fall crop.
Growth and Nutrition of Two Cultivars of Zinnia elegans Under Saline Conditions
Authors: Carter Christy T. , Grieve Catherine M.
Published: February 2019

Zinnia elegans, because of its economic value and the hardiness of its wild relatives, was selected as a potential salt-tolerant cut flower crop to grow in greenhouse systems using recycled agricultural wastewater. Using recycled wastewater for irrigation of cut flowers provides an alternative to high-quality water. This is especially important in coastal and inland growing regions of California where competition for high-quality water is increasing between urban and agricultural users and provides economic and environmental benefits because groundwater contamination is reduced or even prevented. A completely randomized design was used to determine the effects of water ionic composition and salinity on the growth and leaf mineral composition of Zinnia elegans. Two cultivars (Benary's Giant Salmon Rose and Benary's Giant Golden Yellow) were grown under irrigation with two different water ionic compositions mimicking dilutions of sea water (SWD) and concentrations of Colorado River water (CRW) at increasing salinity levels with electrical conductivities of 2.5 (control), 4.0, 6.0, 8.0, and 10.0 dS·m−1 in greenhouse sand tanks in Riverside, CA. Leaf mineral concentrations were determined for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), chlorine (Cl), total sulfur (S), and total phosphorus (P). At harvest, final plant measurements included time to flowering, stem length, stem diameter (recorded at the soil line), internode length (recorded at the middle of the stem), inflorescence diameter, ray length, plant shoot fresh weight, number of leaves per plant, and number of shoots per plant. For both cultivars, plant tissue concentrations of Mg, Cl, Na, and total S increased as salinity increased in the irrigation water. Conversely, plant tissue concentrations of Ca, K, and total P decreased as salinity increased in the irrigation water. Both cultivars demonstrated high selectivity for K over Na as salinity increased in CRW and SWD with ‘Golden Yellow’ demonstrating a higher selectivity than ‘Salmon Rose’. Additionally, measured growth parameters tended to decrease as salinity increased in both irrigation water types for both cultivars. Stem lengths of 79 cm and 51 cm were found for ‘Salmon Rose' growing in 10 dS·m−1 in concentrations of CRW and SWD, respectively. ‘Golden Yellow' produced stem lengths of 74 cm and 46 cm in 10 dS·m−1 in response to concentrations of CRW and SWD, respectively. Inflorescence diameters of both cultivars approximated 8.0 cm at the highest salinity for both water types. Although significant differences were found, the minimum of 46 cm indicates that marketable flowers can be produced using both water types at least as high as 10 dS·m−1.
A Survey of Tomato and Potato Fields in Florida Reveals Unique Genotypes of Phytophthora infestans between 2005 and 2007
Authors: Schultz Diana , Donahoo Ryan S. , Perez Frances G.M. , Tejeda Sucel , Roberts Pamela D. , Deahl Kenneth L.
Published: February 2019

Late blight, caused by Phytophthora infestans, affects tomatoes and potatoes in Florida during the winter–spring crop season. During the 2005 season, severe late blight epidemics were observed in Florida prompting our survey. Isolates from 2005 to 2007 were characterized phenotypically based on growth on three media, mating type, pathogenicity, and sensitivity to metalaxyl and genotypically based on two isozymes, mitochondrial DNA (mtDNA), and genomic profiling using the RG57 probe. Isolates collected in this survey were all A2, mtDNA Ia, and either 100/100 (2005), or 100/122 (2006/2007) at the Gpi locus, and homozygous 100 at the Pep locus. Novel genotypes infecting tomato in Florida were observed based on the Gpi locus and RG57 genomic profile. We propose US-20 for the collection of clonal isolates recovered during the 2005 season and US-21 for clones recovered during 2006 and 2007. In addition to these novel genotypes recovered from tomato, one isolate was recovered from potato representing the US-8 clonal lineage. The findings of the survey in south Florida and their implications are presented.
Suppression of Phytophthora Infection in Citrus Infected with Viroids
Authors: Thomas Tina P. , Kunta Madhurababu , da Graça John V. , Sétamou Mamadou , Skaria Mani , Bhattacharya Apurba
Published: February 2019

Citrus viroid-induced resistance to Phytophthora infection in citrus was measured by the number of Phytophthora sporangia in ‘Rio Red’ grapefruit (Citrus paradisi Macf.) bait tissue infected with citrus viroids compared with non-inoculated controls. Different viroid isolates containing mixtures of viroids [Citrus exocortis viroid (CEVd), Hop stunt viroid (HSVd), Citrus viroid III (CVd-III), Citrus viroid IV (CVd-IV)] were designated by plant numbers and sources. Source 13E was associated with the lowest number of sporangia in bark, leaves, and roots used as baits, whereas CEVd E9, a known severe CEVd isolate, significantly reduced the number of sporangia in leaves and bark. Sources 1A, 2E, 3E, 4D, and 6E showed a significantly reduced number of sporangia on bark, leaves, and roots compared with healthy plants and 44A; however, their effect was not as pronounced as that of E9 and 13E. Sources 12E and 44A did not suppress sporangia production. Previous reverse transcriptase–polymerase chain reaction analysis showed that all source plants had mixed infections with several viroids, whereas 12E and 44A contained no viroids. In addition to confirming the earlier reports on the suppression of Phytophthora infection in general, our study showed significantly reduced Phytophthora sporangia development resulting from a number of viroids in mixed infection, but there did not appear to be any effect related to viroid species. To determine if concentration affected resistance to Phytophthora, phenolic acids were extracted. Extraction of phenolic acids with 80% ethanol was more efficient compared with 100% methanol and an acetonitrile–water mixture. High-performance liquid chromatography revealed no notable detection of salicylic acid in healthy and viroid-infected plants, but there was a small peak corresponding to salicylic acid in Phytophthora-infected and both viroid and Phytophthora-infected plants. Flavone was detected in all the source plants with a slight increase in Phytophthora-infected and both viroid and Phytophthora-infected plants. A peak corresponding to quercetin dehydrate was detected in Phytophthora-infected plants. Efficient use of the right viroid isolate(s) can result in suppression of Phytophthora infection of citrus.
Improvement of In Vitro Proliferation and Elongation of Habanero Pepper Shoots (Capsicum chinense Jacq.) by Temporary Immersion
Authors: Bello-Bello Jericó J. , Canto-Flick Adriana , Balam-Uc Eduardo , Gómez-Uc Eunice , Robert Manuel L. , Iglesias-Andreu Lourdes G. , Santana-Buzzy Nancy
Published: February 2019

This article describes the performance of nodal segments from Habanero pepper (Capsicum. chinense) during shoot induction and elongation under different semisolid and liquid culture conditions with various degrees of ventilation in which they were exposed to different levels of immersion and growth regulators. The ethylene content in non-ventilated containers, the age of the explant donor plants as well as the effect of thidiazuron and paclobutrazol on shoot induction and of gibberellic acid and AgNO3 on shoot elongation were also evaluated. A temporary immersion bioreactor (BioMINT™) was used for the multiplication and elongation of isolated shoots with very good results. We report an efficient protocol for the in vitro propagation of Habanero pepper that produces plants with a high survival rate when transplanted to soil.