bluuebunny/crossref_metadata_2025 huggingface dataset:
352 Using Winter Cover Crops For Seedless Watermelon Production
Authors: Rangappa M. , Bhardwaj H.L.
Published: February 2019

Cover crops offer an excellent source of nutritional requirements for production of vegetables in sustainable agricultural system. By using this concept, field experiments were conducted in l998 at three locations in Virginia; Petersburg, James City, and King and William County, and five cover crop treatments; Hairy Vetch (HV), Crimson Clover (CC), HV+Rye, CC+Rye, and a conventional bare-ground control were used for their potential support of nutritional requirements for production of a seedless watermelon crop. The results indicated that the yield levels of seedless watermelon following cover crop treatments had significantly higher number of fruits per acre and the crimson clover treatment had higher fruit size in one of the sites (King William County) as compared to the other four treatments and two sites suggesting that cover crop/crops alone have the potential to support nutritional requirements for seedless watermelon to sustain production, thus becoming a viable and profitable alternative to using inorganic nitrogen source. The effects of cover crops on chemical composition of seedless watermelon were generally not significant. The results also indicated that watermelons produced using sustainable crop production methods are comparable to those produced using conventional methods. Our studies support using seedless watermelon as a viable alternative and high-value cash crop for Virginia farmers' especially tobacco growers, other small-scale producers, and limited resource farmers.
402 Compost and Solarization Affect Broccoli Head Weight, but Not Yield
Authors: Roe Nancy , Schmidt Johnnie R. , Fojtik Tobin
Published: February 2019

Some possible alternatives to soil fumigation with methyl bromide include soil solarization and the use of composts to modify soil microorganism populations. We tested combinations of solarization and compost on a broccoli (Brassica oleracea var. botrytis L.) crop on an organic farm. Treatments were: solarization with compost (SC); solarization without compost (SW); compost only (NC); and an untreated control (NW). Dairy manure compost was applied manually to compost plots at 22 Mg/ha, raised beds were constructed, and solarization plots were covered with clear polyethylene from 13 July to 26 Aug. Black polyethylene mulch was applied to all plots, covering the clear polyethylene. Broccoli, cv. Packman, transplants were planted into the beds and fertilized with fish emulsion fertilizer three times for a total of ≈22 kg/ha N. Broccoli heads were harvested on 1, 5, and 9 Dec., trimmed to 15 cm, weighed and counted. Marketable yields were 8704, 7117, 8169, and 8374 (kg/ha) and mean head weights were 353, 228, 286, 313 (g) for SC, SW, NC, and NW, respectively. Under these conditions, head weights were highest with compost and solarization, and marketable yields were similar.
407 Nitrogen Retention and Release by Paper Pellets in the Bottom of Nursery Containers
Authors: Glenn J.O. , Gilliam C.H. , Edwards J.H. , Keever G.J. , Olive J. , Knight P.R.
Published: February 2019

Recycled paper pellets in the bottom of containers were evaluated for retention of N from container leachate. `Formosa' azalea were transplanted on 15 Apr. in 2.8-L containers in a pine bark/peat substrate (3:1; v/v). Treatments included paper (0 or 2.5 cm depth) in the bottom of containers and two rates of Osmocote 18–6–12 (0.68 kg or 1.36 kg N/yd3). Immediately after transplanting, plants were topdressed with 3.2 g of 12–4–6 fertilizer. Data collected included leachate samples every 2 weeks for NO3-N and NH4-N levels and destructive sampling every 4 weeks for shoot dry weight, foliar N, and total paper N. Nitrate-N and NH4-N leachate concentrations were reduced with the 0.68 kg N/yd3 fertilizer rate and with paper. For example, 28 days after planting (DAP) NO3-N leachate concentrations were reduced 36% with the 0.68 kg N/yd3 fertilizer rate and 46% with paper in the bottom of containers. NH4-N in the leachates was reduced 53% with the 0.68 kg N/yd3 fertilizer rate and 59% with paper. Azalea shoot dry weight was not affected by paper or fertilizer rate up to 112 DAP; however, as the study progressed, plants with paper in the bottom of containers grew larger than plants in no paper treatments (29% at 168 DAP, 31% at 196 DAP). Total N absorbed by paper was not affected by fertilizer rate, and peaked at 168 DAP [980 (0.68 kg N/yd3) to 1066 (1.36 kg N/yd3) mg per container, or 41% – 28% of applied N], after which it began to decline. This decline in paper N was associated with greater growth of azalea with paper.
413 Development of a Tropical Horticulture Course on CD-ROM
Authors: Sarmiento Mauricio José , Kuehny Jeff S. , Motsenbocker Carl , Picha David
Published: February 2019

Tropical horticulture is a senior-level course in most horticulture curricula. A combination of notes, slides, and hands-on demonstration with tropical crop products is the traditional presentation format for this course. Our project integrated computer-based learning models in a comprehensive courseware package suitable for teaching an entire undergraduate tropical horticulture course covering 14 crops from the areas of fruits, vegetables, ornamentals, and floriculture. The user-friendly multimedia course includes hypertext class notes, animated graphics, videos, and pictures. The CD-ROM will be available and will be tested by students registered in the tropical horticulture class in Louisiana State Univ. and will also be translated to Spanish.
432 Irrigation Frequency Affects Growth and Water Use Efficiency of Two Xeriphytic Landscape Plants
Authors: Stabler Linda B. , Martin Chris A.
Published: February 2019

Growth and water use efficiency (WUE) of two Southwest landscape plants under various regimes of irrigation frequency was studied in a greenhouse experiment. Red bird of paradise (Caesalpinia pulcherrima L.) and blue palo verde (Cercidium floridum Benth. ex A. Gray) were grown at three levels of irrigation frequency intended to mimic a range of watering practices determined via survey data from the Phoenix, Ariz., metropolitan area. During two irrigation cycles, measurement of mid-day water and osmotic potentials, lysimetric whole-plant transpiration (T), and mid-day shoot gas exchange was made. Irrigation frequency treatments affected Cercidium more than Caesalpinia. Frequent irrigations increased Cercidium shoot length and dry weight. For both species, infrequently irrigated plants showed patterns of osmoregulation in response to drying soil. Transpiration (T) was consistently highest for infrequently irrigated plants. WUE was affected by treatment for Cercidium, but not Caesalpinia. Gas exchange was unrelated to plant growth or T. Instantaneous transpiration efficiency (ITE) was negatively correlated to the ratio of intracellular CO2 to ambient (CICA) in all treatments, suggesting that under well-watered conditions, WUE might be reduced by negative feedback effects of high internal CICA ratios.
444 Forcing Requirements of Seed-propagated Easter Lilies
Authors: Anderson Neil O.
Published: February 2019

Seed-propagated lilies have the potential to revolutionize Easter lily production, eliminating clonal disease transmission, costly production and shipping. Five F1 interspecific hybrids, Lilium × formolongo (L. longiflorum × L. formosanum), were evaluated to establish an initial forcing schedule. The hybrids included `Raizan Herald', `Augusta F1', `Raizan No. 1', `Raizan No. 2', and `Raizan No. 3'. Two hundred seeds/hybrid were sown in early July in plug trays. Ten weeks after sowing, seedlings were transplanted into 3-inch pots. At the 20-week stage, the seedlings were repotted into 6-inch standard pots for the final production phase. All hybrids had low germination rates (<20%). Hybrids were grown under two photoperiod treatments (short, long days) at 21 °C with n = 10 reps/hybrid/treatment. Plants were evaluated for no. days to visible bud, leaf unfolding rate, final plant height, leaf number, bud count, flowering dates, and the no. of shoots/bulb. Ten weeks after sowing, hybrids had one to four leaves/plant. At 20 weeks, the leaf number had increased to as many as 40. Despite the lack of a cold treatment, most hybrids initiated flower buds. Visible bud date occurred as early as 20 weeks after sowing. Photoperiod had no effect on leaf number, stem height, and flower bud initiation. Plant height exceeded 15 inches by week 16 in most hybrids, indicating the need for plant growth regulator applications. The next steps in product development for seed-propagated Easter lilies will be outlined.
451 Transplant Depth can Overcome “Elephant's Foot” Disorder in a Hydroponic Greenhouse Sweet Pepper Crop
Authors: Jovicich Elio , Cantliffe Daniel J.
Published: February 2019

A physiological disorder, “Elephant's Foot”, can develop in greenhouse hydroponic sweet pepper (Capsicum annuum L.). In a plant with this disorder, the base of the stem becomes swollen below the cotyledon level and wounds develop at the base of the stem's epidermis, what might predispose it to a localized rot and result in a sudden permanent plant wilt. Salt accumulation at the base of the stem could be a possible cause of the epidermis wounds. The effects of soilless media type (perlite, coconut coir, pine bark, and peat–perlite–vermiculate mix), transplant depth, and amount of nutrient solution applied per day were studied to evaluate the development of “Elephant's Foot” on a summer–fall sweet pepper greenhouse crop in Gainesville, Fla. Seedlings grown in polyethylene containers were transplanted 29 June 1999 into 11.4-L pots at three transplant depths: a) at half of the cell height, discarding only the bottom of the container (TOP); b) at the cotyledon level (LEVEL), and c) at the second stem node (DEEP). Plants were irrigated with 2, 2.5, 3, 3.5, and 4 L/day per plant of solution. The percentage of plants with epidermis wounds at the base of the stem was highest (82.5%) on TOP plants, compared to LEVEL (5.8%) and DEEP plants (0%). TOP plants had higher values of electrical conductivity on the stem epidermis than LEVEL and DEEP plants. There was a positive linear relationship (r = 0.82) between the percentage of plants with epidermis wounds and the electrical conductivity. Early yield of extra large and large fruits was higher in DEEP (1.05 kg·m–2) than in TOP plants (0.82 kg·m–2). Transplanting sweet pepper with the cotyledonary node under the soilless media could minimize salt accumulation and epidermis damage at the base of the stem level.
452 Stand Reduction and Foliage Damage Reduce Yield of Onion for Dehydration
Authors: Clough George H.
Published: February 2019

Field trials were conducted at Hermiston, Ore., from 1995 through 1998 to determine the impact of stand loss and plant damage at different growth stages on yield of onions grown for dehydration. The experiment was a complete factorial with four replications. Stand reduction (0%, 20%, 40%, 60%, 80%) and foliage damage (0%, 25%, 50%, 75%, or 100%) treatments were applied at 3-, 6-, 9-, and 12-leaf onion growth stages. All average onion production characteristics decreased linearly as stand reduction increased (plant population decreased) at all plant growth stages except average bulb weight which increased as stand was reduced. Bulb weight was not changed by up to 100% foliage removal at the three-leaf stage of growth. At the 6- and 12-leaf stages, bulb weight was reduced when >50% of the foliage was removed. The most severe response occurred at the nine-leaf stage when bulb weights were reduced the most. At the three-leaf stage, yield was not affected by foliage damage. At the six-leaf growth stage, yield was reduced by 75% or more foliage loss, but at the 9- and 12-leaf stages, >50% foliage removal reduced expected yields. As with bulb weight, the impact of foliage removal on yield was most severe at the nine-leaf growth stage.
462 Nursery Management Offered Via Videotape for Place-bound Students
Authors: Tripepi Robert R.
Published: February 2019

Nursery management, a course covering practices involved in production of woody landscape plants, was developed for delivery to place-bound students at distant sites around the state. Course subject matter was divided into 41 modules and involved aspects of site selection, cost accounting, plant propagation, nursery trade associations, licensing, as well as container and field production practices. Each module began and ended with a 1- to 2-min introduction and summary to the subject matter, and these segments were taped on location at nurseries in the Pacific Northwest. The lecture portion of each module was taped in a multimedia classroom, and presentation software was used to present text, slides, drawings and animation. Videotape footage of some cultural practices was also inserted into lectures as a “field trip.” Students in the course also received a lecture note guide for all modules in the course. In Idaho, the videotapes were distributed to education centers around the state. The first time the course was offered, 11 students at distant sites and three time-constrained students on campus enrolled. Students contacted the instructor by phone or e-mail. Homework assignments were sent via FAX or e-mail attachments, and tests were sent to the education centers where proctors gave three exams and a final exam. All tests and homework assignments were graded by the instructor located on campus. A videotaped course in nursery management can adequately convey principles involved in landscape plant production, but logistics of mailing videotapes and grading assignments and tests should be carefully evaluated when deciding if a course should be offered at a distance.
464 The Biochemical Basis for Purple, Blue and Red Flower Colors in Calibrachoa LaLlave & Lexarza
Authors: Griesbach R.J. , Waterworth R.A.
Published: February 2019

Recently, several new Calibrachoa La Llave & Lexarza cultivars have been developed with novel red and blue flowers. Most of the wild species of Calibrachoa have purple flowers. The difference in color between the red, blue, and purple flowers was not due to anthocyanin composition but to vacuolar pH. The pH of the red flowered cultivar was 4.8, while that of the blue flowered cultivar was 5.6. The wild purple flower species had an intermediate pH of 5.0. The difference in pH was genetically inherited.
475 Performance of Koelaria macrantha (Ledeb.) J.A. Schultes `Barkoel' and Low Maintenance Turfgrass Species for Orchard Floor Management
Authors: Willmott J.D. , Foster E.T. , Pavis R. , Frecon J.L.
Published: February 2019

Various turfgrass species and cultivars are utilized for orchard floor management. Selection and establishment of low-maintenance species compatible with site conditions results in less need for mowing, fertilizing, and pesticide applications. Koelaria macrantha (Ledeb.) J.A. Schultes is a new turfgrass species that has demonstrated outstanding low-maintenance characteristics. This study evaluated the only commercially available cultivar `Barkoel' and three other species, including Festuca arundinacea Schreb (tall fescue), Festuca rubra L. ssp. falax Thuill (chewings fescue), and Festuca longifolia auct. non Thuill (hard fescue). Turf was seeded in a commercial peach orchard in Oct. 1996 and evaluated through Oct. 1999. After 3 years, the hard fescue cultivars had the best quality, with excellent density and low weed populations. Chewings fescue also had good density and few weeds. Tall fescue had good density, but more weeds than the hard and chewings fescues. Koelaria macrantha `Barkoel' had unacceptable quality, with poor density and the highest weed populations. The fine fescues, hard and chewings, suffered damage from orchard maintenance equipment. Damage was most severe during heat and drought stress in Summer 1999. Growers should limit equipment traffic on hard and chewings fescues during heat and drought stress. Tall fescue showed no significant damage from equipment, but it demonstrated a faster vertical growth rate. This increases the need for mowing. Koelaria macrantha `Barkoel' was not damaged by equipment. While Koelaria had the least density and most weeds after 3 years, it has performed well in our other tests. Higher seeding rates or modifications in seedbed preparation may improve density and reduce weed infestations.
502 Reassessment of Leaf Potassium Critical Values in Almond
Authors: Reidel Edwin J. , Brown Patrick H. , Duncan Roger A. , Weinbaum Steven A.
Published: February 2019

Almond [Prunus dulcis (Mill.) D.A. Webb] yields have increased substantially since the 1961 publication of the Univ. of California (UC) guidelines for leaf potassium (K). Numerous growers and reputable analytical laboratories are concerned that the recommendations for leaf K are inadequate. A highly productive almond orchard with low leaf K was selected to reassess the leaf K critical value of 1.1% to1.4% and determine the relative sensitivity of various yield determinants to inadequate K availability. Baseline yields for 100 individual trees were measured in 1998 and four rates of potassium sulfate were applied under drip irrigation emitters to establish a range of July leaf K concentrations between 0.5% and 2.1%. No relationship was observed between leaf K and post-treatment yield measurements made in 1999. We also monitored individual limb units on trees from the treatment extremes for effects of low K availability on flower number, percentage fruit set, fruit size, spur mortality, and vegetative growth (potential fruiting sites in subsequent years). Those measurements indicated that although current-year yield determinants (percentage fruit set and fruit size) were not influenced by K deficiency, components of future yield were impacted negatively by low K availability: mortality of existing fruiting spurs was increased by K deficiency and growth of fruiting wood was reduced.
537 Impacts of Farming Systems and Soil Characteristics on Processing Tomato Fruit Quality
Authors: Colla Giuseppe , Mitchell Jeff , Poudell Durga
Published: February 2019

A 2-year field study was conducted within the Sustainable Agriculture Farming Systems Project at the Univ. of California, Davis, to evaluate the effects of long-term conventional (CONV), low-input (LOW), and organic (ORG) production practices on processing tomato fruit mineral composition and quality. To establish relationships between soil chemical properties, soil water content, fruit mineral composition, and quality, this study characterized soil chemical properties and monitored soil water content through each tomato season. Soil total C, N, soluble P, exchangeable Ca, K,and Na were higher in the organic system than in the conventional system. Higher soil electrical conductivity was found in the CONV system compared to the other systems. Low input plots had soil characteristics intermediate to the other farming systems. Marketable and unmarketable yields were similar among the farming systems. Fruit N and Na were lower in the organic and low-input systems than in the conventional system. Fruit P and Ca contents were higher in the organic system than in the conventional system as a result of 11 years of manure applications. Soluble solids content, titrable acidity, color, and soluble solids yield were lower in 1998 in the organic system than in the conventional system, while no differences were found in 1999. Soil water content during the ripening stage was the major factor affecting the soluble solids content of the organic system. In the low input and conventional systems soluble solids content was most related to soil exchangeable Ca and EC, respectively.
540 Influence of Calcium Nutrition on Growth and Tissue Electrolyte Leakage in Carrot (Daucus carota)
Authors: Cho Keun Ho , Lee Chiwon W. , Cihacek Larry J. , Stack Robert W. , Kang Hoon
Published: February 2019

The influence of calcium (Ca++) nutrition on the growth and root tissue electrolyte leakage (EL) of carrot (Daucus carota) was investigated using a hydroponic culture system. Seedlings of `Navajo' carrot were grown for 10 weeks with roots submersed in hydroponic nutrient solutions containing 0, 0.1, 1, 2, 4, or 8 meq/L Ca++. The nutrient solution was replenished weekly with its pH maintained at 5.8 for the entire experimental period. The tap root lengths increased as solution Ca++ concentration increased. The diameter and fresh and dry weights of the tap roots increased as Ca++ concentration increased up to 4 meq/L, and then decreased at 8 meq/L Ca++. The root and petiole concentrations of sugar, potassium, and nitrate were unaffected by changes in nutrient solution Ca++ levels. The tissue EL, when tested for the stored roots, decreased as solution Ca++ concentration increased (r = 0.602). Results of this experiment suggest that calcium nutrition is essential for maintaining cell wall integrity in hydroponically grown carrot roots.
549 Three New Cultivars of Flowering Dogwood Resistant to Powdery Mildew
Authors: Trigiano R.N. , Windham M.T. , Witte W.T.
Published: February 2019

Powdery mildew (Microsphaera pulchra) of flowering dogwood (Cornus florida L.) has become a significant problem of trees in nursery production as well as in the landscapes and forests of the eastern United States. The disease significantly reduces growth and berry production by older established trees and may contribute to the inability of younger trees (liners) in production to survive winter dormancy. Disease resistance in named cultivars is limited to partial resistance found in `Cherokee Brave'—all other cultivars are extremely susceptible. Until now, the only disease control measure was to establish an expensive, labor-intensive, preventive fungicide program. We examined >22,000 seedlings and identified 20 that were extremely resistant to powdery mildew. Three trees with white bracts were selected from the 20 and released as patent-pending cultivars. `Karen's Appalachian Blush' has long, non-overlapping, pink fringed bracts with a delicate appearance. `Kay's Appalachian Mist' has creamy white, slightly overlapping bracts with deeply pigmented clefts. `Jean's Appalachian Snow' has large, strongly overlapping bracts with non-pigmented clefts. The three powdery mildew-resistant cultivars will be entered into an existing breeding program with `Appalachian Spring', a cultivar released by the Tennessee Agriculture Experiment Station and resistant to dogwood anthracnose, in an attempt to produce trees that are resistant to both diseases.
560 Rose Plant Tolerance to NaCl Salinity
Authors: Cabrera Raul I.
Published: February 2019

Yield, quality, and nutrient status of `Bridal Pink' (on R. manetti rootstock) roses were evaluated under increasing NaCl salinity and mixed NO3–/NH4+ nutrition. Container-grown plants were irrigated over eight flushes of growth and flowering with nutrient solutions having 100 NO3- : 0 NH4+, 75 NO3– : 25 NH4+, and 50 NO3– : 50 NH4+ ratios in combination with three NaCl concentrations. During the first four flowering flushes, NaCl was supplemented at 0, 5, and 10 mm, but these concentrations were increased to 0, 15, and 30 mm during the last four flushes. Interestingly, NO3– : NH4+ ratios and NaCl concentration had no main effects over any flower yield or quality component evaluated over the 13-month experimental period. Furthermore, visual symptoms of apparent salt injury were just observed during the last three flowering cycles, and mostly on the oldest foliage of plants receiving the highest salt concentrations (30 mm). Leaf N and Na concentrations were not significantly affected by the treatments over the course of the experiment, averaging 3.34% and 45 mg·kg–1, respectively. Leaf Cl concentrations were significantly increased by salt additions, ranging from 1000 to 15,000 mg·kg–1 [0.1% to 1.5% dry weight (DW)]. Correlation analyses revealed that relative dry weight yields increased with leaf Cl concentrations up to 3000 mg·kg–1 (0.3% DW) but were significantly depressed at higher concentrations. These results confirm recent reports suggesting that roses are more tolerant to salinity than their typical classification of sensitive. Furthermore, this is the first known study to report an apparent positive effect of moderate leaf Cl concentrations on rose biomass yields.
565 Use of Cooperative Learning Exercizes to Introduce Concepts in Potted Plant Production Classes
Authors: Anderson Neil O.
Published: February 2019

In production classes, students often commence the class by learning complicated crop-specific production cycles. Rarely are they afforded the opportunity of spending several class periods to first understand the major differences between commercial crops for production time, labor input, and market share. A cooperative learning exercise was created for the first week of lectures in potted plant production class (Hort 4051) at the Univ. of Minnesota (n = 18 students). Students were assigned to working groups for discussion and synthesis of the assignment. One week later, each group turned in their recommendations and one lecture session was devoted to in-class discussion of their answers. The exercise was in the form of a memo from a commercial company, Floratech, addressed to the students as the newly hired potted plant production specialists. In the memo, a graphical summary was presented of 13 major and minor potted crops, contrasting total production time, labor input, and market share for each crop. As production specialists, the student's primary task was to interact with all staff (other students role-playing various positions within the company) to answer the following question: “What is the most realistic, cost-effective location on the graph that Floratech should aim to move all crops?” Group discussions, both within and outside of class, focused on the noticeable trends depicted by the graph and the limiting factors that prevented crops from moving to the ideal location. Growers and breeders were quizzed on what factors kept each crop in the specific locations on the graph. The majority of student chose the midpoint of the graph as the best location. The exercise successfully peaked student's awareness of crop differences and the limiting production factors. Throughout the semester, students referred back to this graph to pinpoint the location for each crop covered.
599 Evaluation of Two Metholds for Estimating Average Fruit Weight for Apple Trees
Authors: Marini Richard P.
Published: February 2019

Average fruit weight from two apple-thinning experiments was estimated by sampling 20-fruit/tree or harvesting all fruit on three branches/tree. The estimated values were compared with the true average fruit weight calculated from the entire crop on a tree. The value of a fruit was calculated from packout data obtained from the two sampling methods and was compared to the true value obtained from the entire tree. Statistical techniques, typically used by biometritions in medical research, were used to assess the agreement between the values obtained with the estimation methods and the true values. Estimates of average fruit weight obtained from 20-fruit/tree may differ from the true value by about 13% and estimates obtained from weighing all fruit on three limbs/tree may be within about 11% to 19% of the true mean. Estimates of fruit value obtained from a 20-fruit sample may differ from the true value by about 4 cents per fruit and estimates from three limbs/tree may differ from the true mean by about 7 cents per fruit. Analysis of variance was performed on each data set and the resulting P values differed for the three methods of estimating fruit weight and fruit value. Thus, erroneous conclusions may result from experiments where fruit weight and fruit value is estimated from relatively small samples.
605 Agrobacterium-mediated Cranberry (Vaccinium macrocarpon) Transformation
Authors: Qu Luping , Polashock James , Vorsa Nicholi
Published: February 2019

Putative transgenic cranberry plants have been achieved via Agrobacterium-mediated transformation. Leaf explants were transformed with a supervirulent Agrobacterium tumefaciens strain EHA 105, harboring the binary vector P35SGUSint and nptII selectable marker genes. Inoculation of precultured explants (≈10 days on regeneration medium) coupled with sonicasion improved transformation efficiency significantly. Adventitious shoots were directly regenerated from explants. Putative transformed shoots were identified by being kanamycin-resistant and GUS-positive. Stable GUS gene expression (turning blue) could be detected within 1 h of incubation at 37 °C. Confirmation of transformation by molecular analysis is in progress. Eight putative transgenic cranberry plants were obtained. All appeared morphologically normal. This appears to be the first success in achieving cranberry transformed plants by Agrobacterium-mediated method. Optimizing the transformation system is ongoing.
643 The Effect of Nitrogen and Sulfur Applications on Hydrangeas
Authors: Helpingstine Willie , Paparozzi Ellen T. , Stroup Walter W.
Published: February 2019

Hydrangeas are sold as a potted florist plant during the spring, usually around Mothers Day and Easter. They are considered “heavy feeders” because of their high requirement for nitrogen. Two experiments were conducted to determine if the addition of sulfur (S) would allow lower rates of nitrogen (N) to be applied without sacrificing plant color and quality. Hydrangea macrophylla `Blue Danube' were fertilized with four levels of N (50, 100, 200, and 450 ppm) in combination with six levels of S (0, 6, 12, 24, 48, and 96 ppm) during a typical forcing program. The experimental design was a randomized complete block with a complete factorial treatment design. Data collected included visual observations (using the Royal Horticultural Society Color Chart) on leaf color and uniformity of flower color as well as flower shape. Quantitative data included flower diameter, floret diameter, height, and N an S leaf concentrations. Soil pH was monitored throoughout the experiment and remained fairly constant (range of 5.0–6.0). Additional sulfur seemed to have no effect on leaf color at the higher levels of N. Lower concentrations of N produced more true blue flower color. Also, at lower N concentrations, higher S resulted in larger flowers with larger florets.
655 Role of Postharvest Storage in Meeting World Food Needs
Authors: Kader Adel A.
Published: February 2019

Postharvest losses of horticultural perishables between the production and retail distribution sites are estimated to range from 2% to 23%, depending on the commodity, with an overall average of about 12% of what is shipped from U.S. production areas to domestic and export markets. Estimates of postharvest losses in developing countries are two to three times the U.S. estimates. Losses in dried grains, legumes, nuts, fruits, vegetables, and herbs and spices range from 1% to 10%, depending on their moisture content, temperature and relative humidity of transport and storage facilities, and protection against pathogens and insects. Reduction of these losses can increase food availability to the growing population, decrease the area needed for production, and conserve natural resources. Strategies for loss prevention include use of genotypes that have longer postharvest-life, use of an integrated crop management system that results in good keeping quality of the commodity, and use of the proper postharvest handling system that maintains quality and safety of the products. Biological (internal) causes of deterioration include respiration rate, ethylene production and action, rates of compositional changes, mechanical injuries, water loss, sprouting, physiological disorders, and pathological breakdown. The rate of biological deterioration depends on several environmental (external) factors, including temperature, relative humidity, air velocity, and concentrations of carbon dioxide, ethylene, and oxygen. Socioeconomic factors that contribute to postharvest losses include governmental regulations and policies, inadequate marketing and transportation systems, unavailability of needed tools and equipment, lack of information, and poor maintenance of facilities. Although minimizing postharvest losses of already produced food is more sustainable than increasing production to compensate for these losses, less than 5% of the funding of agricultural research is allocated to postharvest research areas. This situation must be changed to increase the role of postharvest loss reduction in meeting world food needs.
676 Effects of Volatiles on Postharvest Shelf Life and Quality
Authors: Forney Charles F.
Published: February 2019

Volatile compounds make a significant contribution to the quality and storage life of fresh strawberries, blueberries, and raspberries. Strawberry aroma is composed predominately of esters, although alcohols, ketones, and aldehydes are also present in smaller quantities. The major volatiles contributing to aroma include ethyl butanoate, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, ethyl hexanoate, methyl butanoate, linalool, and methyl hexanoate. In lowbush (wild) blueberries, aroma is predominated by esters and alcohols including ethyl and methyl methylbutanoates, methyl butanoate, 2-ethyl-1-hexanol, and 3-buteneol, while highbush blueberry aroma is dominated by aromatic compounds, esters, terpenes and long chain alcohols. The aroma of raspberries is composed of a mixture of ketones and terpenes, including damascenone, ionone, geraniol, and linalool. The composition and concentration of these aroma compounds are affected by fruit maturity and storage conditions. As fruit ripen, the concentration of aroma volatiles rapidly increases. This increase in volatile synthesis closely follows pigment formation both on and off the plant. In strawberry fruit, volatile concentration increases about 4-fold in the 24-h period required for fruit to ripen from 50% red to fully red on the plant. In storage, volatile composition is affected by storage temperature, duration, and atmosphere. Postharvest holding temperature and concentrations of O2 and CO2 can alter the quantity and composition of aroma volatiles. The effects of postharvest environments on volatile composition will be discussed.
The SFA Mast Arboretum Plant Evaluation Program
Authors: Creech David , Grant Greg , Parish Dawn
Published: February 2019

The SFA Mast Arboretum began as a landscape plant materials class project on the south side of the Agriculture building in 1985. In 2000, over 20 theme gardens now occupy 18 acres. The garden is computer mapped and an accessioning system is in place. Theme garden developments include daylilies, herbs, a rock garden, a xeriscape, plants for shade, wetland, and bog conditions, a line of vines, an Asian Valley, conifers and hollies, and numerous gardens that trial and display herbaceous perennials. Recent developments include a children's garden and, the biggest project to date, an 8-acre SFA Ruby Mize Azalea garden, with a grand opening in Apr. 2000. Theme gardens are utilized to display collections. Significant assemblages include Rhododendron (400 cultivars and selections), Acer (168 cultivars), Camellia (210 cultivars), Loropetalum (18 taxa), Cephalotaxus (43 taxa), Magnolia (47 taxa), Abelia (37 taxa), Ilex (73 taxa), and others. Plant performance and observational information is recorded. Second author Grant has numerous plant introductions in the past 5 years, many that are well represented in the nursery industry and recognized by TAMU's Coordinated Educational and Marketing Assistance Program (CEMAP) as “Texas Superstar” promotions (trademarked). SFA Mast Arboretum plants are promoted via distributions, trade articles, and the Arboretum's website: www.sfasu.edu/ag/arboretum.
Missing Plants in Sweetpotato
Authors: Main Jeff L. , Thompson Paul G.
Published: February 2019

Three treatments were used to evaluate the effects of missing plants on sweetpotato yield: a single plant missing, two adjacent plants missing and two plants missing separated by a single plant. Individual plant yields of the four plants in the same row in each direction from the missing hill were taken. Yields were also taken from corresponding plants in the rows on each side of the row with the missing plant. A plot therefore consisted of three rows with the center row containing eight or nine plants and one or two missing hills and the other two rows containing nine to 12 plants. A single missing plant tended to increase yield of all grades of the plant in the same row next to the missing hill, but differences were nonsignificant. Two missing plants did not result in individual plant differences, but did increase overall plot yield of jumbo and cull grades. The single plant between two missing hills produced a greater number of small-sized No. 1 roots. No. 1 yield of plants in adjacent rows across from the single plant produced lower No. 1 yields.
Climatic Effects on Sweetpotato Yield in Southern Ontario
Authors: McKeown A.W.
Published: February 2019

Sweetpotato (Ipomea batatas L) was one crop chosen for development in Ontario in response to demand for alternative crops to tobacco and increasing demand for nontraditional vegetables. A wide range of vegetable crops can be grown in the sandy soils on the north shore of lake Erie. In 1999, there were ≈75 acres of sweetpotatoes grown in Ontario. Lack of an early cultivar to fit a short, warm season was a factor limiting production of sweetpotatoes in southern Ontario. Over an 11–growing season period, cultivars of sweetpotato from several breeding programs in the United States were evaluated for suitability to Ontario climatic conditions. Planting to harvest date season totals for heat units, precipitation, vapor pressure deficit (VPD), potential evapotranspiration, and solar radiation were calculated. Yield was regressed on these climatic variables using multiple linear regression. Of the cultivars evaluated, `Beauregard' replaced `Jewel' as the local industry standard after one season's evaluation. Of the numbered lines evaluated, NC9317 appears suitable for commercial trials. Yields varied greatly among years, and the seasonal VPD explained the largest amount of variation in year-to-year yield. Cultivars vary in their response to seasonal VPD. Yield of `Beauregard' increased with increasing seasonal VPD while NC9317 decreased. Cultivars require ability to yield in a short season and the ability to consistently produce under a range of atmospheric VPDs dictated by interannual climatic variation.
Enhancement of Seed Germination in Common Carpetgrass and Centipedegrass Seed
Authors: Bush Edward W. , Wilson Paul , Shepard Dennis P. , McClure Gloria
Published: February 2019

Priming or presoaking seed of common carpetgrass (Axonopus affinis Chase) and centipedegrass [Eremochloa ophiuroides Munro. (Kunz)] increased germination percentage and decreased mean time of germination (MTG) at 20, 25, and 30 °C. The effect of presoaking and priming was dependent on grass species and temperature. The optimum seed germination temperature for both of these warm-season species was 30 °C. Maximum effect on common carpetgrass or centipedegrass seeds was achieved by priming in 2% KNO3; higher concentrations did not improve germination percentage or MTG, and 4% was in some cases detrimental. Germination was higher and MTG lower at 20 and 30 °C than at 15 °C. Presoaking common carpetgrass and centipedegrass seeds was the most efficient seed enhancement treatment for germination at 30 °C.
Cranberry Establishment and Growth at Varying Water Tables
Authors: Lampinen Bruce D.
Published: February 2019

Although capillary rise plays an important role in providing water to cranberry plants, the relation between water level and plant establishment and growth has not been adequately studied. The aim of this study was to maintain constant water levels and to monitor the effects on establishment, root growth, and aboveground growth in greenhouse-grown cranberries. Cuttings from cranberry (Vaccinium macrocarpon Ait.) cultivar Stevens were rooted in sand-filled pots in the greenhouse for ≈2 weeks and then transplanted to sand-filled PVC tubes. The water level in the tubes was set 7.5, 15, 22.5, 30, or 37.5 cm below the top of the sand surface. Pan evaporation was estimated using PVC tubes filled with water to the same level as the sand in the planted tubes. Extension growth of uprights and runners was measured every 3 days. After growing in the PVC tubes for 90 days, all plants were harvested and upright length, runner length, leaf dry weight, stem dry weight, root length, and root dry weight were measured. There was a similar mortality rate among plants in all of the treatments. Water use varied among the treatments, with the 7.5-cm water level treatment using the least water. The 15-cm water level used the most water, with water use then decreasing in a linear fashion for the 22.5-, 30-, and 37.5-cm treatments. At the conclusion of the study, aboveground dry weight was significantly less for plants in the 7.5-cm treatment compared to any of the other treatments, while it was highest in the 15-cm water level treatment and decreased with lower water levels in a linear fashion as did the average daily water use. The patterns of root dry-weight accumulation were different among the treatments with the highest accumulation in the 22.5-cm water level treatment and decreasing root dry weight with both higher and lower water level treatments. This study points out the detrimental effects of a too high water table, but it also shows that there are costs associated with establishing a deeper rooting system. The benefit of the deeper root system probably outweighs the cost of production however, since shallow root systems lead to increased susceptibility to drought stress and decreased access to nutrients.
Improved Shoot Organogenesis from Leaf Explants of Highbush Blueberry
Authors: Cao X. , Hammerschlag F.A.
Published: February 2019

As part of a program to develop transgenic highbush blueberry (Vaccinium corymbosum L.) cultivars, studies were conducted to determine optimum conditions for high efficiency shoot regeneration from leaf explants of shoots propagated in vitro. The effects on shoot organogenesis of age of explant source, length of dark treatment, the addition of either thidiazuron (TDZ) at 1 or 5 μm, or zeatin riboside at 20 μm to the regeneration medium, and a photosynthetic photon flux (PPF) of either 18 ± 5 or 55 ± 5 μmol·m–2·s–1 were investigated. A maximum of 13.0, 13.0, 12.6, and 4.6 shoots regenerating per explant for cultivars Duke, Georgiagem, Sierra, and Jersey, respectively, occurred on regeneration medium with zeatin riboside and under a PPF of 55 ± 5 μmol·m–2·s–1. `Duke' regenerated equally well on medium with either zeatin riboside or 1 μm TDZ, whereas the number of shoots per explant for `Georgiagem' and `Sierra' was significantly higher on zeatin riboside. Regeneration of `Duke', `Jersey', and `Sierra' on zeatin riboside was significantly better under a PPF of 55 ± 5 μmol·m–2·s–1 than under 18 ± 5 μmol·m–2·s–1, but the higher PPF inhibited regeneration of `Duke' on 5 μm TDZ. There were no significant differences in percentage of regeneration or the number of shoots per explant from leaf explants derived from either 1-, 2-, or 3-week-old shoot cultures, or when either 1 week or 2 weeks of darkness preceded light treatments. Chemical names used: 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea (thidiazuron, TDZ); 9-(-β-ribofuranosyl)-6-(4-hydroxy-3-methyl-but-2-enylamino)purine (zeatin riboside).
Influence of Sublethal Glyphosate Rates on Leaf Mineral Concentration of Tomato
Authors: Gilreath James P. , Chase Carlene A. , Locascio Salvadore J.
Published: February 2019

Glyphosate at sublethal rates was applied prebloom, at-bloom, or postbloom relative to the first flower cluster to tomato (Lycopersicon esculentum Mill.) to determine the effect on foliar concentrations of N, P, K, Ca, and Mg. Glyphosate rates of 0, 1, 6, 10, 60, and 100 g·ha-1 were used to simulate the effects of spray drift. In three studies, plant vigor declined with increased glyphosate rates and younger plants were more sensitive than older plants. Plant height decreased as glyphosate rate increased, but the response differed with time of evaluation and with stage of development. In Expt. 1, N content decreased with increasing rate of glyphosate, regardless of stage of development, but response varied with time of evaluation with prebloom and at-bloom applications. In Expt. 2, prebloom glyphosate applications reduced N content, but applications at-bloom did not. P declined with prebloom and at-bloom glyphosate applications in Expt. 1, but only with prebloom applications in Expt. 2. In Expt. 3, P concentrations generally declined with glyphosate rates ≤10 g·ha-1, but were unchanged or increased with rates of 60 and 100 g·ha-1. Tissue K, Ca, and Mg concentrations were not consistently affected by glyphosate rate and sample times. Although significant changes in foliar concentrations of N, P, K, Ca, and Mg occurred, leaf mineral analysis was not considered to be a reliable method of quantifying sublethal effects of glyphosate in tomato. Mineral deficiency did not occur in response to glyphosate application. Chemical name used: N-(phosphonomethyl)glycine (glyphosate).
Depletion of an Artificial Weed Seed Bank during the Dormant Period via Heating and Subsequent Chilling of Soil
Authors: Chandran Rakesh S. , Singh Megh
Published: February 2019

Depletion of the weed seed bank by stimulating germination during winter months and subsequently exposing the seedlings to adverse air temperatures is a possible means of controlling weeds in small-scale horticultural operations. Johnsongrass [Sorghum halepense (L.) Pers.], hemp sesbania [Sesbania exaltata (Raf.) Rydb. ex A.W. Hill], and barnyardgrass [Echinochloa crus-galli (L.) Beauv.] were seeded in soil trays and maintained for 4 days at 4 or -12 °C, then heated to 32 °C for 4 days using electric heating pads. Germination percentages, after heating soils, were: 55% and 70% for hemp sesbania, 82% and 72% for barnyardgrass, and 45% and 55% for johnsongrass, respectively; for seeds kept at -12 and 4 °C, respectively. Subsequent exposure of seedlings to -12 °C for 7 days killed all seedlings, while exposure to 4 °C killed only 18% to 28%. The temperature regimes of -12 °C for 4 days, and 32 °C for 4 days followed by -12 °C killed 95%, 78%, and 68% of the johnsongrass, hemp sesbania, and barnyardgrass, respectively.
A Greenhouse Screening Protocol for Fusarium Root Rot in Bean
Authors: Schneider Kristin A. , Kelly James D.
Published: February 2019

Root rot, caused by Fusarium solani f.sp. phaseoli, is a serious disease of bean for which successful control has been elusive. Genetic resistance to the pathogen is considered quantitative and is strongly influenced by environmental factors. To reduce environmental variation and facilitate selection in earlier generations, an accurate, consistent, and nondestructive greenhouse screen was developed for the evaluation of Fusarium root rot resistance in bean. We describe a protocol that involves the germination of seedlings in perlite, inoculation of roots and hypocotyls 10 days after planting and evaluation within 4 weeks. The accuracy of this greenhouse screen was confirmed by demonstrating significant correlations between greenhouse and field ratings. Two experiments that included 24 and 21 diverse bean genotypes, respectively, were performed in the greenhouse and the ratings were correlated with field ratings over two growing seasons. Correlation coefficients between the greenhouse and field ratings were significant and as high as 0.99. Numerous genotypes can be evaluated within a short time for relatively minimal costs and labor. Furthermore, once roots have been rated and dipped in fungicide, plants can be transplanted for production of seed. This simple, rapid, and inexpensive protocol reduces environmental variation inherent to field ratings, thereby more accurately representing physiological resistance while maintaining a close association with observed field ratings.