bluuebunny/crossref_metadata_2025 huggingface dataset:
067 SHOOT ORIENTATION AFFECTS PEACH SHOOT AND FRUIT GROWTH
Authors: Gross Paula M. , Myers Stephen C.
Published: February 2019

One-year old fruiting shoots averaging 50 cm in length were tagged according to naturally-occurring orientations ranging from vertical to horizontal throughout the canopies of dormant `Encore' peach (Prunus persica L Batsch) trees. Following fruit set, tagged shoots were thinned to two or three fruit per shoot. Fruit diameter, terminal shoot extension, and shoot orientation were measured at intervals throughout the season. Fruit were harvested at uniform maturity based on ground color for assessment of fresh weight, diameter, percent red blush, and red color intensity. A linear relationship (p=.001) was found between final fruit size and initial orientation, with fruit diameters 6 percent larger on shoots initially oriented horizontally than those initially vertical. Fruit size differences were not detected until the last two to three weeks of growth. Fruit size response to orientation was found to be independent of light. Red color development was not influenced, probably due to fairly uniform light environments within the canopies. Terminal shoot length was linearly related to initial orientation, with shoots initially oriented horizontally having the least terminal shoot extension. Development of lateral shoot growth in relation to shoot orientation will be discussed.
071 EFFECT OF EXCESSIVE SOLAR RADIATION ON FRUIT QUALITY AND MINERAL NUTRITION OF `GRANNY SMITH' AND `DELICIOUS' APPLES
Authors: Curry Eric A.
Published: February 2019

Warm daytime and cool nighttime temperatures during fruit maturation are conducive to anthocyanin synthesis and starch degradation in many apple cultivars. In parts of the world, high temperatures during fruit maturation result in sunburn of varying degrees of severity ranging from slight bleaching of the pigments in the epidermal layer to cracked and desiccated skin. This experiment assessed the effects of sunburn on fruit quality and mineral nutrition at harvest. In September 1990, about 2000 `Granny Smith' or `Delicious' apples were examined for sunburn and sorted into the following categories: none, light, bleached, bronzed, buckskin, and cracked. Twenty fruit were collected for each category. Each fruit was subdivided into exposed and shaded halves. Each half of each fruit was evaluated for firmness, soluble solids, and acidity. Tissue samples were analyzed for sugars, total nitrogen, and mineral content. Data suggest that excessive heat due to solar radiation creates a gradient of sugars and minerals within the fruit resulting in increased disorders in certain areas of the fruit.
073 A COMPARISON OF NATURAL AND SYNTHETIC MULCHES WITH CONVENTIONAL ORCHARD-FLOOR MANAGEMENT SYSTEMS
Authors: Merwin Ian , Rosenberger Dave , Engle Cathy
Published: February 2019

In several northeastern USDA Low-Input Sustainable Agriculture (LISA) projects, we compared natural (hay-straw, wood-chips, recycled newspaper pulp) and synthetic (polypropylene films and polyester fabrics) mulch materials with mowed sodgrass, tillage, and residual herbicides, as orchard groundcover management systems (GMS). Treatments were applied in 2m-wide strips under newly planted apple (Malus domestica cvs. Liberty, Empire, Freedom. and others) trees on MARK rootstock, planted at 3 by 5m spacing, in 1990. Edaphic, economic, tree nutritional and fruit yield impacts of these GMS were evaluated for four years in five Hudson Valley orchards. All the mulches cost more to establish and maintain ($450 to 4500/ha) than mowed sod ($150/ha), tillage ($120/ha), or residual herbicide ($50/ha) systems. There were few differences in soil water or nutrient availability, leaf nutrient content, tree growth or fruit yield in the mulch systems compared with herbicide or tillage GMS. Meadow voles (Microtus spp.) caused considerable damage to trees in the synthetic and straw mulches, despite the use of trunk guards. Wood-chips were the most enduring, least expensive, and most effective natural mulch. There were insufficient short-term benefits to offset the greater costs of synthetic mulch fabrics or films, in comparison with conventional herbicide snip systems for orchard floor management.
075 MODELING ORIENTAL LILY `STARGAZER' DEVELOPMENT RATE TO CREATE A DECISION-SUPPORT TOOL
Authors: Heins Royal D. , Faust James
Published: February 2019

A decision-support tool for the Oriental lily `Stargazer' was developed from developmental data. Flower buds were measured twice a week on plants growing in greenhouses maintained at 15, 18, 21, 24, or 27°C. For each temperature, days to flower (DTF) was modeled as a linear function of the natural logarithm of bud length, DTF = b0 + b1* In (bud length). Both parameters (b0 and b1) of the linear function were a quadratic function of average daily temperature (ADT). Both parameters of the linear function were then modeled so DTF = (397.6 - 24.5 * ADT + 0.469 * ADT2) + (-83.5 + 5.13 * ADT - 0.098 * ADT2) * In (budlength in mm). A decision-support tool, shown below, was developed from the model to assist with crop timing.
077 Modeling Nitrogen Status of Chrysanthemum in a Growing Container
Authors: Yelanich Mark V. , Biernbaum John A.
Published: February 2019

A model was constructed to dynamically simulate how the nitrogen concentration changes in the root zone of a pot grown chrysanthemum. The root zone concentration of nitrogen is predicted at any time during the crop by predicting the root zone contents of nitrogen and water. The root zone content of nitrogen is predicted by integrating the rates of nitrogen applied, taken up by the plant and entering the top layer of the pot. The root zone water content is predicted by integrating the rates of water applied, evaporated from the media surface and transpired by the plant. Simple models were constructed to predict the various rate processes. For example the rate of nitrogen uptake was modeled as a function of the dry mass accumulation and was broken down into demands of nitrogen by the plant for maintenance of the current dry mass and for support of new growth. Dry mass accumulation was modeled as a function of the amount of PPF which could be intercepted by the plant. The model was validated using plants grown in growth chambers and greenhouses at various PPF levels and fertilizer concentrations. The model will be used to test the risks involved in using various fertilizer strategies and to develop more efficient fertilization strategies.
081 A PLANT-BASED MEASURE FOR DETERMINING TREE WATER NEEDS
Authors: Shackel K. , Southwick S. , Lampinen B.
Published: February 2019

To be useful for indicating plant water needs, any measure of plant stress should be closely related to some of the known short and medium term plant stress responses, such as stomatal closure and reduced rates of expansive growth. Methods for the measurement of plant water potential (Ψ) are available, but conflicting results have led to disagreement as to whether any of these give an appropriate biological index of plant water stress. Some pressure chamber results may be attributed to an artifact of water loss following excision. Leaf and stem Ψ however, in addition to being numerically different, may not be equivalent indices of plant stress, and midday stem Ψ has proven to be a useful index of stress in a number of fruit trees. Day to day fluctuations in midday stem Ψ under well irrigated conditions is well correlated to midday Vapor Pressure Deficit, and hence can be used to predict a non-stressed baseline. A 50% decline in water use at both the leaf and canopy level were associated with relatively small reductions (0.5 to 0.6 MPa) in midday stem Ψ from this baseline in prune. In cherry, midday stem Ψ was correlated to both leaf stomatal conductance and rates of shoot growth, with shoot growth essentially stopping once midday stem Ψ dropped to between -1.5 to -1.7 MPa. In pear, increased fruit size, decreased fruit soluble solids and increased green color were all associated with increases in midday stem Ψ.
083 FRUIT HYDRAULIC BUDGETS IN FRENCH PRUNE (PRUNUS DOMESTICA L. CV. FRENCH) AND THEIR EFFECTS ON FRUIT GROWTH AND CRACKING
Authors: Milad Rémy E , Shackel Kenneth A
Published: February 2019

End cracking of French prune fruits occurs when previously water stressed trees are irrigated during early July. Fruit phloem, xylem and transpiration flows (P, X and T, respectively) were measured diurnally during 72 h periods in mid June, early July and mid July (before, during and after the crack-susceptible period). Midway through each 72 h period, the previously stressed trees were irrigated. In mid June, X was larger than P, whereas P was larger than X during early July. In mid July, P and X were similar. In early July, the period preceding irrigation was characterized by an ourflow of phloem sap during the day and phloem inflow during the night. After irrigation, larger phloem inflows were observed and no phloem outflow occurred. Fruit transpiration rates were highly correlated with VPD. They exhibited a gradual decrease during the season, reaching minimum values during early July, before increasing again. The sum of P and X was virtually identical for the three periods i.e. stronger P's compensated for weaker X's and vice versa. Our results suggest that properties intrinsic to the fruit play the primary role in modulating water and photosynthate movements between the tree and the fruit. The possible role of these properties on fruit growth and cracking will be examined.
090 THE EFFECTS OF WATER-STRESS, ROOTSTOCK AND CROP LOAD ON VINE AND ROOT GROWTH IN SEYVAL GRAPEVINES.
Authors: McLean Mike , Howell Stan , Smucker Alvin
Published: February 2019

This experiment was conducted to evaluate interrelationships between differing crop loads and water stress on carbohydrate partitioning for above and below-ground tissues of Seyval grapevines grafted on three different rootstocks. Fine root development and depth were determined by quantifying root images from video recordings taken to depths of 80 cm at approximately 2 week intervals throughout the growing season. Two-year own-rooted Seyval grapevines, and Seyval grafted to 5BB and to Seyval were grown under a rain exclusion shelter and provided with 10 or 2.5 liters of water/plant/week. Treatments were cropping level, either 0 or 6 clusters per vine. Shoot length, number of mature nodes, leaf area and dry leaf weight of vines under high cropping level were reduced compared to vines growing under the low cropping level; so was root number and depth of penetration. Conditions of low soil-moisture resulted in carbohydrate partitioning in favor of the clusters at the expense of the roots, and carbohydrate partitioning in favor of the roots at the expense of the above-ground vegetation.
093 POSITION OF SUNLIGHT-EXPOSED CLUSTERS INFLUENCES DIURNAL PATTERNS OF FRUIT TEMPERATURE
Authors: Zabadal Thomas J. , Dittmer Thomas W.
Published: February 2019

Sunlight-exposed clusters of Vitis vinifera L. cv. Chardonnay at twelve positions on a N-S oriented, single curtain trellis were monitored for temperature to determine their patterns of heat summation and diurnal temperature.

Diurnal patterns of temperature differed greatly among these clusters. These differences reflected the solar insolation on individual clusters. Point-in-time measurements among clusters during mid-day varied as much as 12°C. 24-hour heat summation for these clusters revealed little difference among them. Heat summations for periods of daylight or solar insolation indicate more heat accumulation for clusters on the top of the trellis, at ground level and on the west side of the trellis than on the east side of the trellis. These differences might be usefully exploited when training vines to maximize aspects of fruit maturation in relatively cool climates.
103 EVALUATION OF COMPOSTS FOR PRODUCTION OF SOD-GROWN CROPS
Authors: Barker Allen V. , O'Brien Tara A.
Published: February 2019

An agricultural compost of chicken manure and cranberry pomace, a municipal compost of biosolids and mixed municipal solid wastes, and a compost of autumn leaves were evaluated for production of turfgrass sods and wildflower sods. Composts made during the year of the experiment and one-year-old composts were compared. The experiment was conducted outdoors with composts layered on sheets of plastic laid on the soil surface. The sheets of plastic controlled soil-borne weeds and facilitated harvest of sods. The best sods measured by stand and growth were produced with the agricultural compost, which was rich in N (avg. 1.7%) and low in NH4+ (avg. 135 mg/kg). High NH4+ (>900 mg/kg) appeared to limit stand establishment with the fresh municipal compost. The leaf compost was too low in N to support sod growth without fertilization. Aging of each compost improved its capacity to support sod production, apparently as a result of changes in the N status in the media.
105 PULSING MICROIRRIGATION IN CONTAINERS INCREASES TREE GROWTH
Authors: Beeson Richard C.
Published: February 2019

Pulsing consists of applying subvolumes of a normal daily irrigation volume several times per day. Previous studies have shown splitting overhead irrigation into two subapplications increased growth of container-grown landscape ornamentals in the southeastern U.S. In Florida, water restrictions prohibit overhead irrigation during the critical mid-afternoon when irrigation is most beneficial. Using individual microirrigation spray stakes, only 25% of the water required for overhead irrigation per bed area was necessary to produce similar plants if irrigated once per day. When the same daily volume was pulsed as 2 or 3 subvolumes, tree growth was significantly increased. Data suggest 2 pulses are sufficient for trees with a xeric nature while mesic trees prefer 3 pulses per day. Root:shoot ratios were unchanged by pulsing. Lower cumulative diurnal water stress was measured on pulsed trees.
106 INTERMITTENT SPRINKLER IRRIGATION AFFECTS PLANT GROWTH AND N LEACHING
Authors: Karam Nabila S. , Niemiera Alexander X.
Published: February 2019

The influence of intermittent and continuous irrigation on the growth, substrate nutrient accumulation and leaching from container-grown marigolds was determined. During a three week period. Tagetes erecta L. `Apollo' in a pine bark substrate received 12 irrigations. Each irrigation allotment was applied intermittently (multiple applications) or continuously (single application). Irrigation occurred when bark reached a targeted water content; irrigation water contained a complete nutrient solution. Leachates were cumulatively collected for each container and analyzed for N; plant dry weight. size, and nutrient composition were determined. Compared to continuously irrigated plants, intermittently irrigated plants had 43% greater root dry weight, 0.7% greater N concentration, and 43% more N leached from the substrate. Shoot mass. size. K, and P concentrations, substrate (pour-through extraction) and leachate N concentration were unaffected by irrigation method. Results demonstrated that. compared to conventional irrigation practices, intermittent irrigation was an effective method to reduce fertilizer effluent and increase N absorption for container-grown plants.
107 THE USE OF HYDROLYZED GRAIN PROTEINS AND DIPEPTIDES AS NATURAL NEED CONTROLS IN HORTICULTURAL CROPS
Authors: Christians Nick E. , Liu Dianna L.
Published: February 2019

It has previously been reported that a byproduct of the corn (Zea mays L.) wet-milling process, corn gluten meal, has potential as a natural preemergence herbicide for use in turf and certain horticultural crops. In 1993, two additional patents were issued on the technology. The first is on the use of hydrolyzed proteins from corn and other grains that were shown to have higher levels of herbicidal activity than the corn gluten meal. These materials are water soluble and can be sprayed on the soils surface. The second patent was on 5 dipeptides extracted from the hydrolyzed corn gluten meal. These dipeptides were shown to have the same type of biological activity observed when the corn gluten meal and the hydrolyzed meal are applied to the soil. The possible use of the hydrolyzed grains and the dipeptides as natural preemergence herbicides in horticultural crops will be discussed.
122 THE INTERACTION OF TEMPERATURE AND VAM FUNGI ON DIURNAL LEAF GAS EXCHANGE OF `EUREKA' LEMON TREES
Authors: Martin Chris A. , Stutx Jean C. , Garcia Richard L.
Published: February 2019

Eureka lemon (Citrus limon L. `Eureka') trees were inoculated with ecotypes of VAM fungi isolated from either a subtropical desert (HVAM) or a temperate grassland (LVAM), and grown for five months at 40.5C/32.2C (high) or 29.4C/21.1C (low) day/night, respectively. Diurnal measurements of leaf carbon assimilation (A), transpiration (E) and stomatal conductance (gs) were then made with a portable photosynthesis system. At high temperatures, afternoon A, E and gs were highest for trees inoculated with LVAM and lowest for trees inoculated with HVAM. At low temperatures, afternoon A, E and gs were highest for trees inoculated with HVAM and lowest for trees inoculated with LVAM. Compared to controls, trees inoculated with HVAM and LVAM displayed rapid mid-day fluctuations in stomatal conductance. At low temperatures, water use efficiency (WUE) during the morning was lowest for trees inoculated with LVAM; whereas, afternoon WUE was not affected by HVAM or LVAM. HVAM and LVAM did not affect WUE at high temperatures. Results indicate that long-term physiological adaptations of lemon trees to temperature are uniquely affected by different VAM fungal ecotypes.
124 VEGETABLE CROP RESPONSE TO SOIL COMPACTION
Authors: Wolfe David W.
Published: February 2019

Field studies conducted in 1993 on an Eel loam soil compared the growth and yield response of direct-seeded cabbage, cucumber, snap bean, and sweet corn, and transplanted cabbage, to a compacted soil layer (>2.5 MPa penetrometer resistance) at the 15 - 30 cm depth. Direct-seeded cabbage and snap bean were most severely affected by compaction, with 50% yield losses, and much smaller cabbage head size in compacted plots. Transplanted cabbage had a 30% lower yield in compacted compared to uncompactcd plots. Early vegetative growth of cucumber was less stunted by compaction compared to snap bean and cabbage, but compaction nevertheless resulted in a 50% reduction in total cucumber yield. Compaction delayed maturity and reduced early yield of cabbage, snap bean, and cucumber. Sweet corn yield was reduced by only 10% when grown on compacted soil, and there was no delay in maturity. Sweet corn responded more negatively to compaction in a 1992 field experiment,

Greenhouse studies found a reduction in total plant biomass at 21 days after planting of 30%, 14%, 1%. and 3% for snap bean, cabbage, cucumber, and sweet corn, respectively, in pots compacted at the 10 cm depth. Sweet corn had a significantly higher proportion of root biomass in the compacted zone compared to the other crops. For all species, the growth reductions could not be attributed to reductions in leaf turgor, photosynthetic rate per unit leaf area or leaf nutrient status.
126 THE RELATION OF PEPPER FLOWER AND FLOWER BUD ABSCISSION WITH BUD CARBOHYDRATE AND ACC CONTENT
Authors: Wien H. C. , Turner A. D.
Published: February 2019

When bell pepper plants are subjected to high temperatures or low irradiance during flowering, abscission of flowers and flower buds can be severe enough to limit yields. Both types of stresses may lead to reduction of carbohydrate levels in the reproductive structures, and evolution of the abscission-causing hormone ethylene. In two greenhouse experiments, plants were subjected to combinations of 30 or 20 C air temperature and unshaded or heavily shaded conditions for one week at anthesis of the first flower. In a third experiment, plants were subjected to total darkness and temperatures of 30, 20 or 15 C for one week at the same stage of growth. In all experiments, levels of soluble carbohydrates and starch declined under low or zero light conditions, with rate of decrease proportional to the air temperature. Abscission of reproductive structures was not well correlated with carbohydrate levels: in spite of low sugars and starch, plants darkened for 7 days at 15 C showed no abscission. Levels of the ethylene precursor ACC in the buds, though variable, rose just before abscission began, but remained low in non-abscising treatments.
140 DEVELOPMENT OF SUPERFICIAL SCALD ON `D'ANJOU' PEARS DURING COLD STORAGE AS INFLUENCED BY GROWING ELEVATION
Authors: Chen Paul M. , Varga Diane M.
Published: February 2019

`D'Anjou' pears (Pyrus communis, L.) growing in 3 locations with the elevation at 150 meters, 380 meters, and 610 meters respectively in Hood River valley, Oregon were harvested at the commercial maturity with the flesh firmness of 62.3 Newton (±2.2 N) and stored in air at -1°C. Regardless of different growing elevations, the incidence of superficial scald became noticeable after 2.5 months of storage and became substantial after 3 months. The rate of scald development was higher on the fruit from 150 meters elevation than those from higher elevations. Alpha-farnesene and conjugated trienes in the peel tissue accumulated at faster and higher rates in the fruit from 380 meters and 610 meters elevations than those from 150 meter elevation. The threshold level of conjugated trienes which causes superficial scald disorder was different from the fruit grown at different elevations.
144 INFLUENCE OF ROOTSTOCKS AND CALCIUM SPRAY RATES, TIMING,AND MATERIALS ON SPRAY INJURY AND FRUIT QUALITY OF `DELICIOUS' APPLES
Authors: Raese J. Thomas , Drake S. R.
Published: February 2019

Sprays of calcium materials were applied at high volume rates (620 g Ca/400 liters) with a handgun during early June, late June, and mid-July versus mid-July, early August, and late August for five years, 1985 to 1989. Leaf injury was most severe for the late sprays but no spray injury was observed on the fruit surfaces. Bitter pit was markedly reduced with all sprays except CaSO4. In some years, bitter pit was controlled better with the early sprays. Either early or late sprays improved fruit quality including overall appearance, reduced scald development, improved red color of the skin, increased fruit firmness and reduced incidence of bitter pit in cold air (0°C) storage. Soluble solids and acidity in the fruit was not affected by calcium sprays. Leaf Ca was higher from the late spray applications than from the earlier applications. All calcium chloride spray materials resulted in increased fruit peel and cortex Ca. Calcium nitrate sprays tended to increase fruit nitrogen concentrations leading to undesirable higher N:Ca ratios in the fruit.
151 HIGH YIELDS OF SUMMER SQUASH LINES AND HYBRID COMBINATIONS.
Authors: Ortega Sergio Garza , Amaya Andres Tacho
Published: February 2019

The Gray Zucchini cultivar of summer squash is widely consumed as a fresh market vegetable in Northwest Mexico but is highly suceptible to viral diseases. Gray Zucchini type lines were developed by interspecific hybridization using a local landrace of Cucurbita moschata, which has shown high levels of viral resistance, as male parent and suceptible C. pepo cv. classic as female. The lines were obtained after 4 backcrossing and 3-5 selfing generations. In 1993 average commercial yield of first generation hybrids between lines was 28,155 kg/ha followed by line × Gray Zucchini hybrids, lines, commercial hybrids (Classic. Corsair, Onyx, Raven), and open pollinated cultivars (Gray Zucchini, Black Zucchini) with 26,594, 21,062, 18,862 and 10,172 kg/ha respectively. Yield was inversely related to symptoms of viral infection.
154 WATER QUANTITY AFFECTS QUALITY OF DRIP-IRRIGATED TOMATO FRUIT
Authors: Brecht J.K. , Locascio S.J. , Bergsma K.A.
Published: February 2019

Tomatoes (var. Sunny) were grown using drip irrigation and polyethylene mulch in a three-year study with water applied to plots at 0, 0.25, 0.50, 0.75 and 1.00 times pan evaporation in one application per day. Breaker stage fruit were harvested twice each season at 7 to 10 day intervals and evaluated after storage for 11 days at 20C. Response to water application varied with seasonal rainfall levels. Soluble solids levels decreased with increasing water quantity only in the first (relatively dry) season, while titratable acidity levels decreased with increasing water in all three seasons. Fruit color was not affected by water quantity in the first season but hue angle increased and chroma decreased with increasing water in the second and third seasons. Decay incidence (associated primarily with blossom end rot) was higher in nonirrigated than irrigated treatments and in the second harvests. Internal white tissue, a symptom of irregular ripening, was more common in irrigated treatments and in the wetter second and third seasons
164 THE POTENTIAL OF COIR (COCONUT MESOCARP PITH) AS A PEAT SUBSTITUTE IN CONTAINER MEDIA.
Authors: Meerow Alan W.
Published: February 2019

Coir is the name given to the fibrous material that constitutes the thick mesocarp of the coconut fruit (Cocos nucifera L.). The long fibers of coir are extracted from the coconut husk and utilized in the manufacture of various products. The short fibers and dust (“pith”) left behind have accumulated as a waste product. Coir pith is light to dark brown in color and consists primarily of particles in the size range 0.2-2.0 mm (75-90%). In composition, it is 65-70% lignin and 20-30% cellulose. To date, few replicated tests have assessed the performance of coir pith as a plant growth medium. From April, 1993 to April, 1994, four ornamental crops (pentas, ixora, anthurium and majesty palm) were grown in container media that differed only in the peat fraction (40%), either sphagnum, Florida (sedge) peat, or coir pith. On the basis of plant growth parameters, coir pith was superior to sedge peat as a medium component (though only marginally for the anthurium) and at least equal to sphagnum peat. In addition to physical qualities equal to or better than sphagnum peat, coir decomposes more slowly than either sedge or sphagnum peat, withstands compression better and is easier to wet than peat. There are also no ecological drawbacks to the use of coir -- a waste product -- relative to the harvest of peat from wetland ecosystems.
174 USING FERAL AND COMMERCIAL BUMBLE BEES FOR POLLINATION OF CRANBERRIES AND PEARS
Authors: Patten Kim , Macfarlane Rod , Mayer Dan
Published: February 2019

The pollination of cranberries and pears by honey bees is often inadequate. The pollination efficacy of feral (Bombus spp.) and/or commercial bumble bees was evaluated for these crops. Preliminary evaluation of commercial B. vosnesenskii and B. occidentalis hives indicated poor forage activity on pears, but good activity on cranberries. Hive stocking densities of B. occidentalis on cranberries required to match feral Bombus populations was 8-10 hive/ha. Hives required 1-2 weeks in the field prior to full bloom to achieve suitable forage density during bloom. Parasitism of commercial hives by wax moth and bumble bee brood fly was common. Commercial colonies did not appear to be cost effective at this time. Only short-tongued feral Bombus species foraged on cranberries. Acceptance of artificial domiciles by these species was poor. Enhancing feral populations required provision of supplemental food sources and improved nesting habitat. Management of alternative food resources for feral bumble bees will be discussed.
179 IMPROVED IRON UTILIZATION OF FRUIT TREES THROUGH BIOTECHNOLOGY
Authors: Samuelsen Andrew I. , Bunnag Sumontip , Martin Ruth C. , Mok David W. S. , Mok Machteld C.
Published: February 2019

Two approaches are used to improve iron utilization of fruit trees under iron-limiting conditions: 1) selection of somaclonal variants; and 2) cloning and incorporation of genes encoding Fe(III) reductases. Two somaclonal variants of quince with tolerance to low iron availability have been selected from 2000+ shoots regenerated from leaf discs. In greenhouse tests, under iron stress conditions, the variant clones continued to show improved iron utilization, having significantly higher chlorophyll concentrations in the new leaves when compared to the quince control. Cloning of Fe(III) reductase genes is based on mutant rescue utilizing a yeast mutant deficient in Fe(III) reduction (Dancis et al., PNAS 89:3869, 1992). A shuttle vector is used to incorporate a tomato root cDNA library into the yeast mutant. Complementing cDNAs, restoring growth to wild-type levels, are selected for further analyses. Cloning of genes involved in iron utilization will eventually lead to transgenic plants with improved iron efficiency.
181 AN ULTRACELLULAR LOOK AT LIGHT-TREATED IPT-TRANSGENIC TOBACCO
Authors: Barbour Sandra L. , Decoteau Dennis R.
Published: February 2019

Similarities exist between the effects of phytochrome and cytokinins on plant growth and development (e.g., chloroplast development. amaranthin synthesis, seed germination, photomorphogenesis). It is unclear. however, if and how these two systems interact.

To determine the effects of phytochrome activity on cytokinin synthesis and ultracellular plant development, we utilized tobacco transformed with the Agrobacterium tumefaciens isopentenyl transferase (ipt) gene. This gene encodes for isopentenyl transferase (iptase) which is an enzyme active in cytokinin biosysthesis.

Ipt-transgenic tobacco cultures were treated with end-of-day red or far-red light for 15 minutes. After 15-30 days of treatment, the plant tissue was harvested and ipt expression was verified by SDS-PAGE and western blot analysis. Polyclonal antibodies specific to iptase were used as a primary antibody. Colloidal gold conjugated to goat. anti-rabbit antiserum served as an electron dense, secondary antibody and a probe to light-influenced iptase synthesis and distribution within the cell.

A Hitachi 600AB transmission electron microscope was used to determine the influence of phytochrome/light treatments on the ultrastructure of ipr-transgenic cells.
186 INFLUENCE OF HYDROGEN CYANAMIDE AND WILTH IN ON BLOSSOM THINNING OF APPLE AND PLUM
Authors: Fallahi Esmaeil , Simons Brenda R. , Williams Max W.
Published: February 2019

Effects of hydrogen cyanamide and Wilthin on blossom thinning and the consequences of thinning on fruit set, yield and fruit quality of `Rome Beauty' was studied. A full bloom application of hydrogen cyanamide at the rate of 0.25% (Dormex formulation) or 0.25% of Wilthin both followed by a fruit thinning by Sevin + NAA effectively thinned mature trees of `Rome Beauty' and had a similar effect on fruit set, yield and fruit quality. The effects of these two chemicals at these rates on several aspects of fruit set, yield and quality were similar to the effects of Elgetol. Hydrogen cyanamide, Elgetol and 0.25% Wilthin at full bloom resulted in a higher percentage of single fruit set, thus, less labor for hand thinning. Application of 0.37% Wilthin at 20% bloom or at full bloom resulted in larger fruit size, but induced fruit russetting. Soluble solids of fruit from trees with Elgetol, 0.37% Wilthin at 20% bloom or at full bloom were higher than fruit from other treatments. Hydrogen cyanamide at 0.50% resulted in a satisfactory level of blossom thinning in `Friar' plums.
191 SEASONAL VARIATION IN THE RESPONSE OF ENDODORMANT PEACH TO BIOREGULATORS AND THEIR INTERACTION WITH ETHYLENE
Authors: Mitchell William C. , Lang Gregory A.
Published: February 2019

Fall application of 2-chloroethylphosphoric acid (ethephon) is known to delay spring budbreak in peach (Prunus persica). To study seasonal variation in peach response to dormancy-breaking plant bioregulators and their possible interaction with ethylene, peach shoots were cut in the field at various intervals during endodormancy. Shoots were dipped in the dormancy-breaking bioregulators hydrogen cyanamide (H2CN2, 100 mM) or gibberellic acid (KGA3, 130 μm), alone or in combination with 1.38 mM ethephon. Treated shoots were held in beakers of either tap water or 1 mM silver thiosulfate (STS), and placed in growth chambers with potassium permanganate traps, 12/12 h photoperiods and 21/26 C temperature regimes. Dormancy-breaking efficacy (apical budbreak at 21 days) of both bioregulators increased as endodormancy progressed. At all intervals, H2CN2, broke dormancy more effectively than KGA3. The addition of ethephon to H2CN2 application prior to any CU accumulation (20 Oct) had no effect on efficacy (80% budbreak), but its addition after accumulation of ∼50 CU (8 Nov) or ∼320 CU (14 Dec) reduced subsequent budbreak to 25% and 40%, respectively. The addition of ethephon to KGA3 applications reduced budbreak both prior to (27 Oct) and after (8 Nov) initial CU accumulation. STS in the beaker solution increased both the extent (27 Oct) and the rate (14 Dec) of KGA-induced budbreak The interaction of ethylene, bioregulator type, and endodormancy regulation will be discussed.
204 POTENTIAL OF BLOWN AIR AS A THIGMIC STRESS FOR TEMPORARY NONCHEMICAL PRIMOCANE SUPPRESSION OF RED RASPBERRY
Authors: Kostman T. , Cameron J. S. , Chen C. , Klauer S. F.
Published: February 2019

The red raspberry industry of the Pacific Northwest depends upon chemical primocane suppression to temporarily reduce competing vegetation during fruit development. This practice increases yield and harvest efficiency, but can reduce cane vigor, number and diameter over time. Few chemicals are available for this purpose and thus the potential of nonchemical alternatives is being explored. The purpose of this project was to evaluate the potential of blown air as a thigmic stress to temporarily suppress primocane growth.

Blown air treatments were applied once (12 PM) or twice (12\4pm) per day, five days per week using a portable leaf blower generating winds of 273 km per hr. Treatments also included several rates of three experimental herbicides and an untreated control. All treatments were applied when primocanes were 10-15 cm in length and blown air treatments continued through fruit development. Primocane development was monitored over the course of the season.

Blown air reduced primocane length by 15-30% prior to harvest giving control equivalent to current chemical methods. Blown air increased cane diameter but reduced yield by reducing fruit numbers. Reductions in fruit numbers are likely due to flowering\fruiting points removed by blown air.
229 PHYLOGENETIC RELATIONSHIPS OF PISTACIA SPECIES FROM ANALYSIS OF CHLOROPLAST DNA VARIATION
Authors: Parfitt Dan E. , Badenes Maria L.
Published: February 2019

PCR amplification and restriction analysis of a 3.2 kilobase hypervariable chloroplast DNA, as well as hybridization of the entire restricted chloroplast genome with tobacco chloroplast DNA probes permitted the development of a phylogeny for 10 Pistacia species. The genus divided into two major groups. P. Vera was most ancestral. P. weinmannifolia, an Asian species, is most closely related to P. texana and P. mexicana, new world species. The 3 sp. are more recently diverged, suggesting that a common ancestor of P. texana and P. mexicana originated in Asia. P. integerrima and P. chinensis are distinct species while species within two tertiary groups were monophyletic, P. vera:P. khinjuk and P. mexicana:P. texana. A general evolutionary trend from large to small nuts and leaves with few, large leaflets to many, small leaflets was documented. Pistacia had an unusually low chloroplast DNA mutation rate, more than 20x less than expected.
239 RESPONSE OF KIWIFRUIT SOFTENING TO ETHYLENE APPLICATION
Authors: Chene Guiwen , Crisosto Carlos , Garner David
Published: February 2019

During the 1993 and 1994 seasons, the response of Kiwifruit (Actinidia deliciosa var. Hayward) flesh softening to exogenous ethylene applications was studied on fruit collected weekly from cold storage and directly from the vines. Fruit samples from both sources, were induced to ripen with and without ethylene preconditioning treatment (10 ppm, 24h at 0C).

During the first 3 weeks of fruit collection, flesh firmness decreased and SSC accumulation increased faster in ethylene treated kiwifruit than in the untreated. After this period, when kiwifruit had close to 9 pounds flesh firmness, ethylene treated and untreated kiwifruit softened at the same rate. Ethylene treatment did not enhance kiwifruit CO2 and ethylene production except at the first harvest time. Furthermore, ethylene treated kiwifruit did not have higher respiration and ethylene rates than untreated kiwifruit when measured at 0, 5 and 20C.
240 RELATIONSHIP OF GROWING LOCATIONS, HARVEST MATURITY, SUMMER PRUNING, SOIL NITROGEN APPLICATION, AND STORAGE ON FRUIT POSTHARVEST PERFORMANCE IN `HAYWARD' KIWIFRUIT
Authors: Gu Sanliang , Crisosto Carlos H. , Johnson R. Scott , Cochran Robert C. , Garner David
Published: February 2019

Fruit from 8 `Hayward' kiwifruit vineyards in central California were harvested at 2 week intervals after soluble solids content (SSC) reached 6% and subjected to 4 and 6 months of storage at 0°C in an ethylene free environment. Fruit characteristics at harvest and postharvest performance varied considerably among locations. Fruit stored for 6 months had the same fresh weight, less flesh firmness and higher SSC, than the 4 months storage. Later harvested fruit had greater fruit flesh firmness and higher SSC after storage. SSC after storage was predictable based on ripe soluble solids content (RSSC) at harvest. Summer pruning reduced while soil nitrogen application increased fruit SSC.
242 WATER, NUTRIENT, AND ACID REQUIREMENTS FOR CROPS GROWN HYDROPONICALLY IN A CELSS
Authors: Wheeler R.M. , Mackowiak C.L. , Berry W.L. , Stutte G.W. , Sager J.C.
Published: February 2019

Requirements for water, nutrient replenishment and acid (for pH control) were monitored for stands of wheat, soybean, potato, and lettuce grown in a recirculating hydroponic culture using a modified 1/2 Hoagland solution with NO3-N. Water use at full canopy cover for all crops ranged from 4 to 5 L m-2 day-1. When averaged over the entire crop cycle, nutrient stock solution (∼0.9 S m-1) use varied from 0.2 L m-2 day-1 (lettuce: to 0.75 L m-2 day-1 (wheat), while acid use varied from 6 mmol m-2 day-1 (lettuce and soybeans) to over 40 mmol m-2 day-1 (wheat). Water-per unit biomass was highest for soybean and lettuce (0.3 to 0.4 L g DW), and least for wheat and potato (0.15 L g DW). Nutrient replenishment per unit biomass was highest for lettuce, 34 mL g-1 DW, with other crops ranging from 21-26 mL g-1 DW. Acid requirements were highest for wheat, 1.2 mmol g-1 DW, and lowest for potato, 0.7 mmol g-1 DW. On a PAR basis, acid needs were highest for wheat, 0.6 mmol mol-1 photons, with all other crops near 0.4 mmol mol-1. Acid data suggest that wheat nutrient uptake favors anions more strongly than the other species, or that more nitrate loss (e.g., denitrification) may occur during wheat growth.
253 MICROPROPAGATION, A MEANS TO ENHANCE SWEETPOTATO YIELD AND QUALITY
Authors: Schultheis Jonathan R. , Collins Wanda W. , Averre Charles W.
Published: February 2019

Micropropagated sweetpotato is utilized in California as pan of its seed production program. Sweetpotato yields and quality might be improved in North Carolina by incorporating micropropagation as pan of its plant production scheme. Field studies were conducted in 1992 and 1993 to determine the effects of micropropagation, virus, and hill selection on yield and qualify of Jewel and Beauregard varieties. In 1992, yield was increased in Beauregard with micropropagated plants compared with plants that were derived from the North Carolina seed program. However, no yield advantage was measured when Jewel was micropropagated. In 1993, yield from micropropagated Beauregard sweetpotato plants was the same as when plant material was derived from the North Carolina Certified Seed program. Virus-free micropropagated Beauregard plants yielded more number one and canner grade roots than micropropagated plants that harbored the virus at planting. Russet crack symptoms were significantly greater in roots that were not micropropagated compared with micropropagated plants. Total marketable yield of Jewel was increased when obtained from micropropagated versus nonmicropropagated plant stock. Micropropagated Jewel obtained from a California selection yielded nearly 20% less than the North Carolina selection. Yields from micropropagated planting stocks consistently were equal to or better (typically 10 to 20%) than from plant stock not micropropagated.
254 KJELDAHL N:DUMAS N RATIOS FOR SELECTED CROPS
Authors: Simonne E.H. , McCrimmon J.N. , Scoggins-Mantero H.L. , Mills H.A.
Published: February 2019

With recent advances in N analyzers, the Dumas method becomes more attractive as a replacement for Kjeldahl N. Kjeldahl N (K_N):Dumas N (D_N) ratios were determined for anthurium (A), orchid (O), fern (F) and turf (T). Dry tissues were ground to pass a 20-mesh seive. D_N was determined using 0.2 g of sample and a Leco FP-428. K_N was determined by digesting 0.4 g tissue with a CuO/TiO/K2SO4 catalyst and 10 mL H2SO4 at 450°C for 2 hr. Ammonium in the digest was assayed by colorimetry (Lachat analyzer). Overall (n=397 obs.), D_N was a good estimator of K_N: K_N = 0.90(p<0.01) D_N + 0.09(p=0.03), R2=0.93, over the 0.4-6.6 N range. K_N:D_N ratio was significantly (p<0.01) affected by plant type. Ratios of 0.85 for A, 0.92 for T, 0.99 for O, and 1.00 for F may be used to estimate K-N from D-N for the diagnosis of N nutrition, along with existing interpretative data.
257 LEAF PETIOLE NITRATE AND POTASSIUM LEVELS IN POTTED PLANTS GROWN AT THREE NITROGEN AND POTASSIUM LEVELS
Authors: Bergman Erica M. , Marshal Michelle , Weesies Brian , Argo Bill , Biernbaum John
Published: February 2019

Twelve species of flowering potted plants were grown in a peat-based medium with water soluble fertilizer concentrations of 50, 100, or 200 mg·liter-1 N and K2O. Leaf blade or leaf petiole samples were collected six to eight weeks after planting. Sap was expressed using a hydraulic press and levels of nitrate nitrogen and potassium were determined using Cardy flat sensor ion meters. Petiole nitrate level ranged from 520 to 6300 mg·liter-1 and potassium levels ranged from 870 to 3600 mg·liter-1. The petiole nitrate concentration and change in petiole nitrate levels with changes in media nitrate levels was crop dependent. Leaf blade nitrate and potassium concentrations were lower than leaf petiole concentrations. The relationship of petiole nitrate to final plant fresh and dry mass and appearance at flowering will be presented.
262 FERTIGATION VERSUS DRY APPLICATION OF NITROGEN AND PHOSPHORUS FERTILIZER IN IRRIGATED `GALA' AND `FUJI' APPLES
Authors: Peryea Frank J.
Published: February 2019

Differential fertilizer application method (single dry, split dry, fertigated liquid), irrigation method (drip, microjet), and nutrient source (N vs. N+P in year 2+) were established in Spring 1992 in a newly planted Gala and Fuji apple orchard. In Spring 1993, the drip-fertigated Gala trees had 3 times and the drip-fertigated Fuji trees had 8 times more flower clusters per tree than the other treatments Fruiting was not allowed in 1993. Trunk cross-sectional area (TCSA) in Fall 1992 was not influenced by treatments. By Fall 1993, TCSA was still independent of treatment for the Fuji trees; however, the Gala trees fell into two size groups - (larger) microsprinkler-fertigated and split dry broadcast; and (smaller) drip fertigated and single-time spring dry broadcast. TCSA had increased 284% (Fuji) and 265% (Gala) since planting. None of the treatment effects were substantially influenced by fertigating with N+P vs N only. Leaf concentrations of most nutrients were consistently lower in 1993 than in 1992. Leaf Fe was higher in 1993 because the orchard was dustier. Leaf N was lower in the microsprinkler-fertigated trees than in all other treatments. Fertigation with N+P did not consistently produce higher leaf P than the N-only treatments. Leaf Mn varied with treatment: microsprinkler fertigated < drip fertigated, single dry < split dry. Treatment effects on all other elements were inconsistent (K, Ca, Mg, B, Cu) or absent (Zn, Fe).
263 RESPONSE OF SOIL SOLUTION NO3-N TO N FERTIGATION
Authors: Neilsen Gerry H. , Neilsen Denise , Parchomchuk Peter , Hogue Eugene
Published: February 2019

Soil solution monitoring has been suggested as an appropriate procedure to optimize fertigation timing and application rate. Soil solution NO3-N concentrations were measured for two growing seasons on a sandy loam soil when 5, 20 or 30 g N per season per tree were fertigated daily to apples as calcium nitrate from mid May-mid July. Soil solution NO3-N concentrations at 30 cm depth changed rapidly in response to both the initiation and cessation of fertigation, with values ranging from 10-20 ppm, 60-100 ppm and 100-200 ppm for the low to high treatments respectively. The rapid response to NO,-fertilizers implied a potential to control closely the timing of N fertilizer applications. In another experiment, `Empire' apple trees were fertigated 5 times/week from May 31 to August 9 with 30 g N/tree applied either as ammonium sulphate or as calcium nitrate. With calcium nitrate as the N source, NO3-N rapidly increased when fertigation was initiated and fell when fertigation ended. In contrast, with ammonium sulphate, NO3-N was low for about 30 days after initiation of fertigation, then increased to 100 ppm and remained elevated for 40-50 days after fertigation ended. The potential control of N nutrition appeared to be less exact when fertigating NH4-N.
273 PRODUCTION OF VOLATILE COMPOUNDS BY `BING' SWEET CHERRIES AFTER CONTROLLED-ATMOSPHERE STORAGE
Authors: Mattheis James , Buchanan David , Fellman John , Reed Nathan , Growers Stemilt
Published: February 2019

Sweet cherry ripening is slowed during low oxygen and/or high carbon dioxide controlled atmosphere storage. Cherry flavor can be impacted by prolonged CA storage, therefore ripening after CA and storage was evaluated including production of fruit volatile compounds. `Bing' sweet cherries were harvested at commercial maturity and stored for up to 12 weeks at 1C in air or 5% O2, with 0.1, 10, 15 or 20% CO2. Fruit quality and condition were evaluated after removal from storage plus 1 or 4 days at 20C. Changes in fruit color were slow ed by all atmosphere treatments with differences most notable after longer storage durations. Volatile synthesis changed as storage duration increased, however, treatment differences were not significant. Soluble solids content was maintained at 15 and 20% CO2, but treatment differences were significant only after longer storage durations. High CO, treatments were effective at reducing decay incidence, but residual suppression after removal from storage decreased as storage duration increased. Significant treatment effects were evident for titratable acidity retention after 8 and 12 weeks storage, however, titratable acidity significantly declined in all treatments compared to the initial concentration.
280 GENETICS OF FLOWERING TIME IN LETTUCE: CROSSES WITH C-2-1-1, HOMOZYGOUS FOR LATE FLOWER TIME
Authors: Ryder Edward J.
Published: February 2019

In an earlier study, two genes controlled flowering time in certain lettuce crosses. Early alleles (Ef-1, Ef-2) at both loci are partially dominant; flowering time in the greenhouse ranges about 100 days from double dominant to double recessive. Crosses between C-2-1-1, a double recessive line, and four cultivars were analyzed to study further the distribution of these genes. Empire and Salinas flower at the same time as C-2-1-1, while Vanguard 75 and Prizehead are earlier than C-2-1-1. Empire × C-2-1-1 and Salinas × C-2-1-1 showed unimodal distribution in F2, indicating segregation of several genes or environmental variation. A linear relationship between F2 plant values and F3 family means from both crosses suggested a polygenic basis. The F2 distribution of Prizehead × C-2-1-1 was similar but showed a greater range of flowering times. An additional major gene was indicated in Vanguard 75 × C-2-1-1, with earliness recessive.