bluuebunny/crossref_metadata_2025 huggingface dataset:
Distinguishing Pacific Northwest Red Raspberry Cultivars using RAPD Markers
Authors: Moore Patrick P.
Published: February 2019

Randomly amplified polymorphic DNA markers (RAPDs) were used to distinguish among seven Pacific Northwest red raspberry (Rubus idaeus L.) cultivars. Random 10-base sequences were used to distinguish among `Chilcotin', `Chilliwack', `Comox', `Meeker', `Qualicum', `Tulameen', and `Willamette'. The seven cultivars could be distinguished even though there is considerable relatedness among the cultivars. `Chilliwack' and `Comox' share `Skeena' as a parent, and `Chilliwack' is a parent of `Qualicum'. `Willamette' is a parent of `Meeker'. This technology shows promise as a means of distinguishing cultivars and developing a genetic map to aid in breeding.
Influence of Simulated Transport on Keeping Quality in Miniature Potted Roses
Authors: Borch Kristian , Hoyer Lars
Published: February 2019

Stressing miniature roses during transport can reduce their appearance and keeping quality. Factors that stress plants during transport are: storage in darkness, fluctuating temperatures, exposure to ethylene, high humidity, and mechanical damage. The post-production keeping quality of three cultivars of Parade® miniature potted roses (Rosa × hybrida) from three growers in Denmark were evaluated during winter and summer 1994, using three levels of simulated transport (ST) for 0, 2, or 4 days. The main causes of decreased keeping quality were wilting of flowers, infection by botrytis, and an increased number of yellow buds. After 18 days, there was no difference in the percentage of wilted flowers between 0 and 2 days of ST for all cultivars. However, for two of the three cultivars exposed to 4 days of ST the percentage of wilted flowers increased, while there was no significant effect from the ST on the percentage of wilted flowers. The degree of wilting was also dependent on origin of the plants and was less severe in summer than in winter. The number of yellow buds and infection by botrytis increased in plants exposed to 4 days of ST, and was more pronounced in winter. We conclude that, if the initial quality of the miniature potted rose is good, and the stress conditions during transport are controlled, damage can be kept at a minimum level.
The Influence of Removal of Specific Wavelengths of Light on the Height of Chrysanthemum Plants
Authors: Reddy Venkat K. , Rajapakse Nihal C.
Published: February 2019

The influence of removal of specific wavelengths [red (R), blue (B), and farred (FR)] from sunlight on the height of chrysanthemum plants was investigated by overlaying Roscolux™ colored acetate films on 4% CuSO4 or water (control) spectral filters. CuSO4 filters removed FR wavelengths and significantly reduced plant height and internode length compared to control plants that received B, R, and FR wavelengths of light. Plants grown under Roscolux blue filters did not receive R light and were significantly taller compared to plants from any other treatments. Plants grown under Roscolux red filters did not receive B light and were significantly shorter compared to plants from other treatments. Leaf area, leaf dry weight, and stem dry weight were highest in plants grown under Roscolux red and control filter combination. The amount of leaf chlorophyll and the ratio of Chl A: Chl B was highest in plants grown under Roscolux blue filters. In general, plants that received FR light (control + film) were taller than the plants that did not receive FR light in the corresponding (CuSO4 + film) filter combination. The influence of removal of specific wavelengths on plant height control and developmental physiology will be discussed.
Hormonal Effects on the Germination Response of Chasmanthium latifolium
Authors: Harp Derald A. , Wade Michael , Gilman D. Frank , Calahan John
Published: February 2019

Caryopses of Chasmanthium latifolium removed for the florets, treated with solutions containing 0.02 M KNO3, 0.5 mM GA3, and/or 0.1 mM kinetin, placed in germination chambers at alternating temperatures of 15/30C, and percentage germination was checked at 7, 14, and 21 days. Treatments with kinetin and/or KNO3 significantly increased germination percentage over other treatment combinations. The maximum germination percentage for Chasmanthium latifolium was achieved by removing the caryopsis from the floret, treating the caryopsis with 0.02 M KNO3, and germinating for 14 days at alternating temperatures of 15/30C.
Potato Production and Deficit Irrigation
Authors: Shock Clinton C. , Feibert Erik B.G. , Saunders Lamont D.
Published: February 2019

Potato response to water stress and changes in soil available-N levels in relation to irrigation management were evaluated in 1992, 1993, and 1994. Potatoes were grown on silt loam with sprinkler irrigation in an adequately irrigated check (100% of crop evapotranspiration replaced at –60 kPa) and three deficit irrigation regimes. Water stress treatments were achieved by partial or complete replacement of crop evapotranspiration when soil water potential reached –80 kPa. In 1992 and 1994, relatively warm years, tuber yield and grade were significantly reduced by water stress. In 1993, a relatively cool year, yield was reduced by water stress, but grade was not. Each year, soil available-N accounting for the season showed large surpluses for all treatments. Potato cultivars grown as subplots varied in their response to deficit irrigation.
Growth, Yield, and Water Consumption of Greenhouse Tomato Plants as Affected by High Electrical Conductivity of Nutrient Solution and Low Water Content in Substrate
Authors: Xu Hui-lian , Gauthier Laurent , Gosselin André
Published: February 2019

Tomato plants were grown in peatmoss-based substrate and supplied with nutrient solution of high (4.5 mS·cm–1) or low (2.3 mS·cm–1) electrical conductivity (EC) under high (95%) or low (55% of capillary capacity) substrate water content (SWC) to examine the effects of high EC and low SWC on growth and physiology. Salts were allowed to accumulate in the substrate for 7 weeks. Both high EC and low SWC significantly decreased dry matter production (DMP) and fruit yield (FY). Fruit harvest index was lower in high EC- or low SWC-treated plants. Decrease in marketable FY was attributed to both the decrease in total FY and the increase in small and abnormal (cracked and rot) fruits. Both high EC and low SWC decreased photosynthesis (PN) and leaf water potential (ΨL). However, chlorophyll content and respiration were increased by high EC under both high and low SWC. Water consumption based on both whole plant and unit of leaf area was decreased by high EC and low SWC. ΨL and transpiration were depressed by high EC and low SWC, especially at midday. There was a significant positive correlation between fruit yield and water consumption. The effects of high EC and low SWC were additive on most of the variables. Decreases in ΨL might ultimately account for water consumption reduction, PN depression, and FY decrease.
Nuclear Genome Organization of Asymmetric Intergeneric Somatic Hybrid Plants between Lycopersicon esculentum × L. pennellii and Solanum melongena
Authors: Samoylov Vladimir M. , Sink Kenneth C.
Published: February 2019

Asymmetric somatic hybrids were obtained by PEG/DMSO fusion of protoplasts of a kanamycin-resistant (KmR+) interspecific tomato hybrid L. esculentum × L. pennellii with protoplasts of S. melongena eggplant. Elimination of tomato chromosomes was directed by application of 100, 250, 500, 750, and 1000 Gy of γ-rays to the donor protoplasts. The hybrid nature of selected KmR+ calli was confirmed by RAPDs, PCR amplification of the NptII gene, and Southern hybridization. Flow cytometry revealed that asymmetric hybrid plants were regenerated only from selected somatic hybrid calli that had a ploidy level close to 4n. The amount of donor DNA in three somatic hybrid plants was quantified by dot-blot hybridization with tomato species-specific probes, and was found to be 5% to 7%. Therefore, presence of four to five tomato chromosomes in asymmetric hybrid plants has been calculated. Detection of tomato-specific chromosomes in hybrid plants by RFLP analysis will be presented.
Tests for Allelic Relationships Among Potyvirus Resistance Genes in Cucumis sativus
Authors: Kabelka Eileen , Grumet Rebecca
Published: February 2019

Cucumbers and other cucurbit crops are subject to severe losses due to an array of potyviruses, including zucchini yellow mosaic virus (ZYMV), watermelon mosaic virus (WMV), and the watermelon strain of papaya ringspot virus (PRSV-W). Sources of resistance to these viruses have been identified within the cucumber germplasm, including resistance to ZYMV, WMV, and PRSV in `TMG-l'; resistance to PRSV in `Surinam'; and to ZYMV in `Dina'. In this study, we sought to determine the allelic relationships between resistance to PRSV in `Surinam' and `TMG' and resistance to ZYMV in `Dina' and `TMG'. Segregation ratios among F1, F2, and backcross progeny of `Surinam' and `TMG' indicated that the alleles are at the same locus. Similarly, progeny analysis indicates that the alleles for ZYMV resistance in `Dina' and `TMG' are at the same locus. In each case, however, the alleles appear to differ from one another with respect to dominance relationships, symptom expression, and/or response to different viral strains. We are further characterizing these differences by screening progeny of crosses to a common susceptible parent.
Chemical Defoliation of Almond in Warm Climates of Northwestern Mexico
Authors: Grijalva-Contreras Raul Leonel , Lopez-Carvajal Arturo
Published: February 2019

Almond production in hot climate areas of Mexico uses low-chilling cultivars. One problem in young almond trees is that timely leaf drop does not occur; therefore, budbreak is late and uneven. With the objective of chemical defoliation, foliar applications of different compounds [urea (5%), ZnSO4 (5%), CuSO4 (5%), NH4NO3 (5%), ZnSO4 (2.5%) + urea (1.5%)], hand defoliation, and a nondefoliation control were made on `R-633' young almond trees (2 years old). The percent defoliation was high (77% to 86%) after 6 days of the application in the majority of treatments, except for NH4NO3 (5%), urea (5%), and the control; but 3 days later, all treatments showed >80% defoliation. Nondefoliated trees had an uneven budbreak and occurred 3 and 6 days later. The yield was greater for ZnSO4, with 435 g/tree and only 55.6 g/tree for the control. Fruit quality was the same for all treatments. No injury to branches were observed with any compounds.
Selective Pruning of Young Lemon Trees to Increase Fruit Size
Authors: Wright Glenn C. , Wilcox Mark A. , Tilt Philip A.
Published: February 2019

Growth of young lemon trees (Citrus limon Burm. f.) is extremely vigorous, and is characterized by the appearance of highly vigorous upright shoots that originate in the scaffold branches and trunk of the tree. While maturing, these shoots are considered to be in competition for photosynthates with smaller fruit in the spring and with mature fruit in the fall. During 1993 and 1994, we selectively removed these shoots 12, 6, 4, and 1 (1994 only) times per year, with the objective of increasing fruit size. Neither yield nor fruit quality was affected by the pruning treatments during 1993, but pruning trees 12 times per year increased fruit size by 30% compared to unpruned trees. In 1994, lemon trees pruned 4 times per year had 50% less cull fruit than unpruned trees, and 22% more fruit of size 140 or larger. However, >99% of the flowers and small fruit on trees pruned 4 times per year were aborted, compared with 95% abortion on the unpruned trees. Trees pruned 4 times per year also had 40% less yield compared with those that were unpruned.
Recycled Newspaper: An Effective Mulch for Micropropagated Raspberry Transplants
Authors: Warmund Michele R. , Starbuck Chris J. , Finn Chad E.
Published: February 2019

Micropropagated `Redwing' raspberry plants were grown with various mulch treatments to determine their influence on vegetative growth and fruit yield. Treatments included shredded hardwood bark mulch; degradable black plastic; sawdust; wheat straw; ground, shredded, or ground + shredded newspaper; and an unmulched control. During the year of establishment, high soil and air temperatures near the surface of the black plastic most likely reduced plant survival. The following year, vegetative growth and fruit yield of plants that were previously mulched with black plastic were also reduced. Plants mulched with bark, sawdust, straw, and all newspaper treatments had greater yields than those established with black plastic or in the unmulched control plots. Although yields were similar among plants in all newspaper mulch treatments, ground newspaper was lost under windy conditions and tended to mat down after rainfall, resulting in soggy soil conditions.
Protective Rain Covers Influence the Rain-inducing Cracking and Quality of Sweet Cherries
Authors: Cline John A. , Webster Tony D.
Published: February 2019

For many years, researchers and growers have attempted to find methods to alleviate the rain-induced cracking of sweet cherries. Cracking is thought to be caused primarily by the osmotic uptake of rain water through the fruit skin. A 3-year study was conducted at East Malling to test the hypotheses that rain covers reduce, while irrigation increases, fruit cracking. Two types of rain shelters, with and without trickle irrigation, were compared against control treatments on 8-year-old `Merchant'/Colt trees. Covers reduced cracked fruit by up to 11% in 1991, 7% in 1992, and 25% in 1993 when natural cracking on uncovered trees was ≈20%, 25%, and 40%, respectively. Trickle irrigation was associated with a 6% increase in fruit cracking in all 3 years. Tree covers and irrigation also tended to increase fruit size and maturity. Fruits from beneath covers were lower in soluble solids concentration and were firmer in comparison with fruits from uncovered trees. This study indicates that tree covers, while affording some protection against rain-induced cracking, do not altogether prevent the problem. Furthermore, irrigation appears to aggravate cracking when used with tree covers. A mechanism for cracking under covers will be discussed in relation to rainfall, fruit transpiration, and tree water relations.
Iron Chelate Photodegradation in Fertilizer and Nutrient Solutions Affect Iron Acquisition
Authors: Albano Joseph P. , Miller William B.
Published: February 2019

Iron chelate photodegradation is a problem in tissue culture where limited soluble Fe in agar reduces callus tissue growth. Our objectives were to determine if Fe chelate photodegradation occurs in commercial fertilizers used in greenhouse plant production and, if so, the effects on plant Fe acquisition. Commercial 20N–10P–20K soluble fertilizers containing Fe-EDTA were prepared as 100x stocks based on a 100 mg N/liter (1x) concentration. A modified Hoagland's solution with Fe-DTPA was prepared as a 10x stock based on a 200 mg N/liter (1x) concentration. Samples then were kept in darkness or were irradiated with 500 μmol·m–2·s–1 from fluorescent and incandescent sources for ≤240 hours. Soluble Fe in the irradiated commercial fertilizer solutions decreased 85% in 240 h. Soluble Fe in the Hoagland's solution, prepared in the lab, decreased 97% in 72 h. There was no loss in soluble Fe in any dark-stored treatment; demonstrating photodegradation of Fe-chelates under commercial settings. Excised roots of marigold (Tagetes erecta L.), grown hydroponically in the irradiated solutions, had Fe(III)-DTPA reductase activity 2 to 6 times greater than roots of plants grown in solutions kept in darkness. Plants growing in irradiated solutions acidified the rhizosphere more than plants growing in solutions kept dark. The increase in Fe reductase activity and rhizosphere acidification are Fe-efficiency reactions of marigold responding to the photodegradation of Fe-chelates and subsequent decrease in soluble Fe in both commercial fertilizers and lab-prepared nutrient solution.
Low-temperature Exotherms and Freeze Tolerance in Three Taxa of Deciduous Trees
Authors: Lindstrom Orville M. , Anisko Tomasz , Dirr Michael A.
Published: February 2019

Although differential thermal analysis has been routinely used to evaluate cold hardiness, the relationship between deep supercooling ability and plant survival is not clear. We compared seasonal profiles of changes in low-temperature exotherm (LTE) occurrence and visually determined lowest survival temperature (LST) of Acer rubrum `Armstrong', Fraxinus americana `Autumn Purple' and Zelkova serrata `Green Village' growing in three locations representing plant cold hardiness zones 8, 7 and 5. Between December and February, LTE in Acer rubrum and Fraxinus americana occurred at temperatures 10 to 25C lower than the LST. The difference between LTE and LST was not significant for Zelkova serrata from January to April, and for Acer rubrum and Fraxinus americana in March. Data indicate that LTE could be used as an estimate of LST in Zelkova serrata but not in Acer rubrum and Fraxinus americana. This study demonstrated that LTE does not provide a reliable estimate of cold hardiness in all species that deep supercool.
Heat Tolerance in Phaseolus lunatus
Authors: Keeler Sharon J. , Frett John J. , Kitto Sherry L.
Published: February 2019

Heat stress on field grown Phaseolus lunatus (lima bean) can have a significant influence on yield. Lima bean crops grown in Delaware typically yield less pounds per acre than the same cultivars grown in California. Part of this effect may be due to extreme heat conditions or fluctuations during Delaware's summers, which can affect blossom and pod set. Our purpose was to analyze the heat tolerance of various cultivars of P. lunatus using quick bioassays and to establish a relationship to yield in greenhouse temperature trials. Two assays were used. The first, a hypocotyl extension assay, consisted of a treatment of germinated seedlings at 25, 35, or 42 for 2 h and observations of hypocotyl extension at 72 and 96 h posttemperature treatments. Three cultivars [`Fordhook' 1072 (heat-sensitive), `Jackson Wonder' (heat-tolerant), and `Early Thorogreen' (heat tolerant)] were analyzed. Initial results indicated that `Jackson Wonder' and `Early Thorogreen' are capable of surviving the 42C heat shock, but `Fordhook 1072' is not. In the second assay, we measured electrical conductivity of a solution containing hypocotyl sections following incubation at various temperatures (R1). Tissue samples then were boiled and conductivity was measured again (R2). The ratios of R1/R2 × 100 were determined as percent injury. Preliminary data suggests that `Jackson Wonder' is more heat-tolerant in this assay than `Fordhook 1072'. Subsequent experiments will analyze the induction of specific heat shock proteins as a function of cultivar-specific heat tolerance.
Occurrence of Winter-kill to Apple Trees in the Okanagan Valley of British Columbia and Its Relation to Autumn and Winter Temperatures
Authors: Caprio J.M. , Quamme H.A. , Berard R.
Published: February 2019

Winter freeze events, identified by horticulturists to lower yields or kill trees (estimates vary by year from 1000 to >200,000 trees), have occurred in the Okanagan Valley of British Columbia 18 times in 94 years (1 in 5 years). To determine the association of winter temperatures and production, 72 years (1920–91) were separated into quartiles by level of production. Then, a maximum χ2 value was produced by a scanning iterative technique comparing each of the extreme quartiles with the combined mid-quartiles. A strong association was found between level of production and the low minimum temperatures in November, December, and February but not January. This result agrees with the historical records that indicate three winter-kill events occurred in November, five in December, one in January, and three in February during the same time period. Warm temperatures in September were associated with low production, indicating the possibility that warm temperatures at this time delay acclimation. Warm temperatures in January also were associated with low production, indicating a possible effect in hastening deacclimation.
Temperature Stress Enhances Antioxidant Enzyme Activities Associated with Budbreak in Woody Plants
Authors: Wang Shiow Y. , Faust Miklos
Published: February 2019

The ability of low and high temperatures to overcome endo- and paradormancy along with the possible mechanisms involved in these treatments for breaking apple (Malus domestica Borkh. `Anna') bud dormancy were studied. All these treatments induced budbreak in paradormant (in July) and endodormant (in October) buds. Cold and heat treatments increased ascorbic acid, the reduced the form of glutathione (GSH), total glutathione, total non-protein thiol and non-glutathione thiol, whereas dehydroascorbic acid and oxidized glutathione (GSSG) decreased. The treatments also increased the ascorbic acid: dehydroascorbate and GSH: GSSG ratios and the activity of ascorbate-free radical reductase, ascorbate peroxidase, dehydroascorbate reductase, ascorbate oxidase, and glutathione reductase in the buds. These results indicate that budbreak induced by cold and heat treatments is associated with the removal of free radicals through activated peroxide-scavenging systems.
The Effect of Heat Shock on the Induction of Chilling Tolerance in Cucumber Seedling Roots
Authors: Zhang Hua , Jennings Paul H.
Published: February 2019

Heat shock was applied to 32-h-old cucumber seedlings before chilling at 2.5C. Two cultivars, `Poinsett 76' and `Ashley', with different chilling tolerances, were tested. Using root growth after chilling as a measure of chilling tolerance, three heat shock regimes were found to induce chilling tolerance in both cultivars, with the most effective and uniform induction by heat shock at 40C for 3 h. `Ashley', the more chilling tolerant cultivar, exhibited a greater response to heat shock induction of chilling tolerance than `Poinsett 76'. Protein samples from roots were subjected to SDS-PAGE. Three low molecular weight heat shock proteins accumulated to a greater extent in the protein profile of heat-shocked `Ashley' roots. No such increase was found in the `Poinsett 76' roots. The induction of low molecular weight HSPs are discussed in relation to the heat-shock induction of chilling tolerance.
Effect of Temperature on Chemical Apple Thinning Results
Authors: Byers Ross E. , Smith Alson H.
Published: February 2019

An analysis of daytime high temperatures for the 10-year period from 1984 to 1993 indicated that, in the 21 days after full bloom (AFB) in 7 of 10 years, there were 3 days or more above 29.5C. In the 15- to 21-day period AFB, when fruit are considered at their optimum diameter (8 to 12 mm) for thinning, only 3 days above 29.5C were recorded. In the 15 to 21 days AFB, the high temperature was only 24C for 7 out of 10 years. Thus, growers would have to spray at temperatures 5.6C degrees lower if they were to choose to spray the warmest 3 days during the 15- to 21-day period when fruit are 8 to 12 mm in diameter. NAA caused thinning of `Golden Delicious' fruit at 8-mm fruit diameter. Tank mixing of one of several pesticides (regulaid or guthion, captan, carzol, imidan, polyram, lorsban, omite, or lannate) had no effect on NAA efficacy. Comparison of identical chemical thinning treatments (carbaryl + Accel + oil) applied to `York' and `Red Delicious' apple trees indicated that more thinning occurred with the PF treatments than at 8 mm. Average 2-day high temperatures at PF were 7.1C higher at PF for the `Red Delicious' experiment and 5.6C higher for the `York' experiment. The higher temperatures at PF could account for the differences in thinning response and not the spray timing. Pollination and fertilization inhibitors caused some fruit thinning at the highest rates and multiple applications. The MYX4801 caused more thinning and more injury to fruit than other materials. Endothall gave good thinning without fruit injury. Wilthin (GWN-6592) did cause some thinning, but fruit injury was a problem in one experiment.
Thinning and Enhanced Fruit Quality of Stone Fruits with Gibberellins
Authors: Fritts Robert , Ward Daniel L.
Published: February 2019

Release LC (Abbott Laboratories), a commercial formulation of gibberellins, was applied to apricot, cling peach, freestone peach, nectarine, and plum varieties. Application was by commercial airblast sprayer. Fruit firmness was increased in the season of application in all crops. Meta analysis of the data indicated a maximum response for each crop differed over the rate range of 16 to 48 g a.i./acre. Changes in fruit soluble solids were slight. No differences in fruit color were observed. Reduction in flower bud density (thinning) was observed the following season. The reduction in bud density reduced the time required to hand-thin to a commercially acceptable level. A difference in thinning sensitivity to gibberellin was evident between crops.
Effect of GA3 Bloom Sprays on Fruit Set and Yield of Rabbiteye Blueberry
Authors: Williamson J.G. , Darnell R.L. , Krewer G. , NeSmith S.
Published: February 2019

Field and growth chamber experiments, and grower trials, were conducted to determine the effects of GA3 sprays on yield and fruit quality of rabbiteye blueberry (Vaccinium ashei Reade) in northern Florida and southern Georgia. Multiple GA3 sprays at various stages of flower development increased fruit set and yield in field experiments (Florida) and grower trials (Georgia) when compared to controls. Nonpollinated rabbiteye flowers sprayed with GA3 had greater percent fruit set and delayed fruit development compared to hand pollination. Percent fruit set and average fruit weight were reduced at 21C night temperature when compared to 10C night temperature for both hand-pollinated and GA3-treated fruit. Overall, yields were increased by multiple applications of GA3 during bloom, but average fruit size was reduced and the fruit development period was lengthened.
Controlling Vegetative Growth and Flowering of Four Azalea Cultivars with Uniconazole and GA
Authors: Schuch Ursula K. , Biernacka Barbara
Published: February 2019

Four azalea cultivars [Rhododendron × `White Lace' (WT), `Southern Charm' (SC), `Formosa' (F), and `George Tabor' (GT)] with different growth and flowering habits were treated with a foliar spray of uniconazole (U) at 0, 10, or 15 mg·liter–1 with or without a surfactant. GA was applied at 0 or 15 mg·liter–1 as a foliar spray to half of the plants on 23 Sept. 1993, 53 days after the uniconazole application. U reduced number, length, and dry weight of bypass shoots, and increased number of flower buds for all cultivars by Dec. 1993. Application of GA after U further increased the number of flower buds on SC and GT, which otherwise had few flowers. At the final evaluation in Mar. 1994, time to anthesis for cultivars F and GT was not affected by any treatment. Anthesis of SC and WL treated with 15 mg U and GA/liter started 6 days earlier than those treated with 15 mg U/liter. Number of flowers at anthesis and number of flower buds was increased two to four times on U-treated vs. nontreated plants. U decreased plant height, size, leaf area, and shoot dry weight of all cultivars. Shoot elongation of F and GT was further reduced with the 15 vs. 10 mg U/liter treatment. Application of GA increased the retarding effects of U on plant height for WL, SC, and GT, and on leaf area and shoot dry weight for WL.
Chloroplast DNA Polymorphisms in Sweet, Sour, and Ground Cherry
Authors: Brettin Thomas S. , Iezzoni Amy F.
Published: February 2019

Sour cherry (Prunus cerasus) is an allotetraploid with sweet cherry (P. avium) and ground cherry (P. fruticosa) as the proposed progenitor species. Three cpDNA markers from eight sweet, four ground, and 26 sour cherry selections were analyzed to investigate the relatedness of their cp genomes. To date, two RFLP polymorphisms have been identified with both the P2 and P4 fragments of tomato cpDNA, while four length polymorphisms of an intergenic spacer have been identified by PCR amplification. Sweet and ground cherry have different cp polymorphisms, while sour cherry individuals have been identified that have the sweet and ground cherry polymorphisms plus a unique polymorphism. Additional individuals chosen to represent the diversity within each species will be screened to provide a more complete assessment of cp diversity. In addition, progeny from a sour cherry cross where the parents have different cp polymorphisms are being evaluated to determine if the chloroplasts are exclusively maternally inherited.
Optimization of the Colchicine Dropper Technique for Use in Vitro with Fragaria vesca
Authors: Bors Bob , Sullivan J. Alan
Published: February 2019

Previous research has optimized the colchicine dropper technique for chromosome doubling under greenhouse conditions. In recent years, in vitro germination of cut strawberry achenes has greatly increased germination rates. Combining the two techniques would be especially useful when chromosome doubling is desired for interspecific hybridization. Fragaria vesca was chosen for initial study. Treatments included colchicine levels of 0%, 1%, 2%, 3%, 4%, or 5% (w/v); exposure time to colchicine was from 6 to 16 to 26 hours; application was at the cotyledon stage or after the first true leaf formed; presence or absence of 3 g activated charcoal/liter; and presence or absence of DMSO. Media consisted of MS salts and vitamins, 30 g sucrose/liter, and 2.5 g phytogel/liter. Charcoal enhanced upward growth of seedlings, thus allowing better placement of colchicine droplets. Reduced exposure time and application at the first true-leaf stage allowed higher levels of colchicine to be used without greatly reducing the vigor of treated seedlings.
Interspecific Crossability of Fragaria vesca as a Female Parent
Authors: Bors Bob , Sullivan J. Alan
Published: February 2019

Fragaria vesca has been introgressed into F. ×ananassa in the form of decaploids and synthetic octoploids. As F. vesca is self-incompatible and crosses with most diploid Fragaria species when used as a female parent, it could serve as a bridge for introgression of additional genetic material. A primary goal of this study was to screen selections of F. vesca for interspecific crossability among diploid species. The F. vesca collection included 10 cultivars of the alpine strawberry, F. vesca var. semperflorens, as well as 30 wild runnering types gathered from around the world. The following diploid species were represented by one to three genotypes each: F. viridis, F. nubicola, F. nipponica, F. nilgerens, F. iinumae, F. daltoniana, F. gracilis, as well as two unnamed species from China. Fragaria vesca was used as the female parent and the other species provided the pollen. Crossing took place in the greenhouse, with one pollination occurring during the “popcorn” or “balloon” stage. Germination was performed in vitro using cut achenes shortly after fruit ripening. The alpine strawberry cultivars were easier to cross than wild selections of F. vesca. Their continuous blooming habit combined with higher positioning of flowers allowed for easier and perhaps less-damaging emasculation. Crossability, as measured by seed set and germination, was more variable in wild-type F. vesca and generally lower than alpine strawberry cultivars.
Nitrite Accumulation and Nitrogen Immobilization in Potting Media Containing Compost
Authors: Sanchez-Escarcega Alicia , Elliott George C.
Published: February 2019

Growth inhibition has been observed with plants grown in potting media containing compost. The objective of this study was to determine if \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{2}^{-}\) \end{document} toxicity or N immobilization might be involved. Two potting media were blended from aged pinebark, vermiculite, sphagnum peat, and compost, along with a control medium without compost, and cropped with Dendranthema ×grandiflorum `Bravo'. Pots were fertilized weekly with a 15N–1.1P–12.5K soluble fertilizer at 24 mM N. Plants were harvested and media samples were collected at intervals. Saturated media extracts (SME) were prepared immediately. Separate samples were incubated at 25C for 4 days following addition of 2.5 mmol urea-N/cm3. In SME of one compost-containing medium, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{2}^{-}\) \end{document} was present at 0.25 ± 0.03 mM 2 weeks after transplant, and at progressively lower concentrations thereafter. In incubated samples of the same medium, accumulation of \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{2}^{-}\) \end{document} was observed after 3 weeks of cropping, with peak accumulation of \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(0.7{\pm}0.32{\ }{\mu}{\ }\mathrm{mol}\mathrm{NO}_{2}^{-}{/}\mathrm{cm}^{3}\) \end{document} after 9 weeks of cropping. Nitrite was scarcely detectable in other media. Some indication of N immobilization was obtained, as NH+4levels decreased during incubation without any increase in \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}, and \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document} present at the beginning of incubation disappeared during incubation. In this study, significant effects of media on plant growth were not related to differences in \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{2}^{-}\) \end{document} accumulation or N immobilization. However, subsequent studies appear to have established such a relationship.
Use of Poultry Byproducts in a Production System for Greenhouse-grown Crops
Authors: Klingaman Gerald , Wheeler G.L.
Published: February 2019

In 1993, the Arkansas poultry industry produced 1.048 billion broilers with a total live weight of 2.54 million metric tons. Depending on the type of processing used, from 30% to 50% of live weight can end up in the waste stream. Three primary waste-stream products are generated by the poultry industry: feather meal, poultry meal, and bone meal. Feather meal contains ≈14% N, poultry meal 11% N, and bone meal 8% N. Byproduct additions were made to tomato, marigold, and impatiens transplants at the rate of 6, 12, 24 and 48 g/10-cm pot. The two highest rates killed plants outright, while the lower rates resulted in some growth reduction when compared to the control. Studies are under way to further evaluate the use of these byproducts in an organic production system for tomatoes and bedding plants.
Effect of Water-soluble Fertilizer Nitrogen Form on Root-medium pH, NH4-N, and Impatiens Tissue Nitrogen
Authors: Argo William R. , Biernbaum John A.
Published: February 2019

Impatiens were grown in media containing either hydrated or carbonate dolomitic lime and subirrigated for 17 weeks with four irrigation water qualities (IWQ) and three water-soluble fertilizers (WSF). The WSF concentration was 14N–0.6P–5K mol·m–3 but contained either 50%, 25 %, or 3 % NH4-N. After 8 weeks, rootmedium pH ranged from 4.5 to 8.0. In general, the higher the percent NH4-N content of the WSF, the lower the root-medium pH, although there were significant interactions between IWQ and lime type with WSF on root-medium pH. With the same WSF, the concentration of NH4-N measured in the root media depended on root-medium pH. For example, with WSF containing 50% NH4-N, root-medium pH with the various IWQ ranged from 4.5 to 6.0, and media NH4-N ranged from 5.0 to 0.1 mol N/m3. Tissue N concentrations were higher with the higher NH4: NO4 ratio WSF at all four sampling dates. The effect of IWQ on tissue N resulted from the root-medium pH effects produced by the various IWQ/WSF combinations. Shoot fresh and dry weights were unaffected by the NH4: NO3 ratios in the WSF.
Response of Several Grass and Legume Species to Paper Deinking Sludge
Authors: Fierro A. , Norrie J. , Gosselin A. , Beauchamp C.J.
Published: February 2019

Paper recycling generates large quantities of de-inking sludge, which is disposed of mainly by landfilling. More ecological disposal alternatives include land application and use as a container nursery medium. In this study, raw de-inking sludge was evaluated as a medium component supplemented with applications of four N fertilization regimes for the growth of three grass species (Festuca ovina duriuscula, Agropyron elongatum, Alopecurus pratensis), and four regimes of P fertilization for the growth of three Rhizobium-inoculated legumes (Medicago lupulina, Galega orientalis, Melillotus officinalis). Fertilizer was applied on the basis of sludge rate to maintain a uniform C: N ratio across sludge treatments. In one experiment, sand was mixed with 0, 10%, 20%, and 30% sludge by volume and 20% perlite, while in a second experiment, mineral soil was mixed with 0, 27%, 53%, and 80 % sludge and 20% perlite. Results indicate that shoot dry weight of all species increased with the amount of sludge in the mixture in tests with sand. In the soil mixture experiment, grasses showed the best response to treatments of 53% sludge mixture at the two highest N treatments. In general, shoot dry weight was more directly related to the total amount of N applied than to the C: N ratio of the substrate. The nutritional status (foliar N and P) also was investigated for one grass and one legume species.
Effect of Temperature on Time to Flower of Coreopsis grandiflora, Chrysanthemum superbum, Gaillardia grandiflora, and Rudbeckia fulgida
Authors: Yuan Mei , Carlson William H. , Heins Royal D. , Cameron Arthur C.
Published: February 2019

Scheduling crops to flower for specific dates requires a knowledge of the relationship between temperature and time to flower. Our objective was to determine the relationship between temperature and time to flower of four herbaceous perennials. Field-grown, bare-root Coreopsis grandiflora `Sunray', Gaillardia grandiflora `Goblin', Rudbeckia fulgida `Goldsturm', and tissue culture-propagated Chrysanthemum superbum `Snow Cap' were exposed to 5C for 10 weeks. They were grown at 15, 18, 21, 24 or 27C under 4-h night interruption lighting. Time to visible bud (VB) and first flower (FLW) were recorded. Days to VB, days to FLW, and days from VB to FLW decreased as temperature increased. Time to flower at 15C was 70, 64, 96, and 54 days and 24, 39, 48, and 36 days at 27C for Coreopsis, Gaillardia, Rudbeckia, and Chrysanthemum, respectively. The 27C temperature apparently caused devernalization on Coreopsis because only 40% of the plants flowered. The effects of temperature on flower size, flower bud number, and plant height also are presented.
Shade Levels, Wind Speed, and Wind Direction Influence Air Temperature in Mini-shadehouses
Authors: Vladimirova S. , McConnell D.B. , Bucklin R.A.
Published: February 2019

The effect of four shade levels (47%, 63%, 80%, and 91%) on air temperature was evaluated using 24 arch-shaped, open-ended shadestructures oriented with their longitudinal axis in north–south direction. The mini-shadehouses were 80 × 185 × 80 cm (width × length × height). Six replicates per treatment (shade level) were randomly assigned within the experimental plot. Light levels were measured using Sunceram solar cells. Copper-Constantan thermocouples were installed 60 cm from ground level and 20 cm from the north entrance. The experiment was initiated in July 1994 and terminated in Oct. 1994. Data from 20 consecutive days in August were analyzed. Eighty percent shade had the highest air temperature; however, the average difference between 47%, 63%, and 91% shade was less than 1C. Wind direction and speed affected air temperature with north or south winds correlated with highest temperatures. Analysis of the data shows averaged air temperatures differed by ≤1C for all shade levels. Consequently, these structures may be used for replicated research studies involving plant growth.
Graphical Tracking Leaf Count to Support Easter Lily Crop Timing Decisions
Authors: Fisher P.R. , Heins R.D.
Published: February 2019

Timing of Easter lily (Lilium longiflorum Thunb.) for sales is complex because the date of Easter and the number of leaves formed on plants before flower bud initiation vary from year to year. A process control chart was developed that uses a leaf unfolding rate model of Easter lily to control development rate towards flowering. The technique allows observed and target leaf count to be tracked on a graph and compared visually over time. The optimum leaf unfolding rate and average temperature can be read directly from the chart without the need for mathematical calculation. The approach provides an intuitive method for transferring quantitative models to growers and can be applied to other management problem areas.
Growth and Carbohydrate Metabolism of Wheat Plants Grown with Red-light Emitting Diodes
Authors: Yorio N.C. , Sanwo M. , Brown C.S.
Published: February 2019

Light-emitting diodes (LEDs) are a potential light source for growing plants in space flight systems because of their superior safety and reliability, small mass and volume, electrical efficiency, and longevity. To determine the influence of narrow-spectrum LEDs on plant growth and metabolism, wheat (Triticum aestivum L. `Superdwarf') plants were grown under red LEDs (peak emission 660 nm) and compared to plants grown under daylight fluorescent, red LEDs + 1% blue fluorescent light (BL), and red LEDs + 10% BL. Plants were taller, had longer flag leaves, and delayed seed development when grown under red LEDs or red LEDs + 1% BL compared to those grown with 10% BL or under daylight fluorescent. Viable seeds (290% germination) were produced in all plants regardless of the light treatment. Total dry matter (DM), head DM, and seed DM were similar in the plants grown under the four light regimes, and there were no differences in the starch content of the seeds. Starch levels were 4-times greater and sucrose levels were 2.5-times greater in leaves of plants grown under the red LEDs compared to daylight fluorescent. Daylight fluorescent leaves showed a 1.8-fold increase in sucrose phosphate synthase (SPS) activity, a regulatory enzyme of sucrose synthesis. These results indicate that wheat can be grown successfully under red LEDs, but there are differences in carbohydrate concentration and metabolism in photosynthetic tissue.
Soil Temperature Influences the Response of Lettuce to Phosphorus
Authors: Gardner B.R. , Sanchez C.A.
Published: February 2019

Lettuce is planted in the southwestern U.S. desert from September through December and harvested from November through April each year. During this period mean soil temperatures range from 7 to 30C. Lettuce produced on desert soils shows a large yield response to P. Soil solution P is replenished by desorption from the labile soil P fraction and this process is temperature sensitive. A field study was conducted over 6 years to evaluate the response of lettuce to soil solution P levels under different ambient soil temperature regimes. The soil temperatures under which lettuce was grown were varied each year by altering planting dates. Soil solution P levels were established and maintained each season using P sorption isotherm methodology. Lettuce responded to P in all experiments. Phosphorus levels required for maximum yield varied with each experiment. Soil P levels required for optimal yield were best correlated to mean soil temperatures during the last 20 days before harvest. Lettuce accumulates over 70% of its P during the heading stage of development and it is likely that during this period of rapid growth and nutrient uptake, solution P becomes limiting when soil temperatures are cool.
Photosynthesis in Leaves, Fruits, Stem, and Petioles of Tomato Plants Grown in Peat Bags with Different Fertigation Management
Authors: Xu Hui-lian , Gauthier Laurent , Gosselin André
Published: February 2019

Tomato plants were grown in peat bags in greenhouse to examine the effects of variation of the nutrient solution electrical conductivity (EC) and substrate water potential (Ψsub) on photosynthesis in leaves, fruits, stem, and petioles. EC of the nutrient solution delivered to peat bags varied between 1 to 4 dS·m–1 with Ψsub of either –5 kPa or –9 kPa as the setpoint for starting the irrigation. The EC variation was adjusted by a computer system according to potential evapotranspiration. Gross photosynthetic capacity (PC) decreased as the leaf age developed. PC in the 10th, 15th and 18th leaves from the top was only 76%, 37%, and 18% of PC in the 5th leaf, respectively. However, low quantum use efficiency (QUE) was only observed in the 18th leaf and low dark respiration (RD) was only in 15th and 18th leaves. Net photosynthesis (PN) was only observed in young fruits (≈10 g FW) or young petioles and no PN was observed in large fruits (50 g or more FW) and stems. Both PC and RD were lower in older fruits and petioles or in the lower part of the stem compared to the younger ones or upper parts. EC variation increased PC, QUE, and RD in most parts. Low Ψsub increased RD in most parts and decreased PC in fruits, stem, and petioles. It is suggested that EC variation increased plant physiological activity of tomato and low Ψsub increased carbon consumption, although it was not severe enough to depress leaf PC.
Growth Performance of Potted Poinsettia in Crab Waste Compost
Authors: Ku Catherine S.M. , Bouwkamp John C. , Gouin Frank R.
Published: February 2019

Maryland Chesapeake Bay crab industry generates ≈20 tons of crab waste annually. The crab waste compost (CWC) was a mixture of crab chum and saw dust that had an initial EC of ≈26 dS·m–1. In Fall 1994, soft-pinched single stem `Annette Hegg Red' poinsettias (Euphorbia pulcherrima) in 15-cm azalea pots were grown in media containing Sunshine mix, 1 CWC: S base mix (BM), 1 CWC: 2 BM,. 1 CWC: 1 BM, or 2 CWC: 1 BM. Base mix is a 1 peat: 1 perlite (v/v). Fertigation treatment with 266 mg·liter–1 N from 30N–4.4P–8.8K was began on the 1st, 2nd, or 3rd week after potting. The total fertigations ranged from 8 to 10 for the 13-week study. With Sunshine mix, shoot height and canopy diameter were ≈15% greater than with 16% CWC mix and were ≈27% greater than with 67% CWC mix. There was a ≈10% decreased in the shoot height and canopy diameter with increasing %CWC in mix from 17% to 67%, but there was no difference in number of branches among the CWC mixes.
Maintaining Impatiens Seed Quality
Authors: Cross David , Styer Roger
Published: February 2019

Impatiens (Impatiens wallerana Hook.f.) flower seeds are believed to be sensitive to storage temperature and humidity conditions. A study was conducted to evaluate seed quality changes occurring during a 1-year period of storage under various temperature and humidity combinations. Four seed lots of `Super Elfin Red' and `Super Elfin White' impatiens were studied. Constant humidity treatments were obtained using saturated salt solutions; 15% relative humidity (RH) with LiCI, 25% RH with KAc, 33% RH with MgCl2, and 43% RH with K2CO3. Constant temperature treatments were 5, 15, and 22C. At 3-month intervals, replicate samples were sown in plug flats in the greenhouse. Seed quality was evaluated as the percentage of usable seedlings 21 days from sowing. Rapid deterioration of seed quality was seen under high temperature and high humidity storage conditions. Seeds became less sensitive to humidity at 5C. Conditions of 20% to 25% RH and 5C are recommended for impatiens seed storage.