bluuebunny/crossref_metadata_2025 huggingface dataset:
Seed Germination and Seedling Growth of the Endangered Azorean Cherry Prunus azorica
Authors: Barros Moreira Orlanda Cristina , Martins José , Silva Luís , Moura Mónica
Published: February 2019

Prunus azorica is an Azorean endemic tree considered as a priority species for conservation. It is important as a laurel forest component, particularly at medium altitude, and as a food source for the endangered bird Pyrrhula murina. The best conditions for seed germination were investigated after removal of the outer layers of the fruit by determining the effect of 1) using stones or seeds; 2) stratification regime (six treatments and a control); 3) incubation temperature (four alternating temperature regimes); and 4) gibberellic acid concentration (three levels). This resulted in a fully factorial design with 168 (2 × 7 × 4 × 3) treatments with three replicates per treatment and 25 seeds per replicate. Cumulative germination percentages were determined at the end of the trial. Globally, there was a significant effect of endocarp removal (49% germination with seeds and 15% with stones). Both for stones and seeds, there was a significant effect of incubation temperature, stratification regime, and growth regulator concentration. Stones attained a maximum germination of ≈80% under several stratification treatments including cold (4 °C) or warm (20 °C) followed by cold and at 10/5 °C without the addition of a growth regulator. Seeds attained a maximum germination of greater than 90% without stratification at 10/5 or 15/10 °C without the addition of a growth regulator. During the stratification process, germination occurred only for seeds, particularly for longer treatments, for example, those corresponding to 3 or more months of stratification, including warm followed by cold (75% to 80%) or cold alone (77%). According to seed morphology and germination results, the seed appears to have a non-deep physiological dormancy. Seeds of P. azorica can thus be efficiently germinated after endocarp removal at temperatures of 10/5 or 15/10 °C with a daily light period of 12 hours. This protocol allowed producing hundreds of viable seedlings that were used in the reforestation of a laurel forest stand in a LIFE project.
Resistance to Marssonina coronaria and Alternaria alternata Apple Pathotype in the Major Apple Cultivars and Rootstocks Used in China
Authors: Li Yan , Hirst Peter M. , Wan Yizhen , Liu Yingjiao , Zhou Qian , Gao Hua , Guo Yunzhong , Zhao Zhengyang , Wang Leicun , Han Mingyu
Published: February 2019

A comparison of field tolerance of 25 apple (Malus ×domestica) cultivars and 39 apple rootstocks to the pathogens Marssonina coronaria and Alternaria alternata apple pathotype was performed. Although most apple cultivars grown in China were susceptible or highly susceptible to both pathogens causing two diseases, considerable variation in the level of resistance to both pathogens was observed. Only three cultivars, Qinguan, Jiguan, and Xiangyanghong, exhibited resistance to both pathogens. Among the rootstocks tested, 30 of 39 (77%) were susceptible or highly susceptible to M. coronaria and 32 (82%) were susceptible to the A. alternata apple pathotype. Four rootstocks, ‘P.22’, ‘SH12’, ‘Za’ai 76’, and ‘Qingdao598’, were resistant to both pathogens. The correlation between resistance to both pathogens was highly significant in the 74 apple cultivars and rootstocks tested suggesting common genetic resistance factors to these two pathogens. Data represented horizontal resistance in the germplasm. The resistant local germplasm should be used in disease resistance breeding programs.
Susceptibility of Zoysiagrass Germplasm to Large Patch Caused by Rhizoctonia solani
Authors: Obasa Ken , Fry Jack , Kennelly Megan
Published: February 2019

Fourteen new zoysiagrass (Zoysia spp.) germplasm lines from parental crosses including Z. japonica (Steud.), Z. matrella (L.) Merr., and Z. pacifica (Goudswaard) were evaluated for susceptibility to large patch caused by the fungus Rhizoctonia solani Kühn anastomosis group (AG) 2-2 LP. The germplasm lines were compared with ‘Meyer’ (Zoysia japonica Steud.), the most widely used cultivar in the transition zone of the United States, under growth chamber and field conditions. Large patch susceptibility in the growth chamber study was estimated five days post-inoculation and thereafter for 25 days. Three pots of each line and ‘Meyer’ were randomly selected and rated for disease incidence by determining the percentage of individual shoots in each pot with distinct, water-soaked brown lesions on the leaf sheath. Field assessment of large patch susceptibility was carried out weekly and was by direct measurement of patch sizes as well as by digital image analysis of plots for the percentage of diseased turf. All 14 progeny had similar disease levels compared with ‘Meyer’ in the growth chamber, but only six consistently had disease levels as low as ‘Meyer’ in the field. Growth chamber results did not correlate to field results.
Determining the Flowering Requirements of Two Aquilegia Cultivars
Authors: Whitman Catherine M. , Runkle Erik S.
Published: February 2019

Flowering of the herbaceous perennial Aquilegia is generally considered to require vernalization after seedlings are mature, whereas photoperiod has little or no effect. We performed experiments to determine the flowering responses for two Aquilegia ×hybrida varieties, one of which reportedly has reduced cold requirements. Seedlings of Aquilegia ‘Origami Blue and White’ and ‘Winky Double Red and White’ with three to five leaves were either placed directly into a 5 °C cooler with low-intensity lighting for 9 hours/day or transplanted to 13-cm containers and grown (bulked) for 0, 3, or 6 weeks at 20 °C under 9-hour short days (SDs) or 16-h long days (LDs). Plants were then cooled at 5 °C for 0, 5, or 10 weeks and placed in a common forcing environment at 20 °C under LDs. Flowering response of the two cultivars differed markedly. All Aquilegia ‘Origami Blue and White’ plants placed directly into the forcing environment flowered and in a mean of 93 days. Flowering percentage of plants cooled in the plug tray decreased with increasing duration of cold treatment, and only 15% flowered after a 10-week cold treatment. All plants bulked for 3 or 6 weeks before cold treatment flowered after 25 to 36 days in the forcing environment. Adding bulking and forcing time together, time to flowering of ‘Origami Blue and White’ was complete and most rapid (62 days) when plants were bulked for 3 weeks under SDs and then forced under LDs. In contrast, no ‘Winky Double Red and White’ plants flowered without cold treatment, and 6 weeks of bulking followed by 10 weeks of cold was required for 100% flowering. These results indicate that ‘Origami Blue and White’ has a relatively short juvenile phase and flowering was promoted by SD bulking or cold treatment, whereas ‘Winky Double Red and White’ has a longer juvenile phase and requires cold for flowering.
Influence of Humidity and Temperature on Postharvest Needle Abscission in Balsam Fir in the Presence and Absence of Exogenous Ethylene
Authors: MacDonald Mason T. , Lada Rajasekaran R. , Dorais Martine , Pepin Steeve
Published: February 2019

Ethylene accumulation increases after harvest and culminates in needle abscission in balsam fir [Abies balsamea (L.) Mill.]. We hypothesize that water deficit induces ethylene evolution, thus triggering abscission. The purpose of this research was to investigate the role of temperature and humidity on postharvest needle abscission in the presence and absence of exogenous ethylene and link vapor pressure deficit (VPD) to postharvest needle abscission in balsam fir. In the first experiment, branches were exposed to 30%, 60%, or 90% humidity while maintained at 19.7 °C (VPD of 1.59, 0.91, or 0.23 kPa, respectively); in the second experiment, branches were exposed to 5, 15, or 25 °C (VPD of 0.35, 0.68, or 1.26 kPa, respectively) while maintained at 60% relative humidity. Needle retention duration, average water use, xylem pressure potential relative water content, and ethylene evolution were response variables. Reducing water loss or xylem tension by changing temperature or humidity effectively delayed needle abscission, although the 90% humidity treatment had the most profound effects. In the absence of exogenous ethylene, branches placed in 90% humidity had a fivefold increase in needle retention, 67% decrease in average water use, and had a final xylem pressure potential of –0.09 MPa. There was a near perfect relationship between VPD and needle retention (R2 = 0.99). These findings suggest that increasing xylem tension or decreasing water status may trigger ethylene synthesis and needle abscission. In addition, these findings demonstrate an effective means of controlling postharvest needle abscission by modifying temperature and/or relative humidity.
Conventional and In Vitro Propagation of Lechenaultia macrantha (Goodeniaceae)
Authors: Png Guochen K. , Downes Katherine S. , Tan Beng H.
Published: February 2019

Lechenaultia macrantha K. Krause (Goodeniaceae) is a species with great horticultural potential that is endemic to the sandy and gravelly soils of central, southwestern Australia. The effectiveness of several conventional and in vitro propagation techniques were assessed. Seeds possessed non-deep physiological dormancy, and a combination of seed nicking and imbibition in 10% (v/v) smoke water for 24 hours resulted in 81% germination after 33 days of incubation. Softwood stem cuttings produced adventitious roots readily without the need for exogenous auxin application. In vitro microcuttings produced shoots in response to cytokinins. However, optimal or suboptimal cytokinin concentrations resulted in hyperhydric shoots, which poses an obstacle to successful micropropagation. The use of auxin was necessary for the initiation of adventitious roots in vitro. This information will assist in the horticultural development of this species.
The ASHS Outstanding Fruit Cultivar Award: A 25-year Retrospective
Authors: Volk Gayle M. , Olmstead James W. , Finn Chad E. , Janick Jules
Published: February 2019

The Outstanding Fruit Cultivar Award is a medal presented annually by the Fruit Breeding Working Group of the American Society for Horticultural Science (ASHS) for noteworthy new fruits released over the previous 35 years. Since 1987, 38 cultivars have been recognized with medals presented at the Annual Conference of the Society. The awards celebrate the progress achieved by fruit breeders and their contributions to the world’s fruit industry.
Evaluation of Response to Pecan Scab Pathogen Race Using a Detached Leaflet Protocol
Authors: Conner Patrick J.
Published: February 2019

A detached leaflet protocol was developed for the evaluation of resistance to Fusicladium effusum in a seedling pecan population segregating for resistance. Leaflets at half to full expansion were detached from seedling trees, sprayed with a conidial suspension (isolate De-Tif-3), placed in a polyethylene bag in a growth chamber, and evaluated microscopically 7 and 14 days after inoculation. The percentage germinated conidia producing subcuticular hyphae was the best determinant of susceptibility with genotypes producing more than 15% subcuticular hyphae considered susceptible. Leaflets at half expansion had higher percentages of subcuticular hyphae and gave a clearer separation between susceptible and resistant genotypes than leaflets at full expansion. An evaluation period of 14 days was preferable to 7 days to allow slower reacting genotypes to be better evaluated. The detached leaflet protocol was evaluated in contrasting environments and was found to be robust to differences in shading and leaflet wetness. Detached leaflet tests gave similar results to field inoculations but were superior in consistently detecting susceptible genotypes. This protocol will be useful in evaluating the inheritance of pecan leaf scab resistance in breeding progenies.
Influence of Prohexadione Calcium on Sweetpotato Growth and Storage Root Yield
Authors: Njiti Victor N. , Xia Qun , Tyler Leonna S. , Stewart Lakeisha D. , Tenner Antione T. , Zhang Chunquan , Alipoe Dovi , Chukwuma Franklin , Gao Ming
Published: February 2019

Excessive vine growth in sweetpotato has been associated with lower storage root yield. Prohexadione–calcium (Pro-Ca), a plant growth retardant, has been used to reduce vegetative growth and increase harvest efficiency and yield in many fruit and row crops. The influence of Pro-Ca on sweetpotato (Ipomoea batatas Lam.) vegetative growth and storage root yield was evaluated in this study. In 2010 and 2011, the sweetpotato cvs. Beauregard, Porto Rico, O’ Henry, and SC1149-19 were sprayed with 0 and 810 mg a.i./L Pro-Ca in a split plot randomized complete block. Each plot received two sprays, the first at 2 weeks after transplanting and the second at 6 weeks after transplanting. When averaged across cultivars, Pro-Ca significantly (P ≤ 0.05) reduced vine length and vine yield and increased total root yield compared with the control. There was no significant Pro-Ca × cultivar interaction on any trait. Total biomass was not significantly (P ≤ 0.05) different between Pro-Ca-treated and control plants. However, the treated plants had more total root yield, whereas the control plants had more vine yield, suggesting that Pro-Ca treatment affected the distribution of assimilates. Data from this study suggested that it may be possible to use Pro-Ca to manipulate the source-sink relationship for higher storage root yield in sweetpotato.
Preharvest Foliar Applications of Ethephon Increase Skin Lignin/Suberin Content and Resistance to Skinning in Sweetpotato Storage Roots
Authors: Wang Xiang , Arancibia Ramón A. , Main Jeffrey L. , Shankle Mark W. , LaBonte Don R.
Published: February 2019

Skinning or surface abrasion in sweetpotato [Ipomoea batatas (L.) Lam.] roots during harvest causes a substantial loss of marketable products in storage as a result of rots, loss of moisture, and simply unattractive marketable appearance. In 2008, 2010, and 2011, changes in skinning incidence/severity and skin lignin/suberin content in response to preharvest foliar applications of ethephon or defoliation/devining were investigated. Field-grown ‘Beauregard’ (B-14) sweetpotato plots were treated with ethephon at 0.84, 1.68, and 2.52 kg·ha−1 (based on the recommendations for tobacco) applied at 1, 3, and 7 days before harvest (DBH). Defoliated/devined treatments were applied at 0, 1, 3, and 7 DBH. Skinning incidence and severity were reduced with ethephon when applied 3 and 7 DBH in 2 of 3 years compared with 1 DBH. The force required to skin the storage root was measured at harvest in 2011 and it increased with defoliation/devining and ethephon applications at 3 and 7 DBH. Skin lignin/suberin was higher in roots from ethephon-treated plants but was weakly correlated (r = 0.51) with the force required to peel the skin. Ethephon applications also increased cortex phenolic content and either decreased or maintained skin phenolic content in storage roots compared with defoliated/devined treatments. These results suggest that skin set and/or skinning resistance in sweetpotato appears to be influenced by other factors in addition to skin lignification/suberization.
Carbon Dioxide Enrichment during Photoautotrophic Micropropagation of Protea cynaroides L. Plantlets Improves In Vitro Growth, Net Photosynthetic Rate, and Acclimatization
Authors: Wu How-Chiun , Lin Chun-Chih
Published: February 2019

The effects of CO2 enrichment on the in vitro growth and acclimatization of Protea cynaroides L. plantlets were investigated. Three CO2 enrichment concentrations were used: 0 (control), 1000, 5000, and 10000 μmol·mol−1. Plantlets in the control treatment were cultured on half-strength Murashige and Skoog (MS) medium supplemented with sucrose, whereas those enriched with different CO2 concentrations were grown on sucrose-free MS medium. Compared with the control, significant improvements were observed in the growth of plantlets enriched with CO2 irrespective of the concentration. Plantlets enriched with 5000 μmol·mol−1 CO2 produced the highest number of leaves and the largest leaf area. In addition, the photosynthetic ability of plantlets enriched with CO2 was enhanced, which resulted in significant increases in shoot growth and dry matter accumulation. In particular, the shoot dry weight of plantlets cultured in 5000 μmol·mol−1 CO2 and 10000 μmol·mol−1 CO2 were, respectively, 2.1 and 4.2 times higher than those without CO2 enrichment. During acclimatization, the survival percentage, rooting percentage, and leaf number of plantlets grown in elevated CO2 were, respectively, up to 4.5, 1.8, and 2.7 times higher than plantlets without CO2 enrichment. The improvements in survival percentage and ex vitro growth of these plantlets were the result of their enhanced photosynthetic ability in vitro, which resulted in the production of high-quality plantlets. Significant improvements in the overall growth of P. cynaroides plantlets were achieved through the use of photoautotrophic micropropagation with CO2 enrichment.
Ammonium in Nutrient Solutions Decreases Free Chlorine Concentration from Sodium Hypochlorite
Authors: Meador Dustin P. , Fisher Paul R.
Published: February 2019

The objective was to quantify the effect of water-soluble fertilizers on concentration of free chlorine level in a sodium hypochlorite solution. Research on the disinfestation strength and phytotoxicity risk of chlorine compounds is needed, because control of waterborne pathogens has been based on response to free chlorine, whereas dual injection of fertilizer and chlorine is a common horticultural practice. Free chlorine from sodium hypochlorite was applied at 2.6 mg·L−1 chlorine (Cl) to deionized water only (control) or deionized water with 11 nutrient solutions at 200 mg·L−1 nitrogen (N). Nutrient solutions included reagent-grade ammonium sulfate (NH4)2SO4, ammonium nitrate (NH4NO3), potassium nitrate (KNO3), and urea salts and seven commercial blended N–P–K water-soluble fertilizers that contained both macro- and micronutrients. Commercial fertilizers contained ammonium-N at 0% to 50% of total-N, urea-N at 0% to 14% of total-N, and nitrate-N at 50% to 93% of total-N. Free Cl (mg·L−1), total Cl (mg·L−1), and oxidation-reduction potential (ORP, in mV) were measured 2 min and 60 min after Cl was applied. Combined Cl was calculated as the difference between the total and free Cl measurements. All solutions were maintained at pH 6 and 25 °C. In the control solution, free Cl was 2.6 mg·L−1 after 2 minutes and decreased to 2.2 mg·L−1 after 60 minutes. The ammonium-containing solutions (NH4)2SO4 and NH4NO3 resulted in free Cl below 0.1 mg·L−1 after 2 minutes. Urea reacted more slowly than ammonium salts, whereby free Cl decreased to 2.3 mg·L−1 after 2 minutes and 0.4 mg·L−1 after 60 minutes. In contrast, KNO3 had less impact on free Cl with 2.4 mg·L−1 free Cl available at both 2 minutes and 60 minutes. With all commercial fertilizers tested, free Cl decreased after 2 minutes to below 0.1 mg·L−1. Total Cl remained above 2 mg·L−1 after 60 minutes in all treatments, indicating that the majority of Cl was in a combined form for ammonium and urea salts and commercial fertilizers. The ORP of commercial fertilizer blends and ammonium-containing salts was lower than 600 mV, whereas deionized water, KNO3, and urea treatments had ORP levels above 650 mV. Nutrient solutions containing ammonium or urea required 20 mg·L−1 or more of applied Cl to provide residual free Cl above 2 mg·L−1 at 2 minutes.
Water Relations of Well-watered Citrus Exposed to Cold-acclimating Temperatures
Authors: Barkataky Smita , Ebel Robert C. , Morgan Kelly T. , Dansereau Keri
Published: February 2019

This study was conducted on well-watered citrus to determine changes in water relations during cold acclimation independent of drought stress. Potted sweet orange and Satsuma mandarin trees were exposed to progressively lower, non-freezing temperatures down to 10/4 °C, light/dark temperatures, respectively, for 9 weeks in environmental growth chambers to promote cold acclimation. The trees were watered twice daily and three times on the day water relations data were collected to minimize drought stress. Although soil moisture was higher and non-limiting for plants in the cold than in the warm chamber, cold temperatures promoted stomatal closure, higher root resistance, lower stem water potential (Ψstem), lower transpiration, and lower leaf ψS. Leaf relative water content (RWC) was not different for cold-acclimated trees compared with the controls. Cold acclimation promoted stomatal closure at levels only observed in severely drought-stressed plants exposed to warm temperatures and where Ψstem and RWC are typically much lower than what was found in this study. Ψstem continued to decline the last 4 weeks of the experiment although air temperature, leaf ψS, RWC, stomatal conductance (gS), and transpiration were constant. The results of this experiment indicate that water relations of citrus during cold acclimation vary from those known to occur as a result of drought stress, which have implications for using traditional measures of plant water status in irrigation scheduling during winter.
Khakiweed (Alternanthera pungens Kunth) Growth Response to Mowing Height and Frequency
Authors: Hephner Andrew J. , Cooper Tyler , Beck Leslie L. , Henry Gerald M.
Published: February 2019

The effect of mowing regimens on lateral spread of khakiweed (Alternanthera pungens Kunth) was determined through field studies conducted over a 3-month period in Texas during 2009 and 2010. Treatments were selected to simulate mowing regimens common to intensively managed common bermudagrass [Cynodon dactylon (L.) Pers.] turf and included heights of 1.3 cm (three times/wk), 2.5 cm (two times/week), and 5.1 cm (two times/week). A non-mowed control was included for comparison. Differences in lateral spread of khakiweed among mowing regimens were apparent 4 weeks after initial treatment (WAIT). However, plant diameter increased for all mowing regimens over the course of the trial. Khakiweed plants subjected to the 1.3-cm mowing regimen did not increase in diameter from Week 2 through Week 12, whereas the other two mowing regimens exhibited steady increases in plant diameter over the same time period. By 12 WAIT, non-mowed control plots measured 80.8 cm in diameter, whereas those maintained at 1.3 cm measured 55.3 cm. Comparatively, plants subjected to the 2.5- and 5.1-cm mowing regimens measured 64.7 and 68.8 cm, respectively. Therefore, khakiweed infestations may be more prevalent in bermudagrass mowing heights commonly used for golf course roughs, athletic fields, and home lawns (2.5 cm or greater). However, the production of a thick taproot high in carbohydrate content may enable khakiweed to regenerate from frequent defoliation common to fairway mowing regimes (2.5 cm or less). Adjustments in mowing height may not be enough to effectively reduce khakiweed populations in bermudagrass turf.
Essential Oil Composition and Yield of Anise from Different Distillation Times
Authors: Zheljazkov Valtcho D. , Astatkie Tess , O'Brocki Barry , Jeliazkova Ekaterina
Published: February 2019

Anise (Pimpinella anisum L.) is a spice, an essential oil crop, and a medicinal plant with a long history of use. Anise seed oil is extracted from anise seed through steam distillation. There is no experimentally established optimal time for distillation of anise seed. We hypothesized that the distillation time (DT) can be customized for optimum yield and composition of anise essential oil. In this study, we determined the effect of nine steam DTs (5, 15, 30, 60, 120, 180, 240, 360, and 480 minutes) on essential oil yield and essential oil composition of anise seed. We developed regression models to predict essential oil yield, the concentration of individual constituents, and the yield of these constituents as a function of DT. Highest essential oil yield (2.0 g/100 g seed, 2%) was obtained at 360-minute DT. The concentration of transanethole, the major anise oil constituent, varied from 93.5% to 96.2% (as a percent of the total oil) and generally was high at 15- to 60-minute DT and low at 240- to 480-minute DT. However, the yield of transanethole (calculated from the essential oil yield and the concentration of transanethole in the oil) increased with increasing DT to reach maximum at 360-minute DT. The concentration of the other oil constituents varied significantly depending on the DT, and some of them were higher at the shorter DT than at the longer DT. However, the yields of these constituents were highest at longer DT (either 360 or 480 minutes). DT can be used to obtain anise essential oil with different composition that would benefit the essential oil industry. This study demonstrated the need for providing DT in reports where anise seed essential oil yield and composition are discussed. This article can also be used as a reference point for comparing studies in which different DTs were used to extract essential oil from anise seed.
Resistance of Vitis Germplasm to Elsinoë ampelina (de Bary) Shear Evaluated by Lesion Number and Diameter
Authors: Kono Atsushi , Sato Akihiko , Ban Yusuke , Mitani Nobuhito
Published: February 2019

We evaluated the resistance of 133 grapevine cultivars or selections, including Vitis vinifera and American hybrids, on the basis of lesion number and length to identify sources of resistance to grapevine anthracnose. All germplasms tested in this study showed anthracnose symptoms to some extent, and the distribution of lesion number and diameter was continuous. Most table grape V. vinifera cultivars were highly susceptible, showing many large lesions. However, V. vinifera wine grapes were more resistant with smaller lesions. Some American hybrid grapes such as ‘Ontario’ showed very few and small lesions. There was a significant positive correlation between lesion number and size in American (r = 0.63, P = 0.0041) and Japanese hybrids (r = 0.56, P < 0.001), whereas there was no correlation between these characters in V. vinifera. Japanese tetraploid cultivars were neither highly susceptible nor resistant. High anthracnose susceptibility of most well-known table grape V. vinifera cultivars, including ‘Muscat of Alexandria’, ‘Italia’, ‘Rizamat’, ‘Kattakurgan’, and ‘Thompson Seedless’, indicates that resistance should be introgressed from other cultivars such as American hybrids or wine grapes when these susceptible table grapes or their descendants are used in breeding anthracnose-resistant table grapes.
Drip-irrigated Pecan Seedlings Response to Irrigation Water Salinity
Authors: Deb Sanjit K. , Sharma Parmodh , Shukla Manoj K. , Sammis Theodore W. , Ashigh Jamshid
Published: February 2019

Salinity responses and salinity-related suppression of budbreak of drip-irrigated pecan [Carya illinoinensis (Wangenh.) K. Koch] seedlings under different irrigation water salinity (ECIRR) levels were investigated in the pot-in-pot system. The 1-year-old pecan seedlings of rootstock ‘Riverside’ grafted with ‘Western Schley’ scions were transplanted in pots filled with sandy loam soil and grown for 2 years under the same amount of irrigation water but four irrigation ECIRR treatment levels consisting of 1.4 dS·m−1 (control), and three qualities of irrigation water obtained by using a solution of calcium chloride (CaCl2) and sodium chloride (NaCl) in a ratio of 2:1 (by weight) to reach the ECIRR levels of 3.5, 5.5, and 7.5 dS·m−1, respectively. The leachate electrical conductivity (ECd) was highly correlated with soil salinity (EC1:1) and was significantly higher when the irrigation ECIRR treatment levels increased from 1.4 (control) to 7.5 dS·m−1. However, both ECd and EC1:1 remained nearly constant within the same irrigation ECIRR treatment level during both years. Increasing salinity in irrigation water, particularly the ECIRR levels of 5.5 and 7.5 dS·m−1, showed significantly low seedling height and stem diameter growth and delayed or even inhibited budbreak in the seedlings. The EC1:1 that inhibited seedling heights, stem diameters, and budbreak was somewhere between 0.89 and 2.71 dS·m−1 (or ECIRR between 1.4 and 3.5 dS·m−1 and ECd between 2.10 and 4.86 dS·m−1), providing that soil water content was not a limiting factor in the root zone and irrigation water was uniformly distributed in the confined root zone to obtain uniform salt leaching. The visual symptoms of leaf scorch for irrigation ECIRR levels of 3.5, 5.5, and 7.5 dS·m−1 also indicated that somewhere between 0.89 and 2.71 dS·m−1 of the EC1:1, salt injury started to occur. Increasing salinity in irrigation water significantly increased chloride (Cl–) accumulation but reduced nitrogen (N) content in the scorched leaves, particularly under the irrigation ECIRR levels of 5.5 and 7.5 dS·m−1. Leaf scorch symptoms in pecan seedlings were likely associated with Cl– toxicity. No pecan seedlings under the irrigation ECIRR treatment levels of 5.5 and 7.5 dS·m−1 survived to the end of the 2-year growing period. Thus, threshold EC1:1 was somewhere between 0.89 and 2.71 dS·m−1 beyond which plant injury increases with increasing EC1:1 threatening the survival of pecan seedlings.
White Clover (Trifolium repens) Establishment within Dormant Bermudagrass Turf: Cultural Considerations, Establishment Timing, Seeding Rate, and Cool-season Companion Grass Species
Authors: McCurdy James D. , McElroy J. Scott , Guertal Elizabeth A.
Published: February 2019

White clover (Trifolium repens L.) inclusion is a proposed means of increasing the sustainability of certain low-maintenance turfgrass scenarios through increased pollinator habitat and as a result of the legume’s ability to biologically fix atmospheric nitrogen (N). Proper white clover establishment is key to maximizing stand uniformity and N contribution to associated grasses. However, there are few guidelines for white clover establishment within warm-season turfgrasses. Four studies were conducted to evaluate seeded white clover establishment within a dormant hybrid bermudagrass [Cynodon transvaalensis Burtt-Davy × C. dactylon (L.) Pers.] lawn as affected by 1) pre-seeding mechanical surface disruption; 2) establishment timing; 3) seeding rate; and 4) companion grass species. White clover establishment was improved by scalping before October seeding, but these effects were not further enhanced by the addition of verticutting or hollow tine aerification. Unscalped turfgrass yielded nearly 50% lower white clover densities than those scalped before seeding, possibly as a result of decreased seed-to-soil contact and increased bermudagrass competition. January and February establishment dates generally yielded the lowest spring clover densities, whereas October timing yielded superior establishment. Clover densities resulting from six seeding rates (0, 0.4, 0.8, 1.5, 3.0, and 6.0 g live seed/m2) were fit to the linear model (y = y0 + axb, where y equals trifoliate leaves/m2 and x is equal to initial seeding rate). An important feature of this model was that it accurately represented the diminishing response of increasing seeding rate. Clover establishment was negatively correlated with companion grass densities with the largest densities occurring when planted with tall fescue and the smallest when planted with annual ryegrass. Ultimately, scalping alone or in combination with other mechanical surface disruption should be paired with a clover variety acceptable to the height of cut and the environmental conditions of individual scenarios. Likewise, seeding rates and the decision to include a cool-season companion grass species will be dependent on the use of a turf and the desired green cover.
Fertility and Other Characteristics of F1 and Backcross1 Progeny from an Intersectional Blueberry Cross [(highbush cultivar × Vaccinium arboreum) × highbush cultivar]
Authors: Lyrene Paul M.
Published: February 2019

Fertility and morphological traits were studied in the F1 and BC1 generations of intersectional crosses between tetraploid highbush blueberry cultivars (Vaccinium section Cyanococcus) and colchicine-induced tetraploid V. arboreum (Vaccinium section Batodendron). The goal of the introgression project was to combine desirable plant characteristics from V. arboreum with the large fruit and high fruit quality of highbush cultivars. Highbush × V. arboreum crosses were hard to make, but large numbers of BC1 seedlings were easily obtained using the most fertile F1 plants as parents in backcrosses to highbush. Anther awns, a character from V. arboreum, were present in all F1 seedlings, but fruit sclerids, another V. arboreum trait, were absent in most seedlings. Berry size in the BC1 generation was twice as large as in the F1 generation and was twice as large in the F1 as in V. arboreum. The BC1 generation was extremely variable in vigor and berry quality. Although berries of most BC1 plants were smaller, darker, and less desirable in texture and flavor than highbush berries, the high fertility of BC1 plants and the high variability among plants indicate that useful clones could be selected or developed by further breeding.
The Role of Soluble Sugars in Vase Solutions during the Vase Life of Eustoma grandiflorum
Authors: Chuang Ya-Ching , Alex Chang Yao-Chien
Published: February 2019

The vase life of Eustoma cut flowers can be extended by adding sugars to the vase solution, but the exact role of sugars and how they are translocated in tissues are not clear. Thus, we observed the preserving effect of different sugars in vase solutions on Eustoma and compared sugar concentrations in vase solutions and in the flowers as well as stems and leaves of cut flowers in a solution containing 200 mg·L−1 8-hydroxyquinoline sulfate (8-HQS) with and without 20 g·L−1 sucrose during different flowering stages. Inclusion of glucose, fructose, or sucrose in the vase solution extended the vase life of cut flowers with no significant differences among sugar types. During flower opening, the concentration of added sucrose in the vase solution dropped, and the fresh weight (FW), glucose concentration, and sucrose concentration of flowers in sucrose solutions increased, whereas flowers in solutions without sucrose had lower FW and glucose concentrations. During flower senescence, sugar concentration in the vase solution did not change much, but the FW and sucrose concentrations in all flowers declined, although the FW of sucrose-treated flowers fell more slowly. For stems and leaves in the sucrose solution, sugar concentrations increased during the first 7 days with only glucose slightly declining during senescence, whereas the FW was maintained during the entire vase life. In contrast, FWs of those in the solution without sucrose gradually declined. In conclusion, sucrose in the vase solution promoted flower opening and maintained the water balance of Eustoma cut flowers. Glucose and fructose also extended the vase life, likely in similar ways.
Effects of Rapid Consecutive Postharvest 1-Methylcyclopropene Treatments on Fruit Quality and Storage Disorders in Apples
Authors: DeEll Jennifer , Ehsani-Moghaddam Behrouz
Published: February 2019

The objective of this study was to investigate the effects of rapid consecutive 1-methylcyclopropene (1-MCP) treatments on apple quality and disorders in storage. ‘McIntosh’ and ‘Spartan’ apples were harvested twice from commercial orchards and 1-MCP (1 μL·L−1) was applied postharvest either 1 day after harvest or 1 and 2 days after harvest. Similar fruit from both cultivars were also not treated with 1-MCP, plus an additional treatment of 2 μL·L−1 (double rate) 1-MCP was used on ‘McIntosh’. Fruit were held in either air storage at 0.5 °C for three or six months or in controlled-atmosphere (CA) storage for six or nine months. Overall, 1-MCP treatment improved firmness and acidity retention and reduced internal ethylene in both cultivars. However, ‘Spartan’ stored in CA often maintained these attributes without 1-MCP. ‘McIntosh’ apples treated twice with 1-MCP were often firmer than those treated just once. All 1-MCP treatments substantially reduced superficial scald and there was no difference in scald incidence among the treatments. Core browning was generally reduced by 1-MCP, but fruit treated once with 2 μL·L−1 or twice with 1 μL·L−1 1-MCP sometimes had higher incidence than fruit treated only once with 1 μL·L−1. ‘Spartan’ treated twice with 1-MCP also had higher incidence of internal browning after nine months. 1-MCP increased the incidence of external CO2 injury in ‘McIntosh’ from the first harvest, with fruit treated with 2 μL·L−1 having the highest incidence after six months of CA storage and those treated once with 1 μL·L−1 having the highest incidence after nine months. Storage rots were greatest after six months of air storage and 1-MCP treatments usually reduced the incidence, regardless of treatment. These results suggest that using more than the traditional single application of 1 μL·L−1 1-MCP may improve firmness retention, but there is also some risk associated with increased disorders, especially when storing apples long-term, such as for six months in air or nine months in CA storage.
Fruit Texture Phenotypes of the RosBREED U.S. Apple Reference Germplasm Set
Authors: Schmitz Cari A. , Clark Matthew D. , Luby James J. , Bradeen James M. , Guan Yingzhu , Evans Katherine , Orcheski Benjamin , Brown Susan , Verma Sujeet , Peace Cameron
Published: February 2019

Establishing marker-locus-trait associations to enable marker-assisted breeding depends on having an extensive, reliable database for phenotypic traits of interest in relevant germplasm. A reference germplasm set of 467 apple (Malus ×domestica Borkh.) cultivars, selections, and seedlings (referred to as individuals) was identified as part of the USDA-Specialty Crop Research Initiative (SCRI) project, RosBREED. The germplasm set provides efficient allelic representation of current parents in RosBREED demonstration apple breeding programs at Cornell University, Washington State University, and the University of Minnesota. Phenotyping at the three locations was conducted according to standardized protocols, focusing on fruit traits evaluated at harvest and after 10 and 20 weeks of refrigerated storage. Phenotypic data were collected for the sensory texture traits of firmness, crispness, and juiciness as well as for instrumental texture measures. In 2010 and 2011, fruit from 216 and 330 individuals, respectively, were harvested and a total of 369 individuals were evaluated over the two years. Correlations between sensory and instrumental texture measures were high in some instances. Moderate year-to-year repeatability of trait values was observed. Because each location had a largely unique set of individuals, as well as differing environmental conditions, means, ranges, and phenotypic variances differed greatly among locations for some traits. Loss of firmness and crispness during storage was more readily detected instrumentally than by the sensory evaluation.
Elevated Relative Humidity Increases the Incidence of Distorted Growth and Boron Deficiency in Bedding Plant Plugs
Authors: Krug Brian A. , Whipker Brian E. , McCall Ingram , Frantz Jonathan
Published: February 2019

High relative humidity (RH) can cause lower concentrations of boron (B) accumulating in plants. The common greenhouse practice of controlling excess temperatures by applying mist irrigation to young plants (plugs) can result in elevated RH levels, especially with plugs grown in high heat and humidity conditions of summer. ‘Dynamite Yellow’ pansy (Viola ×wittrockiana Gams.), ‘White Storm’ petunia (Petunia ×hybrida Vilm.), and ‘Festival Apricot’ gerbera (Gerbera jamesonii Bolus) plugs were grown in high or ambient RH conditions to determine the effect RH had on B uptake. Results indicate that an increase in RH decreased the amount of water the plant lost as a result of transpiration resulting in lower concentrations of B in shoot tissue. Boron concentrations in leaf tissue were 9.43, 10.56, and 17.81 mg·L−1 in pansy, petunia, and gerbera plants, respectively, grown in high RH conditions. These values were significantly lower than pansy, petunia, and gerbera plants grown in ambient RH conditions (19.94, 25.49, and 42.71 mg·L−1, respectively). Leaf distortion, consistent with B deficiency symptoms, was present in petunia and gerbera plants. Similar trends were observed when the experiment was repeated and leaf distortion was present in all species. This provides convincing evidence that the distorted growth observed in pansy, petunia, and gerbera plug production is the result of limited B caused by excessive humidity.
Conjoint Analysis of U.S. Consumers’ Preference for Elderberry Jelly and Juice Products
Authors: Mohebalian Phillip M. , Aguilar Francisco X. , Cernusca Mihaela M.
Published: February 2019

This study is the first of its kind in eliciting U.S. consumer preferences for elderberry juice and jelly products. An online survey collected self-reported information from 1043 U.S. residents. Results of a conjoint analysis suggest elderberry products that disclose qualified health claims and are produced locally were the best positioned to compete for greater shares in the jelly and juice product markets. Although consumers were 27% less likely to purchase elderberry jelly and 23% less likely to purchase elderberry juice relative to products containing competing fruit types, ceteris paribus, the fruit type product attribute determined only 9% of jelly and 13% of juice stated purchasing decision. More important than fruit type, consumers valued product price, disclosure of health claims, and origin. Consumers were 3.7 times more likely to choose locally produced jelly products than imported jelly and twice as likely to select products disclosing health claims compared with jelly products without claims. Likewise, consumers were 3.3 times more likely to choose locally produced juice products than imported juice products and 2.1 times more likely to select juice products with health claims than without. Our results indicate that an introductory strategy that combines the strength of preferences for locally produced products along with the disclosure of health claims at a competitive price can be an important tool in expanding the market for elderberry products in the United States.
Manna in Winter: Indigenous Americans, Huckleberries, and Blueberries
Authors: Hummer Kim E.
Published: February 2019

More than 35 species of blueberries (Vaccinium L.) and huckleberries (Vaccinium and Gaylussacia Kunth.) are indigenous to North America. The indigenous North American peoples, wise in the ways of survival, recognized the quality of these edible fruits and revered these plants. Beyond food needs, these plants played significant roles in their culture, sociology, economics, and spirituality. Because these traditions, developed and gathered over millennia, were transmitted orally, documentation of these uses have been determined through archeological data, written records from western civilization after first contact, and recent surveys of present-day native peoples. The wealth of indigenous knowledge on blueberries, huckleberries, and other foods was shared with European immigrants. These fruits were used by many tribes throughout North America. Samuel de Champlain documented that fresh and dried blueberries provided “manna in winter” when other food was scarce. Pemmican, a preserved concoction of lean meat, fat, and blueberries or other fruit, enabled survival. Blueberry products such as ohentaqué, hahique, satar, sakisatar, sautauthig, k’enkash, navag, and nunasdlut’i were important to Native Americans. Roger Williams, Meriwether Lewis, and Henry David Thoreau were each impressed with the uses of blueberries by indigenous Americans. The social, technological, and horticultural changes that gave rise to a commercial wild huckleberry and blueberry gathering and production history are summarized.
Inheritance of Resistance to Pear Psylla Nymphal Feeding in Pear (Pyrus communis L.) of European Origin
Authors: Bell Richard L.
Published: February 2019

Pear psylla are serious pests of pear throughout North America and Europe. Inhibition of nymphal feeding has been identified as a key component of resistance, being correlated with inhibition of oviposition, mortality, and delayed development. Breeding for resistance would be aided by knowledge of the inheritance and relative breeding values of resistant parents. Nine seedling populations derived from crosses among five resistant European P. communis cultivars (‘Batjarka’, ‘Erabasma’, ‘Ilinjaca’, ‘Spina Carpi’, and ‘Zelinka’), a clone labeled ‘Obican Vodenac’, and two susceptible P. communis parents (‘Bartlett’ and ‘Sunrise’) were used in this study. The seedlings, ‘Bartlett’ as a susceptible control and NY10353 (a P. communis × P. ussuriensis backcross hybrid) as a moderately resistant control, were assayed for short-term survival and nymphal feeding after an infestation period of 2 days. There were no significant differences among the progenies and controls in mean proportion of live nymphs after 2 days. The distributions of live and feeding nymphs indicated some dominance for susceptibility in some crosses. There were few significant differences among crosses in the proportion of actively feeding nymphs; however, the two crosses involving ‘Erabasma’ exhibited significantly less feeding, indicating that ‘Erabasma’ transmitted resistance to nymphal feeding to its progeny to a greater degree than the other four resistant parents.
Water Stress Increases Sunburn in ‘Cripps’ Pink’ Apple
Authors: Makeredza Brian , Schmeisser Michael , Lötze Elmi , Steyn Willem J.
Published: February 2019

An experiment that entailed the manipulation of irrigation was carried out to assess the effect of water stress on sunburn development in ‘Cripps’ Pink’ apples. Normal irrigation, half irrigation, and no irrigation treatments were applied for 15 days starting on 14 Mar. 2010 (Southern hemisphere). Stem water potential, fruit surface temperature (FST), sunburn incidence, and sunburn severity were measured. Sunburn was also categorized into browning, necrosis, or bleaching sunburn types. Fully exposed fruit without prior sunburn symptoms were tagged for progressive sunburn assessments, whereas sunburn was also assessed at harvest for all fruit per tree. Soil moisture and stem water potential decreased, whereas FST, sunburn incidence, and severity increased linearly with a decrease in irrigation level. Sunburn necrosis increased with increasing water stress. In conclusion, water stress aggravates sunburn development under conditions conducive for its development by increasing FST.
Chromosome Numbers and Ploidy Levels of Chinese Curcuma Species
Authors: Chen Juan , Xia Nianhe , Zhao Jietang , Chen Jianjun , Henny Richard J.
Published: February 2019

Curcuma L. is an economically important genus in the family Zingiberaceae. Many species are grown as medicinal, culinary, and ornamental crops. As a result of their high morphological diversity and small chromosome sizes, chromosome numbers and species relationships of Chinese Curcumas remain debated. This study examined chromosome numbers of 15 populations representing 11 species of Curcuma from China. Results showed that only Curcuma flaviflora S. Q. Tong was diploid with 2n = 2x = 42 and C. kwangsiensis S. G. Lee & C. F. Liang was tetraploid with 2n = 4x = 84. The other species were triploid (2n = 3x = 63). The study indicated that the basic chromosome number of Curcuma from China could be x = 21. The diploid C. flaviflora produced viable seeds, which was the main means for propagation. The tetraploid and the triploids produced no seeds and relied on rhizomes for propagation. Chromosome sizes of all species were small, ranging from 0.5 to 2.1 μm, which prevented karyotype analysis. The fact that nine of 11 species studied were triploid indicates that triploidy may have some type of competitive advantage over the diploid and tetraploid. In addition, the triploids are popular commercially because of abundant rhizome production and this may contribute to their wide distributions.