bluuebunny/crossref_metadata_2025 huggingface dataset:
Minimal Pruning Influences Vegetative and Reproductive Growth of `Ruby Cabernet' Grapevines
Authors: Striegler R.K. , Berg G.T.
Published: February 2019

Grape growers in the southern San Joaquin Valley of California are increasingly concerned about production costs. Reduced demand for wine grapes from this district has resulted in low prices and a decline in grower profitability in recent years. Minimal pruning is a low-cost production system that was developed in Australia more than 20 years ago. This system offers complete mechanization of pruning and harvesting. In general, there is little information available on the use of minimal pruning in California vineyards. The propose of the experiment was to compare the effects of hand and minimal pruning on growth, yield, and fruit composition of `Ruby Cabernet' grapevines. This experiment was conducted in a commercial vineyard near Huron, Calif., during the 1993 and 1994 seasons. Minimally pruned vines had more shoots and fewer mature nodes than hand-pruned vines. Yield and components of yield were also significantly altered by pruning method. Minimal pruning produced the highest yield and number of clusters, while hand-pruning resulted in larger berry weight, cluster weight, and number of berries per cluster. Pruning method did not significantly affect fruit composition.
Repeated Measures Analyses for Tree Fruit Experiments
Authors: Marini Richard P.
Published: February 2019

Experiments with perennial crops often span several years, and a response variable may be measured on the same plant at several points in time. Such data are often analyzed as a split-plot design, taking time as the split-plot factor. In other cases, separate analyses are performed for each time. The mathematical conditions required for validity of these types of analyses might not hold because measurements repeated on the same plant are not independent. Annual trunk cross-sectional-area (TCSA) measurements from a peach tree training experiment will be used to compare two methods of analyses. The 6-year experiment was a factorial of two heading heights at planting (low vs. high) and two tree forms (central leader vs. open vase). Univariate analysis of variance (ANOVA) and a multivariate repeated measures analysis (MANOVA) was performed. Main effects and interactions were more often significant with ANOVA than with MANOVA. ANOVA performed each year inflated the probability of falsely rejecting a true null hypothesis (Type I error), and was not appropriate for this data set.
Endosulfan Sprays on Bract Disorders of Poinsettia Gross Supjibi
Authors: Blom T.J.
Published: February 2019

Bract edge burn (BEB) has been observed in different greenhouse operations across North America over the past 10 years. The symptoms develop at anthesis or shortly after shipping. Varieties such as `Supjibi', `V-14 Glory', and `Celebrate 2' are considered susceptible cultivars. A number of trials using endosulfan (Thiodan) have been conducted. In 1993, `Supjibi' branched poinsettias were sprayed with either Thiodan, Decis, Thiodan + Decis, or water or remained unsprayed. The sprays were applied in week 39, 42 or 45. For each treatment period, plants were treated three times at 4-day intervals at label recommendations. At anthesis (week 47), plants sprayed with Thiodan or Thiodan + Decis during week 39 showed necrosis in the margin of the transitional bracts. In 1994, single spray applications in week 39, 40, 41, 42, or 45 of Thiodan, Ca (400 ppm), Thiodan + Ca in a tank mix, unsprayed, or Thiodan followed by four calcium sprays (weekly) in November. At week 48, all treatments except the latter showed necrosis, except this time it was marginal flecking in the transitional or primary bracts. In Spring 1995, single vs. multiple Thiodan applications were compared.
Effects of Chlormequat Chloride Rate on Growth and Development of Several Aster Cultivars
Authors: Gagnon Serge , Dansereau Blanche
Published: February 2019

Our purpose was to determine growth regulators rate effects on growth and development of aster Callistephus chinensis. During Spring 1993 and 1994, six aster cultivars were sown into 200-unit plug trays containing Pro-Mix PGX. Seedlings were transplanted into 10-cm pots containing Pro-Mix. Two weeks after transplanting, seedlings were sprayed with chlormequat chloride (CCC) at 750 or 1500 ppm and were compared to nontreated plants. A second application was applied 2 weeks later. Growth and development of asters were affected differently depending on cultivars and experimental season. During Spring 1994, a CCC treatment of 750 and 1500 ppm significantly reduced height and width of Dwarf Carpet Mix and Dwarf Spider Mix without affecting the number of flowers and total production time compared to nontreated plants. Growth regulator treatments had no effect on height and width of `Milady Mix' and `Starlight Rose'. However, the 750 ppm CCC treatment reduced the number of flowers produced by these two cultivars. Results obtained in 1993 also are presented.
The Harrow Expert System for Greenhouse Vegetables
Authors: Papadopoulos A.P. , Shipp J.L , Jarvis W.R. , Jewett T.J. , Clarke N.D.
Published: February 2019

Greenhouse crop production technology is advancing rapidly, and the management of greenhouse crops has become increasingly difficult. Computerized environment and fertigation control of greenhouse crops grown in soilless media offer opportunities for unparalleled manipulation of crop growing conditions. However, the optimization of crop growing conditions for maximum productivity must be practiced with an eye on environmental regulations; worker health concerns; consumer demands for safe food; and ultimately on energy, water, fertilizer, and pesticide use economy. Managing the complex greenhouse cropping system requires a multidisciplinary approach that integrates pest and disease protection strategies with routine cultural practices and environmental and fertigation regimes into a common decision-making process or Integrated Crop Management strategy. This poster describes an Expert System for greenhouse cucumber management based on a general model of Integrated Crop Management for greenhouse crops.
A Comparison of Cucumbers Grown in Rockwool and Perlite at Two Leachate Percentages
Authors: Compton M. Peggy , Schon M.K.
Published: February 2019

Cucumbers (Cucumis sativus L. `Vetomil') were grown in rockwool or perlite to evaluate these media for efficient hydroponic cucumber production under Florida greenhouse conditions. Plants were grown using a double-stem training method, and the frequency of irrigations was controlled by a weighing Iysimeter for each treatment. In experiment 1, plants were grown in rockwool with 29% or 17% leachate and in perlite with 17% leachate. Nutrient concentrations in the solution were N, P, and K at 175, 50, and 180 mg·liter–1, respectively. In Expt. 2, nutrient concentrations were increased to N, P, and K at 225, 60, and 225 mg·liter–1, respectively. Other nutrient concentrations and leachate percentages remained as in Expt. 1. When nutrients were limiting, as in Expt. 1, yields (number and total weight of fruit) were higher from plants grown in rockwool at 29% leachate than from plants grown in rockwool or perlite at 17% leachate. However, when nutrient concentrations were increased in Expt. 2, higher total fruit weight was harvested from plants grown at the lower percent leachate and there was no difference in fruit number. In both experiments, cucumbers did not differ in yield when grown at the same percent leachate in either rockwool or perlite.
The Interaction of Photoperiod and Temperature on Cold Hardiness and the Accumulation of Soluble Sugars in Two Cultivars of Southern Magnolia (Magnolia grandiflora L.)
Authors: Haynes C.L. , Lindstrom O.M. , Dirr M.A.
Published: February 2019

Decreasing photoperiods and decreasing temperatures induce cold acclimation and the accumulation of soluble sugars in many plants. Two cultivars of southern magnolia differing in cold hardiness and acclimation patterns, were monitored to determine photoperiod × temperature interaction on cold hardiness and soluble sugar content. Cold hardiness increased with low temperatures and short photoperiods. Total soluble sugars, sucrose, and raffinose consistently increased in the leaves and stems of both cultivars in response primarily to low temperature. `Little Gem' was less responsive to photoperiod than `Claudia Wannamaker'
Morphological Characteristics of Evergreen Azaleas Correlate with Freezing Survival of Flower Buds
Authors: Gordon Susan H. , Hull Richard J.
Published: February 2019

Frequent winter injury to flower buds is a major deterrent to the widespread landscape use of evergreen azaleas in the northern United States and southern Canada. Field observations indicate that azalea cultivars differ greatly in their capacity for cold acclimation during the fall. Azaleas also express wide variation in morphological features, such as Ieaf number, density, percent abscission, twig Iength, flower bud development rate, number or bud scales, and petal color. We attempted to correlate these characteristics with the establishment of flower bud cold tolerance during the fall season. Young (3-year-old) plants of more than 60 azalea cultivars were investigated under nursery conditions. Twigs were subjected to controlled freezing to quantify frost tolerance of flower buds. Percent live florets per bud and number of dead florets per bud were correlated with morphological characters. Floret development (floret Iength and style Iength) correlated positively with cold acclimation. Stem and Ieaf characters showed no consistent correlation with bud cold tolerance. Petal coloration, although not expressed at time of study, also correlated with cold acclimation. The extent of flower bud development proved to be the best indicator of fall and early winter frost tolerance.
Soil Temperature and Tomato Root Growth Under Black Polyethylene and Hairy Vetch Mulches
Authors: Teasdale John R. , Abdul-Baki Aref A.
Published: February 2019

Temperature and root length at selected locations within a raised bed under black polyethylene (BP), hairy vetch (Vicia villosa Roth) residue (HV), or bare soil (BS) were measured and correlated with tomato (Lycopersicon esculentum Mill.) growth. Early in the season, before the tomato leaf canopy closed, soil temperature was influenced more by vertical depth in the bed than by horizontal location across the bed. Maximum soil temperatures under BP averaged 5.7 and 3.4C greater than those under HV at 5- and 15-cm depths, respectively. More hours at temperatures >20C during the first 4 weeks probably accounted for greater early root and shoot growth and greater early yield of tomatoes grown in BP rater than in HV or BS. After canopy closure, soil temperatures under tomato foliage were reduced compared to those on the outer edge of the beds. Most tomato roots were in areas of the bed covered by the tomato canopy where temperatures in all treatments remained in the optimum 20 to 30C range almost continuously. Soil temperature, therefore, did not explain why total yield was higher in the HV than the BP or BS treatments.
Effect of Elevated Medium Sucrose Levels on Cold Hardiness of `Festival' Red Raspberry in Vitro
Authors: Palonen Pauliina , Donnelly Danielle , Buszard Deborah
Published: February 2019

Low tissue-water content and increased osmotic concentration of cell sap are associated with frost resistance. Changes in total osmotic concentration of cell sap are due mainly to changes in concentration of sugars. Generally, sugar content increases with hardening and decreases with dehardening. This study examined the effect of elevated sucrose levels (3% to 15%) in the medium on the cold hardiness of `Festival' red raspberry (Rubus idaeus L.) shoots in vitro. To determine whether expected hardening is caused by elevated sucrose levels or by osmotic stress, different levels of mannitol in the media have been tested. After growing raspberry shoots on media with different levels of sucrose and mannitol for 2 weeks, shoot moisture content (percent) was determined. Cold hardiness of the shoots was determined by using differential thermal analysis or artificially freezing the shoots and assessing the survival by regrowth test and visual rating.
Pecan Cold Hardiness Determined by Differential Thermal Analysis
Authors: Matta Frank B. , Kawatin Amin
Published: February 2019

Our objectives were to 1) Determine acclimation and deacclimation patterns of buds and stems of four pecan cultivars in Mississippi and 2) to determine the relationship between cold hardiness, based on DTA, and tissue injury, based or viability tests. Stem critical temperatures for September showed that `Hughes' was slower in acclimating than `Jackson'. Maximum hardiness for all cultivars occurred in January, except for `Desirable', which reached maximum hardiness in December but started deacclimating in January. Deacclimation for the remaining cultivars started in February. Bud critical temperatures for September and October also show that `Hughes' was slower in acclimating compared to the remaining cultivars. Maximum bud hardiness for `Desirable' occurred in December, with the remaining cultivars reaching maximum hardiness in January. Bud deacclimation for all cultivars occurred in March. The LD50 for the tetrazolium and electrolyte leakage tests occurred at about –32 and –30C, respectively. In buds, LT50 for the tetrazolium test was –18C. The LT50 electrolyte leakage and browning test was –20C.
Bird Pepper (Capsicum annuum L. var. aviculare) Growth and Fruiting Response to Pinching and Uniconazole Sprays
Authors: Ramcharan Christopher
Published: February 2019

Preliminary experiments using uniconazole (UNZ) sprays at 5 and 10 ppm on bird pepper indicated that UNZ could be used to enhance appearance and improve fruiting of bird pepper, but some refinement of UNZ rates needed to be made. A final experiment was conducted to determine rates of UNZ and pinching level required to maintain a suitable plant size and increase yield and total number of red fruits. Best overall effects were on plants single-pinched 4 weeks after sowing and treated with a foliar spray of 4 to 6 ppm UNZ. Higher UNZ levels produced overly compact plants that required staking of individual branches. Attractiveness of double-pinched plants may be enhanced by delaying UNZ application after the second pinch. Bird pepper, therefore, can be produced as a dual-purpose pot plant by single-pinching followed by foliar applications of UNZ at 4 to 6 ppm.
Molecular Markers for the Scab Resistance (Vf) Region in Apple
Authors: Hemmat Minou , Weeden Norman F. , Brown Susan K.
Published: February 2019

Apple scab, Venturia inaequalis (Cke.) Wint., is one of the most damaging diseases of apples. Although fungicide sprays have been used to control the disease, genetic resistance in existing commercially important varieties would be desirable. Identification of molecular marker(s) would be helpful in devising biotechnological approaches to control the disease. We used bulk segregant analysis to identify RAPD markers that cosegregate or display a tight linkage with Vf gene in Prima × Spartan cross. Using this approach, we are saturating the region around the scab resistance gene for the purpose of bracketing the locus. We have identified several markers associated with the Vf locus. The closest markers have been isolated and sequenced to be used as SCARs. The relationship and distances of the markers with the Vf locus and other previously reported markers will be discussed.
Genetic Relationships among Weedy Purple Loosestrife (Lytrhum salicaria L.) Populations and Cultivars
Authors: Strefeler Mark S. , Darmo Elizabeth , Becker Roger L. , Katovich Elizabeth J.
Published: February 2019

Starch gel electrophoresis of plant proteins was used to genetically identify purple loosestrife (Lythrum spp.) cultivars and weedy populations. Preliminary determinations were made as to what degree weedy loosestrife populations were related (or genetically similar) to populations of L. alatum, L. virgatum, and horticultural cultivars. Cluster analysis of the data indicated that native L. alatum was genetically different from all populations of purple loosestrife and cultivars examined. The L. salicaria and L. virgatum cultivars, as groups, were not genetically distinguishable from the weedy populations analyzed. Seven cultivars of L. salicaria origin analyzed as a group were not distinguishable from the eight cultivars of L. virgatum origin, indicating that separation by cultivar origin may not be feasible. While the two “groups” were not distinguishable, most individual cultivars could be distinguished from one another by isozyme phenotype. Genetic variation was high within populations of weedy purple loosestrife but low among populations, which is characteristic of polyploid, perennial plant species that are widely distributed. Geographic location did not consistently correlate with genetic similarity.
Response of Poinsettia to Different Nitrogen Forms
Authors: Scoggins-Mantero Holly L. , Mills Harry A.
Published: February 2019

`Freedom' poinsettias (Euphorbia pulcherrima Willd. ex Kl.) were grown to flowering in solution culture for 11 weeks. Treatments consisted of five ammonium: nitrate nitrogen ratios: 1:0, 3:1, 1:1, 1:3, and 0:1 with a total N concentration of 150 mg N/liter. The balance of essential nutrients was supplied with a modified Hoagland's solution. Fresh weight, dry weight, and macro- and micronutrient content of bracts, leaves, petioles, stems, and roots were determined at the end of the study. Leaf and bract area also was measured. Maximum bract size was achieved with 100% nitrate (0:1) treatment. Leaves were largest with the 1:3 ratio. Plants receiving ammonium as the sole N source exhibited severe ammonium toxicity symptoms: stunted growth, foliar chlorosis and necrosis, premature leaf abscission, stunted and clubby roots, and delayed or nonexistent bract coloring. Dry weights for bracts, leaves, stems, and roots increased as the ratio of nitrate increased. Elemental uptake was monitored weekly. Nitrogen-form effect on the uptake, concentration, and partitioning of other nutrients also was evaluated.
Response of Calendula officinalis L. Plants to Different Nitrogenous Fertilizers
Authors: Al-Badawy Ahmed A. , Abdalla Nadia M. , El-Sayed Ahmed A.
Published: February 2019

Calendula officinalis L. plants were fertilized with urea (46% N), ammonium nitrate (31% N), and ammonium sulfate (20% N) at 0, 25, 50, or 100 kg N/Feddan (4200 m2). The plants also received calcium superphosphate (15.5% P2O5) and potassium sulfate (48% K2O) at 100 and 50 kg/Feddan, respectively. The results showed that fertilizers enhanced vegetative growth and improved flowering aspects compared to control plants. Application of urea at 50 kg N/Feddan gave the highest flower number (119) and flower dry weight (183 g). Moreover, the applied fertilizers increased the content of photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoids) in leaves and flowers and the N percentage in shoots. Nevertheless, P and K percentages were decreased.
Growth and Phyllode Gas Exchange of Three Acacia Species as Influenced by Developmental Light Level
Authors: Marler Thomas E. , Guzman Louann C. , Lawrence John H.
Published: February 2019

Acacia auriculiformis, A. mangium, and A. koa trees were grown in 5.4-liter containers under conditions of 100%, 44%, or 19% sunlight transmission to determine biomass accumulation and partitioning and phyllode gas-exchange responses to developmental light level. Following ≈100 days of growth, all three species exhibited a linear decrease in relative growth rate and biomass accumulation in response to developmental light level. The influence of reduced developmental light level on growth was similar for the three species, with biomass accumulation under 19% transmission averaging ≈20% of that under full sunlight. In a second study, the diurnal pattern of gas exchange of mature phyllodes was determined. Gas exchange of phyllodes under 19% or 44% transmission depended on photosynthetic photon flux throughout the day. In contrast, gas exchange of phyllodes in 100% transmission was highest in early to midmorning on sunny days. Phyllode gas exchange slowly declined thereafter for A. mangium and A. koa, but rapidly declined then slightly recovered in late afternoon for A. auriculiformis.
Gas Exchange and Mycorrhizal Development of Neem Trees in Response to Phosphorus Nutrition
Authors: Phavaphutanon L. , Davies F.T. , Duray S.A.
Published: February 2019

Cuttings of neem trees (Azadirachta indica) were grown for 65 days at four P levels: 0, 15, 30, and 60 mg P/kg soil. Half of the plants were inoculated with the vesicular–arbuscular mycorrhizal fungi (VAM) Glomus intraradices. VAM increased growth and net photosynthesis (A) at the lowest two soil P levels. Increased A was attributed to increased stomatal conductance (g) and greater leaf P concentration. Nonstomatal inhibition of A due to P deficiency also was observed in non-VAM plants at lower soil P levels. At higher soil P, VAM and non-VAM plants had comparable growth, A, g, and tissue concentration of P and other elements. VAM plants at 0 mg P/kg soil had similar growth and leaf P concentration when compared to non-VAM plants at 15 mg P/kg soil, yet had a 11% higher A, indicating a direct effect of VAM on gas exchange. As soil P increased, total VAM colonization and vesicle formation decreased, while the amount of extraradical hyphae increased. Arbuscule formation was highest at 0 and 15 mg P/kg soil. Apparently, arbuscules and extraradical hyphae play an important role in the enhanced growth and gas exchange of VAM plants at lower soil P levels.
Growth and Development in Irrigated Alpinia purpurata
Authors: Inouye David S. , Criley Richard A.
Published: February 2019

The time frames for shoot emergence (SE) to inflorescence emergence (IE) and harvest (H) were determined for three Alpinia purpurata cultivars irrigated at 0.33, 0.67, 1.0, and 1.67 times the pan factor evaporation rate of the preceding week. Leaf area per shoot, rate of increase in clump area, and yield and quality measurements were also were determined. Cultivar differences were more important than irrigation regimes for the SE–IE and SE–H time frames; however seasonal effects were important for both temporal and quantitative variables. As the amount of irrigation water was increased from pan factor 0.33 to 1.67, yields increased by ≈10 inflorescences per plant (over the 18 months of the experiment), and the proportion of high-quality (fancy) inflorescences harvested increased by 10%.
Quantifying the Effects of Temperature and Plantlet Size on the Reproductivity and Vegetative Axillary Development of the African Violet (Saintpaulia ionantha Wendl.)
Authors: Faust James E. , Heins Royal D.
Published: February 2019

Axillary buds of African violet develop vegetative shoots or reproductive inflorescences. Vegetative axillary development results in a multiple-shoot plant and reduces plant quality. We determined the effect of temperature and plantlet size on axillary bud development. Plantlets were removed from leaf cuttings, graded according to stem diameter, directly stuck into pots 10 cm in diameter, and placed in greenhouses at 18, 22, or 26C. Vegetative development was related to temperature, plantlet size, and nodal position. The number of vegetative axillary shoots per plant decreased from 3.7 to 1.3; that of leaves per vegetative axillary shoot decreased from 10.3 to 4.8 as temperature increased from 18 to 26C. The eight to 10 basipetal nodes developed vegetative shoots or were devoid of axillary development. The percentage of leaf axils in which inflorescences developed increased from 14 on node eight to 100 on nodes 12 and higher. The larger plantlets at the time of transplant had 20% fewer vegetative axillary shoots, whereas reproductive inflorescence development was not affected by plantlet size.
Reduced Nitrogen Fertilization Requirements of Potatoes under Precision Irrigation
Authors: Feibert Erik B.G. , Shock Clinton C. , Saunders Lamont D.
Published: February 2019

Seven potato cultivars were grown on silt loam with six N fertilizer treatments in 1992, 1993, and 1994 to evaluate varietal response to N fertilizer rate and timing under precision sprinkler irrigation. Crop evapotranspiration was replaced when the soil water potential at 0.2-m depth reached –60 kPa. Maximum yield responses were obtained using 0 to 134 kg N/ha, depending on the year and experimental site. In 1993 and 1994, with wheat as the previous crop, 134 kg N/ha maximized yields, over all varieties. In 1992, with alfalfa as the previous crop, there was no positive yield or grade response to N, over all varieties. Each year, available soil N accounting showed large surpluses for all treatments. Nitrogen mineralization contributed from 80 to 280 kg N/ha per year to the soil supply.
Zonal Geranium Growth and Flowering Response to Chemical Growth Retardants
Authors: Whipker Brian E. , Hammer P. Allen
Published: February 2019

Chemical plant growth retardant (PGR) treatments (mg·liter–1) were applied as foliar sprays to three zonal geranium cultivars: chlormequat at 1500, applied two, three, and four times, a combination of chlormequat at 750 and daminozide at 1250, applied one and two times, and paclobutrazol applied once at 5, 10, 20, and 30; twice at 5, 10, and 15; and three times at 5, plus an untreated control. Two paclobutrazol drench treatments at 0.1 and 0.25 mg a.i. per pot were also applied. The results of the PGR applications were significant at the cultivar × treatment interaction for leaf canopy height and plant diameter. Paclobutrazol rates of 10 to 15 mg·liter–1 resulted in acceptable height control for `Medallion Dark Red' and `Aurora'. `Pink Satisfaction' is a less vigorous cultivar and lower paclobutrazol rates of 5 to 10 mg·liter–1 were more suitable. When the total concentration of the single and multiple applications were compared, no additional height control was realized with the multiple applications of paclobutrazol.
Copper Hydroxide is an Effective Control of Root Outgrowth in Plug-grown Seedlings Subirrigated by Capillary Mats
Authors: Geneve Robert L. , Buxton Jack W. , Stafford Myra
Published: February 2019

Capillary mat subirrigation provides uniform water in the growing medium to optimize seedling growth in plugs. It also offers a closed system that allows the grower to regulate the amount of water available to seedlings and to reduce water runoff. However, root outgrowth into the capillary mat can be a significant problem. Copper hydroxide (Spin Out) was painted on the bottom, outside surface of the plug container to control root outgrowth into the capillary mat. Three square and two octagonal plug sizes were treated with copper. Regardless of the plug size or shape, copper treatment was an effective treatment to control root outgrowth in marigold seedlings. Copper treatment reduced overall root outgrowth by 80% to 92%. Marigold and geranium seedlings in copper-treated square plug containers showed some reduced shoot and root development during plug production, but there were no differences in copper-treated plants compared to nontreated plants following transplanting to cell packs.
Establishment of Four Annual Species for Roadside Planting
Authors: Harkess Richard L. , Lyons Robert E.
Published: February 2019

Seeds of Celosia argentea plumosa L. `Pampas Plumes', Cosmos sulphureus Cav., Helianthus annuus L. `7111', and Zinnia elegans Jacq. `Gold Medal Mixture' were mixed with clean sand and hand-broadcast over 6.7-m2 plots at rates of 122 or 244 g/100 m2. Each plot was either left undisturbed after sowing or the seed was raked into the soil surface. Treatments were applied in a complete factorial design and replicated three times. Germination counts were taken 2.5 and 5 weeks after sowing. The dates of flowering, number of plants flowering, and number of weeds present were recorded at anthesis. The Celosia and Zinnia bloomed for 42 days, Cosmos sulphureus for 28 days, and Helianthus for 12 days. Seeding rate had little affect on the number of plants maturing to flower in all species except Cosmos. There were no significant differences in number of weeds between treatments for any of the species. Raking the seed into the soil significantly improved germination at both 2.5 and 5 weeks in Celosia, Cosmos, and Helianthus, but not Zinnia. In Celosia, raking the seed in more than doubled the number of plants maturing to flower, while in Cosmos, the number reaching anthesis was not significant.
Using the Float System and Copper Hydroxide Tray Treatment for Tomato Transplant Production
Authors: Wyatt Jim E. , Akridge Marla C.
Published: February 2019

Conventionally grown tomato transplants were compared with those grown in a float system for growth and productivity. Tomato plants grown in a float system were larger than plants grown conventionally and produced higher early season yields of small, medium, and large fruit. Yields of extra-large fruit and total yield were not affected by production method. Mean fruit size from conventionally grown plants was larger early in the season. Transplant growth in plastic foam tray cells treated with 7% Cu(OH)2 was compared with growth in nontreated cells. Transplants from trays treated with Cu(OH)2 were larger and had fewer roots emerging from the bottom of the trays. Cu(OH)2 treatment had no effect on plant height in the field, seasonal yield distribution, total yields, or mean fruit size.
The Influence of Root-zone Temperature and Fertilization Regime on Early Growth and Development of Pawpaw (Asimina triloba Dunal) Seedlings
Authors: Layne Desmond R. , Kwantes Michael G.
Published: February 2019

A two-factor factorial, randomized block design was used to study the influence of root-zone temperature (RZT) and fertilization regime (Fert) on early growth and development of pawpaw seedlings in the greenhouse. Stratified seeds were sown in 45-inch3 Rootrainer cells in Promix BX potting medium. Plants were watered/fertilized twice weekly to runoff. RZT was at two levels—ambient (75F–Amb) or bottom-heated (90F–Heat), and it commenced at sowing date. Fert was at four levels—125, 250, 500, or 1000 ppm Peter's 20N–20P–20K plus soluble trace elements, and it commenced at emergence date. Bench position in the greenhouse was used as the blocking variable (three blocks). The 20 most uniform seedlings were selected from each treatment/block for weekly growth measurements. At the termination of the experiment (equivalent to time for transplanting to a larger container), 10 plants per treatment/block were harvested destructively. RZT significantly influenced time to seedling emergence where Heat seedlings emerged 10 days earlier than Amb seedlings. Heat plants were significantly taller, had greater trunk diameter, leaf number, and leaf area than Amb plants. Fert at 125 to 250 ppm resulted in the most robust seedlings, with 1000 ppm Fert often inducing early terminal bud set. Impact of RZT and Fert on seedling development over time will be discussed.
Modified Medium to Improve Somatic Tissue to be Used in Callogenesis
Authors: de L. Fortes G.R. , R. Vieira A.M. , Leite D.L.
Published: February 2019

Somaclonal variation has been one way to create variants that could be used in the breeding programs. However, initial explants may not be useful if they show small leaves or nondeveloped stems. The aim of this work was to find a tissue culture medium so that potato shoots cultured in vitro could regenerate somatic material for use in trials aimed at somaclonal variation. Shoots of `Baronesa' and `Monte Bonito' were inoculated in media with or without activated charcoal (3.0 g–liter–1), BAP (1.0 g–liter–1), and different MS salt concentrations (50%, 75%, and 100%). After 30 days in controlled conditions (25C, 16-h photoperiod, and 2000 lux), BAP with activated charcoal improved the percentage of dry matter, and at higher MS salt concentrations, a better response was achieved for `Monte Bonito'. However, the presence of activated charcoal improved leaf development and stimulated higher shoot and bud formation, especially for `Monte Bonito'. This somatic material can be used to initiate callogenesis trials successfully.
Development of Two Screening Methods for Tomato Seedlings Containing the NPT II Selectable Marker Gene
Authors: Layton Jeanne G. , Rangwala Tasneem S. , LaVallee Bradley J. , Rottnek Jeannie M. , Romaine Noelle
Published: February 2019

Two simple, cost-effective methods to screen fresh-market tomato seedlings containing the kanamycin resistance gene construct, in which the nopaline synthase promoter from pMON128 is driving the NPT II gene, have been developed. The assays can reliably distinguish kanamycin-resistant from sensitive progeny for a variety of tomato genotypes. One method is an in vitro germination assay. Two selective agents, geneticin (G418) and kanamycin sulfate, were evaluated for their efficacy, and titrations were performed to determine the optimal concentration of the appropriate agent. The second method is a whole-plant spray test of seedlings to identify kanamycin-resistant progeny. A protocol was developed that could distinguish positives from negatives in 5 weeks. Currently, these assays are being used to screen R1 progeny rapidly to identify positives and obtain segregation ratios. They also are being used to screen R2 progeny to identify quickly those lines that are “true-breeding” or homozygous for field trial evaluation.
Forcing Large-diameter Stems of Adult White Ash in a Greenhouse to Obtain Softwood Shoot Explants
Authors: Bernhard Karen L. , Preece John E.
Published: February 2019

Branches were collected from trees in July. Lengths with a 2.5-cm caliper were cut to 30 cm and placed horizontally into flats of perlite with half of the diameter of each stem above the perlite surface. Flats were watered daily with tap water and stems were kept moist. Buds swelled quickly, and after 6 days, small epicormic shoots were visible. These softwood shoots continued to elongate and retain good turgor for 2 weeks, when they were excised and placed in vitro. Shoottip and nodal explants were placed onto MS medium with 1 μM BA; 1 M IBA; and 0, 3, or 10 μM TDZ where shoots slowly elongated. Forcing large stems in the greenhouse has been superior to forcing smaller stem tips in the laboratory because of lower contamination (40% on shoots from large stems vs. up to 90% on shoots from small stems), longer life of the softwood shoots (less wilting from the larger stems), a longer time during the year for forcing, and the possibility of forcing shoots from more juvenile wood than stem tips.
The Effect of Glass-cracking during Cooling in Liquid Nitrogen on Viability of Mint Shoot Tips
Authors: Towill L.E.
Published: February 2019

Cryopreservation using vitrification has been reported for several plant species. Shoot tips and vitrification solution were placed in semen straws and immersed in liquid nitrogen (LN). Cracking of the external glass occurred, but may be avoided by annealing slightly below the glass transition temperature before immersion. A varying percentage still cracked with some vitrification solutions. Rapid warming also can cause cracking. There is concern that cracking may reduce viability. Shoot tips from Mentha species were used to examine this problem. Glass cracking during either cooling or warming did not produce visible damage to shoot tips. Viability of shoot tips from tubes that cracked during cooling was not different from those that did not crack; however, shoot formation was slightly reduced. Cracking upon warming did not reduce viability nor shoot formation. Very slow warming reduced viability, but warming in either water or air (room temperature) gave higher levels of survival.
Establishment of Excised Date Palm (Phoenix dactylifera L.) Roots in Vitro
Authors: Dlaigan Yousef I. , Said A.E. , El-Hamady M.A.
Published: February 2019

Several trials were conducted with the objective of obtaining an explant for the establishment of date palm root culture in vitro. These trials included disinfecting and germinating seeds of three cultivars on several autoclaved culture media, the influence of incubation temperature on different germination parameters, and the quality of roots before excision and after culture in nutrient media. Three culture media were used: distilled water only; minimal organics that consisted of MS salts, 3% sucrose, modified White's organics, 0.01% inositol, and 0.15% activated charcoal; and 1/2 MS salts mixture, 3% sucrose, and 1/2 modified White's organics. All three media were solidified with 0.7% agar. The seeds were incubated at 25 or 35C for germination. The study revealed the difficulty of seed disinfection. We immersed seeds in 20% to 40% Clorox, with two to four drops of Tween-20, for 30 to 60 minutes and then rinsed them four to five times in deionized distilled water before culturing. The minimal organics medium supported optimal growth of excised roots, and incubation at 35C significantly improved germination. The use of 10-mm-long root tips as explants for culture initiation gave the best growth and elongation. In addition, the growth and elongation of excised root tips increased significantly as the distance from it to the apex of the cotyledonary sheath increased.
Transformation of Grape (Vitis vinifera L.)
Authors: Scorza R. , Cordts J.M. , Gray D.J. , Ramming D.W. , Emershad R.L.
Published: February 2019

Transgenic grapevines were regenerated from somatic embryos produced from immature zygotic embryos of two seedless grape selections and from leaves of in vitro-grown plants of `Thompson Seedless'. Somatic embryos were bombarded with gold microparticles using the Biolistic PDS-1000/He device (Bio-Rad Labs) and then exposed to engineered A. tumefaciens EHA101 (E. Hood, WSU). Alternately, somatic embryos were exposed to A. tumefaciens without bombardment. Following cocultivation, secondary embryos multiplied on Emershad and Ramming proliferation medium under kan selection. Transgenic embryos were identified after 3 to 5 months and developed into rooted plants on woody plant medium with 1 mM N6-benzyladenine, 1.5% sucrose, and 0.3% activated charcoal. Seedless selections were transformed with plasmids pGA482GG (J. Slightom, Upjohn) and pCGN7314 (Calgene), which carry GUS and NPTII genes. `Thompson Seedless' was transformed with pGA482GG and pGA482GG/TomRSVcp-15 (D. Gonsalves, Cornell Univ.) containing the tomato ringspot virus coat protein gene. Integration of foreign genes into grapevines was verified by growth on kan, GUS, and PCR assays, and Southern analyses.
Effect of Urea, Some Micronutrients, and Growth Regulator Foliar Sprays on the Yield, Fruit Quality, and Some Vegetative Characters of Washington Navel Orange Trees: Fruit Pedicel Pectin Content, Flowering Aspects, and Fruit Set, and Dropping Percentages
Authors: Akl Ahmed M. , Eid Abdel-Fattah M. , Hegab Mohamed Y.
Published: February 2019

This part of the investigation studied the effect of foliar spraying with urea (0.5%); a mixture of Zn (0.4%), Mn (0.3%), Fe (0.5%), and Cu (0.3%) in sulphates (from 23% Zn, 28% Mn, 19% Fe, and 30% Cu, respectively); and two growth regulators (GA3 at 25 ppm and α-NAA at 10 ppm); as well as number and date of sprays on fruit pedicel pectin content, some flowering aspects, and fruit set and drop percentages. Applying urea, micronutrients, or both significantly increased pectin content in the pedicels of the attached and dropped fruit. The treatment including urea plus micronutrients resulted in the highest values for pectin in fruit stem. Either GA3 or NAA significantly raised pectin content over that of the water-sprayed control. However, NAA was more effective in increasing pectin content in fruit pedicel. The overall treatment including urea and micronutrients with GA3 or NAA was the most effective in producing the highest percentage of leafy inflorescence in 1991–92 and 1992–93 seasons. Any nutrition treatment was significantly effective in increasing fruit set and reducing fruit drop compared with the water-sprayed control; however, the treatment including all sprayed nutrients was the most effective. Application of GA3 or NAA significantly increased fruit set percentage and reduced June and preharvest fruit drop; however, NAA was more effective in reducing fruit drop than GA3.
High Zinc Concentrations Contribute to Chlorosis in Blueberry
Authors: Gupton C.L. , Spiers J.M.
Published: February 2019

To determine if high Zn concentrations contribute to chlorosis in blueberry, plants of rabbiteye `Climax' and southern highbush `Bladen' were fertilized in sand culture with 30, 60, 90, and 120 ppm Zn solutions at 4, 4.5, 5, 5.5, 6, and 6.5 pH. Only Zn levels significantly affected the degree of chlorosis in plant leaves. No interaction among cultivars, pH, or Zn concentration was significant. The linear response to Zn levels was significant (P = 0.0001), but quadratic and cubic responses were not significant. Cultivars and Zn fertilization levels affected Zn and Mn accumulation; however, no difference in chlorosis rating was observed between cultivars. An inverse relationship existed between Zn fertilization levels and leaf Mn content so that the total concentration of the two minerals was about the same for each fertilization level, suggesting that Mn toxicity would not be expected at high levels of Zn fertilization. We concluded that high levels of Zn may induce chlorosis in rabbiteye and southern highbush blueberry.
Nitrogen and Water Management for Drip-irrigated Tomato
Authors: Sterrett S.B. , Savage C.P. , Hohlt H.E.
Published: February 2019

Tomatoes (Lycopersicon esculentum Mill.) were grown under plastic culture on a Bojac sandy loam soil in 1991, 1992, and 1994 to determine influence of nitrogen rate at planting and water application scheduling by pan evaporation (PAN) on crop yield and fruit size. Marketable yield and percentage of large fruit was significantly increased in 1991, 1992, and 1994 as irrigation application increased from 0.5 to 1.0 or 1.5 PAN (one application per day). Nitrogen applications exceeding 168 kg–ha–1 resulted in lower yield and reduced fruit size in 1992. In 1994 (late planting followed by hot, dry growing season), yield was increased with increasing N to 213 kg–ha–1 with 1.0 PAN, but not influenced by N at 1.5 PAN. Residual soil nitrate concentration was increased with reduced irrigation or increased nitrogen application. Nutrient management plans to address non-point source pollution concerns of EPA will need to reflect crop irrigation needs to maintain yield and fruit size while minimizing nitrate accumulation within the soil profile.
Influence of the Color of Mulch on Development and Productivity of Peppers
Authors: Begin Serge , Calandriello Joe , Dube P.A.
Published: February 2019

The rational use of mulch associated with plasticulture involves the optimization of all bioclimatic parameters so as to minimize the considerable expenses engendered by use of this technology. The primary objective of this project is to study the influence of the transmission and the reflection of light involving different colored plastic film on the development and productivity of peppers. Spectroradiometric measurements between 400 and 1100 nm indicate that brown, red, and gray are the most opaque to light. Higher temperature were measured under clear, red, brown, and green plastic mulch. The greenhouse study shows that young plants subjected to white mulch and gray mulch grew into plants whose leaf surfaces were weaker than those subjected to other materials. Earliest yields were obtained from clear and red mulch. There was no significant differences noted in total yield.
Response of Long- and Short-vine Tropical Pumpkins to Varying Cultural Practices
Authors: Irizarry-Morales J. , Wessel-Beaver L. , Maynard D. , Elmstrom G.
Published: February 2019

Three field experiments were carried out in Lajas, Puerto Rico, to compare the effects of planting method (direct and transplant), plastic mulch (with and without), and planting density (1.8 x 1.8 m, 3.6 x 0.9 m, 1.8 x 0.9 m between and within rows) on production of short-and long-vined tropical pumpkins (Cucurbita moschata). The long-vine genotype produced greater yields and larger but fewer fruit than the short-vine genotype. However, most of the planting densities tested were probably not optimum for short-vine cultivars. Direct seeding of pumpkin was more efficient than transplanting and resulted in the same early and total yield as transplanting. Yields with plastic-covered banks were similar to yields without the use of plastic. However, use of plastic mulch increased the number of fruit and decreased the average fruit weight in the plots. The best planting distance depended on the type of genotype used. The long-vine genotype had the highest yields at 1.8 x 1.8 m, while the short-vine cultivar performed best with half that amount of space per plant (1.8 x 0.9 m). Production of short-vine cultivars might be improved by using even narrower planting distances.
Subirrigated Bell Pepper Production with Reduced Water Table Levels and Fertilizer Rates
Authors: Stanley C.D. , Clark G.A.
Published: February 2019

The effect of water table level and fertilizer rates on bell pepper production grown with the fully enclosed subirrigation (FES) system was studied over three fall growing seasons (1992–94). The FES system uses buried microirrigation tubing in the field to convey water for maintaining a water table level and has shown to achieve application savings of 30% to 40% compared to the conventional subirrigation method that maintains a high water table using lateral field ditches. Controlled water table levels of 45, 60, and 75 cm below soil surface and fertilizer rates of 1194, 1716, and 2239 kg·ha–1 (18–0–21 expressed as N–P–K) were used as treatments replicated in time over 3 growing seasons. The 45-cm water table level and 2239 kg·ha–1 fertilizer rate are considered the conventional commercial practices. Results showed that comparable seasonal production levels were achieved among fertilizer rates and water table levels with no significant interactions between treatments. These data indicate that using a lower target water table level allows lower rates of fertilizer to be used because the susceptibility of the fertilizer to leaching caused by excessive rainfall is lessened due to increased soil water storage capacity.
Potential Uses and Water Demand of Pigeonpeas in Mixed Intensive Horticultural Systems in Dry-subtropical Northwest Mexico
Authors: Troyo-Diguez Enrique , Salinas-Zavala Federico
Published: February 2019

A water demand model based on the plant–water–climate interactions is proposed to establish the effects of the photosynthetically active radiation (PAR) on the water demand processes of a crop. It is shown that a relationship exists between PAR, leaf temperature, and the transpiration of regional ecotypes of Northwest Mexico from Asia in the middle of the century. These ecotypes were found in the influence area of the Sierra de La Laguna, B.C.S., Biosphere Reserve. Estimated relationship was backed by measurements of leaf and ambient temperatures, and PAR, of which the transpiration is dependent. It is concluded that this procedure is useful to establish the expected level of transpiration of pigeonpeas and thus, their water requirements. The observed phenotype characteristics suggest the usefulness of pigeonpeas in intensive ecosystems; grain yield was near 6 Mg·ha–1. The results enable us to design appropriate horticultural systems in the villages of Sierra de La Laguna, which could include understorey horticultural species and pigeonpeas, a low-inputs crop.