bluuebunny/crossref_metadata_2025 huggingface dataset:
Three Methods for Determining Storage Carbohydrate Concentration in Peppermint (Mentha piperita) Rhizomes
Authors: Mitchell A.R. , Rechel E.A. , Dovel R.L.
Published: October 2019

Because peppermint (Mentha piperita L.) grows anew from rhizomes each spring, methods to measure the energy stored in the peppermint rhizomes would be useful. Our objective was to compare three methods of measuring carbohydrate in peppermint samples taken throughout a growing season. Total nonstructural carbohydrate (TNC) is a measure of the water- and acid-soluble sugars. Etiolated growth measurements of nonstructural biomass (NSB) are a reliable method for alfalfa (Medicago sativa L.) taproots. Near infrared spectroscopy (NIRS) is another method that has been used to determine TNC of alfalfa. Rhizomes were sampled monthly from four locations within a field. The NSB was correlated (r = 0.74) with the TNC means from each sampling date. The NIRS calibration was highly correlated with the TNC of all samples (R2=0.96). Both NSB and TNC decreased in summer and increased in the fall as the plant stored carbohydrate for winter survival and regrowth. Any of the three methods could be used to study energy storage, although NIRS is the quickest, and NSB the least technologically sophisticated. Based on the positive results of NIRS, a more comprehensive calibration is warranted.
Change in Chlorophyll Content Over Time Well-differentiated Salt-tolerant, Moderately Salt-tolerant, and Salt-susceptible Cowpea Genotypes
Authors: Dong Lingdi , Ravelombola Waltram , Weng Yuejin , Qin Jun , Zhou Wei , Bhattarai Gehendra , Zia Bazgha , Yang Wei , Shi Linqi , Mou Beiquan , Shi Ainong
Published: October 2019

Previous investigations showed that accumulations of Na+ and Cl− in leaves resulted in reductions in chlorophyll content, thereby affecting photosynthesis. Understanding how chlorophyll content evolves over time will help plant breeders to select cowpea genotypes with better tolerance to salinity by allowing them to choose those with more stable chlorophyll content under salt stress. The objective of this study was to assess how the chlorophyll content of cowpea genotypes changed over the course of 24 d of salt stress at the seedling stage. A total of 24 cowpea genotypes with different salt responses were used in this study. The experiment used a split-plot design with salt treatment as the main plot and cowpea genotypes as the subplot. In the main plot, there were two salt treatments: 0 mm (ionized water) and 200 mm NaCl. In the subplot, the cowpea genotypes were arranged as a completely randomized design with three replicates per genotype. The results revealed that: a1) the time × genotype interaction was significant under conditions with and without salt; 2) chlorophyll content slowly decreased in the salt-tolerant genotypes; 3) chlorophyll content slightly increased on day 6 and day 9 of salt stress in both moderate and sensitive genotypes, but it decreased at a faster rate than in the salt-tolerant genotypes; and 4) salt-sensitive genotypes were completely dead on day 24 of salt stress, whereas the salt-tolerant genotypes were able to maintain a significant amount of chlorophyll content. These results can be used to advance breeding programs for salt tolerance in cowpea.
A Review of Turfgrass Fertilizer Management Practices: Implications for Urban Water Quality
Authors: Carey Richard O. , Hochmuth George J. , Martinez Christopher J. , Boyer Treavor H. , Nair Vimala D. , Dukes Michael D. , Toor Gurpal S. , Shober Amy L. , Cisar John L. , Trenholm Laurie E. , Sartain Jerry B.
Published: October 2019

Urban watersheds include extensive turfgrass plantings that are associated with anthropocentric attitudes toward landscapes. Native and construction-disturbed urban soils often cannot supply adequate amounts of nitrogen (N) and phosphorus (P) for the growth and beauty of landscape plants. Hence, fertilization of landscape plants is practiced. Mismanaged fertilization and irrigation practices represent a potential source of nutrients that may contribute to water quality impairment. This review focuses on turfgrass fertilization practices and their impacts on urban water quality. Research results show that fertilization during active growth periods enhances turfgrass nutrient uptake efficiencies. The major concern regarding the fertilization of turfgrass and landscape plants in urban watersheds, therefore, is selecting the proper combination of fertilizer rate, timing, and placement that maximizes nutrient utilization efficiency and reduces the risk for nutrient loss to water bodies. Encouraging individuals to adopt best management practices (BMPs) is a priority for watershed managers. Research has found that educational programs are an important part of changing fertilization habits and that education needs to be thorough and comprehensive, which is beyond the scope of many seminars and fact sheets currently in use.
The Effects of Nutrition Education and Gardening on Attitudes, Preferences, and Knowledge of Minority Second to Fifth Graders in the Rio Grande Valley Toward Fruit and Vegetables
Authors: Nolan Geralyn A. , McFarland Amy L. , Zajicek Jayne M. , Waliczek Tina M.
Published: October 2019

Child obesity has become a national concern. Obesity in children ages 6–17 years has more than doubled in the past 30 years. Only 20% of children today consume the recommended daily servings of fruit and vegetables. This trend is even more pronounced in minority populations. Past studies have reported a horticulture-based curriculum, including gardening, can improve children’s attitudes toward eating fruit and vegetables. To investigate whether children of a minority population can benefit from gardening combined with a curriculum on nutrition, research was conducted with elementary schools in a primarily Hispanic region of Texas. Elementary school teachers participating in this research agreed to have school gardens and complete all activities in a curriculum on nutrition provided to them through the Texas Agrilife Extension Service. One hundred and forty-one children in the participating schools completed a pre- and posttest evaluating their nutritional knowledge, preference for fruit and vegetables, and snack choices before and after a gardening program supplemented with nutrition education. Differences were detected between pre- and posttest scores for all three variables. After comparing pre- and posttest scores, it was concluded that gardening and nutritional instruction had a positive effect on students’ nutritional knowledge, fruit and vegetable preference (FVP), and snack choices.
Etiolation Improves Rooting of Bigtooth Maple Cuttings
Authors: Richards Melody Reed , Rupp Larry A.
Published: October 2019

Bigtooth maple (Acer grandidentatum) has potential as a small, water conserving landscape tree in western landscapes. This potential has been hindered in part by the difficulty in asexually propagating superior accessions. The ability of etiolation to enhance rooting of softwood cuttings of selected wild accessions was determined by grafting six accessions onto seedling rootstocks to use as stock plants. Etiolation was applied to stock plants by placing open-ended, black, velour, drawstring bags over the end of pruned shoots at bud swell allowing new shoots to develop and grow out the end of the bag while leaving the base of the shoot covered. In 2009 and 2010, cuttings from etiolated and nonetiolated shoots were treated with 4000 ppm indole-3-butyric acid (IBA) + 2000 ppm naphthaleneacetic acid (NAA), stuck in a premoistened 3 perlite:1 peat (by volume) rooting substrate and placed under intermittent mist. After 4 weeks, 89% (2009) and 85% (2010) of the etiolated cuttings rooted and only 47% (2009) and 17% (2010) of the nonetiolated cuttings rooted. Etiolated cuttings produced on average 11.3 (2009) and 7.2 (2010) roots per cutting and nonetiolated 2.1 (2009) and 0.5 (2010) roots per cutting. Etiolation, and its application through the use of black cloth bags, can be an effective way to increase the rooting of bigtooth maple cuttings and the availability of these plants for use in water conserving landscaping.
Foliar Applications of Plant Growth Regulators Affect Stem Elongation and Branching of 11 Kalanchoe Species
Authors: Currey Christopher J. , Erwin John E.
Published: October 2019

Our objectives were to assess the efficacy of various plant growth regulators (PGRs) on stem elongation and branching of 11 kalanchoe (Kalanchoe) species with ornamental characteristics: beauvard’s widow’s-thrill (K. beauvardii), K. glaucescens, lavender scallops or red-leaved kalanchoe (K. fedtschenkoi), K. longiflora, chandelier plant (K. manginii), marnier’s kalanchoe (K. marnieriana), K. millotii, flower dust plant (K. pumila), K. rosei, common kalanchoe or nentabos (K. rotundifolia), and K. streptantha. Foliar spray applications of deionized water, ancymidol (15−60 ppm), benzyladenine (75−300 ppm), chlormequat chloride (750−3000 ppm), daminozide (1250−5000 ppm), ethephon (250−1000 ppm), paclobutrazol (10−40 ppm), or uniconazole (5−20 ppm) were applied 2 weeks after plants were pinched. Stem length at the time of application and 4 weeks after applications and branch number were recorded. While effective chemicals and concentrations varied widely among species, paclobutrazol and uniconazole were identified as providing broad efficacy with respect to inhibition of stem elongation across all 11 species in this study. Additionally, benzyladenine and ethephon increased the number of branches for several species.
Automated Thinning Increases Uniformity of In-row Spacing and Plant Size in Romaine Lettuce
Authors: Chu Qingquan , Liu Jiangang , Bali Khaled , Thorp Kelly R. , Smith Richard , Wang Guangyao (Sam)
Published: October 2019

The low availability and high cost of farm hand labor make automated thinners a faster and cheaper alternative to hand thinning in lettuce (Lactuca sativa). However, the effects of this new technology on the uniformity of plant spacing and size as well as crop yield are not proven. Three experiments were conducted in commercial romaine heart lettuce fields in 2013 and 2014 in Imperial Valley, CA, to compare the effects of automated thinning and hand thinning on uniformity of in-row spacing, plant size, and crop yield. Overhead images taken at 1 week after hand thinning indicate that thinning 8 to 11 days earlier by automated thinners did not affect plant size compared with the hand thinning treatment. However, lettuce plants in the automated thinning treatment were larger than plants in the hand thinning treatment 2 to 3 weeks after hand thinning. Automated thinners increased the uniformity of in-row spacing, increased the percentage of plants with the desired in-row spacing of 24 to 32 cm, and almost completely removed plants with an undesirable in-row spacing of 4 to 20 cm. As a result, individual lettuce plant weight and heart weight from the automated thinning plots was significantly greater and plants were more uniform compared with the hand thinned plants. Despite increases in lettuce plant size and uniformity in all three experiments, yield benefits of automated thinning were only significant in one of the three experiments due to larger plant populations resulting from hand thinning. This study suggests that automated thinning increases lettuce plant size and uniformity and makes it possible for growers to increase plant population and crop yield by optimizing in-row spacing.
Effects of Paclobutrazol and Flurprimidol on Water Stress Amelioration in Potted Red Firespike
Authors: Rezazadeh Amir , Harkess Richard L. , Bi Guihong
Published: October 2019

This study evaluated the effects of paclobutrazol (PBZ) and flurprimidol on the morphological and physiological characteristics of potted red firespike (Odontonema strictum) under drought stress. PBZ and flurprimidol were applied as a soil drench at 0.24 mg/pot. Untreated plants acted as a control. The plants were exposed to drought stress 2 weeks after plant growth regulator (PGR) application. Another group of plants treated with PGRs was watered regularly. A reduction in plant height, plant diameter, and growth index (GI) was observed in plants treated with PGRs and drought stress 5 weeks after beginning the study. Drought stress reduced plant height by 45% compared with control. Flurprimidol under drought stress decreased plant diameter and GI by 36% and 76%, respectively, compared with the control. The least leaf area and plant dry weight were observed in plants drenched with flurprimidol and grown under drought stress. Drought stress also delayed flowering and the number of plants flowering. Plants treated with PBZ had the highest photosynthesis rate, 54% more than untreated plants under drought stress alone. The lowest stomatal conductance (gS) was measured in plants under drought stress alone or drought plus PBZ. Application of PBZ-enhanced red firespike drought tolerance reducing adverse effects of water stress on photosynthesis during the experiment.
Efficient Breeder Seed Production Utilizing Ethephon to Promote Floral and Fruit Abscission in Ornamental Chile Peppers
Authors: Barchenger Derek W. , Coon Danise L. , Bosland Paul W.
Published: October 2019

Controlled abscission of floral structures is an important horticultural technique that has many applications throughout the growing season. A novel use of chemical abscission in chile pepper (Capsicum annuum) is the removal of open flowers and fruit for the production of breeder seed. For efficiency of abscising flower buds, open flowers, and fruit of ornamental chile peppers, two foliar spray treatment levels, 1000 and 2000 ppm ethephon were tested. Ornamental chile peppers were chosen because they are prolific flower and fruit producers, making removal of potentially cross-pollinated fruit and open flowers laborious. Flower bud and flower number were reduced with both 1000- and 2000-ppm ethephon treatments, while fruit number decreased only with 2000-ppm ethephon treatment. ‘NuMex Easter’ was more sensitive to ethephon treatment as compared with ‘Chilly Chili’ and ‘Riot’. Ethephon had no negative impacts on end of the season growth index, mature fruit number, and seed number. We found ethephon can reduce numbers of flower buds, open flowers, and fruit with no long-term effect on mature fruit and seed number, making it a useful tool for the production of breeder seed in chile pepper breeding programs.
Propagation Techniques and Grafting Modify the Morphological Traits of Roots and Biomass Allocation in Avocado Trees
Authors: Fassio Claudia , Cautin Ricardo , Pérez-Donoso Alonso , Bonomelli Claudia , Castro Mónica
Published: October 2019

Root morphological traits and biomass allocation were studied in 2-year-old ‘Duke 7’ avocado (Persea americana) trees propagated using seedling and clonal techniques. The plants either were or were not grafted with the scion ‘Hass’. Whole tree excavation 1 year after planting revealed that the propagation technique affected the root growth angle of the main roots (third order roots), the root length density (defined as the total length of roots per volume of soil), and the number of first and second order roots present. The root system of clonal trees showed a typical morphology of rooted cuttings, with a crown of roots originating from a relatively short stem, resulting in a shallow root system. Clonal trees, compared with seedlings, produced main framework roots with shallower angles and more fine roots (first and second order roots) that increased the root length density (defined as the total length of roots per volume of soil). Nongrafted seedlings exhibited a main taproot and lateral roots with narrow angles that penetrated deeper into the soil and increased the aboveground biomass but had a lower root-to-shoot ratio than nongrafted clonal trees. The grafting of both clonal and seedling trees resulted in similar root architecture and revealed that grafting significantly decreased the soil volume explored and the shoot and root biomass. Although both root systems were shallow, grafted clonal trees had a higher root-to-shoot ratio than grafted seedlings. In this study, a distinct class of roots with large diameter and unbranched growth was more abundant in the root systems of clonal trees. These types of roots (previously undescribed in avocado trees), called pioneer roots, may enhance soil exploration in clonal trees.
Importance of Horticulture and Perception as a Career
Authors: Meyer Mary H. , Needham Douglas , Dole John , Trader Brain , Fox Jennifer , Conley Marnie , Neff Michael , Shaw Jean
Published: October 2019

The American Society for Horticultural Science (Alexandria, VA) and Longwood Gardens (Kennett Square, PA) engaged FleishmanHillard (FH, Washington, DC), a nationally recognized communications and marketing firm, to conduct research with internal and external audiences to determine the public perception of horticulture and careers in horticulture. Through stakeholder focus groups and general public online and phone surveys, the importance of horticulture, career perceptions, and the need for the promotion of horticulture were examined. Students, faculty, industry, and administrators in horticulture have a broad understanding of the field, much more than the public, especially young, ethnically diverse, and lower income participants. Although lack of public awareness is one of the biggest challenges in horticulture, it is also its greatest opportunity. Sixty-five percent of all phone survey participants as compared with 41% of 18–24 years old revealed a general awareness of the word horticulture. General public found agreement (48% to 59%) with four statements about the essential, universal, and invaluable worth of horticulture; however, strong agreement was less, ranging from 26% to 46%. Only 26% of respondents felt strong agreement with the statement, “Horticulture is a diverse area of study, and it offers viable, fulfilling, and respected career paths that I would recommend to others.” The research found strong stakeholder support for a national promotion of horticulture.
The Next Ten Years: Strategic Vision of Water Resources for Nursery Producers
Authors: Fulcher Amy , LeBude Anthony V. , Owen James S. , White Sarah A. , Beeson Richard C.
Published: October 2019

Nursery and greenhouse producers, research and extension faculty, and representatives from allied fields collaborated to formulate a renewed vision to address water issues affecting growers over the next 10 years. The authors maintained the original container irrigation perspective published in “Strategic vision of container nursery irrigation in the next ten years,” yet broadened the perspective to include additional challenges that face nursery crop producers today and in the future. Water availability, quality, and related issues continue to garner widespread attention. Irrigation practices remain largely unchanged due to existing irrigation system infrastructure and minimal changes in state and federal regulations. Recent concerns over urbanization and population growth, increased climate variability, and advancements in state and federal regulations, including new groundwater withdrawal limitations, have provided an inducement for growers to adopt efficient and innovative practices. Information in support of the overarching issues and projected outcomes are discussed within.
Late-season Plastic Canopy Covers Affect Canopy Microclimate and Fruit Quality of ‘Autumn King’ and ‘Redglobe’ Table Grapes
Authors: Fidelibus Matthew W. , Vasquez Stephen J. , Kurtural S. Kaan
Published: October 2019

California table grape (Vitis vinifera) growers cover the canopies of late-season varieties with plastic (polyethylene) covers to shield the fruit from rain. Green- or white-colored covers are commonly used, but there is lack of information whether either cover might be preferable based on canopy microclimate or fruit quality. In late September, ‘Redglobe’ (in 2011) and ‘Autumn King’ (in 2012) table grapevines were covered with green or white plastic, or left uncovered, and canopy microclimate, fungal and bacterial rot incidence, and fruit yield and quality at harvest, and after postharvest storage, were evaluated. Green covers were more transparent and less reflective than white covers, and daily maximum temperature difference in the top center of the canopies of grapevine with green covers was consistently >5 °C than that of grapevine subjected to other treatments, but covers had little effect on temperatures in the fruit zones, which were not enveloped by covers. Effects on relative humidity (RH) depended on location within the canopy and time of day; RH peaked in early morning and was at a minimum in late afternoon. All cover treatments had relatively similar peak RH in south-facing fruit zones and the top center of the canopy. However, in the north-facing fruit zone, vines with green covers had higher RH at night than vines subjected to other treatments. Both covers consistently reduced evaporative potential in the top center of the canopy, but not in fruit zones. Treatment effects on condensation beneath the covers were inconsistent, possibly due to differences in canopy size, variety, or season, but south-facing cover surfaces generally had less condensation than the top or north-facing surfaces. About 0.5 inch of rain fell on 5 Oct. 2011, but no rain occurred during the 2012 experiment. In 2011, green covers delayed fruit maturation slightly, but not in 2012. Covers did not affect vineyard rot incidence, the number of boxes of fruit harvested, or postharvest fruit quality in 2011, but fruit from covered grapevine had less postharvest rot in 2012 than fruit from noncovered grapevines, even though a measurable rain event occurred in 2011 but not in 2012. In conclusion, our results suggest that white covers may be preferable to green since green covers were associated with higher temperatures in both seasons and higher RH in the ‘Autumn King’ trial of 2012, but otherwise performed similarly.
Strategies to Provide Fertilizer for Both Production and Consumer Phases of Petunia
Authors: de Oliveira Sueyde F. , Fisher Paul R. , Huang Jinsheng , Mello Simone da C.
Published: October 2019

The objective of this study was to compare strategies using water-soluble fertilizers (WSF) and controlled-release fertilizers (CRF) to provide adequate nutrition during both production and consumer phases of petunia (Petunia ×hybrida). Strategies included a CRF with a second prill coating (DCT) that delayed initial nutrient release, compared with a conventional single-coated CRF (OSM) and WSF. Rooted cuttings of petunia were grown for 42 days in trade 1-gal (2.84-L) containers (the “production phase”) with WSF only, a low rate of combined WSF and substrate-incorporated OSM, or low and high label rates of WSF and top-dressed (TD) OSM (WSF + OSM TD), WSF and substrate-incorporated DCT (WSF + DCT), OSM, or a commercial blend of substrate-incorporated OSM and DCT (OSM + DCT). By the end of production phase after 42 days, all fertilizer strategies tested produced horticulturally acceptable plants in terms of chlorophyll index and number of flowers. In a subsequent “consumer phase,” plants were maintained in containers or were transplanted into a landscape and irrigated with clear water for 98 days. Plant performance [number of flowers, SPAD chlorophyll index, dry weight, and tissue nitrogen (N) level] was greater during the consumer phase in treatments with high rates of CRF compared with WSF only or lower rates of CRF. On the basis of nutrient release in a sand substrate without plants at 10, 21, or 32 °C, the DCT had delayed nutrient release compared with single-coated CRF. The release rates of all CRF products and the duration of the delay in release from DCT were temperature dependent. A partial budget found that the lowest cost treatment was WSF only at $0.02/container. Comparing at high application rates, using WSF + DCT ($0.085/container) was more expensive than incorporated OSM ($0.05/container) and had a similar cost to WSF + OSM TD ($0.084/container). The greatly improved consumer performance for plants with residual fertilizer compared with WSF provides an opportunity to add value and profitability if a slightly higher sales price could be obtained. Several fertilizer strategies are available depending on material and labor cost and availability and preferred crop management style.
Reviewing the Commercial Potential of Hand Thinning in Citrus with a Cost-benefit Analysis of Summer Hand Thinning of ‘Nadorcott’ Mandarin
Authors: Stander Ockert P.J. , Cronjé Paul J.R.
Published: October 2019

Hand thinning is not often applied as a commercial cultural practice in citriculture due to the practice’s reliance on costly manual labor. However, hand thinning could provide unique benefits such as treatment selectivity and easier control over thinning intensity, as opposed to foliar sprays of chemical thinning agents. In “on-year” ‘Nadorcott’ mandarin (Citrus reticulata) trees, summer (January) and autumn (April) hand-thinning treatments of removal of all fruit <20 and <40 mm diameter were evaluated for effects on leaf carbohydrates and fruit growth rate. Other factors assessed included treatments’ effects on tree total fruit yield, fruit quality, and fruit size distribution. In addition, two different summer hand-thinning treatments (removal of all fruit <20 and <25 mm) were evaluated for effects on fruit size distribution and fruit yield over two seasons to determine their potential financial implications. Summer hand thinning reduced the numbers of small fruit and increased initial growth rate of prevailing fruit. This resulted in larger numbers of premium-sized fruit per tree, without treatments reducing total fruit yield and fruit quality. Additional labor was eliminated by quicker picking of fruit during harvest, and in season 2, fruit yield was higher for summer hand-thinning treatments compared with control. A higher potential income resulted from change in fruit size distribution and the breaking of alternate bearing over the 2-year period. The results provide producers of late mandarin cultivars with an alternative to chemical thinning agents to manage crop load and improve fruit size in individual “on-year” trees.
Yield, Quality, and Storage Characteristics of Onion Cultivars in the Columbia Basin of Washington in 2012–14
Authors: Wohleb Carrie H. , Waters Timothy D.
Published: October 2019

An onion (Allium cepa) cultivar trial is conducted in the Columbia Basin of Washington every year. The trial helps onion growers, packers, processors, and seed companies compare cultivars and identify those most suited to their operations. This report evaluates 54 onion cultivars that were in the trials 2 years or more from 2012 to 2014. Marketable yields of cultivars averaged 764 to 1314 cwt/acre. ‘TTA-747’, ‘Scout’, ‘SV6672NW’, ‘Montero’, ‘XP07716000’, and ‘SV4058NV’ had the highest yields. All cultivars produced more jumbo-sized (3 to 4 inches) bulbs compared with any other size category, but those with the largest percentages of jumbo bulbs were Utrero, Gunnison, and Sedona. ‘Scorpion’, ‘Ruby Ring’, and ‘Purple Haze’ had the largest percentages of medium (2.25 to 3 inches) bulbs, and ‘Montero’ and ‘Ovation’ had the largest combined percentages of jumbo and colossal (>4 inches) bulbs. Cultivar differences were evident in the 2012 and 2014 trials when many of the onions flowered (bolted). Cultivars averaged 0.0 to 15.5 bolted onions per plot when 2012 and 2014 results were combined. ‘Trekker’, ‘Highlander’, ‘Trailblazer’, ‘Ruby Ring’, ‘NUN8003ON’, and ‘Milestone’ had the fewest bolted onions. Cultivar differences were also apparent when several aspects of bulb quality were evaluated after 4 months in storage. ‘Utrero’, ‘Trekker’, ‘NUN7202ON’, and ‘Tamara’ had the most uniformly shaped bulbs. Bulbs of ‘Crockett’, ‘Legend’, and ‘Utrero’ had the most complete skins. ‘Crockett’, ‘Talon’, ‘Utrero’, ‘Legend’, ‘Gunnison’, and ‘Tamara’ had the firmest bulbs. Only 14 of 54 cultivars averaged more than 74% functionally single-centered bulbs. ‘NUN7202ON’, ‘Arcero’, ‘Joaquin’, and ‘Utrero’ had the largest percentages of bulbs with single centers or small multiple centers. There were more rots caused by bacteria (Enterobacter sp.) in bulbs produced in the 2014 trial than in 2012 and 2013, probably due to a high incidence of internal dry scale in 2014. Incidence of bacterial rot in cultivars was not significantly different in 2014, but there were some cultivar differences in 2012 and 2013. Incidence of fungal neck rot (caused by Botrytis sp.) in these trials was low and there were no significant cultivar differences. The results of these trials demonstrate that many new and advanced experimental cultivars have attributes that could make them a good choice for onion growers in the Columbia Basin.
Spectral Characteristics of Citrus Black Spot Disease
Authors: Pourreza Alireza , Lee Won Suk , Ritenour Mark A. , Roberts Pamela
Published: October 2019

Citrus black spot (CBS) is a fungal disease caused by Phyllosticta citricarpa (synonym Guignardia citricarpa). CBS causes fruit lesions and significant yield loss in all citrus (Citrus) species. The most distinguishing CBS symptom is called hard spot, which is a circular lesion with gray tissue at the center surrounded by a black margin. The spectral characteristic of CBS lesions was investigated and compared with the spectral signature of healthy fruit tissue to determine the best distinguishing wave band. Healthy and CBS-affected samples presented similar reflectance below 500 nm and above 900 nm. However, healthy samples reflected more light between 500 and 900 nm, especially within the visible band. Also, spectral reflectance of the same symptomatic lesion was acquired six times over a 2-month period to determine the variation of symptom’s spectral signatures over time after being harvested. A two-sample t test was employed to compare each pair of consecutive repetitions. The results showed that the spectral signature of the CBS lesion did not change significantly over 2 months. The wavelengths between 587 and 589 nm were identified as the distinguishing band to develop a monochrome vision–based sensor for CBS diagnosis. A support vector machine (SVM) classifier was trained using the spectral reflectance data at the selected bands to identify CBS-affected samples in each repetition. The overall CBS detection accuracies varied between 93.3% and 94.6%.
Microclimate and Scion Leaf Removal to Improve the Success of Grafted Tomato Seedlings
Authors: Masterson Sarah A. , Kennelly Megan M. , Janke Rhonda R. , Rivard Cary L.
Published: October 2019

The utilization of grafted tomato (Solanum lycopersicum) plants in the United States shows significant promise, particularly as intensively managed production systems like high tunnels and greenhouses become more popular. However, the availability of grafted plants in the United States is currently a major barrier and a large portion of farmers who would like to use grafted plants would prefer to propagate their own. The objectives of this study were to determine how healing chamber design affects graft survival and microclimate, and to investigate how scion leaf and shoot removal affects graft survival in various healing chambers. Similar experiments were repeated at two locations in Kansas and a split-plot, randomized complete block design (RCBD) was used in each, with three and four replications being conducted over time at each of the locations. Five chamber treatments were tested including a negative control (none) as well as shadecloth alone, white vinyl mesh, polyethylene film and shadecloth, and polyethylene film with shadecloth and a cool-mist humidifier. No statistically significant effects of chamber design were seen on grafted plant success. However, microclimate data from the various healing chambers offer valuable data toward determining the best management practices for grafted plants. Shadecloth alone showed significant promise as this covering provided cooler temperatures during the afternoon when the healing chambers were prone to excessive heat buildup. Three tube-grafting methods were tested, including standard tube-grafted plants (no leaves removed), leaf removal (LR) plants (≈75% of the leaf surface area was removed from the scion), and shoot removal (SR) plants (the apical meristem and all true leaves were removed). The SR method did not affect graft survival, but the LR method increased grafting success from 78% to 84% and was significant as compared with the other methods (P < 0.05). The long-term goals of this work are to develop successful propagation systems that can be used by small-acreage growers with limited greenhouse facilities. The data presented here indicate that high-humidity healing chambers (>85% relative humidity) may not be necessary for tomato, and LR can increase the grafting success rate.
Effects of Foliar Potassium Fertilization on Fruit Growth Rate, Potassium Accumulation, Yield, and Quality of ‘Kousui’ Japanese Pear
Authors: Shen Changwei , Ding Yifei , Lei Xiqiong , Zhao Peng , Wang Shuo , Xu Yangchun , Dong Caixia
Published: October 2019

A field experiment was conducted over three growing seasons (2012–14) to study the effect of the foliar application of different potassium (K) fertilizers [potassium phosphate monobasic (KH2PO4), potassium nitrate (KNO3), and humic acid potassium (HAK)] on the fruit growth rate, yield, and quality of ‘Kousui’ japanese pear (Pyrus pyrifola) trees. Except the first year of study, foliar application of K fertilizers generally led to an increase in the concentration of fruit total soluble sugar, titratable acidity (TA) and sweetness, along with an elevated K accumulation in leaf and fruit at maturity. In 2013 and 2014, compared with the control, KNO3 treatment led to an average 16% higher yield, and HAK led to an average 15% higher soluble solid content (SSC). Furthermore, HAK resulted in 26% higher yield in 2014. KNO3 treatment showed 19% higher leaf K concentration, 38% leaf K accumulation, and 43% fruit K accumulation in maturity than the control in 2014. Different effects were found on the concentration of specific types of sugar and organic acid, of which fructose and malate were consistently increased by the K application. With regard to the amino acids, KNO3 and HAK treatments led to a significant increase in the concentration of aspartic acid, which was 12% and 22% higher than the control, respectively. In conclusion, foliar application of KNO3 is an efficient way to increase ‘Kousui’ japanese pear fruit yield, whereas spraying HAK is an effective way to improve the fruit quality.
High-efficiency Propagation of Mature ‘Washington Navel’ Orange and Juvenile ‘Carrizo’ Citrange Using Axillary Shoot Proliferation
Authors: De Oliveira Maria Luiza , Thomson James G. , Stover Ed
Published: October 2019

In vitro axillary shoot proliferation can be used to increase availability of citrus (Citrus) types in high demand, while limiting somaclonal variation. However, established protocols could be improved to increase efficiency. Therefore, this study investigated some factors [plant growth regulators (PGRs), basal media, and successive subculturing] which affect the in vitro axillary shoot proliferation of mature ‘Washington Navel’ orange (Citrus sinensis) and juvenile ‘Carrizo’ citrange (C. sinensis × Poncirus trifoliata). In ‘Washington Navel’ orange, maximum axillary shoot induction (66.9% explants producing axillary shoots with a mean of 2.45 shoots per explant) was obtained in Driver and Kuniyuki walnut (DKW) medium supplemented with 0.1 mg·L−1 6-benzylaminopurine (BA), 0.05 mg·L−1 naphthalene acetic acid (NAA) along with 1 mg·L−1 6-furfurylaminopurine [kinetin (kin)], whereas in ‘Carrizo’ citrange, axillary shoot production was greatest (82.6% and 87.5% of explants producing axillary shoots with a mean of 4.3 and 4.1 shoots per explant) at 1.0 or 2.0 mg·L−1 BA in DKW medium. The initial nodal propagules (with basal tissue remaining from removed shoots) were repeatedly subcultured for six times every 4 weeks onto DKW medium with the same levels of PGRs used for initial culturing. Woody plant medium (WPM), Murashige and Skoog medium (MS), and DKW were also compared for rooting at quarter to full strength for salt components, all amended with 2.0 mg·L−1 indolebutyric acid (IBA) and 0.5 mg·L−1 NAA. MS at full strength provided the highest rooting in ‘Carrizo’ citrange (93%) and longest root length (58 mm), whereas half-strength MS provided the highest rooting in ‘Washington Navel’ orange (60% to 61%) and the longest roots (26 mm). Addition of 1 μm spermidine to the rooting medium enhanced root length only for ‘Washington Navel’ orange on full-strength MS, but accelerated rooting for both cultivars on all media. The plantlets were successfully transferred to greenhouse conditions, exhibiting normal development, with high uniformity, and no evidence of somaclonal variation.
Planting Time and Flurprimidol Treatment Influence the Growth and Flowering of Lachenalia
Authors: Kapczyńska Anna , Malik Małgorzata
Published: October 2019

The growth and flowering of ‘Rupert’ and ‘Ronina’ lachenalia (Lachenalia) in a greenhouse environment were manipulated by varying planting times and flurprimidol treatments. Bulbs were planted in November, December, January, and February. At each planting date, the following flurprimidol treatments were tested: soaking the bulbs before planting (15 and 30 mg·L−1) or a single foliar spray (15, 30, 45, and 60 mg·L−1). The results showed that foliar application of flurprimidol was ineffective in controlling inflorescence stem height and inflorescence length; only soaking bulbs of ‘Rupert’ in flurprimidol at the concentration of 30 mg·L−1 shortened the inflorescence stem height. Moreover, soaking bulbs in the concentration of 30 mg·L−1 may be recommended for potted lachenalia production, as shorter and wider leaves were obtained and every planted bulb emerged and flowered. The later the date of planting of the bulbs, the more quickly the plants began to flower. As planting time was delayed, inflorescence stem length and leaf length decreased, and the number of florets and leaf width increased. Soaking the bulbs in the retardant (30 mg·L−1) delayed the emergence of flowers for 5–6 days, but the retardant did not affect the number of leaves or the number of florets per inflorescence. Regardless of the factors applied, the two cultivars of lachenalia differed with respect to each of the analyzed traits.
Fostering Creativity in the Horticulture Classroom
Authors: Pritts Marvin , Eames-Sheavly Marcia
Published: October 2019

Creativity is considered important for success in most disciplines. Research has shown career accomplishment to be more correlated with scores of creativity than with standard measures of intelligence. Creativity is positively correlated with one’s ability to adapt to new situations and succeed in today’s world. Horticulture provides a rich context for creative expression, given that it lies at the intersection of science, art, and the humanities. Yet, fostering creativity is often not emphasized in plant science curricula nor identified as a central learning objective. The goals of this paper are to help instructors identify practices that promote creative expression in their classrooms, offer examples of classroom exercises that allow students to express creativity within a plant science context, and provide direction for assessment. From the literature, we identified 10 criteria that characterize behaviors, practices, and attitudes that are considered components of creativity. Then, we shared these criteria with the horticulture faculty at Cornell University, asking for examples of classroom exercises in which these creativity criteria are reflected. Through our observations of submitted examples and comments from instructors, it is clear that class activities that promote creative thought are prevalent, but often not recognized as such by instructors. Classroom norms emphasize scientific knowledge and vocational skills, but it is not the norm to openly promote, encourage, and enhance creative skill use and development. Assessing creativity in students is challenging because there are no widely accepted criteria for evaluating it, and defining exactly what to measure can be subjective. We provide suggestions for how to think about assessing creativity in the classroom.
Low-dose Application of Nonionic Alkyl Terminated Block Copolymer Surfactant Enhances Turfgrass Seed Germination and Plant Growth
Authors: Madsen Matthew D. , Fidanza Michael A. , Barney Nicholas S. , Kostka Stanley J. , Badrakh Turmandakh , McMillan Mica F.
Published: October 2019

Rapid seed germination and vigorous seedling growth are desired when establishing turfgrass lawns from seed. Low-dose concentrations of nonionic, block copolymer surfactants can have a direct effect on plant physiological functions and growth. The objectives were to determine if a low-dose application of a nonionic alkyl ended block copolymer surfactant applied directly to the seed, within a film coating, would 1) influence speed, synchrony, and final germination percentage (FGP), and 2) enhance seedling emergence and the speed of turfgrass establishment under deficit irrigation. Tests were performed with tall fescue (Schedonorus arundinaceus) and perennial ryegrass (Lolium perenne). Surfactant was applied directly to the seed using a rotary seedcoater at 0.1% by weight of seed. In the first experiment, germination was compared between seeds with a surfactant film coating (SFC) and untreated seeds in growth chambers at three different constant temperatures (10, 20, and 30 °C). For both species, the SFC decreased the time for seed germination, and improved germination synchrony, with the greatest treatment response at 10 and 30 °C compared with untreated seed. Application of a SFC did not influence FGP. In the second experiment, untreated and treated seed were compared in a grow-room study, with pots watered weekly to 70% of field capacity (FC). Perennial ryegrass density, cover, and aboveground biomass from the SFC were ≈47%, 48%, and 46% greater than untreated seed, respectively. Tall fescue density, cover, and aboveground biomass from the SFC seeds were ≈22%, 23%, and 28% greater than untreated seed, respectively. Overall these studies demonstrate that SFC can promote seed germination and also enhance turfgrass establishment under deficit irrigation.
Nitrogen Fertilization Strategies for the ‘Hass’ Avocado that Increase Total Yield Without Reducing Fruit Size
Authors: Salvo Jaime E. , Lovatt Carol J.
Published: October 2019

Effects of nitrogen (N) fertilizer application times and rates on ‘Hass’ avocado (Persea americana) yield and fruit size were determined to resolve whether a single dose of soil-applied N [1x N (25 lb/acre)] at each of the five key stages of tree phenology (January, April, July, August, and November) (control) was as efficacious as soil-applied 2x N (50 lb/acre) at one or two key stages or soil- or foliar-applied 3x N (75 lb/acre) at only one stage. All trees received soil-applied N at 125 lb/acre as ammonium nitrate (NH4NO3) annually; trees receiving 2x or 3x N received the remaining N divided evenly at the same phenological stages (months) as trees receiving five 1x N applications. The importance of supplying N during the summer, when June drop, exponential fruit growth, vegetative shoot growth, and floral initiation occur, was determined by testing soil-applied 0.8x N in July plus August only (40 lb/acre N as NH4NO3 annually). Application time proved an important determinant of total yield. Yield of commercially valuable size (CVS) fruit was correlated with total yield (r = 0.80, P < 0.0001). Four-year cumulative total yields were equal for trees receiving soil-applied 1x N at five key phenological stages and trees receiving soil-applied 2x N in April and 18.75 lb/acre N at the four other stages (months). However, trees receiving soil-applied 2x N in April plus November and only 8.3 lb/acre N in the three other months, in particular July and August, had significantly lower 4-year cumulative total yields (P = 0.0362). Additional evidence of the importance of meeting avocado tree N demand in the summer is that trees receiving only 40 lb/acre N split in July plus August produced 4-year cumulative total yields equal to trees receiving 25 lb/acre N at the five key phenological stages; lower annual N would reduce fertilizer expense and protect the environment.
Evaluation of Antitranspirants for Enhancing Temporary Water Stress Tolerance in Bedding Plants
Authors: Park Suejin , Mills Sarah A. , Moon Youyoun , Waterland Nicole L.
Published: October 2019

Water stress during shipping and retailing reduces the postproduction quality and marketability of bedding plants. Antitranspirants can temporarily prevent plants from wilting by either physically blocking stomata or physiologically inducing stomatal closure, limiting transpirational water loss from leaves. The goal of this research was to evaluate the efficacy of commercially available antitranspirants on enhancing temporary water stress tolerance in bedding plants. Two physical antitranspirants [β-pinene polymer (βP) and vinyl-acrylic polymer (VP)], and three physiological antitranspirants [two sugar alcohol-based compounds (SACs) and a biologically active form of abscisic acid (s-ABA)] were applied to begonia (Begonia semperflorens-cultorum), new guinea impatiens (Impatiens hawkeri), impatiens (Impatiens walleriana), petunia (Petunia ×hybrida), african marigold (Tagetes erecta), and french marigold (Tagetes patula). Physical antitranspirants were sprayed on foliage and physiological antitranspirants were drenched to the media. All antitranspirants were applied at half (0.5×), equal to (1×), or twice (2×) the manufacturer’s recommended rate. Extended shelf life was observed when βP or s-ABA was applied. Treatment with βP increased the shelf life of impatiens and african marigold by 1 and 1.3 days compared with control plants, respectively. The application of βP at 2× was more effective at delaying visual wilting than at lower rates (0.5× and 1×) in african marigold. Applications of s-ABA delayed wilting by 1.3 to 3.7 days in all tested cultivars. The shelf lives of impatiens and petunia treated with s-ABA at 2× were extended the most by 3.7 and 3.0 days compared with control plants, respectively. A rapid reduction of stomatal conductance (gS) was observed within 4 hours of βP or s-ABA application in plants showing delayed wilting symptoms. s-ABA treatment appeared to cause marginal leaf chlorosis in impatiens, whereas application of βP damaged the opened flowers in all tested cultivars. The application of VP or SACs did not extend shelf life in any treated plants. These results suggest that foliar application of βP on selected species and treatment with s-ABA on most of species would allow bedding plants to withstand water deficit during shipping and/or retailing.