bluuebunny/crossref_metadata_2025 huggingface dataset:
(56) Transpiration and Photosynthesis of Grafted Watermelon Transplants as Affected by Environmental Factors during Graft Union Formation
Authors: Kim Sung Kyeom , Yu Duk Jun , Bae Ro Na , Lee Hee Jae , Chun Changhoo
Published: February 2019

Grafted transplants are widely used for watermelon culture in Korea mainly to reduce the yield and quality losses caused by soil-borne diseases. It is normal practice to cure the grafted transplants under high relative humidity (RH) and low photosynthetic photon flux (PPF) conditions for a few days after grafting to prevent the wilting of the transplants. Transpiration rate (TR) and net photosynthetic rate (NPR), however, could be suppressed under those environmental conditions. In the present study, TR and NPR of the grafted watermelon transplants were compared during graft union formation under 18 environmental conditions combining two air temperatures (20 and 28 °C), three RHs (60%, 80%, and 100%), and three PPF s (0, 100, and 200 μmol·m-2·s-1). Percentages of graft union formation and survival were also evaluated. TR and NPR dramatically decreased just after grafting but slowly recovered 2 to 3 days after grafting at 28 °C. The recovery was clearer at higher PPF and lower RH. On the other hand, the recovery of TR and NPR was not observed in 7 days after grafting at 20 °C. Differences in TR and NPR affected by RH were nonsignificant. Percentage of graft union formation was 98% when air temperature, RH, and PPF were 28 °C, 100%, and 100 μmol·m-2·s-1, respectively, which was the highest among all the treatments. Percentage of survival was over 90% when air temperature was 28 °C and RH was higher than 80% (when vapor pressure deficit was lower than 0.76 kPa). In addition, higher PPF enhanced TR and NPR and promoted rooting and subsequent growth of grafted transplants. Results suggest that the acclimation process for grafted watermelon transplants can be omitted by properly manipulating environmental factors during graft union formation.
(59) An Examination of Irrigation Volumes and Controlled-release Fertilizer Application Methods and Rates to Reduce Nursery Container Leachate and Fertilizer Use
Authors: Purvis Peter , Chong Calvin , Lumis Glen
Published: February 2019

Plug-rooted liners of common ninebark [Physocarpus opulifolius (L.) Maxim.] were grown in 6-L nursery containers filled with 73% composted pine bark, 22% sphagnum peat moss, and 5% pea gravel (by volume). Plants were fertilized with Polyon (Nutryon) 17–5–12 (17N–2P–5K) 6-month controlled-release fertilizer at various rates (2.5, 4.5, 6.5, and 8.5 kg·m-3) pre-incorporated, topdressed, or dibbled (placed under the liner at potting). Plants were trickle-irrigated daily with low (0.4-L), middle (0.8-L), or high (2.0-L) volumes of water to maintain leaching fractions of <0.15, 0.25–0.35, or >0.60, respectively. Regression analysis indicated that growth of ninebark increased from 30 to 109 g/plant with increasing rates of incorporated fertilizer (mean over irrigation volumes), from 27 to 71 g/plant with topdress and from 59 to 103 g/plant with dibble. Electrical conductivity (EC, mean over five dates) of the leachate throughout the season was highest with dibble (0.85 dS·m-3), intermediate with incorporated (0.81 dS·m-3), and least with topdressed (0.76 dS·m-3). With low irrigation volumes, growth of ninebark increased from 42 to 81 g/plant with increasing rates of fertilizer (mean over methods), and from 39 to 105 g/plant with middle or high volumes (common regression curve). With low irrigation volumes, leachate EC increased from 0.74 to 0.94 dS·m-3 with increasing rates of fertilizer, and from 0.75 to 0.81 dS·m-3 with middle or high volumes.
(62) Field Evaluation of Various Herbicide and Mulch Combinations for Ornamental Weed Control
Authors: Mathers Hannah M. , Case Luke T.
Published: February 2019

Two experiments were conducted at the The Ohio State University Waterman Farm, Columbus, on efficacy and phytotoxicity with evalautions at 30, 60, 90, and 120 DAT using dry weights and visual ratings 0–10 with >7 being commercially acceptable for efficacy, and 1–10 with <3 being commercially acceptable for phytotoxicity. The herbicide-treated mulches and herbicide–mulch application methods were compared to sprays of the five chemicals applied directly to the surfaces of the plots [oryzalin (oryzalin), (AS) Surflan (aqueous solution) 2 lb/acre (a.i.), flumioxazin (SureGuard WDG), 0.34 lb/acre (a.i.), acetochlor 76% (Harness 2.5 lb/acre (a.i.), dichlobenil (Casoron CS) 4 lb/acre (a.i.) and a combination of oryzalin and flumioxazin], two untreated mulches (pine and hardwood) and a weedy. Mulches were applied untreated, over the top of soil surfaces sprayed with the different herbicides. Mulches were also applied untreated to untreated soil surfaces and then sprayed with the different herbicides. Pretreated bark mulches were also evaluated and prepared by placing the mulches on a sheet of plastic, as a single layer thick and sprayed and allowed to dry for 48 hours. Twenty of 38 treatments gave efficacy rating of >7, pooled over all evaluation dates. One was a direct spray, Surflan + SureGuard (7.6). Three were pretreated mulches, Surflan + SureGuard (8.2), Harness (7.8) and Surflan (7.4) treated pine. None of the pretreated hardwood barks provided ratings of >7. Nine were treatments with the herbicides applied under the bark. Seven of the nine provided ratings of >8 and only one involved hardwood bark, Surflan + SureGuard under pine (9.1), Casoron under pine (8.9), Surflan under pine (8.7), Harness under pine (8.3), Harness under pine (8.0) and SureGuard under hardwood (8.0).
Inheritance of Powdery Mildew Resistance and Leaf Macrohair Density in Gerbera hybrida
Authors: Kloos Wesley E. , George Carol G. , Sorge Laurie K.
Published: February 2019

The cultivated gerbera daisy [Gerbera hybrida (G. jamesonii Bolus ex Adlam × G. viridifolia Schultz-Bip)] often contracts powdery mildew (PM) when grown under conditions of high humidity. During field and greenhouse performance trials conducted with gerberas of the North Carolina State University collection, two half-sib field plants and two of their greenhouse-grown progeny were identified as being highly resistant to PM caused by Podosphaera (Sphaerotheca) fusca (Fr.) Blumer emend. Braun & Takamatsu. These plants were also unusual in having smooth glossy leaves with very low numbers of bristle macrohairs (MHs) on the adaxial leaf surface compared to wild type. The primary objectives of this investigation were to determine the mode of inheritance of PM resistance and MH density traits and determine if there was a causal relationship between the phenotypes. Parental genotypes were determined by testcrosses to wild-type, PM-susceptible and MH-high-density leaf cultivars. For each trait, a series of crosses were made to produce PA, PB, F1, F2, BC1A, and BC1B progeny. Linkage relationships among PM resistance and MH density loci were examined by testcrosses. Phenotypic segregation ratios suggested the presence of a dominant allele, Pmr1, determining PM resistance and an unlinked dominant allele, Mhd, determining low density of adaxial bristle MHs and moderate reduction in abaxial smooth MHs. The Pmr1 allele appeared to be incompletely dominant in some heterozygotes where one parent was from a highly PM susceptible background. Modifying genes may have some affect on the level of PM resistance or susceptibility. The Mhd allele appeared to be incompletely dominant in some heterozygotes. Segregation ratios indicated that the wild-type alleles were recessive to the PM-resistance and MH-low-density alleles and given the designation pmr1 and mhd, respectively. Density of leaf MHs did not affect PM resistance.
Honey Bee Pollination Requirements for Triploid Watermelon
Authors: Walters S. Alan
Published: February 2019

Honey bees (Apis mellifera L.) are important pollinators of triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai]. Pistillate (or female) watermelon flowers require multiple honey bee or other wild bee visitations after visiting staminate (or male) flowers for fruit set, and pollination is even more of a concern in triploid watermelon production since staminate flowers contain mostly nonviable pollen. Six honey bee visitation treatments—1) no visitation control, 2) two visits, 3) four visits, 4) eight visits, 5) 16 visits, and 6) open-pollinated control—were evaluated to determine the effectiveness of honey bee pollination on `Millionaire' triploid watermelon fruit set, yield, and quality utilizing `Crimson Sweet' at a 33% pollenizer frequency. `Millionaire' quality characters (hollow heart disorder or percent soluble solids) did not differ (P > 0.05) between honey bee pollination treatments. The open-pollinated control provided the highest fruit set rate (80%) and the greatest triploid watermelon numbers and weights per plot compared to all other honey bee visitation treatments. Fruit set, and fruit numbers and weights per plot increased linearly as number of honey bee visits to pistillate flowers increased from 0 (no visit control) to the open-pollinated control (about 24 visits). This study indicated that between 16 and 24 honey bee visits are required to achieve maximum triploid watermelon fruit set and yields at a 33% pollenizer frequency, which is twice the number of honey bee visits required by seeded watermelons to achieve similar results. This is probably due to many honey bees visiting staminate triploid watermelon flowers (that are in close proximity) before visiting pistillate flowers thus providing mostly nonviable pollen that is useless for fruit set and development. Therefore, more honey bee visits to pistillate triploid watermelon flowers would be required to achieve maximum fruit set and subsequent development compared to seeded watermelons.
Clonally Propagated and Seed-derived Papaya Orchards: II. Yield Comparison
Authors: Fitch Maureen M.M. , Moore Paul H. , Leong Terryl C.W. , Akashi Leslie Ann Y. , Yeh Aileen K.F. , White Susan A. , Cruz Amy S. Dela , Santo Lance T. , Ferreira Stephen A. , Poland Leslie J.
Published: February 2019

Gynodioecious papaya (Carica papaya L.) seedlings in commercial cropping systems in Hawaii are typically multiple-planted and thinned upon flowering to a single hermaphrodite because seedlings segregate for sex expression. Use of clonally propagated hermaphrodites would eliminate the over-planting practice and may provide other advantages. Yields of clonally propagated hermaphrodites were compared with single- and multiple-planted seedlings in three fields on two islands in Hawaii. Cloned hermaphrodites were either rooted cuttings or in vitro micropropagated plants. Clonally propagated plants bore ripe fruit 1 to 3 months earlier than thinned seedlings and had significantly higher early and cumulative yields. At each site, cumulative yields of thinned seedlings never reached the same level as those of clonally propagated plants. The yield benefit from clonally propagated plants was greatest at Keaau, the lowest sunlight and least productive test site.
Paclobutrazol-induced Leaf, Stem, and Root Anatomical Modifications in Potato
Authors: Tsegaw Tekalign , Hammes S. , Robbertse J.
Published: February 2019

Potato (Solanum tuberosum L.) treatment with paclobutrazol resulted in short and compact plants having dark green and thicker leaves, and wider stem and root diameters. Investigating the underlying anatomical modifications in response to the treatment was the objective of the study. Plants of potato cultivar BP 1 were treated with 0, 45.0, 67.5, and 90.0 mg paclobutrazol per plant as a foliar spray. A month after treatment leaf, stem and root materials were taken from the control and plants treated with 67.5 mg paclobutrazol, and histological observations were made using light microscope. Leaves of treated plants showed an increased chlorophyll a and b contents, thicker epicuticular wax layer, elongated and thicker epidermal, palisade and spongy mesophyll cells. paclobutrazol increased stem diameter by about 58% due to induction of thicker cortex, larger vascular bundles, and wider pith diameter associated with larger pith cells. Widening the cortex and the induction of more secondary xylem vessels in response to paclobutrazol treatment increased the root diameter by about 52%. Paclobutrazol treatment remarkably increased the accumulation of starch granules in the stem pith cells and cortical cells of the stem and root. This study is similar to the other relevant studies in reporting an increased leaf thickness, and stem and root diameters; however, most of the underlying anatomical modifications described above have not been reported previously.
Efficacy of Beauveria bassiana on Colonized Millet Seed as a Biopesticide for the Control of Shore Flies
Authors: Stanghellini M.E. , El-Hamalawi Z.A.
Published: February 2019

Shore flies (Scatella stagnalis) have been implicated as an aerial vector of several soilborne plant pathogens of greenhouse crops. A strain of Beauveria bassiana (Bb), isolated from a shore fly cadaver, was evaluated as a biopesticide for the control of shore flies. Bb was grown on autoclaved millet seed for 2 weeks, air-dried at 24°C for 7 days and stored in paper bags. Dried Bb-colonized millet seeds were broadcast on the surface of pots containing potting medium naturally-infested with larvae and pupae or pots infested only with adult flies. Controls consisted of insect-infested pots amended with autoclaved millet seeds. Pots of the same treatment were placed in insect-proof screen cages. At daily intervals for 15 days, adult fly populations were recorded in each cage. In cages initially containing only larvae and pupae, adult fly populations in the control (no Bb) treatment reached a final population of 70 adults on day 15. In contrast only two adult flies were observed in the Bb-treatment. In cages containing only adult shore flies, the entire population was dead within 10 to 12 days in the Bb-treatment. In the absence of Bb, 65% of the initial population of adults was still alive on day 12.
Groundcover Materials Improve Quality and Storability of 'Aroma' Apples
Authors: Tahir Ibrahim I. , Johansson Eva , Olsson Marie E.
Published: February 2019

To decrease the unfavorable effects of herbicides on human health and on the environment, new sustainable mulching methods have been developed. These methods aim to impede weed growth and also result in good yield and high fruit quality. The objective of the present study was to investigate the effects of the replacement of conventional methods (chemical treatments or mechanical) with different groundcover material systems (GCMSs) that use aluminum, bark and black polypropylene on 'Aroma' apple (Malus domestica) fruit maturity and quality, and fruit resistance to bruising and decay. The experiment was carried out from 1995 to 2001. Compared with conventional mulching methods, aluminum mulching was found to control annual weeds more effectively, to increase soil temperature, light reflection, yield, and fruit weight, to decrease bruise occurrence, to intensify and saturate the red coloration of apples, and to increase firmness and acid and sugar contents, resistance to storage disorders and decay after storage and shelf life. The other two used GCMSs, bark and black polypropylene also influenced many yield and quality parameters. However, less positive influences on the different parameters were found for bark compared with aluminum, and the use of black propylene was not favorable compared with the conventional mulching methods. Generally, decreased starch content at early picking dates was found for apples grown with GCMSs, indicating an earlier ripening for these apples compared with apples grown with a conventional mulching system. In summary, aluminum mulching was found to be the best alternative mulching method for production of 'Aroma' apples.
Response of Container-grown Ninebark to Crude and Nutrient-enriched Recirculating Compost Leachates
Authors: Gils Joanna , Chong Calvin , Lumis Glen
Published: February 2019

Ninebark [Physocarpus opulifolius (L.) Maxim] was grown on troughs under greenhouse conditions in 2.5-L containers filled with 100% composted pine bark and fertigated with drip irrigation using the following nutrient solutions: 1) a complete (control) solution, electrical conductivity (EC) of 1.75 dS·m–1, nonrecirculated; 2) solution as in treatment 1 but recirculated; 3) unamended municipal solid waste compost (MSW) leachate, EC 1.75 dS·m–1, recirculated; 4) solution as in treatment 3 amended in order of priority with NO3-N, NH4-N, P, K, Ca and/or Mg, to match the concentrations in the complete solution, EC 2.60 dS·m–1, recirculated; 5) unamended turkey litter compost (TLC) leachate, EC 1.75 dS·m–1, recirculated; and 6) solution as in treatment 5 amended as in treatment 4, EC 2.40 dS·m–1, recirculated. Among the four recirculated compost leachate treatments, shoot (stems and leaves) dry weight of ninebark was least with the unamended MSW, intermediate with amended MSW, and greatest but similar with both unamended and amended TLC. The most growth occurred with the recirculated control solution. Among the four leachate treatments, ninebark grew acceptably well only with recirculated unamended TLC, and was similar to that with the nonrecirculated control solution. Three treatments (nonrecirculated control, recirculated control and unamended TLC) showed no nutrient toxicity or deficiency symptoms. Poorer growth responses in the other treatments (amended TLC, amended MSW and unamended MSW) were related primarily to excess salts and/or nutritional disorders due to imbalance(s) in one or more nutrients.
Pecan Fruit Shuck Thickness is Related to Nut Quality
Authors: Thompson T.E.
Published: February 2019

Pecan [Carya illinoinensis (Wangenh.) K. Koch] fruit presents a considerable weight for the tree to support during the growing season. A major part of this weight is due to the pecan shuck that surrounds the developing nut and kernel. Pecan clones vary considerably for the amount of shuck per nut, and little is known as to the value of this weight in determining final nut quality. Six cultivars differing in basic nut shapes and sizes were studied and found to vary greatly for shuck thickness, and weight of shuck per unit final nut weight and volume. Shuck thickness was shown to be a favorable genetic characteristic since fruit with thicker shucks had slightly greater nut fresh and dry weight, nut volume, nut density, kernel weight and content, and shuck weight per nut volume. `Sioux' had the thickest shucks (4.70 mm), while `Pawnee' had the thinnest shucks (3.72 mm). Fresh weight per fruit varied from 21.25 g for `Podsednik' to 10.18 g for Osage. Weight of fruit per tree was extrapolated using average shuck and nut weights, and it was determined that the fruit on each tree would weigh about 104 kg. This is a considerable weight, and adds substantially to limb breakage. However, thicker shucks contribute to final nut quality.
Mineral Nutrition of Prunus Rootstocks: Leaf Concentrations and Diagnosis by Vector Analysis
Authors: García Antonio L. , Gallego Jesús , Fuentes Vicenta , Nicolás Nuria , Madrid Ramón
Published: February 2019

The effects of different levels of phosphorus fertilization and water provision on the mineral nutrition of two clonal rootstocks of Prunus were studied. Two-year-old Prunus seedlings, Hybrid GF677 (Prunus persica × Prunus amygdalus) (PH) and Pollizo Puebla de Soto 101 (Prunus insititia) (PI) were planted in an uncultivated calcareous soil (a Xeric torriorthent derived from marl) under greenhouse conditions. They were drip irrigated with subterranean water of slightly alkaline pH (7.63), EC 0.88 dS·m–1, with a low chloride and high sulphate content. The experiment lasted two annual cycles. In October of the second year the leaf nutrient concentration and dry weight of the total leaf weight were determined in four trees of each combination of rootstock × irrigation level × fertilization treatment. The nutritive state of these trees was analyzed by vector analysis. The results point to a highly significant influence of the rootstock nature on the leaf concentrations of most nutrients. Very low Zn and Cu concentrations were recorded on both rootstocks, for both irrigation levels and several fertilizing treatments. Vector analysis confirmed the Cu deficiency resulting from several of the fertilizing treatments and both irrigation levels in PH rootstocks.
Brassinosteriod-induced Femaleness in Cucumber and Relationship to Ethylene Production
Authors: Papadopoulou Ekaterina , Grumet Rebecca
Published: February 2019

The Cucurbitaceae family is noted for a diversity of sex expression phenotypes. Typically, a phase of male flowers precedes either female or bisexual flower production. Sex determination of individual flowers is regulated by a combination of genetic, environmental, and hormonal factors. Ethylene, auxins, and gibberellins have all been shown to influence flower sex expression in cucurbits. Ethylene, which promotes femaleness, plays a predominant role. In this study, we tested whether brassinosteroids (BR), a more recently identified class of plant hormones, also influences cucurbit sex expression. Applied epi-brassinolide (epi-BL) caused a significant decrease in time of appearance of the first female flower on monoecious cucumber plants, and increased total female flowers on the main stem. Increasing concentrations had a stronger effect. Of the three species tested, cucumber, melon and zucchini, cucumber was the most responsive to BR. Application of epi-BL also caused an increase in ethylene production by cucumber and zucchini seedlings, suggesting that the BR effect may be mediated by ethylene. To investigate the possible relationship between BR and ethylene on sex expression, we identified the concentration of ethephon (5 ppm) that caused an increase in ethylene production comparable to that induced by 10 μm epi-BL (approximately two-fold). Treatment with 5 ppm ethephon was sufficient to increase femaleness of cucumber plants, but not zucchini plants, suggesting that the difference in response to epi-BL treatment may reflect differences in sensitivity to ethylene. Collectively, our results indicate that application of brassinosteroids to cucumber cause earlier and increased female flower production, and that the effects may be mediated, at least in part, by brassinosteroid-induced production of ethylene.
Antioxidant Capacity and Phenolic Content of Selected Strawberry Genotypes
Authors: Rekika Djamila , Khanizadeh Shahrokh , Deschênes Martine , Levasseur Audrey , Charles Marie Thérèse , Tsao Rong , Yang Raymond
Published: February 2019

Eighteen strawberry genotypes were evaluated for their phenolic content and antioxidant capacity using several methods. High antioxidant capacity was found for `Harmonie', `Saint-Jean d'Orléans', and `Saint-Laurent d'Orléans', which were reported to have better shelf life than `Kent'. `Harmonie', `Saint-Jean d'Orléans', `Orléans', and some advanced selections had higher hydroxycinnamic acids, benzoic acids, and flavonols than `Kent'. The significant variation in antioxidant capacity and total phenolic compounds clearly shows the potential value of certain new cultivars and advanced lines as parents in a breeding program. The future plan is to examine individual antioxidant and their role in disease resistance and extension of shelf life and to use selected genotypes as parents to developed new lines.
Hydrolyzed Casein Reduces Browsing of Trees and Shrubs by White-tailed Deer
Authors: Kimball Bruce A. , Nolte Dale L. , Perry Kelly B.
Published: February 2019

Hydrolyzed casein (HC) and retail products that contain HC are evaluated as repellents to minimize deer damage to trees and shrubs. Three different experiments demonstrate that HC is an effective deer repellent. Technical-grade HC completely eliminated browse damage to evergreen shrubs (Gaultheria shallon Pursh.) and conifers (Thuja plicata Donn.) during the test periods. Retail sources of HC (concentrated baby formula powders) are not as effective as pure hydrolyzed protein, but do offer browse protection when alternative sources of browse are available. For nursery, orchard, and reforestation applications, HC is a promising deer repellent to minimize losses due to browse. For the private homeowner, a simple repellent formulated with glue and a HC-containing baby formula may offer considerable browse protection when alternative forage is available.
Relationship of Instrumental and Sensory Texture Measurements of Fresh and Stored Apples to Cell Number and Size
Authors: Mann Harpartap , Bedford David , Luby James , Vickers Zata , Tong Cindy
Published: February 2019

During storage, many apple (Malus ×domestica Borkh.) genotypes lose their desirable textural qualities, but some like `Honeycrisp', maintain their sensory Crispness and Firmness. To understand this differential response of genotypes to postharvest changes in texture, reliable and quantifiable methods of texture measurement are needed. This study integrated data from a snapping test, confocal laser scanning microscopy (CLSM), and sensory panels to study postharvest textural changes and to predict sensory textural attributes of Firmness, Crispness, Mealiness, and Juiciness. Three separate analyses on fresh, stored, and combined fresh and stored fruit data yielded different predictors for the same sensory attributes. Change in Crispness during storage was successfully predicted by change in Work during storage. Cell number and size were related to fresh fruit texture and its maintenance during storage. Unique textural properties of `Honeycrisp' were found to be inherited by its progeny.
Breeding Low-chill Blueberries and Peaches for Subtropical Areas
Authors: Lyrene Paul M.
Published: February 2019

Breeding to adapt temperate-zone fruit to subtropical production areas has been a formidable objective because so many different characteristics have to be changed, most of which are controlled by many genes. Recurrent selection is the only breeding method that can accomplish the required wholesale reorganization of the physiology of the plant. The principles of recurrent selection, developed and tested using short-generation organisms like fruit flies, rats, and maize, have been applied to the development of low-chill highbush blueberry (V. corymbosum L.) and peach [Prunus persica (L.) Batsch.] cultivars for northern and central Florida. These principles include using many parents per generation of crosses, minimizing the time between cycles of selection, and selecting simultaneously for all heritable traits that are important in the final product, with traits of highest economic importance and highest heritability being given the highest weight in selecting parents. Many characteristics changed during the breeding of low-latitude peach and highbush blueberry cultivars, including chill requirement, photoperiod response, resistance to various disease and insect pests, fruit chemistry, and growth patterns during a long growing season.
Intractable Traits in Eastern U.S. Blackberries
Authors: Clark John R.
Published: February 2019

Eastern U.S. blackberries are heterogeneous tetraploids. Some traits have been quite difficult to improve, and the example of erect-caned, thornless cultivar development is a good example. Thornlessness was associated with semi-erect canes, poor seed germination, and other undesirable traits, thus extending the amount of time to achieve an erect-caned, thornless cultivar. The first release of this type was `Navaho' in 1989. Primocane fruiting is a trait that would not likely be considered intractable, but did not gain substantial attention until the late 1980s. Subsequent work in primocane fruiting has shown substantial progress in a relatively short time of breeding emphasis for this trait. Fruit size gains have been substantial, and even though this trait might be considered intractable, progress has been significant in the last 40 years. Excellent postharvest handling and flavor are additional traits which one might consider intractable. Substantial progress has been made in improving fruit quality for shipping, providing for an expansion in fruit shipped to distant markets. These and other improvements are expanding opportunities for blackberry growers worldwide.
Dark Disk Color in the Flower of Gerbera hybrida is Determined by a Dominant Gene, Dc
Authors: Kloos Wesley E. , George Carol G. , Sorge Laurie K.
Published: February 2019

The cultivated gerbera daisy [Gerbera hybrida (G. jamesonii Bolus ex Adlam × G. viridifolia Schultz-Bip)] produces flowers that have either a dark (shades of dark brown, brown-black, black-purple, or black) or light (shades of green-yellow, yellow-green, or light yellow) central disk. The dark-centered varieties have increased in popularity over the past 20 years and provided an exciting color contrast, especially in white, yellow, and various pastel-colored flowers. The objective of this investigation was to determine the mode of inheritance of disk color in gerberas. A series of crosses were made to produce PA, PB, F1, F2, BC1A, and BC1B progeny to complete the Mendelian genetic analysis. Phenotypic segregation ratios indicated that dark disk color was determined by a single dominant gene, designated Dc, and the light disk color by a recessive gene, dc. Dominance appeared to be complete in that the disk color was similar in both homozygous and heterozygous Dc plants.
The Impact of Early Cropping on Subsequent Growth and Yield of Highbush Blueberry in the Establishment Years at Two Planting Densities is Cultivar Dependant
Authors: Strik Bernadine , Buller Gil
Published: February 2019

The effect of early cropping (no removal of fruit buds the first two years) and in-row spacing (0.45 or 1.2 m) on growth and yield of `Duke', `Bluecrop', and `Elliott' northern highbush blueberries (Vaccinium corymbosum L.) was studied. Plants were grown on raised beds for four years. No yield was produced on the control plants in the planting year (year 1) and year 2. Plant growth at the start of year 3 was adversely impacted by early cropping in years 1 and 2. Early cropping reduced the dry weight of the root system, crown, and 1- to 3-year-old wood in all cultivars. `Bluecrop' plants had less total dry weight than those of `Duke' or `Elliott'. Roots accounted for 30% to 45% of the total plant dry weight depending on cultivar. Early-cropped plants had a lower percentage of fruit buds than control plants. Early cropping reduced yield 44%, 24%, and 19% in year 3, compared to control plants, in `Elliott', `Duke', and `Bluecrop', respectively. Cumulative yield (years 1 through 4) was similar between control and early cropped plants in `Bluecrop' and `Duke', whereas early cropping reduced cumulative yield in `Elliott' 20% to 40%, depending on in-row spacing. Plants spaced at 0.45 m produced 62% to 140% more yield per hectare than those spaced at 1.2 m, depending on cultivar. `Elliott' plants seemed less suited to high density planting due to their large root system.
Partial Defoliation Can Decrease Average Leaf Size but Has Little Effect on Orange Tree Growth, Fruit Yield and Juice Quality
Authors: Yuan Rongcai , Alferez Fernando , Kostenyuk Igor , Singh Shila , Syvertsen James P. , Burns Jacqueline K.
Published: February 2019

The effects of 2 consecutive years of annual defoliation during the harvest season on fruit size, yield, juice quality, leaf size and number were examined in trees of the midseason cultivar `Hamlin' and the late-season cultivar `Valencia' orange [Citrus sinensis (L.) Osb.]. In `Hamlin', removal of up to 50% of the leaves in late November had no effect on fruit yield, fruit number, fruit size, soluble solids yield, juice °Brix, and °Brix to acid ratio of juice the following year. In `Valencia', removal of 50% of the leaves in late March decreased fruit yield and soluble solids yield but did not affect Brix or the Brix to acid ratio of the juice. Leaf size of new flush was reduced by removal of 50% of the leaves in both cultivars but there was little effect on total canopy size. There were no measured effects of removing 25% of leaves from tree canopies. Thus, canopy growth, fruit yield, fruit quality, and leaf size were not negatively impacted when annual defoliations did not exceed 25% of the total canopy leaf area in `Valencia' and `Hamlin' orange trees for two consecutive years. Overall, fruit weight increased linearly with increasing ratio of leaf area to fruit number, suggesting that fruit enlargement can be limited by leaf area.
Impact of Vermicompost on Vegetable Transplant Quality
Authors: Paul Lindsay C. , Metzger James D.
Published: February 2019

Vermicomposting is a promising method of transforming unwanted and virtually unlimited supplies of organic wastes into usable substrates. In this process, the digestive tracts of certain earthworm species (e.g., Eisenia fetida) are used to stabilize organic wastes. The final product is an odorless peat-like substance, which has good structure, moisture-holding capacity, relatively large amounts of available nutrients, and microbial metabolites that may act as plant growth regulators. For these reasons, vermicompost has the potential to make a valuable contribution to soilless potting media. The objective of this study was to evaluate the transplant quality and field performance of vegetable transplants grown in vermicompost. Tomato (Lycopersicon esculentum Mill.), eggplant (Solanum melongena L.), and pepper (Capsicum annuum L.) transplants were grown in a commercial soilless mix including 0%, 10%, or 20% (v/v) worm-worked cattle manure. Growth of vegetable transplants was positively affected by addition of vermicompost, perhaps by altering the nutritional balance of the medium. Transplant quality was improved in peppers and eggplants while tomato transplant quality was slightly reduced. There were no significant differences in field performance.
Effects of Substrate Type on Plant Growth and Nitrate Leaching in Cut Flower Production of Oriental Lily
Authors: Merhaut Don , Newman Julie
Published: February 2019

Four types of media [coir, 1 coir: 1 peat (by volume), peat, and sandy loam soil] were evaluated for their effects on plant growth and nitrate (NO –3) leaching in the production of oriental lilies (Lilium L.) `Starfighter' and `Casa Blanca'. Twenty-five bulbs were planted in perforated plastic crates and placed on the ground in temperature-controlled greenhouses. The potential for NO –3 leaching was determined by placing an ion-exchange resin (IER) bag under each crate at the beginning of the study. After plant harvest (14 to 16 weeks), resin bags were collected and analyzed for NO –3 content. Plant tissues were dried, ground, and analyzed for N content. Results indicated that the use of coir and peat did not significantly influence plant growth (shoot dry weight) relative to the use of sandy loam soil; however, substrate type influenced the amount of NO –3 leached through the media and N accumulation in the shoots for `Starfighter', but not `Casa Blanca'.
Nondestructive Detection of Nitrogen in Chinese Cabbage Leaves Using VIS–NIR Spectroscopy
Authors: Min Min , Lee Won Suk , Kim Yong Hyeon , Bucklin Ray A.
Published: February 2019

Proper nutrient management is essential to increase yield, quality and profit. This study was conducted to estimate the N concentrations of chinese cabbage (Brassica campestris L. ssp. pekinensis `Norangbom') plug seedlings using visible and near infrared spectroscopy for nondestructive N detection. Chinese cabbage seeds were sown and raised in three 200-cell plug trays filled with growing mixture in a plant growth chamber with three different levels (40%, 80%, and 100%) of required N. Reflectance for leaves of chinese cabbage seedlings was measured with a spectrophotometer 15 days after the experiment started. Reflectance was measured in the 400 to 2500 nm wavelength range at 1.1-nm increments. The leaves were dried afterwards to measure their water content and were analyzed for their actual N contents. The experiment was repeated twice (group I and II). Correlation coefficient spectrum, standard deviation spectrum, stepwise multiple linear regression (SMLR), and partial least squares (PLS) regression were used to determine wavelengths for N prediction models. Performances of SMLR and PLS were similar. For the validation data set (group II), SMLR produced an r2 of 0.846 and PLS yielded r2 of 0.840. The most significant wavelength 710 nm, which was identified by all methods, was correlated to chlorophyll. Water content positively correlated with N concentration (r = 0.76). Wavelengths of 1467, 1910, and 1938 nm selected by SMLR from both groups also showed that water had a strong effect on N prediction. Wavelengths near 2136 nm indicated that protein had potential use in N prediction. Wavelengths near 550 and 840 nm could also contribute to N prediction.
Fungicide and Clay Treatments for Control of Powdery Mildew Influence Wine Grape Microflora
Authors: Sholberg Peter , Harlton Colleen , Boulé Julie , Haag Paula
Published: February 2019

There is very little information on the interaction of wine grape microflora with fungicides used to control grape diseases. The objective of this study was to determine how fungicides used in a standard grape pest management program and an experimental clay being developed for control of powdery mildew affect grape microflora. Grape leaves and fruit were surveyed for bacteria, fungi and yeast six times over the growing season in 2000 after treatment with clay or fungicides. In 2001 only clay was studied for control of powdery mildew in `Chancellor' grapes. The total number of propagules present on untreated leaf and fruit tissue were 76% bacteria, 14% yeast, and 9% fungi. Fungicides used for grape disease control significantly reduced epiphytic fungi (P < 0.0001), bacteria (P = 0.03), and yeast (P = 0.0001) on grape berries and epiphytic fungi (P < 0.0001), and yeast (P = 0.03) on leaves. The clay treatment had no detectable effect on grape microflora because no significant differences were recorded between clay or untreated grape berries or leaves on any of the sampling dates. Over the growing season the fungicide spray program reduced incidence and severity of powdery mildew better than clay. Clay controlled powdery mildew on `Chancellor' fruit in 2000 and 2001.
Postharvest Quality of Grape Tomatoes Treated with 1-Methylcyclopropene at Advanced Ripeness Stages
Authors: Ergun Muharrem , Sargent Steven A. , Huber Donald J.
Published: February 2019

Grape tomatoes (Lycopersicon esculentum Mill. `Santa') harvested at light-red (>90% color) and full-red stages were treated with 1 μL·L–1 1-methylcyclopropene (1-MCP) for 24 hours at 20 °C and stored at 20 °C. After 1 day of storage, fruit harvested at light-red stage treated with 1-MCP had a 56% lower respiration rate than untreated fruit. By day 7, respiration rates of the two treatments had converged at about 2 mL·kg–1·h–1. Ethylene production of light-red stage tomatoes treated with 1-MPC was 24% lower than untreated during storage, with rates converging by day 11. For fruit harvested full-red, 1-MCP had similar effects on respiration and ethylene production, although convergence occurred earlier, by day 5. Subsequent tests were conducted only with fruit harvested at full-red stage, since fruit harvested at the light-red stage had lower soluble solids content (4.3%) than fruit harvested at the full-red stage (5.5%). Several combinations of 1-MCP concentrations and exposure times were applied at 20 °C: 1 μL·L–1 for 24 h, 5 μL·L–1 for 6 or 12 h, 25 μL·L–1 for 6 or 12 h, and 50 μL·L–1 for 6 or 12 h; following the respective pretreatment fruits were stored at 20 °C. 1-MCP pretreatment extended marketable life by 1 d, irrespective of pretreatment regime, where untreated and pretreated fruit remained marketable (<15% of fruit soft, decayed and/or shriveled) for 6 and 7 d, respectively. However, 1-MCP did not affect whole fruit firmness, epidermal color, internal color, soluble solids content (6.5%), total titratable acidity (0.64%), or pH (4.3). In a third test simulating commercial handling procedures, full-red harvested tomatoes were treated with 1 μL·L–1 1-MCP for 24 h at either 13 or 20 °C, stored for 4 d at 13 °C, and then transferred to 20 °C. Under these conditions, marketable life for untreated and 1-MCP-treated tomatoes was 7 and 8 d, respectively.
Growth Response of Major U.S. Cowpea Cultivars. I. Biomass Accumulation and Salt Tolerance
Authors: Wilson Clyde , Liu Xuan , Lesch Scott M. , Suarez Donald L.
Published: February 2019

Over the last several years, there has been increasing interest in amending the soil using cover crops, especially in desert agriculture. One cover crop of interest in the desert Coachella Valley of California is cowpea [Vigna unguiculata (L.) Walp.]. Cowpea is particularly useful in that as an excellent cover crop, fixing abundant amounts of nitrogen which can reduce fertilizer costs. However, soil salinity problems are of increasing concern in the Coachella Valley of California where the Colorado River water is a major source of irrigation water. Unfortunately, little information is available on the response of cowpea growth to salt stress. Thus, we investigated the growth response of 12 major cowpea cultivars (`CB5', `CB27', `CB46', `IT89KD-288', `IT93K-503-1', `Iron Clay', `Speckled Purple Hall', `UCR 134', `UCR 671', `UCR 730', `8517', and `7964') to increasing salinity levels. The experiment was set up as a standard Split Plot design. Seven salinity levels ranging from 2.6 to 20.1 dS·m–1 were constructed, based on Colorado River water salt composition, to have NaCl, CaCl2 and MgSO4 as the salinization salts. The osmotic potential ranged from –0.075 to –0.82 MPa. Salt stress began 7 days after planting by adding the salts into irrigating nutrient solution and ended after 5 consecutive days. The plants were harvested during flowering period for biomass measurement (53 days after planting). Data analysis using SAS analysis of variance indicated that the salinity in the range between 2.6 and 20.1 dS·m–1 significantly reduced leaf area, leaf dry weight, stem dry weight and root dry weight (P ≤ 0.05). We applied the data to a salt-tolerance model, log(Y) = a1 + a2X + a3X2, where Y represents biomass, a1, a2 and a3 are empirical constants, and X represents salinity, and found that the model accounted for 99%, 97%, 96%, 99%, and 96% of salt effect for cowpea shoot, leaf area, leaf dry weight, stem dry weight and root dry weight, respectively. We also found significant differences (P ≤ 0.05) of each biomass parameter among the 12 cultivars and obtained different sets of the empirical constants to quantitatively describe the response of each biomass parameter to salinity for individual cowpea cultivars. Since a significant salt × cultivar interaction effect (P ≤ 0.05) was found on leaf area and leaf dry weight, we concluded that salt tolerance differences exist among the tested cultivars.
Petunia Growth and Maintenance in the Landscape as Influenced by Alternative Irrigation Strategies
Authors: Scheiber S.M. , Beeson Richard C.
Published: February 2019

Petunia ×hybrida Vilm. `Midnight' plants were grown in drainage lysimeters to evaluate growth in response to alternative irrigation strategies. Irrigation treatments were tensiometer-regulated automatic irrigation systems, regularly scheduled irrigation using an automated controller, and human perception of plant irrigation need (manual watering). Mean irrigation volumes were reduced by manual watering and tensiometer-regulated treatments, compared to the automated controller. Total mean irrigation volume applied by the automated controller (460 L) was significantly greater than received by the manually watered (293 L) or tensiometer-regulated (286 L) treatments. Regularly scheduled irrigation using an automated controller resulted in higher assimilation rates, final shoot dry mass, final biomass, shoot to root ratios, and growth indices compared to other irrigation methods tested. Assimilation rates were significantly higher for tensiometer-controlled irrigation than the manually watered treatment, but no differences were reported between these two treatments for growth parameters. Visual observations indicated aesthetic quality was compromised among tensiometer-regulated and manually watered treatments relative to the automated controller treatment.
Nitrogen Form and Concentration Affect Nitrogen Leaching and Seedling Growth of Prosopis velutina
Authors: Hahne Kathryn S. , Schuch Ursula K.
Published: February 2019

Velvet mesquite [Prosopis velutina Woot., Syn.: P. juliflora (Swartz) DC. var. velutina (Woot.) Sarg.] has become more popular in arid landscapes of the southwestern U.S., but little information on N requirements during the seedling stage is available. In addition to optimize growth of seedlings, minimizing N in runoff during production is an important consideration. Experiments were conducted to determine how biomass production and N leaching were affected first by different ratios of ammonium and nitrate N in sand culture and second by different N concentrations when seedlings were grown in two substrates. Mesquite seedlings produced the greatest biomass after 120 days when fertigated with a solution of 33 NO3–: 67 NH4+. Loss of N through leachate was 40% greater when NH + 4 comprised two thirds or more compared to one third or none in the fertigation solution. Nitrogen in leachate was highest after 16 weeks of treatment, coinciding with the reduced growth rate of seedlings. The second experiment utilized either sand or commercial growing media and a fertigation solution of 33 NO3–: 67 NH4+. Fertigation with 200 mg·L–1 N after 60 days in either substrate produced greatest biomass, while rates of 25, 50, or 100 mg·L–1 N produced about half of that biomass. With few exceptions, less N in either form was found in leachate when seedlings were grown in media and were fertigated with the two higher N rates compared to seedlings grown in sand at the two higher N rates. Plant morphology, biomass accumulation, photosynthate allocation, and the fate of N in the growing substrate and in leachate were strongly affected by the choice of growing substrate.
Leaf Disk Infection by Colletotrichum acutatum and Its Relation to Fruit Rot in Diverse Blueberry Germplasm
Authors: Ehlenfeldt Mark K. , Polashock James J. , Stretch Allan W. , Kramer Matthew
Published: February 2019

Response to foliar infection by Colletotrichum acutatum Simmonds ex Simmonds was assayed in a diverse group of 149 blueberry cultivars and selections using a detached leaf-disk assay. Disks were inoculated and incubated for one week, then were digitally imaged, and images analyzed for percent leaf decay. Infection percentages across cultivars averaged 32%, and ranged from 8% to 79%. The lowest levels of foliar infection were seen in the cultivars, Burlington, Sharpblue, and Berkeley. Foliar responses were compared to anthracnose fruit rot susceptibility data from a previous study. Several clones were observed to have low levels of both foliar and fruit infection. Cultivars with particularly good resistance to both phases included `Sharpblue', `Sunshine Blue', `Legacy', `Little Giant', `Flordablue', `Elliott', `Blue Ridge', `Blue Rose', and `November Glow'. Little correlation was observed between foliar response and fruit response to anthracnose infection (r = 0.15). Since C. acutatum overwinters primarily in vegetative tissue, breeding new cultivars with foliar resistance may assist in reducing inoculum levels of this disease under field conditions.