bluuebunny/crossref_metadata_2025 huggingface dataset:
Euploid Endosperm of Triploid × Diploid/tetraploid Crosses Results in Aneuploid Embryo Survival in Lilium
Authors: Zhou Shujun , Zhou Guixue , Li Kehu
Published: February 2019

The main objective of the present study was to identify chromosome number variation in the progenies from triploid × diploid/tetraploid (3x × 2x/4x) crosses in Lilium to analyze the survival of aneuploid embryos from 3x × 2x/4x crosses and the potential significance of triploid for lily breeding. Two male-sterile autotriploid Asiatic lily cultivars were crossed with four diploid and/or two autotetraploid Asiatic cultivars. The results showed that the fruits of all triploid × diploid/tetraploid (3x × 2x/4x) crosses fully developed, and seedlings were obtained from the 3x × 2x/4x crosses, indicating that male-sterile autotriploid lilies can be used as female parents. Chromosome preparation showed that the progenies of the 3x × 2x/4x are predominantly aneuploid. Based on megasporogenesis, we deduce that the endosperm of 3x × 2x is 7x and that of 3x × 4x is 8x in Lilium and conclude that the aneuploid embryo survival of 3x × 2x/4x in Lilium is the result of the euploid endosperm. Lily is usually propagated by scaling or tissue culture; therefore, aneuploids obtained from triploid × diploid/tetraploid lilies would be a good source for cultivar breeding.
Genome Size Estimates and Chromosome Numbers of Callicarpa L. (Lamiaceae)
Authors: Contreras Ryan N. , Ruter John M.
Published: February 2019

Genome size estimates and chromosome number information can be useful for studying the evolution or taxonomy of a group and also can be useful for plant breeders in predicting cross-compatibility. Callicarpa L. is a group of ≈140 species with nearly worldwide distribution. There are no estimates of genome size in the literature and the information on chromosome numbers is limited. Genome size estimates based on flow cytometry are reported here for 16 accessions of Callicarpa comprising 14 species in addition to chromosome counts on six species. Chromosome counts were conducted by staining meristematic cells of roots tips using modified carbol fuchsin. Holoploid genome size estimates ranged from 1.34 pg to 3.48 pg with a mean of 1.74 pg. Two tetraploids (2n = 4x = 68; C. salicifolia P'ei & W. Z. Fang and C. macrophylla Vahl GEN09-0081) were identified based on holoploid genome size and confirmed by chromosome counts. There was little variation among species for monoploid genome size. 1Cx-values ranged from 0.67 pg to 0.88 pg with a mean of 0.77 pg. Chromosome counts for six species revealed a base chromosome number of x = 17. Callicarpa chejuensis Y. H. Chung & H. Kim, C. japonica Thunb. ‘Leucocarpa’, C. longissima Merr., and C. rubella Lindl. were confirmed as diploids (2n = 2x = 34). Cytology supported flow cytometry data that C. salicifolia and C. macrophylla GEN09-0081 were tetraploids. The two accessions of C. macrophylla included in the study were found to be of different ploidy levels. The presence of two ploidy levels among and within species indicates that polyploidization events have occurred in the genus.
Manipulation of Whole-vine Carbon Allocation Using Girdling, Pruning, and Fruit Thinning Affects Fruit Numbers and Quality in Kiwifruit
Authors: Boyd Linda M. , Barnett Andrew M.
Published: February 2019

We compared the long-term effects of whole-vine source-sink manipulation on yield, composition, and quality of fruit from mature field-grown kiwifruit (Actinidia chinensis Planch. var. chinensis) ‘Hort16A’ vines. Four contrasting source/sink-modifying treatments were applied to vines each year from Spring 2003 to 2007: 1) control—standard canopy management techniques, no trunk girdle; 2) extended trunk girdle (ETG)—girdle was opened in late summer, kept open over winter, and allowed to heal the next spring; 3) “feast”—cropload was kept low and leaf numbers kept high, no trunk girdle; and 4) “famine”—fruit numbers were kept high and vines were heavily pruned to stimulate regrowth, no trunk girdle. Fruit from the famine vines were smaller with lower dry matter concentration (DMC; dry weight as a percentage of fresh weight) and had delayed maturity relative to fruit from the control vines. Return bloom was reduced in the famine vines, resulting in ≈42% less fruit in the famine vines compared with the feast vines, and this difference remained consistent across all three seasons. Fruit from the feast treatment were larger with advanced maturity relative to fruit from control vines; there were no differences in fruit numbers in subsequent seasons. Fruit DMC was higher and maturity was advanced in the ETG vines relative to the control vines. Fruit numbers in the ETG vines consistently increased relative to the control vines each season. There were no consistent treatment effects on fruit mineral concentrations, except that fruit from the feast vines had higher nitrogen concentrations than fruit from the famine vines. Seasonal variation in the incidence of storage disorders was large; in years when disorders were present, physiological pitting incidence was higher in fruit from the treatments that advanced maturity and the incidence of low temperature breakdown was highest in treatments that delayed maturity. Although the treatments affected vine productivity, fruit DMC, and storage performance, there was no evidence of a gradual decline in quality and productivity after 4 years of treatment application.
In Vitro Regeneration and Genetic Transformation of Cucumis metuliferus through Cotyledon Organogenesis
Authors: Lin Yu-Tsung , Lin Chia-Wei , Chung Chien-Hung , Su Mei-Hsiu , Ho Hsiu-Yin , Yeh Shi-Dong , Jan Fuh-Jyh , Ku Hsin-Mei
Published: February 2019

This study was undertaken to establish for the first time an efficient regeneration and transformation system for Cucumis metuliferus line PI292190, which is the source of a well-defined resistant gene, Wmv, that provides resistance against Papaya ringspot virus type P (PRSV-P) and PRSV-W (formerly known as Watermelon mosaic virus 1, WMV-1). Different combinations of growth regulators were evaluated for the regeneration of cotyledon explants. Adventitious buds or shoot primordia were obtained within 3 to 4 weeks on regeneration medium. After shoot development, adventitious buds or shoot primordia were transferred to elongation medium for 3 to 4 weeks and these shoots were subcultured onto rooting medium for another 1 to 2 weeks. Under optimal culture conditions, a total of 7 to 10 weeks was necessary to obtain C. metuliferus plantlets from cotyledons. Furthermore, transgenic plants were successfully obtained using an Agrobacterium tumefaciens-mediated transformation method as shown by polymerase chain reaction analysis and histochemical β-glucuronidase (GUS) assay. A total of nine transgenic plants were developed from 360 cotyledon explants, giving a transformation frequency of 2.5%.
Seedcoat Permeability: Uptake and Post-germination Transport of Applied Model Tracer Compounds
Authors: Salanenka Yuliya A. , Taylor Alan G.
Published: February 2019

The seedcoat permeability, uptake, and transport of model fluorescent tracers were investigated in snapbean (Phaseolus vulgaris), pepper (Capsicum annuum), tomato (Solanum lycopersicum), onion (Allium cepa), cucumber (Cucumis sativus), and lettuce (Lactuca sativa) seeds. Nine fluorescent tracers and one vital stain were selected to represent a diversity of physicochemical properties (lipophilicity, electrical charge, etc.) and to simulate behavior of applied seed treatments. To study seedcoat permeability, tracers were applied to seeds as dry powders, and treated seeds were sown in moistened sand at 20 °C and removed after 18 to 24 h, a time before visible germination. Imbibed seeds were dissected and fluorescence (staining) was observed in embryos with a dissecting microscope under ultraviolet (365 nm) or visible radiation. Seedcoat permeability of species to solutes was grouped into three categories: 1) permeable—snapbeans; 2) selectively permeable—tomato, pepper, and onion; and 3) non-permeable—cucumber and lettuce. Systemic tracers that failed to permeate seedcoats during seed imbibition were taken up by roots or hypocotyls after visible germination.
Salinity Tolerance of 12 Turfgrasses in Three Germination Media
Authors: Zhang Qi , Wang Sheng , Rue Kevin
Published: February 2019

Salinity tolerance of 12 turfgrasses in four groups, creeping bentgrass (Agrostis stolonifera L.), fescues (Festuca spp.), kentucky bluegrass (Poa pratesis L.), and alkaligrass [Puccinellia distans (Jacq.) Parl.], was evaluated using three germination methods. Seeds were germinated on 1% agar medium, on germination paper, or in a hydroponic system under salinity levels of 0, 5, 10, 15, or 20 g·L−1 NaCl. Germination rate and seedling growth of each grass were determined. Salinity reduced the final germination rate (FGR), daily germination rate (DGR), and seedling leaf area (LA) in all tests. On agar medium, no significant difference in salinity tolerance was observed among the four turf groups; however, ‘Turf Blue’ kentucky bluegrass with a corn starch-based coating (coated ‘Turf Blue’) showed a significant higher salinity tolerance than the uncoated one. Using germination paper, creeping bentgrass required the highest salinity level to cause 50% reduction in FGR followed by alkaligrass, fescues, and kentucky bluegrass. Kentucky bluegrass required the lowest salinity level (9.5 g·L−1) to reduce DGR by 50%. With the hydroponic system, alkaligrass required a salinity level of 26.3 g·L−1 to reduce FGR by 50%, the highest among the four groups. Alkaligrass showed again the highest salinity tolerance with an average of 12.7 g·L−1 needed to reduce LA by 50%. Among the grasses, coated ‘Turf Blue’ kentucky bluegrass, ‘Declaration’ creeping bentgrass, and ‘Fults’ alkaligrass showed the highest salinity tolerance when evaluated on agar medium, on germination paper, or in the hydroponic system, respectively. The present study determined the salinity tolerance of 12 turfgrasses at seed germination and early seedling growth stages and showed that the germination method was a factor affecting the evaluation result and it should be considered in a seed germination test of turfgrass for salinity tolerance.
Levels of Candidatus Liberibacter asiaticus and Xanthomonas citri in Diverse Citrus Genotypes and Relevance to Potential Transmission from Pollinations
Authors: Stover E.W. , McCollum T.G.
Published: February 2019

The diseases huanglongbing [HLB, associated with Candidatus Liberibacter asiaticus (CLas)] and Asian citrus canker [ACC, caused by Xanthomonas citri (Xcc)] are widespread in Florida and many other citrus-growing areas, presenting unprecedented challenges for citrus breeding. Because HLB and ACC weaken trees and compromise cropping, breeding is much less efficient using seed parents that have been exposed to these diseases. Therefore, it would be highly desirable to use unique disease-exposed selections only as pollen parents with pollen applied to disease-free trees. However, there may be a risk of introducing these diseases using such pollen sources. To assess this potential, abundance of the pathogens associated with these diseases was assessed in anthers and flowers using quantitative polymerase chain reaction. Because CLas is systemic, levels on mature leaves from the flower source trees were assessed to see if the presence of CLas in flowers was associated with leaf levels. Disease-exposed trees were tested in 10 genotypes from each of three broad genotypic categories, which reflect different levels of susceptibility to the diseases associated with the pathogens studied: Poncirus trifoliata hybrids (most resistant to HLB), Citrus maxima and hybrids (susceptible to both diseases), and C. reticulata and hybrids (considerable resistance to ACC). Of the 30 samples of each tissue type analyzed for CLas, 88% of mature leaves, 69% of flowers, and 88% of anthers had one or more CLas bacterium per sample. The trifoliate genotypic group had significantly lower levels of CLas than the pummelo and mandarin groups in mature leaf samples, but CLas levels were more similar between groups in anther and flower samples, and the pathogen was present in most of the trifoliate hybrids tested. Mean numbers of CLas detected per nanogram nucleic acid were 100 to 800 times higher in mature leaf samples, most characteristic of HLB symptoms, compared with anther samples. Xcc DNA was detected in 30% of flower samples and 23% of anther samples. No significant differences in Xcc levels were found between tissue type or genotypic group. However, regressions between Xcc levels in flowers and percent of plant pedigree derived from mandarin had a negative correlation and an r2 of 0.159 (P = 0.029). The biology of CLas is consistent with the pathogen being present in anthers from unopened flowers, whereas the ACC pathogen detected inside flowers was likely the result of contamination despite great care in sample collection and handling. Where exceptional diligence to exclude HLB and ACC is appropriate, results suggest that there may be a risk of spreading these pathogens through use of pollen from trees on infected farms.
Native Bees, Honeybees, and Pollination in Oregon Cranberries
Authors: Broussard Melissa , Rao Sujaya , Stephen William P. , White Linda
Published: February 2019

Cultivated cranberry (Vaccinium macrocarpon Aiton) relies on insect pollination for berry production. Honeybees (Apis mellifera L.) have historically provided this service, but their recent decline has underscored the need for additional pollinators. The objective of this study was to determine the richness and abundance of native bees in the cranberry-growing area of southern coastal Oregon and compare foraging behaviors of honeybees and native bees. In a 2-year study, we collected over 27 native bee species in traps set out during and after bloom (mid-May to mid-June). During 67 2-min observations, honeybees (68.1%) and three species of bumble bees (Bombus spp.; 31.6%) comprised 99.7% of foragers. The dominant bumble bee was Bombus vosnesenskii Radoszkowski (56.0%). Multivariate regression of temperature and wind speed data indicated that both were significantly predictive of honeybee and bumble bee foragers (P < 0.001). The interquartile range for foraging was 18.3 to 22.2 °C for bumble bees and 21.1 to 26.7 °C for honeybees. Over 75% of honeybees were seen foraging above the average observed temperature (19.5 °C). Bumble bee pollen loads had a greater dry mass (6.8 ± 12.9 mg) than those of honeybees (2.0 ± 3.6 mg; P < 0.001), and the latter were observed collecting nectar but no pollen more often (during 37.2% of visits) than bumble bees (11.3% of visits). Based on our results, bumble bees in general, and B. vosnesenskii in particular, may be providing significant pollination services for Oregon cranberry farms. However, to maintain current native bumble bee populations, conservation efforts are recommended.
In Vitro Mutation Induction of Saintpaulia Using Ethyl Methanesulfonate
Authors: Fang Jong-Yi , Traore Siguina
Published: February 2019

This study has been performed to investigate the efficiency of the chemical mutagen ethyl methanesulphonate (EMS) to induce mutations in Saintpaulia. In vitro leaf sections of Saintpaulia cv. Crystobal were exposed to various EMS treatments at 0%, 0.2%, 0.4%, and 0.6% for 30, 60, 120, and 240 min after which adventitious shoots were recovered from the treated explants. Shoots producing at least six leaves were induced to root and the resulting plantlets were transplanted to soil. A total of 1838 plantlets was grown to flowering stage and 10 mutants were identified. Four of the mutants were variegated leaf chimeras and the remaining six presented variations at the level of flower color and/or fringe. Results in the present study showed the efficiency of EMS to induce in vitro mutation of Saintpaulia and the method can be used in the future to assist breeding in this popular ornamental plant.
Options for Developing Salt-tolerant Crops
Authors: Loescher Wayne , Chan Zhulong , Grumet Rebecca
Published: February 2019

Soil salinization is an increasing problem worldwide and is often intensified by irrigation. Unfortunately, few new crop cultivars have been developed resistant to saline soils, a consequence, in part, of the complexity of plant responses to salt stress. There are now, however, several non-traditional options to improving salt tolerance as a result of recent progress in better understanding the mechanisms involved. These mechanisms include 1) exclusion of Na+ and Cl– from plant tissues; 2) inclusion of these ions in inert compartments or tissues; and/or 3) some means of osmotic adjustment with solutes that are compatible with the metabolic machinery of the cell. Although there are very few horticultural examples, several lines of evidence indicate that reductions in salt sensitivity through exclusion or inclusion can be achieved by single gene modifications of the ion transport system. Similarly, single genes resulting in osmotic adjustment with solutes compatible with the metabolic machinery of the cell have resulted in significant increases in salt tolerance. Recent advances in sequencing, use of quantitative trait loci, and marker-assisted selection promise to provide other options for improving salt tolerance.
Breeding Vegetables Adapted to High Temperatures: A Case Study with Broccoli
Authors: Farnham Mark W. , Bjorkman Thomas
Published: February 2019

Breeding a vegetable crop for adaptation to a temperature regime that is higher than the recognized optimum for the species in question is an example of breeding for abiotic stress tolerance. Before embarking on a project to breed for such stress tolerance, we propose that several critical considerations or questions must be addressed. These considerations include the following: 1) What is the effect of the abiotic stress on the crop to be improved; 2) what will be the conditions of the selection environment; 3) what germplasm is available that contains the necessary genetic variation to initiate improvement; 4) what breeding scheme will be used to facilitate improvement; and 5) what will be the specific goals of the breeding effort? We use a case study with broccoli to breed for adaptation to high-temperature environments to provide examples of how each of these considerations might be addressed in developing an improvement effort. Based on documented success with this case study in which broccoli quality and performance under high-temperature summer environments has been improved, insights are provided that should be useful to future attempts to breed vegetables more tolerant of an abiotic stress.
Differential Effects of Nitrogen Supply on Skin Pigmentation and Flesh Starch Breakdown of ‘Gala’ Apple
Authors: Wang Huicong , Cheng Lailiang
Published: February 2019

Apple maturity is often assessed by starch hydrolysis index, skin color, soluble solids, flesh firmness, and the rate of ethylene evolution. In red-fruited apple cultivars, the intensity and extent of coloration is an important consideration in determining the time of fruit harvest. Negative relationships have been found between tree nitrogen (N) status and fruit skin pigmentation, but how N affects flesh starch breakdown has not been examined in detail. The objective of this study was to determine how N supply affects flesh starch breakdown relative to skin color development. Seven-year-old ‘Gala’/M.26 trees were provided with four levels of N (8.8, 26.4, 52.7, and 105.4 g N per tree) in a modified Hoagland's solution. The effects of N supply on yield, fruit quality, and fruit maturation were evaluated. At harvest, fruit in the lowest N treatment was significantly smaller and had lower soluble solids but higher starch concentration, better color, and higher firmness than those grown at higher N supplies. Increasing N supply decreased both anthocyanin synthesis and chlorophyll degradation in fruit skin. Flesh starch concentration was higher at higher N supply at 38 days before harvest but was lower at higher N supply at harvest. Starch degradation was completed earlier during cold storage with increasing N supply. These results indicate that increasing N supply delays skin red color development but accelerates flesh starch degradation in ‘Gala’ apples. These differential effects of N supply should be taken into account when assessing fruit maturity for optimizing harvest time.
Iron-[S,S′]-EDDS (FeEDDS) Chelate as an Iron Source for Horticultural Crop Production: Marigold Growth and Nutrition, Spectral Properties, and Photodegradation
Authors: Albano Joseph P.
Published: February 2019

Aminopolycarboxylic acid (APCA) complexones, commonly referred to as ligands or chelating agents, like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), are commonly used in soluble fertilizers to supply copper (Cu), iron (Fe), manganese (Mn), and/or zinc (Zn) to plants. Offsite runoff and contamination of surface waters with these chelating agents is of increasing concern as a result of their reported ability to remobilize heavy metals in sediments and their low susceptibility to biodegradation. The APCA ethylenediaminedisuccinic acid (EDDS) is a structural isomer of EDTA with the [S,S′] stereoisomer of the complexone, a compound naturally produced by actinomycetes, and is biodegradable. Information on the use of [S,S′]-EDDS as a chelating agent in formulating soluble fertilizers for the production of horticultural crops is limited. Therefore, a series of studies were conducted with the objectives of evaluating Fe[S,S′]-EDDS as an Fe-chelate fertilizer agent in the production of marigold and [S,S′]-EDDS (free ligand) and/or Fe[S,S′]-EDDS spectral properties and vulnerability to photodegrdation. Marigold grown in peat-based media were fertilized with complete nutrient solution containing 1 mg·L−1 Fe from FeEDDS, FeEDTA, or FeDTPA. There was no significant difference in foliar Fe or Mn between Fe-chelate treatments, averaging 140 μg·g−1 and 88 μg·g−1, respectively, nor were there significant differences in leaf dry weight (2.30 g) between Fe treatments. Spectra of [S,S′]-EDDS and Fe[S,S′]-EDDS produced from ferrous or ferric sources of Fe absorbed maximally in the 210 to 230 nm and 238 to 240-nm range, respectively. The [S,S′]-EDDS complexone used in the current study, a 30% assay solution, had chromaphoric properties, appearing light yellow in color. When exposed to light, Fe[S,S′]-EDDS quickly degraded at a rate at least twice that of FeEDTA.
Effect of Genotype, Planting Date, and Spacing on Zoysiagrass Establishment from Vegetative Plugs
Authors: Sladek Bradley S. , Henry Gerald M. , Auld Dick L.
Published: February 2019

Slow growth and establishment rate has become a major limitation to the increased use of zoysiagrass (Zoysia spp.) as a turfgrass surface. Two separate field studies were conducted to evaluate the effect of genotype, planting date, and plug spacing on zoysiagrass establishment. Field experiments were conducted in 2007 and 2008 to quantify the establishment rate of six zoysiagrass genotypes from vegetative plugs. ‘Meyer’ exhibited the largest plug diameter (22 cm) 6 weeks after planting (WAP). In contrast, ‘Diamond’ exhibited the smallest plug diameter (13 cm) 6 WAP. A similar trend was observed 12 WAP. ‘Meyer’, ‘Zorro’, and ‘Shadow Turf’ exhibited the largest plug diameters (60, 58, and 57 cm, respectively) 12 WAP. In contrast, ‘Emerald’ and ‘Diamond’ exhibited the smallest plug diameters (41 and 40 cm, respectively) 12 WAP. Although statistically different, all zoysiagrass genotypes reached similar establishment 18 WAP indicating that plugging these genotypes in a comparable environment and using techniques described in this research may result in analogous long-term (18 weeks) establishment. Field experiments were conducted in 2006 and 2007 to determine the optimum planting date and plug spacing of ‘Shadow Turf’ zoysiagrass. ‘Shadow Turf’ zoysiagrass plugs planted on 28 July 2006 (11% to 65% cover) and 14 June 2007 (5% to 39% cover) exhibited the greatest increase in turfgrass cover 6 WAP, except for plugs planted 15.2 cm apart on 26 May 2006 (74% cover). Zoysiagrass cover was greatest for plugs planted on 26 May 2006 (63% to 100%) and 17 May 2007 (46% to 97%) 16 WAP regardless of plug spacing. These planting dates corresponded to the highest accumulative growing degree-days (GDD) experienced by all planting dates in both years. Plugs planted on 15.2-cm centers exhibited the greatest zoysiagrass cover 6 and 16 WAP regardless of planting date. Using late spring/early summer planting dates and 15.2- to 30.5-cm plug spacings may result in the quickest turfgrass cover when establishing ‘Shadow Turf’ zoysiagrass from plugs.
Effect of Geographical Location, Year, and Cultivar on Survival of Malus sp. Dormant Buds Stored in Vapors of Liquid Nitrogen
Authors: Jenderek Maria M. , Forsline Phil , Postman Joseph , Stover Ed , Ellis David
Published: February 2019

Clonal woody crop germplasm collections often originate and are grown in distinct geographical locations. Because the degree of cold-hardiness is known to be a factor in the successful use of dormant bud cryopreservation for Malus, it was suggested that material from relatively warmer climates would not respond to cryopreservation as well as material from colder environments. To test this hypothesis, the effect of growing provenance on cryosurvival of dormant buds from three Malus (apple) cultivars grown in three locations (Geneva, NY; Davis, CA; and Corvallis, OR) was tested in 3 consecutive years. Dormant winter buds were harvested at the three locations, cryopreserved, and bud viability was tested by grafting. The collective 3-year mean viability for cryopreserved dormant apple buds for the three locations ranged from 63% to 81% of the buds surviving with the highest survival from the Corvallis site; however, the Geneva twigs were exposed to the lowest preharvest temperature. These results suggest that the temperature at the growing location may not hinder application of the dormant bud cryopreservation method with Malus to the extent previously speculated.
Nitrogen Availability in Pecan Orchard Soil: Implications for Pecan Fertilizer Management
Authors: Wells M. Lenny
Published: February 2019

Nitrogen (N) fertilizer application to plants at rates not adjusted for the N contribution from soil N availability may result in overapplication of fertilizer. Further understanding of proper timing of N applications based on soil N dynamics and plant demand can be valuable information for the efficient use of fertilizer N. The present study measures soil N dynamics in a pecan orchard under various N fertilizer regimes on a southeastern U.S. Coastal Plain soil. The following treatments were evaluated: 1) crimson clover (Trifolium incarnatum L.); 2) poultry litter; 3) crimson clover + poultry litter; 4) ammonium nitrate (NH4NO3); and 5) untreated control. Crimson clover provided from 20 to 75 kg·ha−1 N over the course of the two growing seasons; however, most of the available N from crimson clover became available late in the growing season. As a result, supplemental N may be required in spring where crimson clover is used as an orchard cover crop. Poultry litter, with and without clover, provided available N consistently throughout the growing season with more N becoming available later in the season than earlier. This suggests that poultry litter applications for pecan should be timed before budbreak. Under optimum environmental conditions, N from NH4NO3 is most available within the first 30 days of application. Thus, it appears that synthetic fertilizer applications using NH4NO3 as the N source should be targeted at or 2 to 3 weeks after pecan budbreak.
Response of Sophora secundiflora to Nitrogen Form and Rate
Authors: Niu Genhua , Rodriguez Denise , Gu Mengmeng
Published: February 2019

Texas mountain laurel (Sophora secundiflora) is a native shrub tolerating drought, heat, windy conditions, and alkaline or wet soils. However, its availability is somewhat low and little information is available on nutrient requirement and other culture information. Two greenhouse experiments were conducted to quantify the responses of Texas mountain laurel to different forms and rates of nitrogen (N) fertilizer. In Expt. 1, 1-year old seedlings were treated for 194 days with three NO3:NH4 ratios at 25:75, 50:50, and 75:25 and two rates of N at 100 and 200 mg·L−1 in a factorial design. There was no interaction between the N rate and form on any growth parameters. Nitrogen form did not significantly affect shoot dry weight, root dry weight, root–to-shoot ratio, or the total dry weight. There was no significant difference between N rate of 100 and 200 mg·L−1 on root dry weight, root-to-shoot ratio, or the total dry weight. The shoot dry weight of Texas mountain laurel fertilized with 100 mg·L−1 was higher compared with that of the plants fertilized at 200 mg·L−1. The reduced shoot dry weight at N of 200 mg·L−1 was the result of the higher substrate salinity. In Expt. 2, seedlings were fertilized with five N rates (50, 100, 150, 200, and 250 mg·L−1) for 203 days. Plants watered with 150, 200, and 250 mg·L−1 were taller than those fertilized with 50 mg·L−1. The shoot height of plants watered with 100 mg·L−1 was only significantly different from 50 mg·L−1. For rapid growth of Texas mountain laurel, a N rate range of ≈150 mg·L−1 was recommended supplied with a combination of NO3-N and NH4-N in the ratios of 0.3 to 3.0.
Media Selection and Seed Coating Influence Germination of Turfgrasses under Salinity
Authors: Serena Matteo , Leinauer Bernd , Sallenave Rossana , Schiavon Marco , Maier Bernd
Published: February 2019

Germination of five turfgrass species [‘Barrister’ kentucky bluegrass (Poa pratensis L.), ‘Barvado’ tall fescue (Festuca arundinacea Schreb.), ‘Premier II’ perennial ryegrass (Lolium perenne L.), ‘Bargusto’ bermudagrass (Cynodon dactylon L. Pers.), and ‘Sea Spray’ seashore paspalum (Paspalum vaginatum O. Swartz)] from coated (ZEBA® cornstarch coating; Absorbent Technologies Inc., Beaverton, OR) and uncoated seeds was evaluated on both filter paper and agar. Final germination percentage (FGP) and germination rate (GR) were determined at salinity levels of 0.6 (tap water, control), 2.2 (saline groundwater from a local shallow aquifer), and 7.0, 12.5, and 22.5 dS·m−1 [sodium chloride and calcium chloride (1:1, w:w) dissolved in tap water]. Final germination percentage for kentucky bluegrass, perennial ryegrass, and tall fescue was greater in agar at all salinity levels but was unaffected by the medium at any of the salinities except for 7 dS·m−1 for bermudagrass and seashore paspalum. Coated seashore paspalum and coated perennial ryegrass seed exhibited greater germination than uncoated seed at four of the five salinity levels. Seed coating had no effect on FGP of bermudagrass at any salinity level and coated kentucky bluegrass seed showed reduced germination at 0.6 and 7.0 dS·m−1. Final germination percentage for seashore paspalum improved from 22% to 54% at 12.5 dS·m−1 and from 8% to 20% at 22.5 dS·m−1 when coated seed was used instead of uncoated seed. Germination rates were unaffected by salinity levels ranging from 0.6 to 12.5 dS·m−1 and were higher on agar (10%/day) than on paper (8%/day). Our study suggests that the choice of medium can influence the outcome of germination tests and that results can also vary depending on the salinity level tested and whether the seed are coated.
Agrostis Species Relationships Based on trnL-trnF and atpI-atpH Intergenic Spacer Regions
Authors: Amundsen Keenan , Warnke Scott
Published: February 2019

The bentgrasses (Agrostis spp.) are among the most important species to the turfgrass industry. They have complex genomes resulting from polyploidization and high rates of interspecific hybridization. An understanding of species relationships would improve the efficiency of developing improved bentgrass cultivars. To elucidate the evolutionary relationships among Agrostis species, phylogenetic analyses were performed on sequences of two chloroplast-encoded intergenic spacer regions. A 298-bp region of the trnL-trnF intergenic spacer and a 451-bp region of the atpI-atpH intergenic spacer were included in the analyses. A total of 47 Agrostis accessions were included with both cultivated and unimproved material from the National Plant Germplasm System. Of these 47 Agrostis collections, there were 10 unique trnL-trnF haplotypes and eight distinct atpI-atpH haplotypes, indicating a high degree of shared sequence identity within these chloroplast intergenic regions. These findings suggest that the chloroplast genomes of A. canina and A. stolonifera are more closely related to each other than either species is to A. capillaris, incongruent with our previous understanding of genome relationships in the genus.
Yields and Soil Quality under Transitional Organic High Tunnel Tomatoes
Authors: Reeve Jennifer , Drost Dan
Published: February 2019

Interest in unheated plastic film-covered high tunnels to extend the growing season of high-value fruits and vegetables is growing rapidly, but sustainable soil management in intensively managed high tunnels is challenging. Yields, fruit quality, and soil quality in transition organic and conventional tomato were measured over the course of three growing seasons. Nitrogen (N) was applied at the rate of 112, 168, and 224 kg total N/ha in the form of chicken manure compost to the organic treatments and a polymer-coated slow-release urea fertilizer in the conventional treatments. Marketable yield of organically grown tomatoes was lower in Year 1 but equaled conventional tomatoes in Years 2 and 3. Soil quality as measured by total carbon (C) and N and microbial activity was significantly greater in organic tomato production at the end of the study. Significant phosphorus (P) and potassium (K) applied with the composted manure resulted in high soil P and K levels in organically managed high tunnels after just 3 years of application. Although compost is the most economical organic fertilizer and results in significant benefits in soil quality during the transition phase to organic production, a maintenance fertility plan is needed once available soil P reaches adequate to high levels. Combinations of compost and high N, low P organic fertilizers are needed for optimum maintenance fertility strategy for organic tunnel house production.
Effect of Steam and Solarization Treatments on Pest Control, Strawberry Yield, and Economic Returns Relative to Methyl Bromide Fumigation
Authors: Samtani Jayesh B. , Gilbert Celeste , Ben Weber J. , Subbarao Krishna V. , Goodhue Rachael E. , Fennimore Steven A.
Published: February 2019

The phase-out of methyl bromide as a soil fumigant for strawberry (Fragaria ×ananassa, Duch.) and increasingly strict regulations of all fumigants suggest that non-fumigant methods of soil disinfestation are needed. In warm climates, solarization controls soilborne pests, but fog and lower summer soil temperatures in coastal California render it unsuitable for pest control relative to chemical fumigation. The first objective of this study was to test the efficacy of steam in controlling soil pests in strawberry production. The second objective was to determine if combining solarization with steam in coastal California would achieve greater pest control and higher yields compared with steam or solarization used alone. The final objective was to determine the economic feasibility of steam and solarization treatments relative to MBPic fumigation. Field studies were conducted at Salinas, CA, in 2007–2008 and in 2008–2009 growing seasons. Treatments included MBPic 67/33% v/v at 392 kg·ha−1, untreated control, solarization, steam, and steam + solarization. For steam + solarization plots, beds were solarized for 2 weeks before and 2 weeks after steam application. Before application of a clear film for solarization, beds were irrigated so the soil moisture was optimal for solarization. Steam was injected into the beds to reach soil temperatures to 70°C or higher up to a depth of 25 cm for 20 min. Soil temperatures during steam and solarization treatments were monitored. Control of soil pests was measured using pathogen and weed propagule bioassays in all treatments. After the 4-week treatment period, ‘Albion’ strawberry was transplanted in all plots. After transplanting, weed density, weed fresh biomass, and hand weeding time were recorded periodically in each treatment over the cropping season. Weed seed viability in steam and steam + solarization-treated plots was the same or lower than MBPic standard fumigation. Compared with MBPic fumigation, solarization alone was less effective in controlling weeds or reducing the hand-weeding time. Steam and steam + solarization treatments resulted in weed control similar to MBPic fumigation. Only certain steam treatments reduced the number of Verticillium dahliae Kleb. microsclerotia similar to the MBPic fumigation at 15-cm depth with no reductions at greater depths. There were no significant differences among treatments in 2007–2008 with regard to yield, but in 2008–2009, yields from steam treatments were comparable to the MBPic-treated plots. Economic analysis performed for the 2008–2009 season showed that net returns from steam or solarization treatments were less than MBPic treatment.
A Narrowly Endemic Dirca from Mexico Outperforms Its Broadly Distributed Congener in the Upper Midwest
Authors: Norris Kelly D. , Graves William R.
Published: February 2019

Shrubs in the genus Dirca are rarely used in landscaping despite their shade tolerance and aesthetic qualities. A trial of 81 plants, 27 of each of three species, was established in 2007 in USDA hardiness zone 5a to evaluate survival and growth. After four winters, survival of Dirca mexicana (89%) was greater than survival of Dirca palustris from Florida (44%) and Dirca occidentalis (41%). Survival of Dirca palustris from Ontario, Canada, was intermediate (56%), but annual stem extension was only 60% that of Dirca mexicana and Dirca palustris from Florida. Surviving plants of Dirca mexicana and Dirca palustris from Ontario showed minimal winter injury, but tips of some stems of Dirca palustris from Florida and Dirca occidentalis were killed. Our data on survival, winter injury, plant health, and stem extension of the California-endemic Dirca occidentalis suggest it will be especially challenging to identify genotypes adapted for use in the Upper Midwest. In contrast, we conclude that another narrowly endemic species, Dirca mexicana, has potential as a new shrub for horticulture. Additionally, our results provide evidence for variation in cold-hardiness and annual stem extension of Dirca palustris. Although over half of plants from Florida had died after the first two winters, no additional mortality occurred over remaining years, and survivors were more vigorous than plants from Ontario. This suggests that exploitable variation in cold-hardiness and vigor exists among and within populations of this broadly distributed species.
Cloning of an Expansin Gene from Chimonanthus praecox Flowers and Its Expression in Flowers Treated with Ethephon or 1-Methylcyclopropene
Authors: Ma Jing , Li Zheng , Wang Bin , Sui Shunzhao , Li Mingyang
Published: February 2019

Expansins are extracellular proteins that are involved in cell wall modifications such as cell wall disassembly, cell separation, and cell expansion. Little is known about expansin gene expression during flower development of wintersweet (Chimonanthus praecox). In the present study, an expansin gene, CpEXP1, was isolated from the wintersweet flower cDNA library through random sequencing; this gene encodes a putative protein of 257 amino acids with the essential features conserved, like in other alpha expansins. The CpEXP1 gene exhibited different transcription levels in different tissues and had a significantly higher expression in flowers than other tissues. It is strongly correlated with the development of the flower. The expression of CpEXP1 increased in the flower buds or whole flowers from Stage 1 to 4 and decreased from Stage 5 to 6 during natural opening. Ethephon (an ethylene releaser) treatment promoted cut flower senescence, whereas 1-methylcyclopropene (1-MCP) (an ethylene perception inhibitor) delayed the process of flower wilting. This result is associated with the concomitant lower transcript levels of CpEXP1 in the ethephon-treated samples as well as the steady expression in the 1-MCP-treated samples compared with that in control flowers. The studies show the interesting observation that the expression of an expansin gene CpEXP1 is correlated with the development of Chimonanthus praecox flowers, the upregulation during flower opening vs. the downregulation during senescence.
Red Light-emitting Diode Light Irradiation Improves Root and Leaf Formation in Difficult-to-propagate Protea cynaroides L. Plantlets In Vitro
Authors: Wu How-Chiun , Lin Chun-Chih
Published: February 2019

The effects of light quality emitted by light-emitting diodes (LEDs) on the growth and morphogenesis, and concentrations of endogenous phenolic compounds of Protea cynaroides L. plantlets in vitro, were investigated. Plantlets were cultured under four light treatments: conventional fluorescent lamps (control), red LEDs (630 nm), blue LEDs (460 nm), and red + blue LEDs (1:1 photosynthetic photon flux). Four phenolic compounds extracted from the plantlets were analyzed: 3,4-dihydroxybenzoic acid, gallic acid, caffeic acid, and ferulic acid. The highest rooting percentage was observed in plantlets cultured under red LEDs (67%) compared with 7% under conventional white fluorescent light, 13% under blue LEDs, and 13% under red + blue LEDs. The highest number of roots per plantlet was also found under red LEDs, whereas a significantly lower number of roots per plantlet was obtained under the other light treatments. Furthermore, red light promoted the formation of new leaves in P. cynaroides plantlets. However, the highest leaf dry weight (53.8 mg per plantlet) was found in plantlets irradiated by the combination of red and blue LEDs. Phenolic analyses showed that the lowest concentrations of 3,4-dihydroxybenzoic acid (4.3 mg·g−1), gallic acid (7.0 mg·g−1), and ferulic acid (7.4 mg·g−1) were detected in plantlets exposed to red light, whereas those irradiated by white fluorescent light contained the highest concentration. A significant inverse correlation (r = –0.419) was established between 3,4-dihydroxybenzoic acid and rooting percentage. Strong inverse correlations were also established between 3,4-dihydroxybenzoic acid and number of roots per plantlet (r = –0.768) as well as between ferulic acid and number of roots per plantlet (r = –0.732). These results indicate that the stimulation of root formation in P. cynaroides plantlets under red LEDs is the result of the low endogenous concentrations of 3,4-dihydroxybenzoic acid and ferulic acid.
Growth and Physiological Response of Fraser Fir [Abies fraseri (Pursh) Poir.] Seedlings to Water Stress: Seasonal and Diurnal Variations in Photosynthetic Pigments and Carbohydrate Concentration
Authors: Kulaç Şemsettin , Nzokou Pascal , Guney Deniz , Cregg Bert Michael , Turna Ibrahim
Published: February 2019

Four-year-old seedlings of Abies fraseri [(Pursh) Poir] (fraser fir) were grown in semicontrolled conditions in hoop houses with five watering regimes (0.00, 0.62, 1.25, 2.50, and 3.70 cm/week) with the goal of determining the seasonal variation in the physiological response to drought stress. Drought stress was monitored by measuring predawn (Ψpd) and midday (Ψmd) potentials in a subset of plants from each treatment. Physiological variables monitored were chlorophyll fluorescence (Fv/Fm), Chl a, Chl b, total carotenes, and total carbohydrate concentrations. Morphological characteristics including height growth, root collar diameter, and terminal shoot growth were also measured. Predawn stem water potential values were generally higher (–0.8 to –1.9 Mpa) than midday values (–1.3 to –2.9 Mpa). Irrigation consistently increased Ψpd and Ψmd compared with non-irrigated treatments. Photosynthetic pigments (Chl a, Chl b, and carotenes) decreased midseason (14 July) and increased toward the end of the season (25 Aug.) in predawn and midday measurements. There was a significant effect (P < 0.05) of drought stress on photosynthetic pigment concentrations in predawn and midday samples in the late-season measurements (25 Aug.). These results were accompanied with a similar significant difference in Fv/Fm between non-irrigated and irrigated trees. We concluded that significant effects observed on photosynthetic pigment concentrations in some of the treatments did not affect carbohydrate concentrations. Exposure of A. fraseri to water stress did not cause a reduction in supply of metabolic carbohydrates; consequently, the decline and mortality in water-stressed plants can only be the result of hydraulic failure caused by xylem cavitation leading to cessation of water flow in tissues, desiccation, and cellular death. Further studies are needed to confirm these preliminary conclusions.
Water Flow Through Sand-based Root Zones Atop Geotextiles
Authors: Rose-Harvey Keisha , McInnes Kevin J. , Thomas James C.
Published: February 2019

An alternative to the time-tested gravel drainage layer beneath a sand-based root zone of a sports field or golf putting green can be constructed from a geotextile atop a highly porous drainage material or structure. The geotextile serves to support the root zone mixture on the drainage layer whose pores can be too large for the sand to support itself by bridging. In such an application, the geotextile should have high enough strength and resistance to stretching to support the root zone mixture atop the pores of the drainage layer and should contain internal pores of appropriate size to retain the bulk of particles in the root zone mixture and to allow free passage of drainage water and eluviating fine particles. The objective of this study was to determine whether geotextiles selected to meet these criteria affect the drainage rates of sand-based root zones and whether they affect the size of particles lost from the root zone–geotextile systems. In a 1-year laboratory study that made use of 150-mm diameter polyvinyl chloride (PVC) test cells, measurements of drainage rates and saturated hydraulic conductivities were made on replicated combinations of 10 geotextiles and three 300-mm deep root zone mixtures. Size distributions and total masses of particles that passed from the root zones through the geotextiles were measured. Statistical analyses showed that drainage rate, saturated hydraulic conductivity, and size distribution and mass of eluviated particles were unaffected by the properties of the geotextiles. The results gave of no reason to prohibit the use of geotextiles to support sand-based root zones in golf putting greens or sports fields.