bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Gamete Selection for Heat Stress and Cool Temperature Tolerance
Authors: Blischak* Leslie , Veilleux Richard. E.
Published: February 2019

Gamete selection was examined as a breeding tool in developing Phalaenopsis hybrids that are more cool or warm temperature tolerant. Four pairs of hybrid cultivars of Phalaenopsis were cross-pollinated, and then exposed to two temperature extremes, 30 °C / 25 °C and 14 °C/9 °C, during pollen tube development and subsequent fertilization. One of each pollinated orchid cultivar was placed in either of two growth chambers and exposed to an 11-h photoperiod with an irradiance of 180 μmol·m-2·s-1 and a relative humidity of 70% during the day and 50% at night for 3-7 days depending on the temperature treatment. The plants were returned to the greenhouse after the initiation of fruit set and the pods were collected after 150 days. Seeds collected from these treatments were surface-sterilized, placed on Phytamax medium and evaluated for protocorm development after 73 days on a thermogradient table ranging from 10 to 30 °C. For the first family for which reciprocal crosses were available, the number of protocorms per plate ranged from 0 in the coldest treatments to 290 at 28 °C. For cold pollinated seeds, protocorm development was optimum at 22 and 28 °C (means of 290 and 250 protocorms per plate, respectively) whereas the greatest protocorm development for warm pollinated seeds occurred at 20 °C (103 protocorms per plate). Of the 1471 total protocorms scored, 1095 were from cold pollinations, whereas 376 were from the warm pollinations. Additional replication is required to confirm the greater germinability of cold-pollinated seed at higher temperatures.
Inheritance of Resistance to the Watermelon Strain of Papaya Ringspot Virus in Watermelon
Authors: Guner* Nihat , Pesic-VanEsbroeck Zvezdana , Wehner Todd
Published: February 2019

Sources of resistance to the watermelon strain of papaya ringspot virus (PRSV-W) have been identified within the watermelon (Citrullus lanatus) germplasm collection. Inheritance of resistance to papaya ringspot virus-watermelon strain was studied in three C. lanatus var. citroides accessions: PI 244017, PI 244019, and PI 485583. The susceptible parent lines `Allsweet', `Calhoun Gray', and `New Hampshire Midget' were crossed with resistant accessions to develop F1, F2, and BC1 generations for six families. A single recessive gene was found to control resistance to PRSV-W. The gene symbol `prv' is proposed for PRSV-W resistance in watermelon. Additional work is needed to determine whether the genes in PI 244017, PI 244019, and PI 485583 are allelic for resistance to PRSV-W.
The Effect of IBA on Rooting of Semi-hardwood Cutting of Three Selected Local Olive Genotypes of Kermanshah Province, Iran
Authors: Talaie* Alireza , Zohouri Majid
Published: February 2019

The experiment was carried out to study the effect of IBA hormones on rooting systems of selected local olive genotypes in Kermanshah province, Iran. This work was designed as a factorial experiment in a complete randomized block with three replications and 10 cuttings in each treatment. The effects of IBA hormone concentrations i.e.: 4000, 3000, 2000 and 1000 PPM in three selected local genotypes of bn42, dd9, D1, and Zard genotype as controlled were studied and compared. The results showed that the ultimate root length was obtained in genotypes bn42, D1, and Zard with application of 3000 PPM concentration and average numbers of roots in genotypes of bn42, dd9, and D1 with 4000 PPM concentration were observed. The average of the longest roots was found in genotype bn42, dd9, D1 and Zard with 3000 PPM concentration, and the average of the highest root number in bn42 and Zard with the concentration of 3000 PPM in genotype dd9, and D1 with 4000 PPM concentration. The highest percentage of rhyzogenesis was observed genotypes of bn42 and dd9 with 2000 PPM concentration and in the genotypes D1 and Zard with 4000 PPM concentration. The average root length was increased consequently in genotypes bn42, D1, Zard, and dd9. The sequence of rhyzogenesis percentage was obtained in bn42, Zard, D1, and dd9. Dry weight percentage was also obtained in genotypes bn42, Zard, D1, and dd9, respectively.
Effects of Three Levels of Midday Stem Water Potential on Chandler Walnut Growth and Yield in California
Authors: Buchner* Richard P. , Fulton Allan , Lampinen Bruce , Shackel Ken , Prichard Terry , Schwankl Larry , Metcalf Sam , Little Cayle
Published: February 2019

Ninth leaf California Chandler Walnuts (Juglans regia) on Northern California Black (Juglans hindsii) or Paradox (English/black hybrid) rootstock were irrigated to achieve three levels of Midday Stem Water Potential (MSWP). Target potentials were: 1) low water stress (average MSWP of -3.2 bars); 2) mild water stress (average MSWP of -6.2 bars); and 3) moderate water stress (average MSWP of -7.3 bars). Stem Water Potential was measured midday (12-4 pm) by placing leaves inside water impervious, light blocking foil bags. Leaves remained bagged for at least ten minutes to achieve equilibrium. Bagged leaves were removed, placed inside a pressure chamber and stem water potential was measured at endpoint. Data are presented for the 2002 and 2003 seasons. Withholding irrigation water had a significant impact on `Chandler' growth, productivity, and profitability particularly on young, vigorously growing trees. Chandler/Black appears to be more tolerant to water stress compared to Chandler/Paradox For Chandler on Paradox, water stress significantly reduced growth, yield, price per pound, percent edible kernel, and resulted in darker kernels. In addition, water stress significantly increased the total percent offgrade. Withholding irrigation does not appear to be a good strategy in young, vigorously growing `Chandler' orchards. Mature trees and trees grafted onto Northern California black rootstock may be more tolerant of moisture stress.
Defoliating Lilac Seedlings in Field Production
Authors: Cregg* Bert
Published: February 2019

Lilac (Syringa vulgaris L) seedlings are commonly grown in many seedling nurseries in Michigan. Typically seedlings are lifted in the fall and stored prior to shipment or stored by the customer. A major problem in field production of lilacs is that seedlings often retain their leaves late in the fall. If the leaves are not removed prior to storage or shipment, the seedlings will mold and deteriorate. Therefore, growers must spend additional labor to remove the leaves, often by hand. The goal of this research was to evaluate chemical alternatives to defoliate lilac seedlings in field nurseries. Two on-farm research trials were conducted in 2001 and 2003 in cooperation with a seedling grower in Saugatuck, MI. In Experiment 1, Florel (1/2 and ¼ dilution) and chelated copper (0.5% and 1% solution) were sprayed by and onto lilac in the seedling bed. Florel and chelated copper effectively reduced leaf area of lilac seedlings. Less than 20% of the initial leaf area remained on the 1% copper and ½ Florel-treated seedlings. The ½ Florel and 1% chelated copper completely defoliated 67% and 40% of the seedlings, respectively, whereas only 17% on the control seedlings lost all their leaves prior to lifting. Both levels of Florel and the 1% copper treatment reduced growth of seedlings after planting. In experiment 2, we applied chelated copper treatments at varying rates (0.25% and 0.5%) and times (1 application and 2 applications) using the cooperators' spray equipment. Repeated applications of chelated copper were more effective in reducing seedling leaf area than a single application at both concentrations tested.
Effect of Pre-treatment Solution on Iris hollandica Flower: Vase life, Anthocyanin Content, and Peroxidase Activity
Authors: Kim* Su-Jeong , Nam Chun-Woo , Yoo Dong-Lim , Ryu Seung-Yeol , Kim Ki-Sun
Published: February 2019

Iris hollandica `Blue Magic' was treated with deionazed water as a control, 3% sucrose (Suc), 3% sucrose plus 0.4 mm silver thiosulphate (Suc+STS), 3% sucrose plus 200 mg·L-1 8-hydroxyquinoline sulphate (Suc+HQS) and 3% sucrose plus 100 mg·L-1 benzyl amino-purine (Suc+BA) for 4hrs and then transferred to tap water. The vase life treated with Suc+BA was extended 4 days longer than that of control. The treatment Suc+STS or Suc+HQS did not improve vase life. The amounts of water uptake and transpiration by all treatments decreased after harvest, but those values were higher in cut iris treated with Suc+BA than in those with control. Cut flowers treated with by Suc+BA markedly improved water balance, comparing with control which was quickly changed to minus value. Anthocyanin content in petals of cut flower treated with Suc+BA was 3.5 fold higher than that of control. The treatment by Suc+BA delayed discoloration in petals and senescence of cut Iris. Peroxidase (POD) activities of all treatments were reached maximum at 4th day after treatment and decreased thereafter. POD activity was highest when the cut iris was treated with Suc+BA. These results show that the use of Suc+BA is most effective treatment for improving the vase life and quality of cut Iris flowers.
Effects of Sunlight Exposure on Cluster Monoterpene Levels of `Traminette' Grapes
Authors: Sobieck* Patricia A. , Bordelon Bruce P.
Published: February 2019

Monoterpenes are organic compounds found in high quantities in certain wine grape varieties, such as Riesling, Gewürztraminer, and muscat-flavored varieties. These compounds exist in free and glycosidic form, and produce the characteristic aromas of such varieties. Traminette, released in 1996 as NY65.0533.13, is a cross between Joannes Seyve 23.416 and Gewürztraminer. This variety may be an alternative to Gewürztraminer in areas where cold temperatures prevent cultivation of such cold-tender varieties. The objective of this study is to determine the extent of which sunlight exposure influences monoterpene production in `Traminette'. Various exposure levels were obtained through synthetic coverings and ambient shading. Fully exposed clusters on a vertically shoot positioned canopy received 55% of ambient light whereas clusters with 50 and 70% shade cloth received 14.7 and 5.3%, respectively. Heavily shaded clusters (3+ leaf layers) received 2% of ambient light, and fully covered clusters received no light from véraison to harvest. Despite large differences in exposure level, cluster temperatures did not differ significantly between treatments. Results of monoterpene quantification show potentially volatile terpene (PVT) levels were 10-fold greater than free volatile terpene (FVT) levels in all treatments. PVT levels differ significantly between exposure groups in all locations at harvest, with exposed fruit having the highest concentration (6.5-7.5 mg L-1). Heavy and moderate shade fruit had 25% lower PVT levels compared to exposed fruit. Fully covered clusters had 34% less PVT, whereas 50 and 70 shade cloth clusters were 20% lower than exposed. Subsequent years of research will further validate preliminary findings of this study.
Mustard Cover Crops for Control Soilborne Disease and Weeds, and Nitrogen Cycling in Cool Season Vegetable Production in the Salinas Valley
Authors: Smith* Richard , Subbarao Krishna , Koike Steve , Fennimore Steve , Barber Adelia
Published: February 2019

Growers in the Salinas Valley are not able to rotate away from lettuce to other crops such as broccoli, as often as would be desirable due to economic pressures such as high land rents and lower economic returns for rotational crops. This aggravates problems with key soilborne diseases such as Sclerotinia minor, Lettuce Drop. Mustard cover crops (Brassica juncea and Sinapis alba) are short-season alternative rotational crops that are being examined in the Salinas Valley for the potential that they have to reduce soilborne disease and weeds. Mustard cover crops have been have been shown to suppress various soilborne diseases and there are also indications that they can provide limited control of some weed species. However, no studies have shown the impact of mustard cover crops under field conditions on S. minor. In 2003 we conducted preliminary studies on the incidence of S. minor and weeds following mustard cover crops in comparison with a bare control or an area cover cropped to Merced Rye (Secale cereale). There was a slight, but significant reduction of S. minor infection in one of three trials following mustard cover crops. Mustard cover crops also reduced emergence of Shepherd's Purse (Capsella bursa-pastoris) and Common Purslane (Portulaca oleracea) these studies. Mustard cover crops have distinct nitrogen cycling characteristics. They were shown to reach a peak of release of nitrogen in 30 to 50 days following incorporation into the soil. The levels of nitrogen that are released by mustard cover crops were substantial and could be useful in nitrogen fertilizer programs for subsequent vegetable crops.
Bleeding Hearts Turn Yellow: A Case Study to Determine the Cause of Chlorosis in a Crop of Cut Dicentra spectabilis
Authors: Spaw Marci , Williams* Kimberly A. , Mallberg Ingrid L. , Hodges Laurie , Paparozzi Ellen T.
Published: February 2019

Case studies promote the development of problem-solving skills, but few have been created for horticulture and related curricula. This web-based decision case presents the challenge of determining the cause of symptoms of foliar chlorosis in a crop of cut Dicentra spectabilis while forcing it for Valentine's Day sales. It provides a tool to promote the development of diagnostic skills for production dilemmas, including nutritional disorders, disease and insect problems, and evaluation of the appropriateness of cultural practices. Cut Dicentra is a minor crop and standard production practices are not well established. Therefore, solving this case requires that students research production protocol as well as nutritional and pest problems to develop a solution. In this case study, which is supported by an image-rich web-based version at www.hightunnels.org/cutflowercasestudy.htm, a grower at Flint's Flower Farm must determine the cause of foliar chlorosis that is slowly appearing on about half of the plants of her cut Dicentra crop. The condition could be related to a number of possible problems including a nutritional disorder, insect attack, disease infection, or production practices. Some resources are provided to aid students in gathering background information. Data accumulated by the grower is presented to allow students to logically eliminate unlikely solutions and predict (a) probable cause(s). The solution, which is rather unique to this crop, is provided. This case study is intended for use in upper-level undergraduate courses of floriculture production, nutrient management, plant pathology, and entomology.
Assessing Color Change in Woody Floral Stems
Authors: Meyer Christine , Paparozzi* Ellen T. , Josiah Scott J. , Blankenship Erin M.
Published: February 2019

Woody floral stems are an emerging specialty crop within the floral industry, and stem color is a key to marketability. This study was conducted to assess stem color change over time in order to determine the optimum window for stem harvest. Plants of `Scarlet curls', `Flame' willow, `Bailey', `Cardinal' and `Yellow twig' dogwood were planted in a randomized complete block design in rows parallel to a windbreak.. Each experimental unit consisted of a group of five plants, each of the same cultivar. Plants were initially tagged at a set height and stem diameter and measured for color. Each stem was also tagged with one of three colored tapes, according to initial color: green for green colored stems, red for stems already showing color change, and pink for intermediate colored stems. Color was assessed initially and on a weekly basis for 10 weeks, starting at the end of September, using the Royal Horticultural Society color chart. Data were analyzed using a repeated measures procedure. `Scarlet curls' and `Flame' stems, already displaying color, attained the darkest color value for their cultivar at an early stage and were at the point of harvest in early November, while stems that were initially green never attained a similar dark color value. `Yellow twig' dogwood stems already displaying color and those beginning to color attained the darkest color value in late November. `Cardinal' stems attained a darker color value more quickly than other dogwood stems. In most cases, stems of `Cardinal' dogwood could be harvested from early October until early December, while early November was the optimum time to harvest `Bailey' dogwood stems. Woody florals planted closest to the windbreak were more variable in color development and, in some cases, appeared to be more vigorous.
Deltiological Analysis of Early Developments in Florida Horticulture
Authors: Fitzpatrick* George , Lamberts Mary , Worden Eva
Published: February 2019

Horticultural activities in Florida have been chronicled in many sources, including the technical literature and the popular press. One often-overlooked source is the visual images on postcards that were sold in Florida in the early years of the 20th century. Many such cards have images featuring scenes of landscape horticulture, olericulture and pomology. While dates of postmarks may not be accurate reflections of publication dates, deltiology, the study of postcards, can involve the analysis of pigments, rag content of card stock, and other measurable parameters to determine the age of particular images. The introduction, development, ascendancy and sometimes decline of certain horticultural crops in Florida are reflected in postcard images taken between the years 1908-1950. Representative images are shown of past and present plants that have been important in Florida horticulture.
Rapid Response Educational Efforts: Keeping Cooperative Extension Ahead of the Curve
Authors: Hlubik William T. , Polanin* Nicholas , DiNardo Madeline Flahive , Weidman Richard , Smela David , Marko James , Convery Sean
Published: February 2019

Today's fast paced and technology-enriched lifestyles require that many traditional educational seminars and workshops be transformed into “sound bites” of “edu-tainment” if Extension is to keep pace with clientele needs for specific and timely information that's useful and straight to the point. To remain a viable source of timely research-based information, Extension can stay ahead of this curve by utilizing today's technology to inform and educate the public on current issues or outbreaks. This presentation will highlight two such cases where technology delivery systems were utilized to maximize audience size and create an informed public in as short amount of time as possible. Public Service Announcements (PSA's) televised over New Jersey's Public Broadcasting Service (PBS), New Jersey Network (NJN), addressed water conservation and landscape issues during the recent northeastern drought. The potential viewing audience is over eight million people, including all of New Jersey and parts of Pennsylvania, Delaware, New York, and Connecticut. The second case study will highlight a fully interactive CD-ROM on the Asian Long Horned Beetle (ALB) that was created within 12 months of the pest's discovery in Jersey City, N.J. This CD-ROM, containing curricula, PowerPoint presentations and evaluative tools, is currently being used throughout the northeast and in Canada for the most recent infestation of ALB. Filming for both Rapid Response efforts was done with a Sony DSR-500 DV Cam Camcorder and a Canon XL-1 Camcorder. Digital editing was completed on an Apple G4 running OS X with Avid Express Meridian Non-Linear Editing Software version 4.5 with 3D effects, Apple Final Cut Pro 3.0, Adobe After Effects 5.5, and PhotoShop 7.0. Stills were taken with a Sony Mavica and Nikon CoolPix digital cameras.
A Rapid and Efficient Method for Determination of Fruit Peel Color
Authors: Infantino Ignazio , Bianco* Riccardo Lo
Published: February 2019

Peel color is a critical index of external fruit quality and consumer appreciation level. Traditional methods for determination of peel color are based on visual analysis or punctual measurements by colorimeter. In this study we present a method based on digital image analysis that integrates the accuracy of an interactive measurement and the efficacy of an image analysis that descibes entire sides of the fruit. A sample of apple, mandarin, grape, and peach fruit was photographed (each fruit on two opposite sides) with a digital camera for determination of peel color. Digital images were converted from RGB to CIE L*a*b* format, and color characteristics were indexed and quantified. The implemented method uses a reference color image cropped from the best fruit (interactively chosen) to calculate a color index for each fruit of the image set. The final index is the weighted sum of the number of pixels of the fruit, where pixels closer to the reference color (distance in the CIE L*a*b space) are considered more relevant. This color index gives integrated information on fruit color quantity (% of cover color) and quality (hue and saturation). The method represents a rapid and efficient way of determining color of the entire fruit surface and overcomes difficulties and approximation of traditional methods. A modification of the same method can be used to determine peel rugosity (mandarin) and average size and number of grape berries per bunch.
Phytochrome Regulation of Carotenoid Biosynthesis during Ripening of Tomato Fruit
Authors: Schofield* Andrew , Paliyath Gopinadhan
Published: February 2019

The accumulation of carotenoids such as lycopene and beta-carotene greatly influences the quality of ripe tomato (Lycopersicon esculentum) fruit because cellular levels of these compounds determine the intensity of red color. As well, lycopene has anti-cancer properties and beta-carotene is a Vitamin A precursor. Recent work has demonstrated phytochrome regulation of the carotenoid pathway but the mechanism is not completely understood. This work investigates phytochrome regulation of 1-deoxy-D-xylulose 5-phosphate synthase (DXS) and phytoene synthase (PSY), two key enzymes of carotenogenesis. A simple procedure for the assay of PSY from crude pericarp extracts was developed and mRNA levels of DXS and PSY1 genes were measured by relative RT-PCR. Discs from mature green tomatoes were ripened in total darkness, or in darkness interrupted by brief daily treatments of red light, or red light followed by far red light. After ten days of incubation, lycopene levels of red light-treated discs had reached ≈12 mg/100 g fresh weight; nearly a 50% increase over discs ripened in total darkness. This increase was not observed in discs treated with red light followed by far red light, demonstrating the red/far red reversibility (and thus phytochrome control) of carotenoid accumulation. Similar patterns of phytochrome control are observed for PSY activity but not for DXS and PSY1 transcript levels, suggesting the mechanism of control may be at the level of post-translational modification of PSY. Potential applications of this regulation of carotenoid accumulation will be discussed.
Harvest Pressure, Irrigation Methods, and Amounts Reduce Asparagus Growth and Yield
Authors: Peterson* R. Seth , Drost Daniel
Published: February 2019

Asparagus producers have reported a decrease in plant longevity and plant productivity in asparagus fields. Irrigation methods and amounts and early harvest pressure are thought to be some factors affecting asparagus longevity and productivity. The objectives of this study were to determine how irrigation method (sprinkler/drip), amount (0, 75, 150% ET), and harvest pressure (yes/no) modify asparagus growth in the year after planting. In April 2002, plots were planted with as-paragus cultivar Jersey Giant. All plots were treated the same during the establishment year. Each plot was 6.1 m long by 2 rows wide. All plots were separated by a guard row. There were 5 replications. Each irrigation method and amount was divided into two harvest treatments. One row was harvested for three weeks in 2003 (952 kg/ha) while the other was not harvested. Irrigation treatments began after harvest. In 2003, 100% ET from 10 June 10 to 14 Sept. was 55 cm. After correcting for precipitation and crop coefficient, the 75% ET treatment received a total of 28 cm of water while the 150% treatments received 47 cm. There was no difference in fern fresh weight between 150% and 75% ET for the drip irrigates asparagus, but both were significantly greater than non-irrigated treatment. In contrast, fern fresh weight decreased linearly as irrigation amounts decreased in the sprinkler treatments. Yield differences are not expected between drip and sprinkler in 2004. Yield reductions are expected relative to irrigation amounts.
Effect of Foliar Copper and/or Iron Application on Growth and Yield of Lowbush Blueberry
Authors: Smagula* John , Fastook Ilse
Published: February 2019

In a commercial lowbush blueberry (Vaccinium angustifolium Ait.) field with low leaf Cu (<7 ppm) and Fe (<50 ppm) concentrations, nine 1.8 m × 15 m treatment plots were established in a randomized complete block design with 6 blocks. Copper Keylate® (Stoller Enterprises, Inc.) containing 5% Cu was used as a foliar spray in a volume of 626 L·ha-1. In a similar volume, the Stoller Enterprises Inc. product Fe Keylate®, containing 5% Fe (5% chelated Iron), was used to provide Fe. Ammonium sulfate (0.7%) was added to the solutions to enhance uptake. Treatment plots received either Cu Keylate® at 0.6 kg·ha-1 Cu or Fe Keylate® at 0.6 kg·ha-1 or a combination of both nutrients in one spray. Treatments included a 19 June prune - or crop-year application of Cu, Fe, or Cu + Fe, and a prune-year Cu + Fe June 7 and June 19. A plot receiving no treatment served as a control. Leaf Cu and Fe concentrations were raised to above satisfactory leaf concentrations (Cu >7 ppm, Fe >50 ppm) by their respective treatments. Concentrations were significantly higher for each element when they were applied together. Two applications were not better than only one. No carry-over effect was seen in the crop year. Crop-year applications of Cu and Fe were effective in raising their respective concentrations. Stem density, length, number of branches or branch length was not affected by treatments at the end of the prune year. Flower bud density and average number of flower buds per stem were not meaningfully affected by prune year Cu or Fe treatments. Berry yield was not influenced by any treatment suggesting that the Cu and Fe standards are too high.
Differential Exothermal Characteristics and the Model of Deep Supercooling Dynamics in Relations to Bud Water Contents and Dormant Periods within the Buds of Some Deciduous Fruit Trees
Authors: Ding* Pinghai , Fuchigami Leslie H.
Published: February 2019

Differential exothermal characteristics in relations to bud water content and dormant periods were dynamically investigated within the buds of apple, pear, peach, plum, Grape, persimmon, and black walnut from late autumn to early spring. Differential thermal analysis (DTA) indicated that bud cold hardiness and two exotherms, the high temperature exotherm (HTE) and low temperature exotherm (LTE), were different among species and dormant periods. According to whether buds have deep supercooling during the dormant winter period the species tested can be divided into two groups. The first group, without supercooling, includes the buds of apple and pear, in which LTE was undetectable. The second group, with supercooling, includes the buds of peach, plum, grape, persimmon, and black walnut, in which LTE was detectable. The second group can be further divided into peach and plum subgroup, and grape, persimmon, and black walnut subgroup. Both HTE and LTE can be detected in the buds of peach and plum subgroup, in which bud cold hardiness can be further divided into three different stages; whereas in the buds of grape, persimmon and black walnut subgroup only LTE can be detected, in which bud cold hardiness can be further divided into five stages according to the detection dynamics of HTE and LTE. Bud differential exothermal characteristics and deep supercooling dynamics are closely related to bud water content and cold hardiness stages. No detection of LTE in the buds of apple and pear and no detection of HTE in the buds of grape, persimmon and black walnut were both closely associated with bud water content.
Standardization of Potting Media for Citrus Nursery Production in Containers
Authors: Khan* Muhammad Mumtaz , Khan Muhammad Azam , Ali Muhammad Asif , Raza Hasnain
Published: February 2019

Six-week-old rough lemon (Citrus jambhiri L.) seedlings uniform in size were transplanted from nursery to pots filled with peat, spent compost of mushroom and leaf manure used at different proportions with soil, sand and farm yard manure and grown in green house environment. Initial physical and chemical analysis of media indicated that electric conductivity (EC), total porosity, bulk density, moisture percentage, available nitrogen, phosphorus and potassium are more suitable for citrus plant growth and development than other media of different compositions. Peat + sand (1:1) had pH 6.7 which is optimum for growth of citrus nursery. After every four weeks plant length, stem diameter, number of leaves and leaf area were measured. Leaf analysis for N, P, K and mortality percentage was measured at the end of the experiment. Peat + sand (1:1) produced highest percentage of transplant success, plant height, stem diameter, and number of leaves as compared to all other treatments tested. At initial stage peat + sand (1:1) gave the highest results in relation to leaf area, but at the end of experiment it was observed that treatment with silt + spent compost (button) + spent compost (oyster) (1:1:1), produced maximum leaf area with lush green leaves however, mortality rate was very high. This study suggests that peat + sand (1:1) may serve as a standard medium for the container grown citrus nursery.
A Survey of Composition and Content of Carotenoids, Sugars, and Ascorbic Acid in Watermelons with Various Flesh Colors
Authors: Yoo* Kil Sun , Loaiza Julio , Crosby Kevin , Pike Leonard , King Steve
Published: February 2019

About 40 watermelon samples with various flesh colors (red, pink, orange, and yellow) were tested for their carotene, sugar, and ascorbic acid contents. Carotenoids were separated and purified by using a preparative HPLC system and identified by comparing the spectra with standard compounds by using a diode array detector. Sugar and ascorbic acid contents were measured by HPLC methods. Red and pink colored watermelon contained lycopene as the major carotenoid, with a wide range of variation (5 to 51 μg·g-1). Beta-carotene was the second major carotenoid and was less than 6 μg·g-1. There were also lutein and violazanthin in less than 1.5 μg·g-1 range. Yellow and orange flesh watermelons contained a complex mixture of carotenes. Prolycopene, lycopene, or beta-carotene was the major component, depending on the variety, and the contents were less than 24, 3, and 9 μg·g-1, respectively. There were also minor carotenoids, such as violaxanthin, lutein, neurosporene, zea-carotene with a 0 to 3.5 μg·g-1 range. Neurosporene, zea-carotene, and prolycopene were not found in the red watermelons. There was great variation in total sugar content, range being from 22 to 102 mg-1, while the °Brix was from 4.0 to 15.5. Sucrose, glucose, and fructose were the main sugars in the watermelon and their composition were grouped as sucrose-dominant or fructose-dominant groups. Some varieties with very low levels of sucrose were generally low in the total sugar content. Watermelon contained fairly low levels of ascorbic acid, less than 58 μg·g-1 and some varieties had nearly no ascorbic acid. Estimation of total carotenoid in the yellow watermelons by measuring absorbency at 435, 485, or 503 nm was tested and 435 nm showed the highest correlation coefficient (r2 =0.845).
Student Expectations and Evaluation of a Horticulture Study Abroad Course
Authors: Haynes* Cynthia , Iles Jeff
Published: February 2019

Beginning in 1998 students in the Dept. of Horticulture at Iowa State Univ. have been given an opportunity to enroll in a semester-long study abroad course, culminating in a two-week visit to the country of interest. Students participating in a recent study abroad experience to England were asked several questions prior to their departure including: 1) their motivation for participating and goals for the site visit; 2) fears or concerns related to the trip; 3) expectations about the course and trip; and upon arriving home 4) their overall evaluation of the course and trip. A questionnaire containing ten closed-ended and six open-ended questions was given to all 25 students enrolled in the course. We learned most students participated in the course to learn about and experience a different place and culture. Thirty-nine percent of responding students said issues related to packing for the trip was their biggest concern or fear. Twenty-six percent were concerned abut using a foreign currency while another 17% said interacting with other sudents on the trip was their greatest concern. A large majority (90%) of students felt the course and trip met their expectations and 80% said they would participate in another international experience. Other survey questions revealed students gained better insight about themselves, became more tolerant of people and other customs, felt they were better able to adapt to new situations, developed close friendships with traveling companions, and experienced an increased interest in horticulture.
Organic Cultivation of Radicchio rosso di Chioggia (Chicorium intybus var. silvestre) in Iowa
Authors: Sambo* Paolo , Nutter Forrest W. , Guan Jie , Friedrich Heather
Published: February 2019

An experiment was carried out at the Iowa State Univ., Neely-Kinyon Research Station (Greenfield, Iowa) to asses the possibility of growing organic radicchio rosso (Chicorium intybus var. silvestre) in Iowa and to determine the effectiveness of different organic fertilizers. The experiment was a factorial combination of three radicchio cultivars (very early, medium early, and early), three organic fertilizers treatments (non-fertilized control, liquid, and compost based), and two planting dates (11 July and 7 Aug). Treatments were arranged in a split plot design with four replicates. In each sub-plot, plants were transplanted, maintaining 30 cm between plants and 75 cm between rows (4.4 plant per m2). During the growth cycle the crop was managed according to typical production techniques adopted for lettuce. Beginning the first week after transplanting, canopy reflectance measurements were taken every 2 weeks until harvest, using a multispectral radiometer MSR 87 (Cropscan, Inc. Rochester Minn.). At harvest, total and marketable yields were measured and dry matter production was calculated. Yield loss was determined after 15 days of cold storage (4 °C). Cropscan measurement showed no differences among fertilizers treatments, mainly because of the high fertility of the soil (6% organic matter), but different growing patterns among radicchio types. The mediumearly type grew quicker than the other types, and showed the lowest percentage of bolted plants (<4%) and the least preharvest weight loss (5%). Moreover, radicchio demonstrated resistance from the hot and dry Iowa summer even without irrigation, representing a useful alternative crop for both organic and conventional farmers.
Specific Surface Versus Particle Diameter of Limestones
Authors: Rippy* Janet F.M. , Nelson Paul V. , Hesterberg Dean L. , Kamprath Eugene J.
Published: February 2019

Agricultural limestone is classified based on particle-size distribution, a key factor influencing neutralization capacity. This property is an effective basis for liming recommendations for agronomic purposes which allow for gradual rise in soil pH and residual neutralization for three years. Inconsistencies are prevalent when agricultural limestone is used for horticultural applications which require rapid attainment of target pH and residual neutralization for only four months. Variations in pH among batches of substrate produced with the same limestone rate and pH drift from the same initial pH during crop production infer that factors other than particle diameter also influence limestone neutralization capacity. In this study the relationship between specific surface and diameter of limestone particles was examined. Limestones obtained from twenty North American quarries were wet-sieved into eight particle diameter fractions from 600 to <38 μm (passing 30 through 400-mesh screens). Specific surface (m2/g) of particles was measured in three replications for each fraction following the BET theory that dinitrogen gas (N2) condenses in a continuous mono-molecular layer on all particle surfaces. At each particle diameter fraction, specific surface varied significantly (five-fold differences) among quarries. Large specific surface may indicate many reactive interfaces, hence high neutralization capacity. In containerized production, typical to horticulture, preponderance of root over substrate mass and short crop duration dictate narrower characterization of limestone than is currently used. Specific surface may describe limestone neutralization capacity more finely than does particle diameter.
Radio Frequency Heating of Persimmon and Guava Fruit as an Alternative Quarantine Treatment
Authors: Monzon* Maria , Biasi Bill , Wang Shaojin , Tang Juming , Hallman Guy , Mitcham Elizabeth
Published: February 2019

The Mexican fruit fly infests many tropical and subtropical fruits, consequently fruits must be treated for quarantine security. Although chemical fumigations are the most common quarantine treatments, interest in using cold and heat treatments has increased due to concerns over environment and human health. Recently, shorter heat treatments such as those provided with radio frequency (RF) energy have been studied on walnuts and various fresh fruits as a possible quarantine treatment. Preliminary studies with a heating block system showed that reaching temperatures of 50 °C with a holding period of 2 min. or 48 °C for 6 minutes was required to achieve 100% insect mortality of 600 third instar Mexican fruit flies (the most heat resistant insect stage). Doubling the holding time required to achieve 100% insect mortality would likely be necessary to provide for Probit 9 security. Fresh fruits such as persimmons and guavas are commonly infested by the Mexican fruit fly. Persimmon and guava fruit were treated with RF energy to temperatures ranging from 48 to 52 °C at different holding periods. After treatments fruit were evaluated for external appearance, decay, soluble solids, titratable acidity, internal flesh quality, and ethylene production and respiration rate. Persimmon fruit tolerated the lower temperature, 48 °C for up to 18 min., but temperatures above 50 °C for more than 1 minute caused internal damage. Preliminary studies with guava indicate that fruit may tolerate 50 °C, but fruit quality after storage is still to be evaluated.
Eradication of Common Liverwort from a Soilless Growing Medium
Authors: Stamps* Robert H. , Chandler Annette L.
Published: February 2019

Common liverwort (Marchantia polymorpha L.) is an increasingly troublesome weed in containerized plant production. Postemergence applications were made to try to eradicate established stands of liverwort. Treatments consisted of sprays of quinoclamine at 1× and 2× rates and oxadiazon at the highest label rate, broadcast applications of sodium carbonate peroxyhydrate at 1x and 3x rates and four granular herbicides (flumioxazin, oxadiazon, oxyfluorfen + pendimethalin, and prodiamine) applied at label rates. The granular herbicides were applied both alone and with the sodium carbonate peroxyhydrate treatments. Herbicides were applied to common liverwort growing on an 80% aged pine bark: 20% Sphagnum peat-based soilless growing medium contained in 10-cm diameter plastic pots located in a double-poly covered greenhouse. At 2 weeks after treatment (WAT), control was best (93% to 100%) for both quinoclamine and the 3× peroxyhydrate treatments, intermediate (68% to 83%) for the 1× peroxyhydrate treatments, and not significant for any of the preemergence herbicides used alone. At 4 WAT, slight regrowth was evident in plots in which the treatments had an initial effect and the 1x peroxyhydrate + flumioxazin was as effective as the 3× peroxyhydrate and the 2× quinoclamine treatments. At 6 WAT, control was excellent in the 3× peroxyhydrate and 1× peroxyhydrate + flumioxazin treatments. Control was less, but still evident, in the quinoclamine and other 1× peroxyhydrate treated plots. While none of the treatments had completely eradicated common liverwort in all replications at 10 WAT, control was still excellent to good in many of the peroxyhydrate + preemergence herbicide-treated plots.
Optimizing Continuous Canopy Shakers for Late Season `Valenica' Harvest
Authors: Buker* Richard S. , Burns Jackie K. , Roka Fritz M.
Published: February 2019

Continuous canopy shakers (CCS) were developed in the late 90's and have been used to commercially harvest citrus in Florida. A viable mechanical harvester in Florida must be able to selectively remove mature `Valencia' fruit. A study was conducted to evaluate the effect of operating conditions on mature and immature fruit removal during the 2003 harvest season. The study was conducted in the southern flat woods and northern ridge areas. The study treatments were completely random and replicated four times. The CCS treatments were 145, 215, 230, and 245 cycles per minute (cpm) and a hand picked control. The harvest occurred on 17 and 19 June at the southern and northern sites, respectively. Mature fruit removal linearly increased from 95.7% to 97.9% between 145 and 245 cpm, respectively. Varying the operating ranges significantly influenced mature fruit removal in the southern flat woods site. The trees at the southern site were taller (>4m), and had a larger crop load. At the northern ridge site where trees were smaller, varying the CCS operating ranges did not significantly influence mature fruit removal. Immature fruit removal was influenced by the operating ranges. Immature fruit removal was increased at least 22% over hand picked controls. The results were interpreted to indicate the frequency of CCS is dependent on tree size. The initial selectivity of the CCS was not equal to hand picking.
Fruit Removal and Recovery during Citrus Harvesting are Improved when Abscission Agent Applications are Used with Mechanical Harvesters
Authors: Burns* Jacqueline K. , Buker Richard S. , Roka Fritz M.
Published: February 2019

A study was initiated in `Hamlin' orange to determine if a selective citrus abscission material, 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP), could improve mature fruit removal and recovery when used with mechanical harvesters. A trunk shaker and continuous-moving canopy shaker equipped with catch-frames were used at the flatwoods and ridge growing regions in Florida. Both trials were conducted during the first 2 weeks of Dec. 2003. Plots were constructed as randomized complete blocks containing four replicates for each treatment. Each replicate contained five trees at the ridge site or four trees at the flatwoods site. CMNP was applied using a commercial airblast sprayer at 0, 125, 250 and 500 mg·L-1 at a rate of 2,800 L·ha-1 4 days before scheduled harvest. The trunk shaker was operated for either 7 seconds or 2 seconds/tree, whereas the canopy shaker was operated at either 260 cpm or 140 cpm/tree. The data show that the correct time was selected for harvest. Over a 50% reduction in FDF was achieved with the 250 and 500 mg·L-1 treatments, while post-application fruit drop was less than 1.5%. The greatest benefit of abscission agent use was seen when the mechanical harvesters were operated at the least aggressive setting (2 seconds or 140 cpm), where increases in % fruit removal and recovery were over 20% higher than the controls. At the most aggressive settings, numeric increases in % fruit removal and recoveries were measured, but these changes were not statistically significant. The results demonstrated that statistically similar % fruit removal and recoveries could be achieved using less aggressive harvester settings with abscission agent use when compared with most aggressive settings using no abscission agent.
Physiological Effects of Mechanical Harvesting in Citrus Trees
Authors: Li* Kuo-Tan , Syvertsen James P.
Published: February 2019

Mechanical harvesting of citrus trees by trunk or canopy shakers can cause leaf and twig removal, bark injury and root exposure. Such problems have restricted the adoption of mechanical harvesting in Florida citrus. We assessed physiological responses of citrus trees that were mechanically harvested with a linear-type trunk shaker, operating at 4 Hz, 70.8 kg mass weight, and 6.5 cm displacement, for 10 or 20 seconds. We measured fruit recovery efficiency, leaf and shoot removal, mid-day stem water potential, leaf gas exchange, and leaf fluorescence emission of mature `Hamlin' and `Valencia' orange trees under restricted or normal irrigation. Shaking treatments effectively removed 90% to 94% of fruit without bark damage. Compared to harvesting by hand, trunk shaking removed 10% more leaf area and twigs, and caused some visible exposure of fibrous roots at the soil surface. There were no significant treatment differences on mid-day stem water potential, leaf gas exchange, and leaf photosystem efficiency. Excessively shaken trees for 20-30 seconds can temporary induce stress symptoms resembling that in trees without irrigation. Trees may have benefited from the low levels of leaf and twig loss after trunk shaking that compensated for any root loss. Long-term effects of trunk shaking will be assessed by tree growth, return bloom, subsequent yield, and carbohydrate reserves.
Current Status of Citrus Gummosis in Kenya
Authors: Wasilwa* Lusike , Kega Viincent M. , Stafne Richelle A.
Published: February 2019

Citrus is one of the most important fruits in Kenya because of it's nutritional value. It is ranked as the highest source of income from tree crops in Kwale district of the coastal region. The average farmer has 0.25 to 4 acres of citrus and earns between 1 to 2 U.S. cents per fruit based on quality. Citrus gummosis (P. citrophthora and P. nicotianae) is of economic importance on citrus in Kenya. P. citrophthora prefers cooler conditions in the highlands and P. nicotianae favours the warm conditions of coastal areas. Several IPM options are being used to control this disease in Kenya. Research to select suitable rootstocks, determine the period when disease development is greatest and the distribution of infected trees in Kwale districts is currently being conducted. Gummosis has also been reported to occur in farmers fields around Marigat (Perkerra) and surrounding areas however the data is scanty and a detailed survey is underway. Gummosis disease incidence in Marigat was first reported in 1989/1990. Since then symptomatic trees have been treated with fungicides e.g. Ridomil. A citrus mother block consisting of 241 trees, established at Perkerra in 1984 now only supports 112 trees or 47% of the original trees. From the 112 trees, only 21 trees are classified as healthy trees. More extensive research needs to be conducted to show the impact of this disease on the small scale farmer and develop better methods of control.