bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterologous Expression of a Carrot Small Heat Shock Protein Increased Escherichia coli Viability under Lead and Arsenic Stresses
Authors: Lee Joohee , Ahn Yeh-Jin
Published: February 2019

The expression and function of DcHsp17.7, a small heat shock protein (sHSP), in carrot (Daucus carota L.) was examined under lead [Pb(II)] and arsenic (arsenate) stresses. In a time course experiment, the level of DcHsp17.7 increased in carrot leaf tissue treated with lead ions or arsenate. To examine the function of DcHsp17.7, the DcHsp17.7 gene was cloned and introduced into Escherichia coli. Heterologous expression of DcHsp17.7 was confirmed by immunoblot analysis using a polyclonal antibody raised against DcHsp17.7. Lead ion and arsenate reduced bacterial cell viability. However, transgenic E. coli with accumulated DcHsp17.7 showed higher levels of survival under both lead ion and arsenate conditions compared with the vector control. Immunoblot analysis showed that the level of heterologously expressed DcHsp17.7 decreased under lead ion conditions, but remained the same under arsenate conditions. Our results suggest that DcHsp17.7 can confer tolerances to lead and arsenic stresses.
Growth of Native Aromatic Xerophytes in an Extensive Mediterranean Green Roof as Affected by Substrate Type and Depth and Irrigation Frequency
Authors: Papafotiou Maria , Pergialioti Niki , Tassoula Lamprini , Massas Ioannis , Kargas Georgios
Published: February 2019

Green roofs could be a way to increase vegetation in the center of old Mediterranean cities. The need for conservation of local character and biodiversity requires the use of native plant species, whereas the deficiency of water, particularly in semiarid regions, requires the use of species with reduced irrigation needs. Moreover, the aged buildings lead to the use of lightweight green roof constructions. Therefore, research was undertaken to investigate the possibility of using three Mediterranean aromatic xerophytes, Artemisia absinthium L., Helichrysum italicum Roth., and H. orientale L., at an extensive green roof in Athens, Greece. Simultaneously, the possibility of using locally produced grape marc compost was investigated. Substrate type and depth and irrigation frequency effects on growth of these species were studied. Rooted cuttings were planted mid-May in plastic containers with a green roof infrastructure fitted (moisture retention and protection of the insulation mat, drainage layer, and filter sheet) and placed on a fully exposed third floor flat roof at the Agricultural University of Athens. Two types of substrates were used, grape marc compost:soil:perlite (2:3:5, v/v) and peat:soil:perlite (2:3:5, v/v, as a control), as well as two substrate depths, 7.5 (shallow) and 15 cm (deep), and two irrigation frequencies, sparse (5 or 7 days in shallow and deep substrate, respectively) and normal (3 or 5 days in shallow and deep substrate, respectively). Increased contents of macroelements, total phosphorus (P) and potassium (K) in particular, were recorded in the compost-amended substrate, whereas both substrates had similar physical properties. Plant growth was recorded from May to October. The deep compost-amended substrate, independent of irrigation frequency, resulted in taller plants with bigger diameter and aboveground dry weight in all species. However, a remarkable result was that shallow compost-amended substrate with sparse irrigation resulted in similar or even bigger plant growth of all plant species compared with deep peat-amended substrate with normal irrigation. Thus, all three species were found suitable for use in Mediterranean extensive or semi-intensive green roofs, whereas the use of grape marc compost in the substrate allowed for less water consumption and the reduction of substrate depth without restriction of plant growth at the establishment phase and the first period of drought.
Use of Intersimple Sequence Repeat Assay for Detection of DNA Polymorphism Induced by Gamma Rays in Curcuma alismatifolia
Authors: Taheri Sima , Lee Abdullah Thohirah , Psyquay Abdullah Nur Ashikin , Ahmad Zaiton
Published: February 2019

In plant breeding programs with vegetatively propagated plants, induced mutations with low physiological effects and strong genetic effects are important approaches for broadening the genetic variation. In the present study, intersimple sequence repeat (ISSR) assays were used to identify DNA polymorphism among the mutant varieties of Curcuma alismatifolia (Chiang Mai Red, Sweet Pink, Kimono Pink) and one hybrid (Doi Tung 554) exposed to 0-, 10-, and 20-Gy optimum doses of acute gamma irradiation. To identify DNA polymorphism among the mutants (10 and 20 Gy) and non-treated (0 Gy) samples through ISSR assay, a total of 25 random primers were screened and 14 gave reproducible polymorphic bands. The number of presumed alleles revealed by the ISSR analysis ranged from three to 19 alleles with mean values of 6.5, 7.8, and 9.2 alleles per locus for doses of 0 (control), 10, and 20 Gy, respectively. The average effective number of alleles, Nei’s gene diversity, Shannon’s information index, and polymorphic information content (PIC) were 1.41 to 1.48, 0.24 to 0.33, 0.35 to 0.45, and 0.21 to 0.25 for the three doses, respectively. Percentages of polymorphic loci for non-irradiated (0 Gy), 10 Gy, and 20 Gy individual plants were 76.4%, 83.7%, and 85.8%, respectively, with an average of 81.9%. Jaccard’s genetic similarity coefficient varied from 0.19 to 1.0 indicating the level of genetic variation among the mutants studied. In terms of variety, the range of genetic variation (0.27 to 0.4) among individuals of the Doi Tung population was more than that observed in the other three varieties. In a dendrogram constructed based on genetic similarity coefficients, the 44 C. alismatifolia individual plants fell into seven major clusters at a coefficient level of 0.35. The study revealed that DNA polymorphism detected by ISSR analysis offered a useful molecular marker for the identification of mutants in gamma radiation-treated plants. Additionally, this research demonstrated that the DNA of the hybrid (Doi Tung 554) showed a greater response in induced mutation compared with the other varieties.
Determining Nutrient Diagnostic Norms for Greenhouse Roses
Authors: Franco Hermida Johnn Jairo , Henao Toro Martha Cecilia , Guzmán Miguel , Cabrera Raul I.
Published: February 2019

Greenhouse-grown cut roses are an economically important and intensive horticultural cropping system receiving large water, fertilizer, agrochemicals, and labor inputs. This study was conducted to establish and validate norms for the nutrient diagnosis techniques Diagnosis and Recommendation Integrated System (DRIS) and Compositional Nutrient Diagnosis (CND) for cut roses (Rosa spp. L.) growing on soil beds within greenhouses in the Bogotá Plateau, Colombia. Information used in this study was obtained from a database of plant tissue and soil analyses, including 1914 foliar analyses of different rose cultivars grafted on the rootstock R. × ‘Natal Briar’. Theoretical validation proved that the generated norms are suitable for crop nutrient status diagnosis, allowing for the correlation of nutrient balance indices with crop flower productivities across a range of cultivars and plant ages. Analysis of the results provided by both DRIS and CND procedures indicated that element relations associated with nitrogen, phosphorous, magnesium, manganese, and boron had a higher influence on the nutritional balance and productivity of roses growing under the conditions of the studied region. In addition, it was preliminarily determined that the use of these diagnostic norms could be extended to rose crops growing under other, and different, rootstocks, production and environmental conditions, and management.
Response of Pecan to Annual Soil Band Applications of Phosphorus and Potassium
Authors: Smith Michael W. , Cheary Becky S.
Published: February 2019

Phosphorus (P) and potassium (K) deficiencies were identified in a ‘Pawnee’ pecan [Carya illinoinensis (Wangenh.) C. Koch] orchard. Deficiencies of P and K have traditionally been difficult to correct in pecan. Broadcast application of P rarely results in a positive response. Broadcast applications of K frequently require 3 or more years before a positive response was noted, particularly in soils with high clay content. A 4-year study was initiated on 10-year-old trees using soil band-applied P, K, blended P plus K, and a non-treated control. Rates were based on trunk cross-sectional area adjusted annually for tree growth. Phosphorus application alleviated leaf deficiency symptoms, increased leaf P concentration, and improved flowering. However, P application resulted in darker kernels than the control or K-treated trees. Band-applied K was not associated with observed leaf symptoms but increased leaf K above the recommended minimum level and increased the percentage of number-1 kernels. Band-applied P or blended P plus K suppressed leaf K concentrations. Blended P plus K applied as a band appeared to improve return bloom 2 of 3 years, although no improvement in leaf K concentration was noted.
Pollen Viability of F1 Hybrids between Watermelon Cultivars and Disease-resistant, Infraspecific Crop Wild Relatives
Authors: McGregor Cecilia E. , Waters Vickie
Published: February 2019

Crop wild relatives (CWRs) are important sources of variation for domesticated crops like watermelon (Citrullus lanatus) where cultivated varieties have a very narrow genetic base. The use of CWRs in plant breeding can be hampered by low fertility, chromosomal rearrangements, marker distortion, and linkage drag in the progeny. Pollen viability can be a quick and easy way to estimate male fertility, which can be a cause of marker distortion and an indicator of chromosomal rearrangements. Pollen viability was determined for F1 hybrids between cultivars and resistant citron and egusi types and the data were used to determine whether the parental cultivars/lines used or the directionality of the cross play a role in pollen viability. F1 hybrids between cultivars and the egusi type showed no reduction in pollen viability compared with parental lines, whereas pollen viability of hybrids with citron types varied between 61.8% and 91.7%. Significant main effects were observed for the cultivar and donor lines used, but the directionality of the cross did not affect pollen viability. F1 hybrids with ‘Crimson Sweet’ as the cultivar parent had significantly higher pollen viability than those with ‘Sugar Baby’ or ‘Charleston Gray’. Our results indicate that the directionality of the crosses between watermelon cultivars and infraspecific CWRs does not affect pollen viability but that the specific cultivars and donor lines used can have a significant effect. The high pollen viability of cultivar–egusi hybrids is supported by previous genetic data and strongly suggests that it should be easier to introgress traits from egusi types than citron types.
Malus sieversii: A Diverse Central Asian Apple Species in the USDA-ARS National Plant Germplasm System
Authors: Volk Gayle M. , Henk Adam D. , Richards Christopher M. , Forsline Philip L. , Chao C. Thomas
Published: February 2019

There are several Central Asian Malus species and varieties in the USDA-ARS National Plant Germplasm System (NPGS) apple collection. Malus sieversii is the most comprehensively collected species native to Central Asia. Other taxa such as M. sieversii var. kirghisorum, M. sieversii var. turkmenorum, M. pumila, and M. pumila var. niedzwetzkyana have primarily been donated to the collection by other institutions and arboreta. We sought to determine if genetic and/or phenotypic differences among the individuals that make up the gene pools of these taxa in the NPGS exhibit unique characteristics. Genetic data, based on microsatellite analyses, suggested that the diversity within each taxa is significantly greater than that among taxa. Trait data also revealed very few differences among taxa, the primary characteristic being the dark red fruit coloration and tinted flesh color of the accessions assigned to M. pumila var. niedzwetzkyana resulting from a known single-gene mutation in anthocyanin production. We found that M. sieversii is a highly diverse species with a range in genetic and phenotypic trait variation that includes the characteristics of the other Central Asian taxa of interest. We conclude that the gene pools that comprise the accessions within the NPGS Central Asian Malus collection are highly overlapping with respect to both phenotypic traits and genotypic characters.
Chlorophyll, Carotenoid, and Visual Color Rating of Japanese-cedar Grown in the Southeastern United States
Authors: Contreras Ryan N. , Ruter John M. , Owen James S. , Hoegh Andy
Published: February 2019

Japanese-cedar has been underused in landscapes of the United States until recent years. There are now over 100 cultivars, many of which are grown in the southeast of the United States. Performance of cultivars has been described from U.S. Department of Agriculture (USDA) Zone 6b to USDA Zone 7b; however, there are no reports on how cultivars perform in USDA Zone 8. The current study was conducted to measure chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid content and assign visual color ratings to determine if there was a relationship between pigment values and perceived greenness, which generally is regarded as a desirable and potentially heritable trait. Total chlorophyll (P = 0.0051), carotenoids (P = 0.0266), and the ratio of total chlorophyll to carotenoids (P = 0.0188) exhibited a positive relationship with greenness after accounting for season and tree effects. In contrast, the ratio of chlorophyll a to chlorophyll b did not have an effect on greenness. There was a linear relationship between total chlorophyll and carotenoid regardless of season (summer R2 = 0.94; winter R2 = 0.88) when pooled across 2 years. The observed correlation between chlorophyll and carotenoid content suggests they could be used interchangeably as predictors of greenness. There were large differences in rainfall between the 2 years that may have resulted in additional variation. Furthermore, the climate in which the evaluation was conducted differs greatly from the native distribution of japanese-cedar occurring in China and Japan.
The Role of Net Development as a Barrier to Moisture Loss in Netted Melon Fruit (Cucumis melo L.)
Authors: Puthmee Thanidchaya , Takahashi Kenji , Sugawara Midori , Kawamata Rieko , Motomura Yoshie , Nishizawa Takashi , Aikawa Toshiyuki , Kumpoun Wilawan
Published: February 2019

The transpiration rate of cuticular membrane and fissures that comprise the netting on fruits of three netted melon cultivars, Life, Andesu, and Gurandoru, were measured during fruit development. Fissures in the equatorial region first developed vertically, then became interconnected by horizontal fissures as the fruit developed. Some cracks remained along the net, even at the fruit ripening stage, regardless of cultivar. Both lignified and suberized cell wall layers in the net tissues of the cultivar Life were thinner than those of the other cultivars, probably because of the shorter developmental period of fruits in the variety. Nevertheless, net transpiration rate did not differ significantly among cultivars at the fruit ripening stage. Peroxidase (POD) activity in the skin tissues of ‘Life’ was lower than that in ‘Andesu’ and ‘Gurandoru’ throughout fruit development and was not correlated with climacteric ethylene production. Among these cultivars, significantly higher ethylene production occurred in ‘Life’ fruit at the ripening stage. This can accelerate membrane permeability of hypodermal tissues, resulting in rapid fruit softening. Our results indicate that the net tissues of netted melons can be as waterproof as cutinized membranes if suberized cell wall layers with wax depositions develop below the net fissures at the fruit ripening stage.
Effect of Arbuscular Mycorrhiza and Temperature Control on Plant Growth, Yield, and Mineral Content of Tomato Plants Grown Hydroponically
Authors: Maboko Martin Makgose , Bertling Isa , Du Plooy Christian Phillipus
Published: February 2019

Mycorrhizal inoculation improves nutrient uptake in a range of host plants. Insufficient nutrient uptake by plants grown hydroponically is of major environmental and economic concern. Tomato seedlings, therefore, were treated with a mycorrhizal inoculant (Mycoroot™) at transplanting to potentially enhance nutrient uptake by the plant. Then seedlings were transferred to either a temperature-controlled (TC) or a non-temperature-controlled (NTC) tunnel and maintained using the recommended (100%) or a reduced (75% and 50%) nutrient concentration. Plants grown in the NTC tunnel had significantly poorer plant growth, lower fruit mineral concentration, and lower yield compared with fruit from plants in the TC tunnel. Leaves from plants in the NTC tunnel had higher microelement concentrations than those in the TC tunnel. Highest yields were obtained from plants fertigated with 75% of the recommended nutrient concentration, and not from the 100% nutrient concentration. Application of arbuscular mycorrhizal fungi (AMF) neither enhanced plant growth, nor yield, nor fruit mineral nutrient concentrations. However, temperature control positively affected the fruit Mn and Zn concentration in the TC tunnel following AMF application.
Growth Responses of Ornamental Annual Seedlings Under Different Wavelengths of Red Light Provided by Light-emitting Diodes
Authors: Wollaeger Heidi Marie , Runkle Erik S.
Published: February 2019

Light-emitting diodes (LEDs) are of increasing interest in controlled environment plant production because of their increasing energy efficiency, long lifetime, and colors can be combined to elicit desirable plant responses. Red light (600–700 nm) is considered the most efficient wavelength for photosynthesis, but little research has compared growth responses under different wavelengths of red. We grew seedlings of impatiens (Impatiens walleriana), petunia (Petunia ×hybrida), tomato (Solanum lycopersicum), and marigold (Tagetes patula) or salvia (Salvia splendens) at 20 °C under six sole-source LED lighting treatments. In the first experiment, a photosynthetic photon flux (PPF) of 160 μmol·m−2·s–1 was provided for 18 h·d−1 by 10% blue (B; peak = 446 nm) and 10% green (G; peak = 516 nm) lights, with the remaining percentages consisting of orange (O; peak = 596 nm)–red (R; peak = 634 nm)–hyper red (HR; peak = 664 nm) of 20–30–30, 0–80–0, 0–60–20, 0–40–40, 0–20–60, and 0–0–80, respectively. There were no consistent effects of lighting treatment across species on any of the growth characteristics measured including leaf area, plant height, or shoot fresh weight. In a second experiment, seedlings were grown under two light intensities (low, 125 μmol·m−2·s–1 and high, 250 μmol·m−2·s–1) consisting of 10% B and 10% G light and the following percentages of R–HR: 0–80, 40–40, 80–0. Shoot fresh weight was similar in all light treatments, whereas shoot dry weight was often greater under the higher light intensity, especially under the 40–40 treatments. Leaf chlorophyll concentration under 40–40low, 80–0low, or both was often greater than that in plants under the high light treatments, indicating that plants acclimated to the lower light intensity to better use photons available for photosynthesis. We conclude that O, R, and HR light have generally similar effects on plant growth at the intensities tested when background G and B lights are provided and thus, selection of red LEDs for horticultural applications could be based on other factors such as economics and durability.
Mulch and Fertilizer Management Practices for Organic Production of Highbush Blueberry. II. Impact on Plant and Soil Nutrients during Establishment
Authors: Larco Handell , Strik Bernadine C. , Bryla David R. , Sullivan Dan M.
Published: February 2019

A systems trial was established in Oct. 2006 to evaluate management practices for organic production of northern highbush blueberry (Vaccinium corymbosum L.). The practices included: flat and raised planting beds; feather meal and fish emulsion fertilizer each applied at rates of 29 and 57 kg·ha−1 nitrogen (N); sawdust mulch, compost topped with sawdust mulch (compost + sawdust), or weed mat; and two cultivars, Duke and Liberty. Each treatment was irrigated by drip and weeds were controlled as needed. The planting was certified organic in 2008. Bed type affected most leaf nutrients measured in one or both cultivars during the first year after planting, including N, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), boron (B), manganese (Mn), and zinc (Zn), but had less of an effect on leaf nutrients and no effect on soil pH, organic matter, or soil nutrients measured the next year. Feather meal contained 12 times more Ca and seven times more B than fish emulsion and resulted in higher levels of soil Ca and soil and leaf B in both cultivars, whereas fish emulsion contained three times more P, 100 times more K, and 60 times more copper (Cu) and resulted in higher levels of soil P, K, and Cu as well as a higher level of leaf P and K. Fish emulsion also reduced soil pH. Compost + sawdust mulch increased soil pH and organic matter and resulted in higher levels of soil nitrate-N (NO3-N), P, K, Ca, B, Cu, and Zn than sawdust alone and increased leaf K and B. Weed mat, in contrast, resulted in the lowest soil pH and increased soil ammonium-N (NH4-N). Weed mat also reduced soil Ca and Mg, but its effects on leaf nutrients were variable. Leaf Ca, Mg, and B were below levels recommended for blueberry the first year after planting when plants were fertilized with fish emulsion, whereas leaf N was low or deficient on average in the second year when plants were fertilized with feather meal. Leaf B was also low the second year in all treatments, and leaf Cu was marginally low. Leaf K, conversely, increased from the previous year and was becoming marginally high with fish emulsion. Fish emulsion, weed mat, and compost were generally the most favorable practices in terms of plant and soil nutrition. However, given the impact of each on soil pH and/or plant and soil K, further investigation is needed to determine whether these practices are sustainable over the long term for both conventional and organic production of highbush blueberry.
Effect of Potassium Bicarbonate (MilStop®) and Insecticides on the Citrus Mealybug, Planococcus citri (Risso), and the Natural Enemies Leptomastix dactylopii (Howard) and Cryptolaemus montrouzieri (Mulsant)
Authors: Hogendorp Brian K. , Cloyd Raymond A.
Published: February 2019

Both laboratory and greenhouse experiments were conducted to determine if the fungicide, MilStop® (BioWorks, Victor, NY), which contains the active ingredient, potassium bicarbonate, has direct activity on the citrus mealybug, Planococcus citri Risso. Spray applications of four different rates (4.5, 5.9, 7.4, and 14.9 g·L–1) were applied to green coleus, Solenostemon scutellarioides (L.) Codd., plants infested with citrus mealybugs. In addition, experiments were conducted to assess both the direct and indirect effects of MilStop® on two natural enemies of the citrus mealybug: the parasitoid, Leptomastix dactylopii (Howard), and the coccinellid beetle, Cryptolaemus montrouzieri (Mulsant). MilStop® provided between 56% and 86% mortality of citrus mealybug; however, the highest rate (14.9 g·L–1) was phytotoxic to coleus plants. Percent mortality associated with the second highest rate (7.4 g·L–1) was 82%, which was comparable to acetamiprid (84%) applied at 0.05 g·L–1. For the natural enemies, MilStop® treatment rates of 1.5 and 3.5 g·L–1 resulted in 16% mortality, whereas the 5.5- and 9.0-g·L–1 rates resulted in 33% mortality of L. dactylopii adults. MilStop® treatment rates of 3.5, 5.5, 9.0, and 12.0 g·L–1 resulted in 30%, 60%, 40%, and 90% mortality, respectively, of C. montrouzieri adults. Therefore, depending on the application rate, this fungicide may inadvertently kill citrus mealybugs when used to control fungal plant pathogens. It should not disrupt biological control programs targeting citrus mealybug in greenhouses that involve releases of L. dactylopii when used at low application rates, whereas MilStop® applications should be properly timed when using C. montrouzieri.
Germinating and Culturing Axenic Poison Ivy Seedlings
Authors: Benhase Elise B. , Jelesko John G.
Published: February 2019

Urushiols are the chemical constituents responsible for causing the characteristic skin rash resulting from contact with poison ivy [Toxicodendron radicans subsp. radicans (L.) Kuntze] plant tissue. Future detailed physiological and molecular studies of T. radicans urushiol metabolism will require the production and cultivation of axenic T. radicans plants in controlled environments. To this end, the present study focused on treatments to enhance germination and reduce microbial contamination to obtain axenic T. radicans seedlings. Toxicodendron radicans drupes treated singularly with water, bleach, cold, or gibberellic acid showed very low germination frequencies. In contrast, concentrated sulfuric acid strongly promoted seedling germination by removing exocarp, mesocarp, and causing pitting of the brachysclereid and osteosclereid layers of the endocarp. Most T. radicans drupes harbored significant amounts of fungal and bacterial contaminants. Although the serial mechanical scarification, sulfuric acid, and bleach treatments promoted seedling germination, this serial treatment regime was not adequate to render the majority of drupes microbe-free. Nevertheless, ≈25% of treated T. radicans drupes were axenic, and these needed to be promptly separated from adjacent fungal-contaminated drupes to avoid cross-contamination. The isolated axenic T. radicans drupes germinated at high frequency producing viable seedlings that grew well in sterile plant culture conditions.
Supplementary Potassium Sustains Fruit Yield in Bell Pepper under High Ammonium Nutrition
Authors: Hernández-Gómez Elvia , Valdez-Aguilar Luis A. , Castillo-González Ana M. , Colinas-León María T. , Cartmill Donita L. , Cartmill Andrew D. , Lira-Saldívar R. Hugo
Published: February 2019

The uptake of nitrogen (N) in nitrate or ammonium (NH4+) form affects physiological and metabolic processes and toxicity may develop in plants receiving high concentrations of NH4+. The objective of the present study was to delineate the response of bell pepper plants to varying proportions of NH4+ combined with increasing concentrations of potassium (K) in the nutrient solution. Bell pepper plants were tolerant to moderate proportions of NH4+ (25% or less or 50% or less); however, higher proportions resulted in growth reduction. The application of higher K concentrations in the nutrient solution did not ameliorate the growth on vegetative plant parts; however, when K was increased to 9 mm, the yield was sustained even when 50% of total N was in the NH4+ form. Decreased shoot:root ratio and harvest index indicated that biomass accumulation was affected more in the shoot than in the root and in the fruit than in the shoot, respectively. There was a lower concentration of NH4+ in the roots compared with leaves, suggesting that the higher K concentration that resulted from the increased K in the nutrient solution was associated with NH4+ translocation through the xylem. A decrease in calcium and magnesium detected in leaves suggests an antagonistic relationship with NH4+ and K in the nutrient solution, which was correlated with the acidification of the growing medium. Higher yields when K was at 9 mm may be the result of the high photosynthetic rate and stomatal conductance (gS) detected in plants fertigated with 25% of total N as NH4+ and the higher leaf water potential when the proportion of NH4+ was 50%. The biochemical composition of fruits was affected because both high NH4+ and increased K resulted in higher ethylene production, lipid peroxidation, superoxide dismutase activity, and carotenoids.
Potassium Nutrition in Lilium: Critical Concentrations, Photosynthesis, Water Potential, Leaf Anatomy, and Nutrient Status
Authors: Barrera-Aguilar Enoc , Valdez-Aguilar Luis A. , Castillo-González Ana M. , Cartmill Andrew D. , Cartmill Donita L. , Avitia-García Edilberto , Ibarra-Jímenez Luis
Published: February 2019

The present study was conducted to determine the critical optimum and toxic concentrations of potassium (K) using segmented analysis and its relationship with some physiological, anatomical, and nutritional responses to increasing K in hydroponically grown Lilium sp. L. cv. Arcachon. Plants were fertigated with nutrient solutions containing K (Kext) at 0, 2.5, 5.0, 7.5, 12.5, 17.5, 22.5, and 30 mmol·L−1. Maximum flower diameter occurred when, on a dry mass basis, shoot K (Kint) ranged from 504 to 892 mmol·kg−1; however, a lower Kint was required to obtain maximum biomass accumulation and shoot length (384 and 303 mmol·kg−1, respectively). Potassium increased in all plant organs as K in the nutrient solution increased. Nitrogen increased in young leaves and magnesium (Mg) decreased as Kext increased. Concentrations of Kext from 5 to 17.5 mmol·L−1 increased the size of chlorenchyma and occlusive cells; however, metaxylem vessels were unaffected. Net photosynthetic rate was higher in young leaves, whereas water potential increased in both young and mature leaves when Kext was greater than 22.5 mmol·L−1. Critical concentrations varied according to the growth parameter. Optimum Kint ranged from 303 to 384 mmol·kg−1 for vegetative parts, whereas parameters related with flower growth ranged from 427 to 504 mmol·kg−1. Concentration of 504 mmol·kg−1 Kint was associated with optimum growth for all the parameters assessed, whereas a Kint greater than 864 mmol·kg−1 was associated with a decline in growth; thus, these concentrations were considered as the critical optimum and critical toxicity levels, respectively. The optimum and toxicity critical Kint were estimated when Kext in the nutrient solutions was 5.6 and 13.6 mmol·L−1, respectively.
Evaluation of Heat and Drought as Components of Summer Stress on Tall Fescue Genotypes
Authors: Cross James W. , Bonos Stacy A. , Huang Bingru , Meyer William A.
Published: February 2019

Heat and drought are two major abiotic stresses causing a decline in quality in cool-season turfgrasses during the summer. The objectives of this study were 1) to determine whether genotypic variations in turf performance during summer stress in New Jersey is related primarily to heat tolerance or drought tolerance of tall fescue; and 2) to make selections of plants tolerant to summer stress for breeding efforts. Twenty-four tall fescue genotypes exhibiting differential performance during summer months in field conditions (12 summer stress-tolerant and 12 summer stress-sensitive) were selected from the germplasm pool present at the New Jersey Agricultural Experiment Station. Plants of these 24 genotypes were exposed to heat, drought, or heat + drought. There were generally no significant differences in turf quality, photochemical efficiency, relative water content, or electrolyte leakage between summer stress-tolerant and -sensitive genotypes, except in the heat treatment in which the summer stress-tolerant selections performed significantly better. The results indicate that the superior performance of the summer stress-tolerant plants under field conditions is mainly the result of superior heat tolerance.
Using Amplified Fragment Length Polymorphism Markers to Confirm Identity and Correct Labeling of Japanese Barberry (Berberis thunbergii) Cultivars in the Market
Authors: Obae Samuel G. , Brand Mark H. , Kaitany Richard C.
Published: February 2019

Japanese barberry (Berberis thunbergii DC.) is a popular ornamental shrub used in garden and urban landscaping. Currently there are over 60 B. thunbergii cultivars in the market. To better distinguish its cultivars, we used the amplified fragment length polymorphism (AFLP) technique to develop DNA marker profiles for 59 cultivars and hybrids. These markers were used to authenticate the trueness-to-name of B. thunbergii cultivars in production and in the market, control for intracultivar genetic variants, and develop a molecular key to identify cultivars approved for importation in Canada. Polymorphic markers from seven primer combinations were able to clearly differentiate 57 of 59 cultivars evaluated. Two cultivars, Aurea and Aurea Nana, could not be differentiated because they had identical marker profiles. Among the 274 plants tested, 263 were confirmed to be true-to-name and correctly labeled, whereas 11 plants could not be confirmed true-to-name. Seven of the 20 cultivars evaluated exhibited detectable intracultivar genetic variation. ‘Crimson Pygmy’ had the highest number of plants exhibiting genetic variability. Overall, nursery producers and retailers do not appear to be mixing or mislabeling cultivars. A molecular key developed from a subset of 25 markers was able to accurately identify and differentiate the 11 B. thunbergii cultivars approved for importation in Canada. This key could be used in a cultivar verification program to facilitate international trade of B. thunbergii cultivars where wheat rust is a concern.
A Novel Screening Method for Evaluation of Lettuce Germplasm for Bacterial Leaf Spot Resistance
Authors: Lu Huangjun , Raid Richard
Published: February 2019

Bacterial leaf spot of lettuce, caused by Xanthomonas campestris pv. vitians, is a devastating disease of lettuce worldwide. Because there are no chemicals available for effective control of the disease, host-plant resistance is highly desirable to protect lettuce production. A new method for fast screening and accurate identification of bacterial leaf spot (BLS)-resistant lettuce has been developed in our laboratory. A total of 79 lettuce genotypes (69 germplasm lines and 10 adapted cultivars) were evaluated with this technique for response to X. c. vitians. Disease incidences ranged from 92% to 100% and disease severities were between 1.6 and 3.6 on the 0 to 4 scale. No highly resistant genotypes were identified. However, 12 genotypes did not significantly differ for disease severities from the moderately resistant ‘Little Gem’ lettuce that was used as a resistant control. Comparison of disease severities of 10 commercial cultivars and three moderately resistant germplasm lines tested at the seedling stage and adult stage showed a high positive correlation (r = 0.87, P < 0.0001) between tests. The new screening method should be useful in breeding programs, in which great numbers of plants need to be tested during germplasm evaluation, and for single plant selection as well as other studies. The identification of new sources of moderate resistance in this study could facilitate development of cultivars with a higher level of resistance through the gene pyramiding approach.
Evaluation of a Light-activated Nanoparticle Formulation of Titanium Dioxide with Zinc for Management of Bacterial Leaf Spot on Rosa ‘Noare’
Authors: Paret Mathews L. , Palmateer Aaron J. , Knox Gary W.
Published: February 2019

Bacterial leaf spot on roses caused by a Xanthomonas sp. is a new disease affecting commercial rose production with the potential to cause major economic losses. In the past few decades, antimicrobial photocatalyst technology has emerged from basic research and development to provide convenient formulations of titanium dioxide (TiO2) nanoparticles, which have the ability to destroy bacteria on surfaces in the presence of light. In this study, a TiO2 nanoparticle formulation containing zinc (TiO2/Zn) was tested for management of bacterial leaf spot on Rosa ‘Noare’. TiO2/Zn caused significant reduction in the survival of Xanthomonas sp. strain Xr-1 on glass coverslips coated with the nanoparticles on exposure to light at 3 × 104 lux for 10 minutes. There was no reduction of bacterial viability in non-coated or non-illuminated controls. Field applications of TiO2/Zn at ≈500 to 800 ppm on Rosa ‘Noare’ significantly reduced bacterial spot severity compared with the untreated control. TiO2/Zn activity was better or on par with the ornamental industry standard for management of rose diseases.
Best Management Practices for the Conversion of Established Bermudagrass to Buffalograss
Authors: Hoyle Jared. A. , Henry Gerald M. , Williams Travis , Holbrook Aaron , Cooper Tyler , Beck Leslie L. , Hephner Andrew J.
Published: February 2019

Growing concern over the sufficiency and variability of present water supplies in the arid Southwest has led to the examination of buffalograss [Buchloe dactyloides (Nutt.) Engelm.] for water conservation. Increasing acceptance of buffalograss will require investigation into conversion techniques for its establishment. The objectives of this study were to evaluate the effects of seedbed preparation and seeding rate on the establishment of buffalograss after bermudagrass desiccation with glyphosate. Research was conducted at the Texas Tech Quaker Research farm in 2009 and 2010 on a mature ‘Riviera’ common bermudagrass [Cynodon dactylon (L.) Pers.] rough. Bermudagrass was sprayed with glyphosate at 1.1 kg acid equivalent (ae)/ha 5 and 1 weeks before seedbed preparation. Plots were scalped after desiccation. Treatments were arranged in a two × four factorial, randomized complete block design with four replications. two buffalograss seeding rates and four seedbed preparation treatments. Seedbed preparation treatments consisted of no seedbed preparation, topdressing alone (0.6-cm layer), hollow-tine aerification + topdressing, or verticutting + topdressing. ‘TopGun’ buffalograss was planted on 1 June 2009 and 4 June 2010 at 146 or 195 kg·ha−1. Grid counts were conducted to determine buffalograss cover one, two, and three months after planting (MAP). Counts were then converted to percent cover (0% to 100%). Greater buffalograss cover was observed when seed was applied at the higher rate (196 kg·ha−1) except within treatments that did not receive seedbed preparation treatment. No seedbed preparation resulted in unacceptable buffalograss cover. Percent buffalograss cover three MAP was 75%, 83%, and 86% for topdressing alone, aerification + topdressing, and verticutting + topdressing treatments seeded at 195 kg·ha−1, respectively.
Individual Shoot Defoliation Minimally Affects Pecan Return Bloom
Authors: Smith Michael W. , Cheary Becky S.
Published: February 2019

Alternate bearing of pecan [Carya illinoinensis (Wangenh.) K. Koch] remains the leading problem of the industry. Several cultural practices have been developed or improved to mitigate alternate bearing. Premature defoliation was one problem identified that substantially decreased return bloom. The objective of this study was to determine the response of individual shoots exposed to various defoliation treatments. In one study, individual vegetative or bearing shoots were hand-defoliated in mid-September. Defoliation was the basal one-half, distal one-half, entire shoot, or not defoliated. Another study applied the same defoliation treatments to bearing shoots in July, August, or September. Defoliation had minimal effects on return bloom and rarely affected the percentage of current-season shoots fruiting the next year. Defoliation date also had little effect on return bloom. These data indicate that individual shoot response to defoliation was not autonomous and has implications for determining crop overload and needed mechanical fruit thinning.
A Simple and Nondestructive Technique for Estimating the Newly Grown Roots of Potted Phalaenopsis Plants
Authors: Chang Keng Heng , Chang Kuan Ting , Chung Ren Shih , Lu Chun Tang , Hsieh Ting Fang
Published: February 2019

A simple and nondestructive technique, based on the line intersect principle, was developed for estimating simultaneously more traits of the newly grown roots of potted Phalaenopsis plants. Two kinds of root distribution counting pot (RDCP) were used in the present study, namely, RDCP with a large drawing grid (RDCPL) and RDCP with a small drawing grid (RDCPS). Fifty Phalaenopsis plants were randomly sampled during the cultivation period of two to eight months after transplantation for each kind of pots. The grid number of the newly grown roots of each plant was determined by both RDCPS and RDCPL, followed by measurement of other traits such as number, fresh weight, dry weight, and length of the roots. Data were subjected to regression analyses for the selection of predictive equations. The results revealed that the grid number determined by RDCPS correlated better with the traits of the newly grown roots of potted Phalaenopsis [coefficients of determination R2 = 0.71 to 0.90; low mean squared error (MSE)] than the grid number obtained with RDCPL (R2 = 0.66 to 0.83; high MSE). Without tedious and time-consuming measurements, the four linear equations obtained with RDCPS can be a simple and nondestructive estimation for predicting the number, fresh weight, dry weight, and length of the developing roots of Phalaenopsis plants grown in pots. Another 48 Phalaenopsis plants were randomly sampled during the cultivation period of two to eight months after transplantation for the validation of selected predictive equations. The accuracy of the predictive equations of the traits of newly grown roots obtained with RDCPS was different in the following order: length > dry weight > fresh weight > number.
Narcissus Cultivar Differences in Response to Saline Irrigation When Application Began Either Pre- or Postemergence
Authors: Veatch-Blohm Maren E. , Chen Dorothy , Hassett Matthew
Published: February 2019

Salinity affects crop production worldwide and can be particularly problematic for ornamental plants. Daffodils (Narcissus sp. L.) are one of the most popular bulb plants, in demand for both landscapes and cut flowers. In this study we examined how moderate salinity, imposed as NaCl, affected growth, flower production, and leaf physiology when salinity treatment began either pre- or postemergence. Salinity did not affect growth rate or flower production for the three early-season cultivars (‘Dutch Master’, ‘Ice Follies’, and ‘Tete-a-Tete’) regardless of when salinity treatment began, but there were reductions in dry shoot biomass production under the highest salinity (50 mm NaCl). The mid-/late-season cultivar (‘Actaea’) had growth reduction and decreased flower production at the highest salinity when salinity treatment began preemergence. Within 28 days of greenhouse growth, the plants in the 50 mm NaCl treatment had carbon assimilation rates of only 25% to 32% of the 0 mm NaCl control. Sodium concentration increased 35% to 900% in the leaves in response to salinity for all cultivars when salinity treatment began preemergence but significantly increased only for ‘Actaea’ and ‘Tete-a-Tete’ (42% to 235%) when salinity treatment began postemergence. Potassium concentration in the shoot was mostly stable in response to salinity. The ability to maintain potassium (K) content within the plant may help daffodils tolerate the negative effects of sodium (Na). We believe that ‘Actaea’ was more negatively affected by salinity than the other three cultivars because, as a mid-/late-season cultivar, it had a much longer exposure period to salinity than the three early-season cultivars. However, moderate salinity does not seem to have a significant impact on growth and visual quality for ‘Dutch Master’, ‘Ice Follies’, or ‘Tete-a-Tete’ indicating that at least some saline water can be used for plant production without losses in plant quality.
Factors Affecting Seed Germination of Ilex latifolia and I. rotunda
Authors: Tezuka Takahiro , Yokoyama Hisa , Tanaka Hideyuki , Shiozaki Shuji , Oda Masayuki
Published: February 2019

Mature seeds of Ilex species usually contain immature embryos and are extremely difficult to germinate. Ilex latifolia and I. rotunda, two species that are grown as ornamentals, also produce seeds that are difficult to germinate. In the present study, we investigated some factors affecting seed germination in those species. Although seeds of I. latifolia and I. rotunda could imbibe water, they did not germinate. When embryos were cultured in vitro, germination was observed in I. latifolia but not in I. rotunda. Interestingly, a transient decrease in germination frequency occurred in I. latifolia embryos isolated from seeds collected in September or October. Among five types of I. latifolia seeds that differed in the presence of the endocarp, testa, and endosperm, germinability of isolated embryos was highest. Good germination was also observed in quarter-seeds with or without endocarp followed by half-seeds. Treatment of seeds with sodium hydroxide (NaOH) had no effect on seed germination in I. latifolia. Cold stratification at 5 °C increased the germination frequency of I. latifolia embryos. In conclusion, the data suggested a mechanical barrier by the endocarp and inhibitors contained in the endosperm, testa, and/or endocarp inhibited seed germination in I. latifolia. Although no seeds or embryos of I. rotunda germinated, cold stratification in combination with other treatments deserves further investigation. Chemical name: sodium hydroxide (NaOH).
Pecan Response to Nitrogen Fertilizer Placement
Authors: Wells M. Lenny
Published: February 2019

Application method and placement can improve the efficiency of applied nitrogen (N) per unit of yield, potentially minimizing N loss and increasing the profit margin for pecan producers. The following treatments were evaluated for their effect on pecan leaf N concentration, pecan yield, nut quality, agronomic N use efficiency (AEN), and alternate bearing intensity (I); 1) emitter-adjacent application of liquid urea ammonium nitrate (UAN) (28N–0P–0K) with 5% sulfur (S); 2) broadcast application of dry ammonium nitrate (34N–0P–0K); 3) broadcast-band application of dry ammonium nitrate; 4) broadcast ground-spray application of liquid UAN; and 5) untreated control (2009–12). Leaf elemental tissue analysis, pecan yield, quality, and alternate bearing intensity indicate that pecans can be effectively fertilized with N using any of the application methods used in the current study. Based on AEN, it appears that pecans can be effectively fertilized at a lower field rate of N than is currently recommended and that the volume of fertilizer applied to pecan orchards can be significantly reduced by minimizing the area in the orchard to which N fertilizer is applied and eliminating excessive applications to vegetated row middles, which apparently offer little additional benefit to pecan leaf N, pecan quality, or yield.