bluuebunny/crossref_metadata_2025 huggingface dataset:
A Postharvest Dip Treatment with Lysophosphatidylethanolamine, a Natural Phospholipid, May Retard Senescence and Improve the Shelf Life of Banana Fruit
Authors: Ahmed Zienab F.R. , Palta Jiwan P.
Published: February 2019

Banana is one of the most consumed tropical fruits around the world. It is marketed nearly all year-around and has a relatively short shelf life. Fruits are harvested mature green and treated with ethylene to stimulate ripening before distribution and sale. The fruits generally ripen within 4–5 days after ethylene treatment and sold primarily at yellow stage of ripening. After turning yellow the fruit becomes unsuitable for marketing in 1–3 days. Thus 1–2 days of improvement in the fruit shelf life could enhance the market value of banana. Previous studies conducted in our laboratory have demonstrated that both pre- and postharvest application of lysophosphatidylethanolamine (LPE) can retard aging and improve shelf life of various fruits. The objective of this study was to investigate the possibility of improving shelf life of banana fruit by a postharvest dip in LPE. For this purpose, whole fruits obtained from the market at ripeness stage of 2.5 (about 75% green) were dipped in solution of 500 ppm LPE for 30 minutes and observed for a period of five days at room temperature. Each treatment was applied to 50 uniform fruits. From each hand bought, an equal number of fruits were separated for LPE and control treatments to reduce the variability. Five days after dip treatment, the fruit treated with LPE were firmer and thicker as compared with the control. Starch breakdown was also delayed in the LPE-treated fruits. LPE treatment slowed the development of brown spots on the peel tissue. Both peel and pulp tissue of LPE-treated fruits had lower ion leakage compared with the control. Fruit peel slices treated with LPE for 3 hours also showed a decrease in ion leakage and respiration rate at 24 hours after treatment. Results of the present study indicate that a postharvest dip treatment with LPE may improve shelf life of banana fruit by 1–2 days. These results suggest that LPE may improve shelf life by maintaining membrane integrity, reducing respiration, and slowing the breakdown of starch and cell walls during ripening and senescence of banana fruit tissue.
Causes and Breaking of Seed Dormancy in Flowering Dogwood (Cornus florida L.)
Authors: Liu Hailin , Qian Cunmeng , Zhou Jian , Zhang Xiaoyan , Ma Qiuyue , Li Shuxian
Published: February 2019

Cornus florida seeds show strong dormancy. In this study, we investigated the causes of the dormancy by assessing the permeability of the stony endocarp, the germination of seeds after mechanical dissection, and the effect of endogenous inhibitors. Water uptake by intact and cracked seeds during imbibition showed that the endocarp formed a strong barrier for water absorption. Meanwhile, extracts from endocarp decreased the germination frequency of chinese cabbage seeds from 99.3% (control) to 2.7%. Therefore, the endocarp was the mechanical barrier and contained endogenous inhibitors for seed germination. However, the germination percentage of decoated seeds and dissected seeds with the exposed radicle were only 13.3% and 28.7%, respectively. It was found that the endosperm also played a role in seed dormancy. Extracts from endosperm decreased the germination frequency of chinese cabbage seeds from 99.3% (control) to 53.0%. By contrast, extracts from embryo did not affect the germination of chinese cabbage seeds. When tested with the excised embryos, germination percentage was up to 85.3% at the 16th day of incubation. Taking these results together, we concluded that the endocarp and endosperm were responsible for seed dormancy in C. florida. To break the seed dormancy of C. florida, stratification and soaking in sulfuric acid are the effective means. The highest germination frequency was achieved by immersing seeds in 98% sulfuric acid for 10 minutes, then soaking the seeds in 500 mg·L−1 gibberellic acid (GA3) for 72 hours before cold stratification at 5 °C for 60 days.
Plant Regeneration of Iris germanica L. from Shoot Apexes via an Improved Somatic Embryogenesis Protocol
Authors: Xu Li , Huang Suzhen , Han Yulin , Yuan Haiyan
Published: February 2019

An improved three-stage protocol for plant regeneration via somatic embryogenesis of the horticulturally important plant Iris germanica L. was developed using shoot apex segments as explants. At the first stage of the experiment, 60% of callus was obtained from shoot apex segments of I. germanica on Murashige and Skoog’s (MS) medium supplemented with 4.52 μm 2,4-dichloropheoxyacetic acid (2,4-D) and 0.44 μm 6-benzyladenine (6-BA). When nonembryogenic calli were subcultured on MS medium with 11.31 μm 2,4-D and 0.44 μm 6-BA, maximum frequency of embryogenic callus (66.0%) was obtained. At the second stage, the treatment of 9% (w/v) sucrose resulted in the optimum somatic embryo (SE) formation (70.0%). More than 90.0% of SEs germinated with bipolar structure and regenerated into plantlets on plant growth regulator-(PGR)free MS medium during the third stage. Regenerated plantlets were successfully acclimatized in greenhouse environment with little somaclonal variation. Histological study showed that somatic embryogenesis stages were asynchronous and SEs developed from the surface and inner tissue of embryogenic calli.
Nitrogen Management in Organic Processing Tomato Production: Nitrogen Sufficiency Prediction Through Early-season Soil and Plant Monitoring
Authors: Bustamante S. Castro , Hartz T.K.
Published: February 2019

Organic processing tomato (Solanum lycopersicum L.) production is a significant industry in California, yet little nitrogen (N) fertility research is available to guide N management. A total of 37 certified organic processing tomato fields in the Sacramento Valley of California were monitored during the 2012 and 2013 production seasons, with two objectives: 1) to document current N management practices and 2) to investigate the utility of early-season soil and plant N monitoring techniques in predicting seasonal crop N sufficiency. Between ≈3 and 11 weeks after transplanting (WAT) soil mineral N (SMN), leaf N and petiole NO3-N were determined every other week. In 22 fields, whole plant N concentration at ≈11 WAT was determined as a measure of crop N sufficiency. Growers were surveyed regarding N management practices used and fruit yields achieved. Net N mineralization (Nmin) was measured for 20 fields soils by aerobic laboratory incubation. Carbon mineralization (Cmin) in 24 hours following rewetting of air-dried soil and water extractable organic nitrogen (WEON) and carbon (WEOC) were also determined and evaluated as predictors of Nmin. Nitrogen management was primarily based on the application of manure or manure compost in the fall. Organic fertilizers were applied mainly in spring (pre- and post-transplanting). SMN in the top 60 cm at 3 WAT ranged from 6 to 32 mg·kg−1. About 30% of fields were N deficient by 11 WAT. Sensitivity analysis showed that SMN (whether measured from 0 to 30 or 0 to 60 cm) and leaf N at 5 WAT correctly predicted late-season plant N status in >60% of the fields. Nmin in 28 days ranged from 8 to 31 mg·kg−1, representing an average of 2% of total soil N. Correlation between Nmin and Cmin was weak (r = 0.44, P = 0.051) while stronger correlations were observed between Nmin and WEOC, WEON and total soil N (r = 0.63, 0.61 and 0.51, respectively, all P < 0.03). A multiple linear regression model that used 3 WAT SMN (0–30 cm) and WEON as independent variables improved Nmin prediction (adj. R2 = 0.67). Significant fruit yield increase with sidedress N application of feather meal at 5–6 WAT was observed in 2 of 4 field trials, demonstrating the ability to remedy a soil N limitation identified by early-season N monitoring.
Cold Acclimation Treatment–induced Changes in Abscisic Acid, Cytokinin, and Antioxidant Metabolism in Zoysiagrass (Zoysia japonica)
Authors: Xu Lixin , Zhang Mili , Zhang Xunzhong , Han Lie-Bao
Published: February 2019

Zoysiagrass (Zoysia spp.), a warm-season turfgrass species, experiences freezing damage in many regions. The mechanisms of its cold acclimation and freezing tolerance have not been well understood. This study was designed to investigate effects of cold acclimation treatment on leaf abscisic acid (ABA), cytokinin (transzeatin riboside (t-ZR), and antioxidant metabolism associated with freezing tolerance in zoysiagrass (Zoysia japonica). ‘Chinese Common’ zoysiagrass was subjected to either cold acclimation treatment with temperature at 8/2 °C (day/night) and a photosynthetically active radiation (PAR) of 250 µmol·m−2·s−1 over a 10-hour photoperiod or normal environments (temperature at 28/24 °C (day/night), PAR at 400 µmol·m−2·s−1 and 14-hour photoperiod) for 21 days in growth chambers. Cold treatment caused cell membrane injury as indicated by increased leaf cell membrane electrolyte leakage (EL) and malondialdehyde (MDA) content after 7 days of cold treatment. Cold treatment increased leaf ABA and hydrogen peroxide content and reduced t-ZR content. Leaf superoxide dismutase (SOD), ascorbate peroxidase (APX) activity, and proline content increased, whereas catalase (CAT) and peroxidase (POD) activity declined in response to cold treatment. Cold treatment increased freezing tolerance as LT50 declined from −4.8 to −12.5 °C. The results of this study indicated that cold acclimation treatment might result in increases in ABA and H2O2, which induce antioxidant metabolism responses and improved freezing tolerance in zoysiagrass.
Irrigation Water Quality and Trinexapac-ethyl Effects on Bermudagrass Response to Deficit Irrigation
Authors: Hejl Reagan W. , Wherley Benjamin G. , Thomas James C. , White Richard H.
Published: February 2019

As the need for landscape and golf course water conservation increases, use of low-quality irrigation water combined with deficit irrigation practices is becoming more common. Information is lacking concerning the effects of water quality on bermudagrass response to deficit irrigation, as well as the extent to which plant growth regulators may ameliorate or delay the negative effects of water stress on warm-season turfgrass. The objectives of this 10-week greenhouse study were to 1) characterize growth, quality, and evapotranspiration (ET) of ‘Tifway’ bermudagrass (Cynodon dactylon × C. traansvalensis Burt Davy) when irrigated at full (1.0 × ETa) or deficit (0.3 × ETa) levels of actual turfgrass evapotranspiration (ETa) using three irrigation water sources [reverse osmosis (RO), sodic potable, and saline] and 2) determine whether application of trinexapac-ethyl (TE) could mitigate turfgrass quality decline under deficit irrigation. Results indicated that turf irrigated with sodic irrigation water exhibited significantly elevated ETa and shoot growth compared with turf receiving RO or saline irrigation water in both studies. Irrigation water source affected turfgrass quality differently at each irrigation level. TE application improved turfgrass quality and/or delayed firing under soil moisture stress in both studies, with the greatest benefit noted under the less intense conditions of the spring experiment. Elevated canopy temperatures were observed within all deficit irrigation treatments, regardless of water chemistry. Results demonstrate that irrigation water quality may influence turfgrass ET rates. In addition, they suggest that trinexapac-ethyl may offer short-term mitigation of drought stress under deficit irrigation.
Potential Drift of Pollen of Cycas micronesica on the Island of Guam: A Comparative Study
Authors: Hamada Trenton , Terry Irene , Roemer Robert , Marler Thomas E.
Published: February 2019

We have investigated the potential movement on air currents of pollen from Guam’s native cycad, Cycas micronesica, proposed as ambophilic. We measured wind velocities and directions in different cycad habitats that vary in their exposure to trade winds, determined pollen settling velocities, and then modeled the potential horizontal pollen drift distance in each habitat. Similar measurements were performed on several entomophilous Zamia cycads and six zoophilous tropical trees used in horticulture or landscaping. All cycad species’ pollen exhibited relatively slow mean settling velocities (0.73–1.29 cm·s−1) with C. micronesica pollen in the middle of this range. Our models predicted that wind in more open habitats with wind directions east northeast (ENE) to northeast (NE) and velocities >2 m·s−1 could transport C. micronesica pollen, either single grains or clumps, hundreds of meters downwind from the pollen source before falling 1 or 2 m. In forested habitats and at typical heights of cycad cones in the understory, the mean wind velocities ranged from <0.03 m·s−1 to ≈1 m·s−1. In habitats with mean winds ≥0.2 m·s−1, models predicted pollen transport distances of tens of meters from the pollen source. In sheltered habitats with velocities near 0.03 m·s−1, the potential wind transport of pollen was limited to less than a few meters, suggesting that wind would be an ineffective vector in such areas. Pollen grains of all angiosperm species were larger except one, and the species with larger grains had settling velocities 3–26 times faster than that of cycad pollens. Even so, winds in most Guam environments could transport pollen of most angiosperm species over 50 m before falling 1 m. In summary, the results suggested that pollen size, clumping tendencies, and drift of most of these species do not preclude a role for wind in moving pollen in habitats exposed to trade winds, and that other physical and plant characteristics affect their pollination mode. For C. micronesica, these pollen and plant attributes do not preclude entomophily, and insects are likely required in the deep understory where cycads are present.
Growth of the Native Xerophyte Convolvulus cneorum L. on an Extensive Mediterranean Green Roof under Different Substrate Types and Irrigation Regimens
Authors: Tassoula Lamprini , Papafotiou Maria , Liakopoulos Georgios , Kargas Georgios
Published: February 2019

The possibility of using Convolvulus cneorum L., a native Mediterranean xerophyte, with compact dome-like canopy and extended blooming period, on extensive green roofs in areas with semiarid Mediterranean climate was investigated in a 27-month experimental period, which included three summers (the dry season of the year). The aim was to preserve the local character and biodiversity, as well as to reduce water consumption and construction weight. Convolvulus cneorum rooted cuttings were planted in the beginning of July 2011 in experimental modules on a fully exposed flat roof at the Agricultural University of Athens, with a green roof infrastructure (substrate moisture retention and protection of the insulation, drainage element, and filter sheet). Two types of substrate with 10 cm depth were used, one with soil, i.e., grape marc compost:perlite:soil:pumice (3:3:2:2, v/v) and a lighter one without soil, i.e., grape marc compost:perlite:pumice (3:3:4, v/v). Two irrigation frequencies were applied during the dry periods, i.e., every 5 days (normal) and 7 days (sparse) in 2011 and 2012 and every 4 days (normal) and 6 days (sparse) in 2013. The chemical properties of the two substrates were similar, while their physical properties differ slightly as the substrate that contained soil was holding more water at saturation and it had lower saturated hydraulic conductivity and higher easily available water (EAW). The substrate type affected growth since plant height and diameter, shoot number, and aboveground dry weight were promoted by the soil substrate. Irrigation frequency did not affect plant growth. However, plants cultivated on soil substrate and irrigated normally had the highest growth, particularly compared with plants in soilless substrate under sparse irrigation. Flowering was abundant in April (spring) and in the first year flower number was promoted by the soil substrate. During the dry periods, sparse irrigation resulted in increased stomatal resistance one day before irrigation, indicating that water availability was marginal for the plants, while normal transpiration rate was restored the day after irrigation. According to photosystem II photochemical parameters measured one day before and the morning after an irrigation event, no evidence of damage to the photosynthetic apparatus was recorded in any of the treatments. In general, after 27 months of culture, plant size and roof coverage was appearing more or less similar in all the experimental treatments, therefore the combination of the lighter soilless substrate with sparse irrigation is highly suggested for C. cneorum cultivation on Mediterranean green roofs.
Evaluation of Genetic Diversity Among Kongpo Monkshood (Aconitum kongboense L.) Germplasm Accessions Revealed by Inter Simple Sequence Repeat Markers
Authors: Meng Fanjuan , Wang Ruoding , Peng Mu , Wang Chao , Wang Zhongkui , Guan Fachun , Li Yajun
Published: February 2019

Inter simple sequence repeat (ISSR) were used to evaluate the genetic diversity of Kongpo Monkshood (Aconitum kongboense L.) in Motuo, Tibet Plateau. From 70 accessions of three populations, 10 out of 100 informative ISSR primers were chosen for polymorphism analysis. Percentage of polymorphic bands was 50% to 66.67% with a mean of 58.42%. The effective number of alleles (Ne) was between 1.545 (population 3) and 1.586 (population 2), and the mean value was 1.564; the Nei’s gene diversity (h) ranged from 0.315 to 0.327 with the average value of 0.320; the value of Shannon’s information index (I) ranged from 0.459 to 0.478, with the mean of 0.469. Based on molecular data, cluster analysis classified the 70 cultivars into three groups. Most accessions were related to the geographical origin and their genetic backgrounds. Bayesian structure and PCoA analysis were consistent with the dendrogram result. Based on the analysis, it will provide a reference for Kongpo Monkshood breeding purposes and contribute to identification, rational exploitation, and conservation of germplasms.
Inheritance Analysis and Quantitative Trait Loci Detection of Head Splitting Resistance in Cabbage (Brassica oleracea L. var. capitata)
Authors: Su Yanbin , Liu Yumei , Shen Huolin , Xiao Xingguo , Li Zhansheng , Fang Zhiyuan , Yang Limei , Zhuang Mu , Zhang Yangyong
Published: February 2019

Head splitting resistance (HSR) in cabbage is an important trait closely related to appearance, yield, storability, and mechanical harvestability. In this study, a doubled haploid (DH) population derived from a cross between head splitting-susceptible inbred cabbage line 79-156 and resistant line 96-100 was used to analyze inheritance and detect quantitative trait loci (QTLs) for HSR during 2011–12 in Beijing, China. The analysis was performed using a mixed major gene/polygene inheritance method and QTL mapping. This approach, which uncovered no cytoplasmic effect, indicated that HSR can be attributed to additive-epistatic effects of three major gene pairs combined with those of polygenes. Major gene and polygene heritabilities were estimated to be 88.03% to 88.22% and 5.65% to 7.60%, respectively. Using the DH population, a genetic map was constructed with simple sequence repeat (SSR) markers anchored on nine linkage groups spanning 906.62 cM. Eight QTLs for HSR were located on chromosomes C4, C5, C7, and C9 based on 2 years of phenotypic data using both multiple-QTL mapping and inclusive composite interval mapping. The identified QTLs collectively explained 37.6% to 46.7% of phenotypic variation. Three or four major QTLs (Hsr 4.2, 7.2, 9.3, and/or 9.1) showing a relatively larger effect were robustly detected in different years or with different mapping methods. The HSR trait was shown to have a complex genetic basis. Results from QTL mapping and classical genetic analysis were consistent. Our results provide a foundation for further research on HSR genetic regulation and molecular marker-assisted selection (MAS) for HSR in cabbage.
Inventory, Descriptions, and Keys to Segregation and Identification of Liriopogons Cultivated in the Southeastern United States
Authors: Fantz Paul R. , Carey Dennis , Avent Tony , Lattier Jason
Published: February 2019

Liriopogons is a name used for cultivated genera of Liriope and Ophiopogon, Ruscaceae. Liriopogons are the most important clonal groundcovers sold by the nursery industry in the southeastern United States. Accurate segregation and identification of cultivars is difficult as cultivar descriptions used in nursery catalogs, literature, and plant patents are qualitative in substance, and often limited in morphological data. Also, existing inventories are limited in data. Many cultivars are assigned to the wrong species, and sometimes to the wrong genus. A taxonomic project of nearly 30 years’ working with liriopogon cultivars has culminated in this article. Included are the project history, nomenclatural history, cultural practices that degrade cultivar integrity, ornamental morphological genetic traits, and an inventory of cultivars. The inventory includes nearly 225 valid and invalid names, plus temporary names for clones under evaluation, an ordering of the nomenclature, quantitative morphological descriptions, cultivar origins where known, sources of material studied, and pertinent notes and observations. Provided is a key to segregation and identification of cultivars, a tool that can assist those in the industry and those seeking plant patents.
Simple Sequence Repeat Marker Analysis of Genetic Diversity among Progeny of a Biparental Mapping Population of Sweetpotato
Authors: Yada Benard , Brown-Guedira Gina , Alajo Agnes , Ssemakula Gorrettie N. , Mwanga Robert O.M. , Yencho G. Craig
Published: February 2019

Genetic diversity is critical in sweetpotato improvement as it is the source of genes for desired genetic gains. Knowledge of the level of genetic diversity in a segregating family contributes to our understanding of the genetic diversity present in crosses and helps breeders to make selections for population improvement and cultivar release. Simple sequence repeat (SSR) markers have become widely used markers for diversity and linkage analysis in plants. In this study, we screened 405 sweetpotato SSR markers for polymorphism on the parents and progeny of a biparental cross of New Kawogo × Beauregard cultivars. Thereafter, we used the informative markers to analyze the diversity in this population. A total of 250 markers were polymorphic on the parents and selected progeny; of these, 133 were informative and used for diversity analysis. The polymorphic information content (PIC) values of the 133 markers ranged from 0.1 to 0.9 with an average of 0.7, an indication of high level of informativeness. The pairwise genetic distances among the progeny and parents ranged from 0.2 to 0.9, and they were grouped into five main clusters. The 133 SSR primers were informative and are recommended for use in sweetpotato diversity and linkage analysis.
Screening USDA Lettuce (Lactuca sativa L.) Germplasm for Ability to Germinate under Cold Conditions
Authors: Grahn Charlene M. , Hellier Barbara , Benedict Chris , Miles Carol
Published: February 2019

Low temperatures can slow down emergence, decrease weed competitiveness, and lead to uneven crop maturity in direct-seeded crops such as baby leaf lettuce (Lactuca sativa L.). In this study, seeds of 103 single-parent lineage, homozygous lettuce accessions (53 cos and 50 leaf type) from the USDA National Plant Germplasm System (NPGS) and six commercial standard lettuce cultivars (three cos and three leaf type) were evaluated in replications for percent germination after 7 and 10 days at 5 °C in a germination chamber. Cos and leaf types were selected for this study as they are most commonly used for baby leaf lettuce production. Differences were observed among entries in percent seeds germinated after both 7 and 10 days. Overall, an average of 68% of seeds germinated after 7 days and 94% germinated after 10 days. Although several NPGS accessions had higher percent germination than the commercial cultivars, the average percent germination was not statistically different between the two seed sources at 7 or 10 days. Percent germination also did not differ between entries of cos and leaf type after 7 or 10 days. Similarly, no difference in percent germination between entries of dark and white seed color was observed after 7 or 10 days. No relationship between 100 seed weight and percent germination was observed after 7 days (r2 = 0.07) or 10 days (r2 = 0.13). Thus, lettuce seed type, color, and 100 seed weight do not appear to be good predictors of germination under cold conditions in lettuce. The accessions with the highest percent germination after 7 days at 5 °C have the potential to be used for the development of new lettuce cultivars suitable for an extended, early season production in temperate climates when soil temperature is lower than optimal for lettuce germination. Further studies are needed to assess the ability of these accessions to germinate rapidly under cold field soil conditions.
Weed Management, Training, and Irrigation Practices for Organic Production of Trailing Blackberry: I. Mature Plant Growth and Fruit Production
Authors: Dixon Emily K. , Strik Bernadine C. , Valenzuela-Estrada Luis R. , Bryla David R.
Published: February 2019

Weed management, training time, and irrigation practices were evaluated from 2013 to 2014 in a mature field of trailing blackberry (Rubus L. subgenus Rubus Watson) established in western Oregon. The field was planted in 2010 and certified organic in 2012, before the first harvest season. Treatments included two cultivars (Marion and Black Diamond), three weed management practices [nonweeded, hand-weeded or bare soil, and weed mat (black landscape fabric)], two irrigation strategies (irrigation throughout the growing season and no postharvest irrigation), and two primocane training dates (August and February). When averaged over the other treatments, ‘Marion’ and ‘Black Diamond’ had similar yields in both years. However, the presence of weeds reduced vegetative growth and yield, especially in ‘Black Diamond’, while weed mat increased growth and yield over hand-weeded plots by 13%. Withholding irrigation after harvest reduced water use by an average of 44% each year without adversely affecting yield in either cultivar. The effects of training time were primarily seen in 2014 after a cold winter. August-trained ‘Marion’ plants had more cold damage than February-trained plants and, consequently, had fewer and shorter canes, less biomass, fewer nodes, and 1 kg/plant less yield than February-trained plants. ‘Black Diamond’ was cold hardier than ‘Marion’, but was more readily infested by raspberry crown borer (Pennisetia marginata Harris). As the planting reached maturity, yields in the best performing organic production systems (both cultivars under weed mat and ‘Marion’ that was February-trained) averaged 11 and 9 t·ha−1, for ‘Black Diamond’ and ‘Marion’ respectively, similar to what would be expected in conventional production.
Evaluation of Multipass Mechanical Harvesting on ‘Skeena’ Sweet Cherries Trained to Y-trellis
Authors: He Long , Zhou Jianfeng , Zhang Qin , Karkee Manoj
Published: February 2019

A study on multipass harvesting using a mechanical harvesting prototype was proposed for mechanical harvesting of fresh market sweet cherries. Fruit damage rate, fruit removal rate, and fruit maturity level were three of the measures used to compare the performance of the multipass harvesting method against single-pass harvesting. The multipass harvesting was conducted in four consecutive days with short duration of 2.5 seconds at each day, while the single-pass harvesting was one-time harvesting with long duration of 10 seconds at a single day. To generate baseline information for comparison, single-pass harvestings were performed on the first and the last days of the multipass harvesting. Fruit maturity level was determined by comparing the fruit skin color against a standard color chart with seven color levels. Field test results showed that the percentage of under-mature fruit (maturity levels ≤ 5) was substantially lower with multipass harvesting than that with day 1 single-pass harvesting. Similarly, the percentage of over-mature fruit (maturity level 7) was noticeably lower with multipass harvesting than that with day 4 single-pass harvesting. Multipass harvesting achieved a fruit removal rate of 83.4% ± 10.3% and a harvest-induced fruit damage rate of 5.0% ± 4.4%. The corresponding fruit removal rates from single-pass harvesting tests were 48.0% ± 16.1% on day 1 and 66.7% ± 16.2% day 4. Harvest-induced fruit damage rates with single-pass harvesting were 20.1% ± 9.9% on day 1 and 11.8% ± 6.0% on day 4. The results supported the hypothesis that multipass of short-duration shaking offer a potential to achieve a higher overall harvesting efficiency with better fruit quality, and therefore could lead to an optimal solution for mechanical harvesting of fresh market sweet cherries. It is noted that comprehensive economic analysis will be necessary to establish commercial viability of the system in comparison with single-pass solutions.
The Differential Response of Two Chrysanthemum Cultivars to Shading: Photosynthesis, Chloroplast, and Sieve Element-companion Cell Ultrastructure
Authors: Han Shuang , Jiang Jiafu , Li Huiyun , Song Aiping , Chen Sumei , Chen Fadi
Published: February 2019

The response to reduced light intensity of two contrasting cultivars Puma Sunny (shade intolerant) and Gongzi (shade tolerant) was characterized in terms of plant height, the root/shoot ratio, photosynthetic capacity, and the morphology and ultrastructure of their chloroplasts and phloem companion cells. The initial response to shading of cultivar Puma Sunny plants was to extend their stems, and while the equivalent response of cultivar Gongzi was less marked. Shading depressed the maximum relative electron transport rate (rETR) in both cultivars, and while the efficiency of light capture in cultivar Puma Sunny was compromised by shading, this was not the case for cultivar Gongzi. Low levels of incident light inhibited the formation of starch grains in the chloroplast and increased the volume of interspace between the grana lamellae. In cultivar Puma Sunny, but less so in cultivar Gongzi, the chloroplasts became more slender and the stroma lamellae more swollen. Adjusting chloroplast morphology by developing extra layers of grana lamellae and maintaining the integrity of the phloem companion cells are both adaptations which help make ‘Gongzi’ a more shade-tolerant cultivar.
Yield, Composition, and Antioxidant Capacity of Ground Cumin Seed Oil Fractions Obtained at Different Time Points during the Hydrodistillation
Authors: Zheljazkov Valtcho D. , Shiwakoti Santosh , Astatkie Tess , Salamon Ivan , Grul'ová Daniela , Mudrencekova Silvia , Schlegel Vicki
Published: February 2019

Cumin (Cuminum cyminum L.) is an important essential oil (EO), medicinal, and spice plant from family Apiaceae. Cumin seed EO has wide applications in the food, liquor, pharmaceutical, and aromatherapy industries, and is extracted via steam or hydrodistillation of either whole or ground seed. The hypothesis of this study was that by capturing oil eluted at different timeframes during the hydrodistillation process (HDP), we could obtain oils of differential composition and bioactivity. The objective was to evaluate the EO fractions captured at different timeframes of the HDP. In this study, we collected nine different EO fractions following nine hydrodistillation time (HDT) frames: 0–2, 2–7, 7–15, 15–30, 30–45, 45–75, 75–105, 105–135, and 135–165 minutes. In addition, continuous HDT of 165 minutes was conducted as a control and the complete cumin seed oil was collected at the end of this time. HDT significantly affected the concentrations of the following constituents in the oil (as percentage of total oil): α-pinene (0.2% to 2.1%), β-pinene (5% to 35.8%), mycrene (0.3% to 1.7%), para-cymene (12.0% to 26.4%), γ-terpinene (4.8% to 25.9%), cumin aldehyde (3.8% to 51.1%), α-terpinen-7-al (0.2% to 11.2%), and γ-terpinen-7-al (1.3% to 13.1%). Some of the constituents were eluted early in the HDP and were highest in the oil fraction collected at the beginning of the HDP, others were highest in the fractions collected midway in the HDP, and another group of constituents were eluted later and were the highest in the oil fractions collected during the last HDT (135–165 minutes). Due to their altered chemical composition, the oil fractions expressed different antioxidant capacities; the one eluted at 105–135 minutes HDT had the greatest oxygen radical absorbance capacity (ORAC) values. The ORAC values were positively correlated to the concentration of cumin aldehyde (0.962), α-terpinene (0.889) and γ-terpinene (0.717), which suggest that these compounds in cumin oil may be responsible for the measured antioxidant capacity. This study demonstrated that cumin oil with dissimilar chemical profile and antioxidant activity could be obtained from the same batch of seed by capturing oils at different timeframes during the same HDP. The resulting products (EO fractions) could have diverse industrial, medical, and environmental applications. The method for cumin seed grinding and EO extraction described in this study could be used by industry to reduce energy inputs and oil losses, and for fast oil extraction.
The Use of Sawdust Mixed with Ground Branches Pruned from Wax Apple or Indian Jujube as Substrate for Cultivation of King Oyster Mushroom (Pleurotus eryngii)
Authors: Hwang San-Gwang , Li Yi-Ying , Lin Huey-Ling
Published: February 2019

The king oyster mushroom [Pleurotus eryngii (DC.:Fr.) Quél.] is gaining popularity across the world due to its excellent taste, high nutritional quality, medicinal value, and long shelf life. Conventional substrates for king oyster mushroom cultivation consist of sawdust derived from various tree species. Sawdust demand is increasing worldwide, creating a need for alternative materials that can at least partially replace sawdust as substrate for king oyster mushroom. In Taiwan, as in other countries that grow fruit trees, pruned fruit tree branches are an expensive agricultural waste, particularly if they are not recycled or reused. In the present study, we evaluated substrates containing sawdust and different proportions of material ground from pruned wax apple or Indian jujube branches for cultivation of king oyster mushroom. Our results suggested that among all five substrate mixes tested, the best substitute for conventional sawdust (100% sawdust) was a substrate that contained 75% sawdust mixed with 25% materials ground from trimmed wax apple branches (Wax apple 25%). Furthermore, determination of mineral element content, pH, and electrical conductivity (EC) levels of the substrates both before spawn inoculation and after harvesting revealed no significant changes in mineral content, a slight reduction in pH value, and a minor increase in EC levels after cultivation. Taken together, results from this study suggest that agricultural wastes from pruned fruit tree branches can partially replace sawdust as the cultivation substrate for king oyster mushroom.
Potassium Fertilization Affects Floricane Mineral Nutrient Content, Growth, and Yield of Blackberry Grown in Brazil
Authors: Pereira Ivan dos Santos , Picolotto Luciano , Gonçalves Michél Aldrighi , Vignolo Gerson Kleinick , Antunes Luis Eduardo Corrêa
Published: February 2019

The objective of this study was to evaluate the floricane leaf nutrient content, vegetative growth, and yield of two blackberry (Rubus spp.) cultivars (Tupy and Xavante), in response to rate of potassium (K) fertilization (0.0, 2.1, 4.2, 6.2, or 8.3 g/plant of K). The research was conducted in a region of low chill (342 chill hours) in southern Brazil (lat. 31°40′ 46.98 S, long. 52°26′ 4.36 W), and soil with pH 5.9, organic matter (OM) 1.1% and K 58.0 g·m−3. In 2009, only calcium (Ca) and magnesium (Mg) leaf concentration were affected by K application, and leaf K level was considered below normal for blackberry in Brazil. In 2010 and 2011, leaf K of blackberry in Brazil increased linearly in both cultivars with an increase in applied K. However, leaf K of blackberry in Brazil only reached its recommended levels for optimal growth in 2010 with the application of 2.1 and 8.3 g/plant of K for ‘Tupy’ and ‘Xavante’, respectively. In 2011, an antagonistic relationship was seen between leaf nitrogen (N)/K and K/Ca and K/Mg ratios with increasing K rates, where increasing K rates were accompanied by a linear decrease in the N/K ratio and a linear increase in the K/Ca and K/Mg ratios. Micronutrients evaluated showed no significant response to applied rates of K. A decrease in floricane leaf concentration of phosphorus (P), iron (Fe), manganese (Mn), and zinc (Zn) was also observed over years of the study. Potassium fertilization rates influenced the vegetative growth of blackberries. ‘Tupy’ showed increased cane density and pruning weights with increased rates of K application up to 8.3 g/plant, whereas cane density was optimized in ‘Xavante’ at 4.2 g/plant. The fruit yield of ‘Tupy’ and ‘Xavante’ increased linearly with K application per plant in all three years, indicating that K fertilization may be limiting the yield potential of these cultivars. These results suggest that the current K fertilizer recommendations may need to be increased for optimal production in Brazil.
Growth Responses of Hybrid Bluegrass and Tall Fescue as Influenced by Light Intensity and Trinexapac-ethyl
Authors: Meeks Meghyn , Chandra Ambika , Wherley Ben G.
Published: February 2019

Interspecific hybrids between texas bluegrass (Poa arachnifera Torr.) and kentucky bluegrass (Poa pratensis L.) are known to exhibit good heat tolerance, which has aided in their adaptation to the warmer climates of the southern United States, but their tolerance to shade has not been investigated. The objectives of this study were to 1) evaluate the growth responses of interspecific bluegrass hybrids (P. arachnifera × P. pratensis) in comparison with kentucky bluegrasses and a shade-tolerant cultivar of tall fescue (Festuca arundinacea Schreb.) under full sunlight and shaded environments, 2) identify optimum times to evaluate shade tolerance using the selected growth measurements, 3) calculate the minimum daily light requirements to retain acceptable turfgrass quality, and 4) determine if trinexapac-ethyl (TE) applications enhance hybrid bluegrass quality under shade. Two 10-week greenhouse experiments (late spring and early fall) were conducted in Dallas, TX. Within each of three light environments a randomized complete block design was used to accommodate three replications of eight genotypes treated with and without TE (0 or 0.228 kg·ha−1 a.i.). Turfgrass quality, leaf elongation rates, clipping dry weights, and percent green cover were measured. Meaningful comparisons were best during the late spring when daily light integrals (DLI) were optimum for healthy plant growth. Shade-tolerant hybrid bluegrasses (DALBG 1201 and TAES 5654) were identified using turfgrass quality and leaf elongation rates. These genotypes exhibited above-acceptable turfgrass quality in all environments, and a reduced leaf elongation rate similar to the tested dwarf-type tall fescue. DLI requirements of DALBG 1201 and TAES 5654 were ≤4 to achieve acceptable quality. TE applications generally did not improve turfgrass quality of genotypes, although leaf elongation rates were significantly reduced in all environments.
Light-emitting Diodes and the Modulation of Specialty Crops: Light Sensing and Signaling Networks in Plants
Authors: Pocock Tessa
Published: February 2019

The technology to drive the output of individual arrays of light-emitting diodes (LEDs) on timescales down to microseconds is enabling plant scientists and growers control over irradiance- and spectrum-induced plant responses. The two light sensing and signaling networks that regulate desired plant responses involve either photoreceptors (PR) and/or photosynthesis (PSN). These networks control morphological, physiological, and developmental processes (e.g., seed development and germination, seedling development, apical meristem formation, differentiation, flowering, etc.) as well as the energy distribution within the plant. Understanding the individual plant responses and the synergy between the PR and PSN networks will assist in the selection and timing of LED light programs for crop regulation and growth. Both networks sense and respond to irradiance and narrow-band spectra between 350 and 750 nm although their modes of action are different. Comparing the PR and PSN networks and their effect on plants shows that the PR network primarily regulates developmental processes in new tissues while the PSN network regulates routine operational processes. The two networks are required for healthy plant growth and are reliant on each other for biological fitness. A balance between these two networks will result in greater plant efficacy and can be achieved by light programs whose irradiance, spectra, duration, and timing can be regulated. Replacing high-intensity discharge (HID) lamps with LEDs is a catalyst for a fundamental change in plant lighting and we are on a steep learning curve to fully realize how to fully control LED technology in plant growth applications.
Blue Wavelengths from LED Lighting Increase Nutritionally Important Metabolites in Specialty Crops
Authors: Kopsell Dean A. , Sams Carl E. , Morrow Robert C.
Published: February 2019

Light is one of the most important environmental stimuli impacting plant growth and development. Plants have evolved specialized pigment-protein complexes, commonly referred to as photoreceptors, to capture light energy to drive photosynthetic processes, as well as to respond to changes in light quality and quantity. Blue light can act as a powerful environmental signal regulating phototropisms, suppression of stem elongation, chloroplast movements, stomatal regulation, and cell membrane transport activity. An emerging application of light-emitting diode (LED) technology is for horticultural plant production in controlled environments. Work by our research group is measuring important plant responses to different wavelengths of light from LEDs. We have demonstrated positive impacts of blue wavelengths on primary and secondary metabolism in microgreen and baby leafy green brassica crops. Results show significant increases in shoot tissue pigments, glucosinolates, and essential mineral elements following exposure to higher percentages of blue wavelengths from LED lighting. The perception of energy-rich blue light by specialized plant photoreceptors appears to trigger a cascade of metabolic responses, which is supported by current research showing stimulation of primary and secondary metabolite biosynthesis following exposure to blue wavelengths. Management of the light environment may be a viable means to improve concentrations of nutritionally important primary and secondary metabolites in specialty vegetable crops.
Key Traits and Promising Germplasm for an Organic Participatory Tomato Breeding Program in the U.S. Midwest
Authors: Hoagland Lori , Navazio John , Zystro Jared , Kaplan Ian , Vargas Jose Gomez , Gibson Kevin
Published: February 2019

Local production of organic tomatoes marketed directly to consumers is growing rapidly in the U.S. Midwest. Growers serving this market need cultivars that are well adapted to local climatic conditions, are competitive under organic management, and have end-use quality characteristics desired by their customers. Participatory plant breeding is a powerful, cost-effective approach with potential to engage growers in development of new cultivars optimally adapted to organic farming systems. To initiate a participatory breeding program for organic tomatoes an online grower survey was conducted to identify key plant traits, and a diverse set of tomato germplasm was evaluated under organic management to better understand horticultural constraints and identify adapted germplasm for further development. Tomato growers rated flavor as their top breeding priority, followed by disease resistance with late blight (LB) (Phytophthora infestans), early blight (EB) (Alternaria solani), and septoria leaf spot (SLS) (Septoria lycopersici) identified as the most problematic diseases. In field trials, foliar diseases were problematic in both years, though many entries exhibited partial resistance. Differences among entries in resistance to insect pests such as hornworms (Manduca sexta) were also observed. Yield varied widely among entries with some of the F1 hybrids and heirloom cultivars performing well despite significant disease pressure. Overall, we identified existing cultivars and F1 hybrids with potential to meet the immediate needs of Midwest organic tomato growers, and segregating breeding populations for further selection to be conducted on working organic farms.
Response of Onion Yield, Grade, and Financial Return to Plant Population and Irrigation System
Authors: Shock Clinton C. , Feibert Erik B.G. , Riveira Alicia , Saunders Lamont D.
Published: February 2019

Onion (Allium cepa) plant population is an important factor in total yield and bulb size, both of which can influence economic return to growers. Different onion bulb marketing opportunities influence the plant populations that growers should target. With the transition from furrow irrigation to a drip irrigation system, growers have doubts as to the onion population that should be planted to assure favorable economic outcomes. Onions were grown on silt loam at the Oregon State University Malheur Experiment Station, Ontario, OR in 2011 and 2012 following bread wheat (Triticum aestivum L.) each year. Long-day onion cultivars Vaquero, Esteem, Barbaro, and Sedona were planted heavily and thinned to nominal plant populations between 222,000 and 593,000 plants/ha under furrow irrigation, subsurface drip irrigation, and “intense bed” subsurface drip irrigation. The intense bed configuration had 50% more rows of onions with three drip tapes per 1.94-m bed instead of two tapes. The experiment had a randomized complete block split-split-plot design with six replicates. Irrigation systems were the main plots, cultivars the split plots, and plant populations the split-split plots. Onion yield and grade responses to plant population for each cultivar and each planting system were determined by regression of yield and grade on the actual onion plant stands. In general, there were few differences among irrigation systems or interactions among irrigations systems, cultivars, and plant populations. Averaging over cultivars, total and marketable bulb yield out of storage increased with plant population, whereas the bulb diameters decreased with plant population. Average marketable yield was 119 Mg⋅ha−1 over the 2 years. Average yield of colossal bulbs >102 mm in diameter decreased with increasing plant population. In 2011, estimated gross economic return increased linearly with plant population, offset in part by increasing seed cost. In 2012, estimated economic return responded quadratically to plant population with maximum return of $45,357/ha at 419,000 plants/ha.