bluuebunny/crossref_metadata_2025 huggingface dataset:
Sweet Corn Crop Nitrogen Status Evaluation by Stalk Testing
Authors: Heckman Joseph R. , Samulis Ray , Nitzsche Peter
Published: February 2019

Sweet corn (Zea mays L.) growers evaluating new practices for N management, such as the presidedress soil nitrate test (PSNT), are interested in relating observations about crop performance at time of harvest to their N fertility program. For this purpose, the concentration of nitrogen (N) in the lower portion of sweet corn stalks was examined on the day of harvest as a basis for evaluating the crop N status. Sweet corn stalk tissue was collected from N-rate experiments by cutting a stalk section at 15 and 35 cm aboveground and removing leaf material from the resulting 20-cm segment. Samples were dried and analyzed for total Kjeldahl N. Relationships between crop yield and stalk N concentration indicated that concentrations <11 g·kg-1 are N deficient and underfertilized; N concentrations between 11 and 16.5 g·kg-1 are marginally deficient; and between 16.5 and 21 g·kg-1 the N status is optimum. Concentrations of N >21 g·kg-1 are above optimum and indicate that sweet corn was overfertilized with N. When soil nitrate concentrations (PSNT >25 mg NO3-N per kilogram) indicated sufficient N at time of sidedressing, stalk N concentrations generally indicated N sufficiency at harvest.
Grafting Fraser Fir onto Rootstocks of Selected Abies Species
Authors: Hinesley Eric , Frampton John
Published: February 2019

Orthotropic shoots (tips of primary axes) from 3-year-old Fraser fir seedlings [Abies fraseri (Pursh) Poir.] were grafted onto rootstocks of Fraser fir, Korean fir (A. koreana Wils.), momi fir (A. firma Sieb. & Zucc.), Nordmann fir (A. nordmanniana (Steven) Spach.), Turkish fir (A. bornmuelleriana Mattf.), and West Virginia balsam fir from Canaan Valley (Canaan fir) [A. balsamea (L.) Mill. var. phanerolepis Fern.]. Firstyear survival in the greenhouse was 92% to 98% except for momi fir (83%). The percentage of grafted plants with orthotropic shoots was 92% to 98%, except for Korean (81%) and momi fir (86%). Plants were subsequently established in replicated field experiments on three sites in the piedmont and mountains of North Carolina. In general, leader elongation of grafted Fraser fir scions was greater than leader growth on nongrafted transplants, including Fraser fir. Differences in survival appear to reflect interspecific variation in resistance to phytophthora root rot and/or tolerance of warm environments. Grafting may offer the potential to grow Abies Christmas trees on previously unsuitable sites, or to reclaim or continue using sites already seriously impacted by root rot.
A Two-step Pretreatment Significantly Enhances Shoot Organogenesis from Leaf Explants of Highbush Blueberry cv. Bluecrop
Authors: Cao Xiaoling , Hammerschlag Freddi A. , Douglass Larry
Published: February 2019

As part of a program to improve highbush blueberry (Vaccinium corymbosum L.) cultivars via tissue culture and genetic engineering, studies were conducted to determine optimum conditions for organogenesis from leaf explants of the previously recalcitrant cv. Bluecrop. The effects of a pretreatment, growth regulators, and age of explant source on shoot organogenesis were investigated. A maximum of 98% explants regenerated shoots with a mean of 11 shoots per leaf explant after 62 days when explants of 2-week-old shoot cultures were incubated on the following regime: pretreatment medium #1 containing 5 μm TDZ and 2.6 μm NAA for 4 days, pretreatment medium #2 containing 7 μm zeatin riboside and 2.6 μm NAA for 3 days, regeneration medium containing 1 μm TDZ for 6 weeks, and last on medium without growth regulators for 10 days. No shoot regeneration occurred if explants were incubated without exposure to pretreatment prior to incubation on regeneration medium. There were no significant differences in percentage of regeneration or the number of shoots regenerating per explant from leaf explants derived from either 1-, 2-, or 3-week-old shoot cultures. Shoot production per explant on regeneration medium containing 1 μm TDZ was about three times that on 0.5 μm TDZ or 20 μm zeatin riboside, and nine times that on 5 μm TDZ. Chemical names used: 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea (thidiazuron, TDZ); 9-(β-D-ribofuranosyl)-6-(4-hydroxy-3-methyl-but-2-enylamino)purine (zeatin riboside).
Assays to Assess Freeze Injury of Satsuma Mandarin
Authors: Nesbitt Monte L. , Ebel Robert C. , Findley Douglas , Wilkins Bryan , Woods Floyd , Himelrick David
Published: February 2019

Containerized `Owari' satsuma mandarin (Citrus unshiu Marc.) on Poncirus trifoliata `Flying Dragon' rootstock were exposed to one of two acclimation regimes (cold acclimated and unacclimated) and frozen in a computer-controlled freezer to five different low temperatures. Whole plant survival was measured and compared to the results of four leaf and stem injury assays. Acclimating plants in growth chambers at 20 °C day and 10 °C night for 14 days, followed by 15 °C day and 4 °C night for 14 to 21 days resulted in an 81% and 80% increase in leaf and stem survival, respectively, when frozen to a low of -8 °C. Electrolyte leakage and phenolic leakage assays effectively detected changes in percent leaf survival, but the TTC stain assay, using leaf disks, did not. Stem survival was best predicted by the TTC assay, using the phloem as the indicator tissue for survival. Electrolyte leakage and phenolic leakage were also reliable assays for predicting stem survival, although survival percentages were different at the same electrolyte leakage values reported in other studies. The callus growth assay accurately predicted survival for cold acclimated satsuma mandarin stems only. Chemical name used: triphenyl tetrazolium chloride (TTC).
Creeping Bentgrass Physiological Responses to Natural Plant Growth Regulators and Iron Under Two Regimes
Authors: Zhang Xunzhong , Schmidt R.E. , Ervin E.H. , Doak S.
Published: February 2019

Creeping bentgrass (Agrostis palustris Huds.) is an extensively used cool-season grass for fine turf areas such as golf course putting greens, but suffers from poor summer stress tolerance. These studies were conducted to investigate the influences of natural plant growth regulators (NPGR) and Fe on creeping bentgrass photochemical activity (PA), antioxidant superoxide dismutase (SOD) activity, root growth and leaf color under two fertilization regimes. The bentgrass was maintained in well-watered field conditions or water-stressed glasshouse conditions. A mature bentgrass was treated monthly during the field season with seaweed (Ascophyllum nodosum Jol.) extract (SWE) at 50 mg·m-2 or humic acid (HA) at 150 mg·m-2 or in combination with or without FeSO4 at 520 mg·m-2 and grown under a low or a high fertilization regime. Foliar application of SWE + Fe increased PA (14% to 15%), while applications of SWE + HA or SWE + HA + Fe increased SOD activity (49% to 114%) of creeping bentgrass in Summer 1997 and Summer 1998. There was no significant fertilization × NPGR interaction for PA and SOD activity. Bentgrass PA was increased by 13% to 46% when treated with NPGR with or without Fe compared to the control measured in May. The addition of Fe with each NPGR application improved fall and winter leaf color. All NPGR and Fe treatments increased root mass (17% to 29%) in Aug. 1997 and 1998, except HA alone in 1998. Under sustained low soil moisture (-0.5 MPa) conditions, application of NPGR with or without Fe increased PA and SOD activity. The data indicate that SWE and HA enhance the physiological function of `Southshore' creeping bentgrass, resulting in improved root growth regardless of low or high fertilization regime. However, addition of Fe to these NPGR served primarily to improve late season leaf color. The results suggest that, in addition to maintaining adequate plant-available nutrients, applications of natural PGRs, such as SWE and HA, prior to and during summer abiotic stresses would be beneficial.
Diquat Used as a Preharvest Desiccant Affects Seed Germination of Spinach, Table Beet, and Coriander
Authors: Miller Timothy W.
Published: February 2019

Diquat was tested to determine its suitability for use as a preharvest desiccant of selected vegetable seed crops during 1997 and 1998. In separate studies, diquat was applied at 0,0.56, or 1.12 kg·ha-1 ai. to spinach (Spinacia oleracea L.), table beet (Beta vulgaris L.), and coriander (Coriandrum sativum L.) plants at usual swathing time. Except for beet seed in 1998, there was no clear trend toward reduced seed weight with increasing diquat rate. Spinach seed germination in 1998 and coriander seed germination in 1997 were reduced by diquat at 1.12 kg·ha-1 compared to seed from nontreated plants or plants treated with 0.56 kg·ha-1. In all crops, diquat at 0.56 kg·ha-1 was adequate for crop desiccation purposes. However, seed producers should consider the potential benefits from chemical desiccation that may potentially lower germination of the harvested seed. Chemical name used: 6,7-dihydrodipyrido[1,2-α:2′,1′-c]pyrazinediium ion (diquat).
Soil Flooding and Fumigant Alternatives to Methyl Bromide in Tomato and Eggplant Production
Authors: Nelson S.D. , Locascio S.J. , Allen L.H. , Dickson D.W. , Mitchell D.J.
Published: February 2019

Methyl bromide (MeBr) is an important and effective soil fumigant commonly used to control weeds and soilborne pests. Because MeBr has been implicated as a contributor to the depletion of stratospheric ozone, it is scheduled for phaseout by 2005. This study examined nonchemical and chemical practices as alternatives to MeBr. Off-season flooding followed by a series of soil preplant chemical treatments [MeBr with 33% Pic; 1,3-D mixed with 17% (C-17) and 35% (C-35) Pic combined with Peb; and metam-Na combined with 1,3-D and Peb were evaluated on spring tomato (Lycopersicon esculentum Mill.) and eggplant (Solanum melongena) production in northern Florida. Pest control and tomato and eggplant yields were not significantly different between the flooded and non-flooded control plots. The most effective alternatives to MeBr were 1,3-D and Pic mixtures (C-17 and C-35) combined with Peb. Tomato and eggplant yields for these chemicals were statistically equivalent to that of MeBr. Tomato, but not eggplant, yield and nematode control were poor with metam-Na combined with 1,3-D and Peb in comparison to the other fumigant combinations. Chemical names used: 1,3-dichloropropene (1,3-D); trichloronitromethane [chloropicrin (Pic)]; S-propyl butyl(ethyl)thiocarbamate [pebulate (Peb)]; sodium N-methyldithiocarbamate (metam-sodium (metam-Na)].
Horticultural and Pathological Aspects of Fusarium Wilt Management Using Grafted Melons
Authors: Cohen R. , Horev C. , Burger Y. , Shriber S. , Hershenhorn J. , Katan J. , Edelstein M.
Published: February 2019

The effect of Cucurbita and melon rootstocks on the horticultural and pathological performance of grafted Fusarium-susceptible melons was studied in four field experiments conducted in Fusarium-infested and Fusarium-free soils. The melon/melon combinations performed better than the melon/Cucurbita combinations regarding yield and disease control. In the 1999 experiment conducted in infested soil, Fusarium wilt symptoms were observed only in the nongrafted susceptible melons whereas all grafted combinations were symptom-free. In the 2000 experiment, nongrafted susceptible melons were totally wilted, whereas disease incidence in the melon/melon combinations and in one of the melon/Cucurbita combinations was low. The response of grafted plants to Fusarium wilt was also affected by the susceptibility of the scion. Among nongrafted melon cv. Ananas Ein Dor and those grafted onto Brava rootstock, 82% and 20%, were diseased, respectively, compared with only 36% and 0%, of the nongrafted and grafted `Ofir' melons, respectively. Negligible quantities of fruit were harvested from the nongrafted plants grown in infested soil, whereas high and moderate yields were obtained from melons grafted onto melon and Cucurbita rootstocks, respectively. The yield of the nongrafted melons in Fusarium-free soils were similar to those of all the grafted plant combinations. Susceptible melon scions grafted onto resistant melon rootstocks were less colonized by F. oxysporum f. sp. melonis than the same melons grafted onto the Cucurbita rootstocks.
High Carbon Dioxide Atmospheres Affect Stored 'Thompson Seedless' Table Grapes
Authors: Crisosto Carlos H. , Garner David , Crisosto Gayle
Published: February 2019

Efficacy of controlled atmosphere (CA) conditions for decay control in 'Thompson Seedless' table grapes was evaluated during the 1998-2000 seasons. During the 1998 season, early (16.5% soluble solids concentration = SSC) and late harvested (19% SSC) grapes were exposed to 5%, 10%, 15%, 20%, or 25% CO2 combined with 3%, 6%, and 12% O2. In 1999 and 2000, 10% or 15% CO2 combined with 3%, 6%, or 12% O2 were used. In all trials, fruit were initially SO2 fumigated and air-stored grapes were used as controls. Storage atmospheres did not affect SSC, titratable acidity (TA), or sugar-to-acid ratio (SSC: TA). The main storage limitations for early harvested 'Thompson Seedless' table grapes were “off flavor” and rachis and berry browning development, which resulted from exposure to >10% CO2. However, ≥15% CO2 was needed to control total decay and nesting development independent of O2 concentrations. High carbon dioxide atmospheres (15% to 25%) were more effective in decay control without detrimental effects on quality when late harvested grapes were used. The combination of 15% CO2 with 3%, 6%, or 12% O2 is suggested for up to 3 months storage only for late harvested 'Thompson Seedless' table grapes; it should not be used for early harvested grapes.
Development of PCR-based Fingerprinting Tool in Banana (Musa sp., AAA) and Conversion of Negative to Positive DNA Marker
Authors: Umali Reynato P. , Kameya Nanako , Nakamura Ikuo
Published: February 2019

The banana (Musa sp., AAA) genome is continuously expanding due to the high frequency of somaclonal variation. Because of this increasing diversity, numerical and morphological methods of taxonomic and phylogenetic identification of banana cultivars became laborious, difficult, and often the subject of disagreements. The aim of this study, therefore, is to develop molecular tools for DNA fingerprinting that can discriminate Musa, AAA Cavendish subgroup cultivars. In this paper, we showed that the plastid-subtype identity (PS-ID) sequence of the noncoding region between rpl16 and rpl14 genes of plastid DNA was highly conserved except for single-base substitution and deletion. These differences separated the clones into three groups (G1, G2, and G3) and suggested that clones within groups are closely related maternally. Using arbitrary primer A13, we later identified negative RAPD markers A133.0 and A131.3 specifically for S4 (selection from Giant Cavendish subgroup, AAA) and S11 (`Morado' from `Red' and `Green Red' subgroup, AAA), respectively. Fragments corresponding to the missing bands were sequenced and used as templates to design new primers with overlapping sequences. Two of these primers, Ba3.0A and Ba1.3A, successfully generated positive markers consistently amplified as Ba3.0A0.8 and Ba1.3A0.6 for S4 and S11, respectively. It is proposed that the method just described can be a better alternative over screening more arbitrary primers in generating positive markers in cases when negative ones were already identified. Results of PS-ID subtype analysis likewise suggested potential use in identifying wild maternal progenitor in polyploid bananas.
Composition and Characteristics of Blended Kentucky Bluegrass Stands
Authors: Lickfeldt Darin W. , Voigt Thomas B. , Hamblin Andrew M.
Published: February 2019

Kentucky bluegrass (Poa pratensis L.) cultivars are often blended to incorporate diverse characteristics. Factors that may contribute to the actual cultivar composition have not been evaluated. Through the use of DNA markers, individual plants in blended stands can be identified. This study evaluated changes in cultivar composition of `Blacksburg', `Midnight', and `Unique' Kentucky bluegrass blends. Characteristics such as seed size, seed moisture content, percent germination, and seedling development did not affect the initial composition of blends at time of seeding. DNA markers were used to demonstrate how the composition of a blended `Blacksburg', `Midnight', and `Unique' turf changed during the first growing season following establishment. The composition of blends did not significantly change from time of seeding in Sept. 1999 to Apr. 2000 or from Apr. 2000 to Oct. 2000. Two of the three blends were significantly different by Oct. 2000 relative to the percentages seeded in Sept. 1999.
Enhanced Seed Germination and Seedling Growth of Tillandsia Eizii In Vitro
Authors: Pickens Kimberly A. , Affolter James M. , Wetzstein Hazel Y. , Wolf Jan H.D.
Published: February 2019

Tillandsia eizii is an epiphytic bromeliad that due to over-collection, habitat destruction, and physiological constraints has declined to near threatened status. This species exhibits high mortality in the wild, and seed are characterized by low percentages of germination. As a means to conserve this species, in vitro culture protocols were developed to enhance seed germination and seedling growth. A sterilization protocol using 70% ethanol for 2 minutes followed by 2.6% NaOCl for 40 minutes disinfested seed and promoted seedling growth. Sucrose incorporated into the culture medium had no effect on germination or growth, while NAA inhibited growth, but not germination. Cultures maintained under a 16-hour photoperiod at 22 °C exhibited greater growth than those grown at 30 °C. Seed that germinated in the dark remained etiolated and failed to develop even after transfer to light conditions. Plants grown in vitro were successfully acclimatized and transferred to the greenhouse. Over 86% survival and rapid growth were obtained with either an all-pine-bark medium, or a mixture of 2 redwood bark: 2 fir bark: 2 potting mix: 1 perlite. This demonstrated that in vitro culture of seed may be used to rapidly produce large numbers of T. eizii, and thus can be used for the conservation and reintroduction of this species.
Approaches to Analyzing Experiments with Factorial Arrangements of Treatments Plus Other Treatments
Authors: Marini Richard P.
Published: February 2019

Experiments with factorial arrangements of treatments plus one or more other treatment(s) are sometimes analyzed with a one-way analysis of variance (ANOVA) and means are separated with a multiple comparison. A set of single degree-of-freedom contrasts in a one-way ANOVA, provides formal tests for main effects and interactions. Data from a 2 × 3 factorial experiment that also contained a control were analyzed with a one-way ANOVA with a multiple comparison. Results from this analysis were compared to results obtained from a two-way ANOVA, a one-way ANOVA with pre-planned contrasts, a two-way ANOVA with least squares means comparisons obtained with SAS/general linear models procedure, and a regression model with an indicator variable and random blocks obtained with SAS/Mixed procedure. Results and interpretation differed depending on how the data were analyzed and these differences are discussed.
Growth Comparisons Between Open-pollinated Progeny of Sugar Maple Grown Under Shade and in Full Sunlight
Authors: Clark S.L. , Schlarbaum S.E.
Published: February 2019

Progeny from two open-pollinated mother trees were grown for 1 year in a commercial tree nursery in Murphy, N.C. Shade cloths were applied to one half of the seed plots from each mother tree and the other half were exposed to full sunlight. Seedlings were fertilized throughout the growing season to increase growth performance for better discernment of progeny and shade effects. Seedlings in shaded plots were significantly taller and had larger root collar diameters (RCD) than unshaded seedlings. An interaction between progeny and shade effects on first-order lateral root number indicates that genetic or other unknown factors were affecting the seedlings' response to changes in light. Results indicate that the use of shade cloths in nurseries may improve seedling quality of 1-0 sugar maple in the southern portion of the species range.
Differential Effects of Lower Day and Night Soil Temperatures on Shoot and Root Growth of Creeping Bentgrass
Authors: Xu Qingzhang , Huang Bingru , Wang Zhaolong
Published: February 2019

Turf quality of creeping bentgrass (Agrotis palustris L.) often declines during summer months. Reducing soil temperature alleviates bentgrass quality decline at supraoptimal air temperatures. The objective of this study was to investigate whether reducing soil temperature during the night is more effective than during the day in improving shoot and root growth when air temperature was supraoptimal for creeping bentgrass. The experiment was conducted in growth chambers using water baths to manipulate soil temperatures. Plants were exposed to the following temperature treatments: 1) optimal air and soil temperature during the day and night (20/20 °C, day/night, control); 2) high air and soil temperature during the day and night (35/35 °C, day/night); 3) lower soil temperatures during the day (20/35, 25/35, and 30/35 °C, day/night); and 4) lower soil temperature during the night (35/20, 35/25, and 35/30 °C) while air temperature was maintained at 35 °C during the day and night. Turf quality (on 1-9 scale) increased to the level of 6.5, 3.0, and 2.5 by reducing day soil temperature to 20, 25, or 30 °C, respectively, at 28 days of treatment, compared to the quality of 2.0 at 35/35 °C. Turf quality increased from 2.0 at 35/35 °C to 7.0, 6.0, and 4.5, respectively, by 28 days of exposure to night temperatures of 20, 25, and 30 °C. Chlorophyll content, root number, and root weight also were increased by reducing day or night soil temperature, and the increases were more pronounced for reduced night temperatures than day temperatures. These results demonstrated that reduced night soil temperature was more effective than reduced day soil temperature in improving shoot and root growth in creeping bentgrass under high air temperature conditions.
Yields of Bell Pepper, Sweet Corn, and Peanut in Rotations
Authors: Russo Vincent M.
Published: February 2019

Abiotic and biotic factors, and government farm policy, affect peanut (Arachis hypogaea L.) production especially in the Southern Plains of the United States. A coincident increase in vegetable production has led to interest in diversification of production on land that has historically supported peanut. A multi-year experiment was conducted from 1998 to 2001 to determine how rotating bell pepper (Capsicum annuum var. annuum L.) and sweet corn (Zea mays L.) with peanut affect yields of all three crops. In the first year, the site was planted to peanut, except for those areas of the field that would have monocultured bell pepper or sweet corn throughout the experiment. In following years, parts of the field that were planted with peanut were planted with either peanut, bell pepper, or sweet corn. Except for the monocultured crops, plots had 2 years of peanut and one year each of bell pepper or sweet corn in one of four rotations. Yields were determined and terminal market value was assigned to crops. Cumulative yields for monocultured bell pepper and sweet corn were 27.8 and 22.8 Mg·ha-1 after 4 years. The best yield of bell pepper or sweet corn in any rotation was 15.3 or 11.3 Mg·ha-1, respectively. Rotation did not affect peanuts, and cumulative yields for monocultured peanut were 8.39 Mg·ha-1 and averaged 2.13 Mg·ha-1 per year in rotations. Cumulative yields for all crops in rotations where vegetables were planted in the last 2 years averaged 21.5 Mg·ha-1 as opposed to 13.8 Mg·ha-1 when vegetables were planted in the middle 2 years of a 4-year rotation. Yields of all crops were modified by environmental conditions, and terminal market price affected crop value so that high yields were not always associated with high returns.
Densely Planted Okra for Destructive Harvest: III. Effects of Nitrogen Nutrition
Authors: Kahn Brian A. , Wu Yaying , Maness Niels O. , Solie John B. , Whitney Richard W.
Published: February 2019

Research was conducted to develop a cultural system that would permit a destructive mechanical okra [Abelmoschus esculentus (L.) Moench] harvest. Okra grown at a highly dense (HD) plant population of 25 × 23 cm and destructively harvested by machine was compared with control plants spaced at 90 × 23 cm and repeatedly and non-destructively harvested by hand. The control N fertilization regime was 45 kg·ha-1 of N preplant, followed by one or two topdressings, each with 22 kg·ha-1 of N. Treatments applied to HD plots were designed to be multiples of the control N fertilization levels. Preplant fertilizer was added such that the sum of residual soil N plus the added fertilizer would total to 45, 90, or 135 kg·ha-1 of N for the standard, intermediate, and highest rates, respectively. Topdressing rates were 22, 44, or 66 kg·ha-1 of N for standard, intermediate, and highest, respectively. Topdressing was timed to follow a mechanical harvest of the HD plots. Since there was only one mechanical harvest in the two 1995 studies, topdress N treatments did not affect yields from mechanical harvest in that year. Nitrogen treatments had few effects on fruit yield per hectare of HD okra, even when stem N concentrations equaled or exceeded those of control plants. The highest N rate tended to delay fruit production. Increasing N rates did not affect the marketable fruit yield obtained by mechanical harvest of HD plants expressed as a percentage of the total cumulative marketable fruit yield from control plants. Physiological factors appear to be limiting the potential for densely planted okra in a destructive mechanical harvest system rather than horticultural factors such as N nutrition.
Stability of Expression and Concentration of Ascorbic Acid in North American Potato Germplasm
Authors: Love Stephen L. , Salaiz Thomas , Shafii Bahman , Price William J. , Mosley Alvin R. , Thornton Robert E.
Published: February 2019

Ascorbic acid (vitamin C) is an essential nutrient in the human diet and potatoes are a valuable source. As a first step in breeding for potatoes (Solanum tuberosum L.) with higher levels of ascorbic acid, 75 clones from 12 North American potato-breeding programs were evaluated for concentration, and 10 of those for stability of expression. Trials were grown in Idaho, Oregon, and Washington in 1999 and 2000, tubers sampled, and ascorbic acid quantified. There were significant differences among clones and clone by environment interaction was also significant. Concentration of ascorbic acid of the clones was continuously distributed over a range of 11.5 to 29.8 mg/100 g. A subgroup of 10 clones was analyzed using an additive main effects and multiplicative interaction (AMMI) model, to diagnose interaction patterns and measure clone stability. The first two principal component axes accounted for over 80% of the variability. Bi-plot analysis showed `Ranger Russet' to be highly unstable across the environments tested. A plot of Tai's stability statistics found six of the 10 clones to be stable for ascorbic acid expression. Appropriate evaluation methods for ascorbic acid concentration must involve multi-year testing.
Field Growth and Yield of Tomato Transplants Grown in the Float System Using Low Phosphorus Fertilizer and Height Restricting Cultural Practices
Authors: Rideout James W.
Published: February 2019

The float system is an efficient method of seedling production. This system requires use of cultural practices to prevent excessive stem elongation of tomato (Lycopersicon esculentum Mill.) seedlings. It is not known how these practices affect field growth and subsequent fruit yield and quality. Experiments were conducted in 2001 and 2002 to determine if restricting P supply, delaying fertilizer application, brushing, clipping, and ethephon application affect field performance of transplants. Transplants subjected to these cultural treatments in the float system were compared to transplants conventionally grown in the greenhouse. In 2001, there was little difference in field performance among transplants produced under the range of cultural conditions. Although differences in total fruit numbers or yields were nonsignificant in 2002, conventionally grown transplants produced higher early yields. Seedlings grown with low P fertilizer and receiving delayed fertilization or delayed fertilization plus brushing performed best of all float treatments in 2002. Ethephon application severely reduced early yield while increasing late-season yield. Production of tomato seedlings with low P in float systems is feasible, at least on a small scale for transplanting locally, when delayed fertilization or delayed fertilization plus brushing treatments are used to control seedling height.
Performance of `Oroblanco' and `Melogold' Pummelo × Grapefruit Hybrids on Nine Rootstocks on a Calcareous, Poorly Drained Soil
Authors: Stover Ed , Pelosi Robert , Burton Michael , Ciliento Scott , Ritenour Mark
Published: February 2019

Adjacent but separate trials of `Oroblanco' and `Melogold', both triploid pummelo [Citrus grandis (L.) Osbeck] × grapefruit (Citrus paradisi Macf.) hybrids, were established on nine rootstocks in the Indian River citrus region of Florida in 1993. The trees on the citrandarin rootstock ×639 [Cleopatra mandarin (C. reticulata Blanco) × trifoliate orange (Poncirus trifoliata L.)] were significantly more productive than trees on any other rootstock tested for `Oroblanco' and all rootstocks except Swingle citrumelo (C. paradisi × P. trifoliata) and Cleopatra mandarin for `Melogold'. Cumulative production of `Oroblanco' on ×639, through year 9, was 50% higher than for Swingle or Volkamer lemon [C. limon (L.)], which were the next highest in yield. `Melogold' displayed extremely low yield, with 45% of trees producing fewer than 50 fruit total in the 9 years of this study. Carrizo citrange (C. sinensis Osbeck × P. trifoliata) produced the smallest trees with both scion varieties, reflecting poor adaptation of this rootstock to the calcareous soil at the trial site. As expected, acidity of `Oroblanco' and `Melogold' was much lower than would be observed for grapefruit when fall harvested, with similar total soluble solids (TSS), and much higher TSS: titratable acidity ratio. Some rootstock effects on internal quality were observed.
Salts Deposited on the Lower Stem of Bell Pepper Contribute to a Basal Stem Disorder in Soilless, Greenhouse-grown Plants
Authors: Jovicich Elio , Cantliffe Daniel J.
Published: February 2019

A physiological disorder in greenhouse-grown pepper (Capsicum annuum L.) plants was observed in Florida, wherein the base of the main stem becomes swollen below the cotyledonary node level and crack-like wounds develop at the base of the stem's epidermis. The disorder may predispose the plant to a localized rot and result in a sudden plant wilt. The effects of soilless media type, transplant depth, and amount of nutrient solution applied per day were studied to evaluate the development of what was termed “Elephant's Foot” disorder, on a greenhouse-grown bell pepper crop in Gainesville, Fla. The percentage of plants with epidermal wounds at the base of the stem was highest (83%) on plants transplanted at half of the cell height (3.8 cm), compared to plants transplanted to the cotyledonary node level (6%) and the second leaf node (0%). Salts were washed from the surface of basal stem epidermis and electrical conductivity measured in the washing solution was expressed per unit area of epidermal sample (ECA). The ECA in the solutions from plants transplanted at half of the cell height was higher than that from plants transplanted to the cotyledonary node level and to the second leaf node. There was a positive linear relationship (r = 0.81) between the percentage of plants with epidermal wounds and the ECA of the solution obtained from washing the epidermal tissues. Salts deposited on the epidermis beneath the cotyledonary node provoked a tissue injury that may predispose the plant to a Fusarium infection. Simple management practices, such as transplanting deep, using cultivars with lower susceptibility to salt damage, and gradually moving back the emitter from the base of the plant after transplanting (to reduce humid conditions near the base of the stem) would help reduce the appearance of this basal stem disorder in soilless-grown peppers.
Growth and Nutrient Status of Six Species of Nursery Stock Grown in a Compost-based Medium with Recycled Nutrients
Authors: Chong Calvin , Lumis Glen , Purvis Peter , Dale Adam
Published: February 2019

Rooted cuttings of `Antonovka' apple, `Lynwood Gold' forsythia, double-flowered kerria, common ninebark, `Goldfinger' potentilla, and `Red Prince' weigela were grown in 2-gal (6-L) nursery containers filled with 1:1 (by volume) of waste compost and composted pine bark, under three fertilizer regimes: 1) liquid nutrients [target concentrations in ppm (mg.L-1): NH4-N, 13; NO3-N, 100; P, 28; K, 120; Ca, 92; Mg, 13; Fe, 1.3; Mn, 0.27; Zn, 0.23; Cu, 0.05; B, 0.22; Mo, 0.05; Na, <50; Cl, <50; and SO4 <300] delivered and recycled twice per day via a computer-controlled multifertilizer injector; 2) same nutrient formula and concentration rate delivered fresh via the injector but without recycling; and 3) Nutryon (Polyon) 17-5-12 controlled-release fertilizer incorporated into the medium at a rate of 11 lb/yd3 (6.5 kg·m-3). With recycled liquid nutrients, all species grew the same or more than with nonrecycled nutrients, and generally the poorest growth was with controlled-release fertilizer. Foliar concentrations of K (all species), N (all species), P (forsythia, kerria, potentilla, and weigela), and Mn (forsythia, potentilla, and weigela) were higher in plants supplied with recycled and/or nonrecycled nutrients than in those supplied with controlled-release fertilizer, while foliar concentrations of Ca (ninebark and kerria) and Mg (apple, kerria, ninebark, potentilla, and weigela) were lower. Compared to nonrecycled liquid nutrients, the amounts of individual recycled nutrients were reduced by (percentage in brackets): NH4-N (30), NO3-N (78), P (76), K (46), Ca (93), Mg (96), Fe (52), Mn (43), Zn (55), Cu (60), B (83), and Mo (66).
Improving In Vitro Plant Regeneration from Leaf and Petiole Explants of `Marion' Blackberry
Authors: Meng Rengong , Chen Tony H.H. , Finn Chad E. , Li Yonghai
Published: February 2019

Experiments focusing on plant growth regulators' concentrations and combinations, mineral salt formulations, and TDZ pretreatment formations were conducted to optimize in vitro shoot regeneration from leaf and petiole explants of `Marion' blackberry. Optimum shoot formation was obtained when stock plants were incubated in TDZ pretreatment medium for 3 weeks before culturing leaf explants on regeneration medium (Woody Plant Medium with 5 μm BA and 0.5 μm IBA) in darkness for 1 week before transfer to light photoperiod (16-hour photoperiod at photosynthetic photon flux of ≈50 μmol·m-2·s-1) at 23 °C ± 2 °C for 4 weeks. Under these conditions, ≈70% of leaf explants formed ≈40 shoots per petri dish that could be harvested and rooted to form plantlets. Chemical names used: N6-benzyladenine (BA); 2,4-dichlorophenoxyacetic acid (2,4-D); gibberellic acid (GA3); indole-3-acetic acid (IAA); indole-3-butyric acid (IBA); α-naphthaleneacetic acid (NAA); N-phenyl-N'-1,2,3-thidiazol-5-ylurea [thidiazuron (TDZ)].
New Intergeneric Somatic Hybrids Combining Amblycarpa Mandarin with Six Trifoliate/Trifoliate Hybrid Selections for Lime Rootstock Improvement
Authors: Medina-Urrutia Victor , Fabiola Karla , Madera Lopez , Serrano Patricia , Ananthakrishnan G. , Grosser Jude W. , Guo Wenwu
Published: February 2019

No presently available rootstock combines all the available rootstock attributes necessary for efficient long-term citriculture (production and harvesting) of Mexican limes and other commercially important scions. In the present study, somatic hybridization techniques were used to combine the widely adapted Amblycarpa mandarin (also known as Nasnaran mandarin) with six different trifoliate/trifoliate hybrid selections: Benton, Carrizo, and C-35 citranges; Flying Dragon and Rubidoux trifoliate oranges; and a somatic hybrid of sour orange + Flying Dragon. The ultimate goal of this research is to generate polyploid somatic hybrids that express the complementary horticultural and disease resistance attributes of the corresponding parents, and have direct potential as improved tree-size controlling rootstocks. Somatic hybrids from all six parental combinations were confirmed by a combination of leaf morphology, flow cytometry, and randomly amplified polymorphic DNA (RAPD) (for nuclear hybridity) and cleaved amplified polymorphic sequence (CAPS) analyses (for mtDNA and cpDNA). This is the first report of citrus somatic hybridization using Amblycarpa mandarin. Unexpected hexaploid somatic hybrid plants were recovered from the fusion of Amblycarpa mandarin + C-35 citrange. Hexaploid hybrids should be very dwarfing and may have potential for producing potted ornamental citrus. Resulting somatic hybrid plants from all six combinations have been propagated by tissue culture and/or rooted cuttings and are being prepared for commercial field evaluation for their potential as improved rootstocks for Mexican lime and other important scions.
Varying Density with Constant Rectangularity: I. Effects on Apple Tree Growth and Light Interception in Three Training Systems over Ten Years
Authors: Hampson Cheryl R. , Quamme Harvey A. , Kappel Frank , Brownlee Robert T.
Published: February 2019

The effect of increasing planting density at constant rectangularity on the vegetative growth and light interception of apple [Malus ×sylvestris (L) var. domestica (Borkh.) Mansf.] trees in three training systems (slender spindle, tall spindle, and Geneva Y trellis) was assessed for 10 years. Five tree densities (from 1125 to 3226 trees/ha) and two cultivars (Royal Gala and Summerland McIntosh) were tested in a fully guarded split-split plot design. Planting density was the most influential factor. As tree density increased, tree size decreased, and leaf area index and light interception increased. A planting density between 1800 and 2200 trees/ha (depending on training system) was needed to achieve at least 50% light interception under the conditions of this trial. Training system altered tree height and canopy diameter, but not total scion weight. Training system began to influence light interception in the sixth leaf, when the Y trellis system intercepted more light than either spindle form. Trees trained to the Y trellis tended to have more spurs and a lower proportion of total leaf area in shoot leaves than the other two systems. The slender and tall spindles were similar in most aspects of performance. Tall spindles did not intercept more light than slender spindles. `Royal Gala' and `Summerland McIntosh' trees intercepted about the same amount of light. `Royal Gala' had greater spur leaf area per tree than `Summerland McIntosh', but the cultivars were similar in shoot leaf area per tree and spur density.
Varying Density with Constant Rectangularity: II. Effects on Apple Tree Yield, Fruit Size, and Fruit Color Development in Three Training Systems over Ten Years
Authors: Hampson Cheryl R. , Quamme Harvey A. , Kappel Frank , Brownlee Robert T.
Published: February 2019

The effect of increasing planting density at constant rectangularity on the fruit yield, fruit size, and fruit color of apple [Malus ×sylvestris (L) var. domestica (Borkh.) Mansf.] in three training systems (slender spindle, tall spindle, and Geneva Y trellis) was assessed for 10 years. Five tree densities (from 1125 to 3226 trees/ha) and two cultivars (Royal Gala and Summerland McIntosh) were tested in a fully guarded split-split plot design. Density was the most influential factor. As tree density increased, per-tree yield decreased, but yield per unit area increased. The relation between cumulative yield per ha and tree density was linear at the outset of the trial, but soon became curvilinear, as incremental yield diminished with increasing tree density. The chief advantage of high density planting was a large increase in early fruit yield. In later years, reductions in cumulative yield efficiency, and in fruit color for `Summerland McIntosh', began to appear at the highest density. Training system had no influence on productivity for the first 5 years. During the second half of the trial, fruit yield per tree was greater for the Y trellis than for either spindle form at lower densities but not at higher densities. The slender and tall spindles were similar in nearly all aspects of performance, including yield. `Summerland McIntosh' yielded almost 40% less than `Royal Gala' and seemed more sensitive to the adverse effects of high tree density on fruit color.
Package Atmosphere Affects Postharvest Biology and Quality of Fresh-cut Cilantro Leaves
Authors: Luo Yaguang , McEvoy James L. , Wachtel Marian R. , Kim Ji Gang , Huang Yun
Published: February 2019

Experiments were conducted to develop a modified atmosphere packaging system for fresh-cut cilantro (Coriandrum sativum L.) leaves, and to determine the effect of package film oxygen transmission rate (OTR) on package atmosphere and the consequence on quality and microbiology of the product. Package film OTR significantly (P < 0.001) influenced the package atmospheres and the resultant postharvest physiology and quality of fresh-cut cilantro leaves under the tested package configuration (bag size 19 × 22 cm, product fill weight 85 g/bag) and storage condition (0 °C). Oxygen and carbon dioxide levels of the packages prepared with 3500 mL·d-1·m-2 OTR films equilibrated at 1.5 to 2.3 kPa and 3.6 to 4.1 kPa, respectively, on day 3 and maintained this level throughout the storage. The gas compositions of the packages with 6200 mL·d-1·m-2 OTR films showed a similar trend, except they equilibrated at a higher O2 (3.6 to 5.6 kPa) and lower CO2 (2.7 to 3.3 kPa) level. Fresh-cut cilantro leaves in both packages exhibited the highest tissue integrity as evidenced by the lowest tissue electrolyte leakage, with high overall visual quality scores (like moderately to like very much) at the end of 14 days storage. However, atmospheres in 1700 mL·d-1·m-2 OTR film packages displayed a rapid depletion of O2 and accumulation of CO2, with essentially no O2 (≈0.02 kPa) and high CO2 (7.7 to 9.0 kPa) levels inside the packages from day 6 until the end of storage. A rapid increase in tissue electrolyte leakage was observed in cilantro leaves in these packages starting on day 6, increasing 6-fold at the end of the storage period. Products in these packages developed a strong off-odor, accompanied by a rapid loss of typical aroma and overall visual quality, with an unacceptable quality rating at the end of storage (dislike slightly). Samples packaged in perforated bags (without modified atmosphere) lost moisture over time, and small numbers of wilted leaves were seen. There was a slow but significant (P < 0.001) increase in aerobic organisms over time with no significant (P > 0.05) difference among treatments. There was an increase in anaerobic microorganisms on cilantro leaves packaged in 1700 mL·d-1·m-2 OTR film, although only ≈0.5 log cfu/g difference was observed among the treatments and over time.
Influence of Fall-applied Treatments on Spring Transition of an Overseeded Bermudagrass Green
Authors: Green Robert L. , Klein Grant J. , Merino Francisco , Gibeault Victor
Published: February 2019

Bermudagrass [Cynodon dactylon (L.) Pers × C. transvaalensis Burtt-Davy] greens across the southern United States are normally overseeded in the fall to provide a uniform green playing surface and tolerance to wear during winter bermudagrass dormancy. The spring transition from overseed grass back to bermudagrass is a major problem associated with overseeding because there can be a decline in putting green quality and playability. There have been recommendations, but relatively few published reports, on the effect of treatments associated with seedbed preparation and overseeding on bermudagrass spring transition. The objective of this 2-year study was to determine if spring transition of an overseeded `Tifgreen' bermudagrass green was influenced by fall-applied scalping level, chemical, and seed rate treatments. Treatment factors and levels were designed to reflect the range of practices used by golf course superintendents in the region at the time of the study. The green was located in the Palm Springs, Calif. area, which has relatively mild winters and a low desert, southern Calif. climate. The first year of the study was from September 1996 to July 1997 and the second year was from September1997 to July 1998. Scalping level treatments included a moderate and severe verticut and scalp; chemical treatments included a check, trinexapac-ethyl at two rates, and diquat; and seed rate treatments included a high and low rate of a mixture of `Seville' perennial ryegrass (Lolium perenne L.) and `Sabre' rough bluegrass (Poa trivialis L.). The plot was maintained under golf course conditions and a traffic simulator was used to simulate golfer traffic. Visual ratings of percent green bermudagrass coverage were taken every 3 weeks from 20 Feb. 1997 to 29 July 1997 and from 11 Nov. 1997 to 22 July 1998. Visual turfgrass quality ratings were taken during the second year of the study. Results showed that spring transition was not influenced by fall-applied treatments during both years. Also, visual turfgrass quality was not influenced during the second year. Chemical names used [4(cyclopropyl-_hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl); 9,10-dihydro-8a-, 10a-diazoniaphenanthrene (diquat).
Productivity and Quality of Green Snap Beans Varieties Under Desertic Conditions in Northwestern Mexico
Authors: Grijalva-Contreras* Raul Leonel , Liñeiro-Celaya Eduardo , Araiza-Celaya Gerardo , Salvador-Rivas Victor , Lopez-Vilchez Francisco
Published: February 2019

The agricultural activity in Caborca, Sonora, depends on fruit trees and vegetable production, and the main crops are grapes, olive, and asparagus. However, is necessary to evaluate other vegetables. An alternative is the green snap beans production. This vegetable can be harvested during the last week of November, when, good prices aare available in the market. The objective of this experiment was to evaluate seven green snap beans varieties with round pod. The experiment was on 24 Aug. The density used was 20 seeds per meter (about 60 kg·ha-1). The experiment was carried out during 2001 with commercial growers. The date of sow was distance between beds was 2.0 m and we used two rows with 36 cm of separation. In our experiment, we used a drip irrigation system. The first harvest was 67 days after the date sowing and it was for 28 days with seven cuttings. The varieties with more yield were Festina, Mercury, and Castaño with 771, 632 and 558 boxes/ha, (30 pounds/box), respectively. The control variety (Savannah) yielded only 345 boxes/ha. The pod quality distribution was 26%, 32%, 50%, and 15% for classification 1, 2, 3, and no commercial value respectively. The Savannah variety was the best pod color (dark green) and more yield during the last cutting. None of the varieties evaluated had problems of pest and diseases.