bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Nodulin Genes are Not Markers of the Capacity of Woody Legumes to Nodulate
Authors: Foster Carol M. , Rosin Faye M. , Schrader James A. , Graves William R.
Published: February 2019

Knowing whether trees can develop nodules in which nitrogen is fixed is important for managing inputs during culture. Early nodulin genes, such as ENOD2 and ENOD12, could function as molecular markers for the capacity to nodulate if they are conserved only in species that nodulate. Several nodulating species are known to possess these genes; but, their occurrence has not been studied among non-nodulating taxa, including Cercis canadensis L. (redbud), Gleditsia triacanthos L. var. inermis Willd. (honey locust), and Gymnocladus dioica (L.) C. Koch (Kentucky coffee tree). Our objective was to determine the relationship between the capacity to nodulate and the occurrence of putative ENOD2 or ENOD12 genes by probing the genomes of these non-nodulating species and the genomes of two legumes that nodulate, Albizia julibrissin Durazz. (silk tree) and Laburnum alpinum (Mill.) Bercht. & J. Presl (Scotch laburnum). ENOD2 and ENOD12 cDNA clones from Glycine max (L.) Merill (soybean) and Pisum sativum L. (pea), respectively, and cloned ENOD2 PCR fragments from Maackia amurensis Rupr. & Maxim. (Amur maackia) and Styphnolobium japonicum (L.) Schott (Japanese pagodatree) were used as probes for Southern hybridizations. Sequences from genomes of silk tree, Scotch laburnum, honey locust, and Kentucky coffee tree hybridized to ENOD2 probes on Southern blots. Putative ENOD12 sequences were detected in the genomes of Scotch laburnum, redbud, and honey locust. Thus, we conclude that ENOD2 and ENOD12 can not be used as markers for the capacity to nodulate.
Pollination Mechanisms of Ebenus cretica
Authors: Lydaki M.E. , Vlahos J.C.
Published: February 2019

Ebenus cretica L., is an endemic plant of Crete with potential as a cut flower or flowering potted plant. It is a herbaceous perennial evergreen subshrub that flowers from April to June. It forms numerous thick racemes with an average of 50 pink or purple flowers 10 to 12 mm long. A great variability in major morphological characteristics exists among the populations of E. cretica on the island; however, color variants are very rare. Selection and breeding is a necessary prerequisite before the plant is marketable; therefore, research conducted at the TEI of Heraklion since 1994 has focused on artificial self- and cross-pollination of pink-flowered ebenus plants. It has been concluded that the zygomorphic flowers of E. cretica are pollinated by insects (bumblebees); the tripping mechanism occurs and seeds are formed by either cross- or self-pollination. For self-pollination, unripe flower racemes were enveloped in paper bags and shaken by hand or wind to release pollen; however, this method gave poor results. Best results were obtained by tripping the flowers while avoiding the introduction of foreign pollen. Self-incopatibility was not observed. Cross-pollination was achieved by emasculating flowers on the female parent, 2 to 4 days prior to the dehiscence of the anthers. The corolla is half-white and half-pink at this stage, turning to a uniform pink when the pollen is ripe. The stigma appears to be fully receptive at least 2 days before the dehiscence of the anthers. Each fertilized ovule gives one mature seed ≈3 weeks after pollination. This research indicates that breeding techniques can be applied without difficulty to E. cretica in order to develop uniform plant material and new varieties/hybrids with desirable characteristic.
Cytokinin and Auxin Sprays Affect the Incidence of Poinsettia Bract Necrosis
Authors: McAvoy R.J. , Bible B.B.
Published: February 2019

In 1996, `Supjibi red' poinsettias were sprayed at initial anthesis with the cytokinin benzyladenine (BA) (10 or 100 ppm), or with the cytokinin analogs CPPU or thidiazuron (1 or 10 ppm), or with Accel (10 or 100 ppm BA)—a 10:1 mixture of BA and gibberellin. A spray of thidiazuron at 1 or 10 ppm, Accel at 10 or 100 ppm, or BA at 100 ppm suppressed the incidence of necrosis relative to untreated plants. However, cytokinin treatments tended to induce the expansion of young bracts and fading of bract color. In a separate 1996 study, plants were sprayed with 100 ppm BA at 2-week intervals between visible bud and initial anthesis; and in 1997, 20 ppm of the auxin indole-3-butyric acid (IBA) was applied at similar intervals. The later in bract development that BA was applied, the lower the incidence of necrosis observed at 6 weeks after anthesis. In contrast to BA treatment effects, necrosis was highest with late IBA applications (when observed 3 weeks after anthesis). Late sprays of IBA induced bract epinasty. A 1:1 mixture of BA plus IBA applied at initial anthesis at 25 or 50 ppm BA, suppressed bract necrosis without causing adverse side effects.
Measurement and Calculation of Total Plant Water Use of Citrus
Authors: Mills T. , Morgan K. , Parsons L. , Wheaton A.
Published: February 2019

This preliminary study serves to parameterize a modified Penman–Monteith equation for young citrus trees. Two-year-old citrus trees (`Hamlin' grafted on Carrizo citrange) were planted individually into 1500-L (1.5-m-diameter) plastic pots in late Oct. 1997. Pots were placed upon industrial scales with a maximum weight capacity of 2270 ± 0.05 kg. Continuous weight measurements were made every minute and average half-hourly values recorded. An automated weather station was located within 10 m of the pots and half hourly values of temperature, humidity, wind speed, rainfall, and net radiation were recorded. Meteorological data, coupled with diurnal measurements of stomatal conductance taken periodically throughout the experimental period and leaf area for each tree allow calcuatiion of total plant water use using a modified Penman–Monteith equation. These calculation may be cross-checked using weight change measurements. Such model parameterization for citrus will aid irrigation management of citrus in the field as it provides a link between the physiological and meteorological aspects which drive plant water use.
Calculation of Genetic Correlation Coefficients Based on Off-spring–Parent Relationships Using a Spreadsheet
Authors: Yao Qiang , Mehlenbacher Shawn A.
Published: February 2019

Genetic correlation coefficients can be used to compare efficiency of direct and indirect selection, estimate correlated response to selection and set up index selection. Information on quantitative traits in parent and offspring can be used to estimate genetic correlation coefficients for fruit and nut crops. However, existing statistical packages do not allow easy calculation of genetic correlation coefficients. In this paper, we demonstrate the use of a spreadsheet to quickly estimate genetic correlation coefficients using data on parents and progeny in the OSU hazelnut breeding program. This procedure can be extended to n traits and m crosses.
Influence of Light on Fruit Set of French Hybrid Grapes
Authors: Ferree D.C. , McArtney S.J. , Scurlock D.M.
Published: February 2019

Four French–American hybrid grape cultivars grown in a greenhouse were subjected to 5 days of 80% shade at four different times around bloom. Fruit set of `Seyval' was reduced by shade imposed before, during, or immediately after bloom. `Vidal' and `Chambourcin' were less sensitive, with fruit set reduced only by shade at bloom. Shade had little effect on fruit set of `DeChaunac'. In a second study, `Chambourcin' vines were exposed to ambient, ambient plus supplemental lights, and 30%, 50%, or 80% shade for 5 weeks beginning just prior to bloom. Fruit set was positively related to light intensity. At harvest, soluble solids, pH, and hue angle had a negative linear relationship to light level. Fruit color developed earliest and most rapidly with the reduced light treatments applied at bloom. Cluster weight was positively related to light intensity.
Bloom Thinning of Peaches with Gibberellic Acid in the Southeast
Authors: Parker Michael L.
Published: February 2019

Thinning peach fruit in the spring of the year is one of the most labor- and capital-intensive operations for peach growers in the southeast. In addition, fruit size can be negatively affected if peach thinning is delayed. The objective of this study was to evaluate the application of gibberellic acid (4% GA3, Ralex—Abbott Labs) in June to reduce peach bloom the following spring. Ralex was applied in June 1995 and 1996 to `Contender' peaches. Bloom density was evaluated in Spring 1996 and 1997 from long and short shoots from the higher and lower portions of the tree's canopy. Applications in 1995 were to trees with a crop load while applications in 1996 were to trees without a crop due to a spring freeze. Bloom densities in 1997 were 300% greater than bloom densities in 1996. The five rates of material evaluated were 0, 59, 79, 99, and 119 g/ha. In 1996, bloom density was significantly reduced with Ralex applications with the greatest reduction with the 99 and 119 g/ha application rates. However, in 1997 only slight differences were detected between all treatments with no difference between the control and 79-g/ha rate.
Control of Dormancy and Budbreak in Sweet Cherry (Prunus avium L.) cv `Bing' with Surfactant + Calcium Ammonium Nitrate and Hydrogen Cyanamide
Authors: Weis K.G. , Southwick S.M. , Yeager J.T. , Rupert M.E. , Coates W.W.
Published: February 2019

Continuing trials (1995–present) advanced budbreak and flowering with a surfactant and calcium ammonium nitrate (CAN17), and in 1997, hydrogen cyanamide (HCN). Chilling in 1996–1997 was marginal in San Joaquin County (SJ, 830 chill hours, 18 Feb.), and low in San Benito County (SB, 612 chill hours, 21 Feb.). When we used the “45 °F” chilling model, the most effective surfactant + nitrate treatment timings for both locations were similar by chill accumulation (≈72 % to 82% of required chilling for `Bing' = 850–880 chill hours), although the two locations differed in total chill accumulation and date of effective treatment. Full bloom (FB) was advanced by 1 week with 4% HCN in SJ, followed by 2% surfactant + 25% calcium ammonium nitrate applied on 21 Jan. (700 chill hours), compared to the untreated control. Bloom duration (full bloom to petal fall) was compressed most by surfactant and CAN17. Bloom in SB was also most advanced by HCN, followed by 2% surfactant + 25% CAN17 applied on 21 Feb. (612 chill hours). Fruit set was improved in SB by surfactant and CAN17 in mid-February; set was too low, however, for real impact. In SJ and SB, HCN advanced fruit maturity most, followed by surfactant and CAN17 applied 21 Jan.; these fruits were softer. We believe that, in order for treatments to be effective in advancing budbreak and full bloom, some minimum amount of chilling must be accumulated prior to application (perhaps 60% to 75% of chilling requirement). We have also determined that where chilling is well below minimum requirement, higher rates of CAN (25%) are necessary to advance bloom. A further advantage of using Armobreak + CAN is improved N level in buds and bark after treatment (1997).
Identification of Molecular Markers Linked to Tomato Mottle Virus Resistance Genes
Authors: Griffiths P.D. , Scott J.W.
Published: February 2019

Tomato mottle virus (ToMoV) is a whitefly transmitted geminivirus threatening the Florida fresh-market tomato (Lycopersicon esculentum Mill.) industry. ToMoV resistance was identified in Lycopersicon chilense accessions LA 1932, LA 1938, LA 1969, and LA 2779, and introgressed into tomato breeding lines. Inheritance studies of populations derived from resistant accessions of LA 1932 and LA 1938 suggest that introgressed resistance is largely additive and multigenic. RAPD polymorphisms were identified using 800 arbitrary primers (decamers), and 88 polymorphisms with good repeatability were identified. Of these, 45 polymorphisms were identified in breeding lines derived from two or more of the four accessions. Analysis of segregating F2 populations has resulted in association of RAPD markers with geminivirus resistance genes, and markers have been identified that are common to different L. chilense resistance sources. Linkage of several markers to each other and to the self pruning (sp) and β-carotene (B) loci on chromosome 6 was also determined.
Influence of Nitrogen and Potassium on Three Zoysiagrasses
Authors: McCrimmon James N.
Published: February 2019

Zoysiagrass has great potential for use in the Gulf Coast states as a turfgrass. There has been minimal research on the nitrogen (N) and potassium (K) fertility response of zoysiagrass and the effect on turf color, quality, and nutrient content. The objective of this study was to evaluate the effects of N and K fertility on zoysiagrass. A study was conducted on three zoysiagrasses: Zoysia japonica × Z. tenuifolia Willd. ex Trin. (`Emerald'); Z. japonica Steud. (`Meyer'); and Z. matrella. The N and K treatment combinations consisted of high (H) and low (L) rates of N and K at the following levels: N levels of 454 and 227 g N/92.9 m2 per month and K levels of 454 and 227 g N/92.9 m2 per month. The treatment combinations were (N and K): HH, HL, LH, and LL and were applied in two split applications monthly from July through November. The study was a randomized complete-block design with three replications. All plots received two applications of a micronutrient fertilizer (late June and August), were irrigated as needed, and maintained at a height of 3.8 cm. Color, density, texture, uniformity, and quality were determined visually for each month. Plant tissue samples were collected (September) and analyzed for macronutrient and micronutrient contents. There were significant differences for color, density, and quality in the following months: September (color and density); October (quality); and November (color and quality). There were differences in leaf texture for all months. There were significant differences for N, magnesium (Mg), and K contents but there were no differences for any micronutrient. This study indicated that all three zoysiagrasses provided acceptable color and quality during the summer and fall, and that N and K rates affected N, K, and Mg contents in the plant.
Affect of Pre-plant Amendment, Mulch, and Nitrogen Level on Mature Highbush Blueberry Root Growth and Mycorrhizal Infection Intensity
Authors: Goulart Barbara L. , Demchak Kathleen , Yang W.Q.
Published: February 2019

The affect of pre-plant rotted sawdust amendment (with and without), mulch (with and without), and nitrogen level (four levels, ranging from 0 to 160 g/plant) were evaluated for their affects on highbush blueberry root and mycorrhizal infection intensity in a field study that was instigated in 1992 at the Russell E. Larson Agricultural Research Center in Rock Springs, Pa. Over the years, mycorrhizal infection intensity was affected interactively by these treatments, however in general, it was negatively correlated with nitrogen level, mulch, and pre-plant amendment. Plants were excavated in Oct. 1998, and it was found that fine feeder roots constituted a much higher percentage of total root mass in unmulched plants, as well in high nitrogen plants, however there was an interaction between nitrogen level and mulching, such that non-mulched high N plants had a higher proportion of feeder roots. Total root mass was unaffected by mulch and pre-plant amendment; however it was increased by nitrogen. Root systems were also sampled for mycorrhizal infection intensity from different locations on the root system and are currently being analyzed.
Transfer of Plum Pox Virus Coat Protein Genes from a Plum Pox-resistant Transgenic Clone of Prunus domestica Plum to Its Progeny through Hybridization
Authors: Scorza Ralph , Levy Laurene , Damsteegt Vern , Callahan Ann , Webb Kevin , Ravelonandro Michel
Published: February 2019

Sharka or plum pox virus (PPV) is a major disease of stone fruit and causes severe economic losses in Europe. There is little resistance to PPV in most Prunus species, thus genetic engineering represents a potentially useful approach to obtain resistant germplasm. Transgenic plums containing the PPV coat protein (CP) or the related papaya ringspot virus (PRV)-CP gene were produced through Agrobacterium tumefaciens-mediated transformation. These transgenic plum clones were then evaluated for resistance to PPV infection in the greenhouse by graft or aphid inoculation with PPV. While symptoms of PPV appeared in most transgenic clones, all plants of PPV-CP transgenic clone C5 were symptomless and ELISA and immunocapture-reverse transcriptase PCR negative for over three years following inoculation with two strains of PPV (Ravelonandro et al., Plant Dis. 81:1231-1235, 1997). Clone C5, which contains multiple copies of the PPV-CP gene, was hybridized with PRV-CP transgenic plants or untransformed plum cultivars. Progeny were obtained containing no transgenes, only the PPV-CP, only the PRV-CP, or both the PRV-CP and PPV-CP transgenes. Seedlings were inoculated with PPV. At 5 and 11 months post-inoculation, seedlings containing the PPV-CP genes from C5 were symptomless and ELISA negative. Seedlings containing only PRV-CP transgenes or non-transformed controls showed symptoms of PPV infection and were ELISA positive. These results indicate that the PPV-CP transgenes can be transferred to progeny through hybridization and that these genes can impart resistance to PPV in transgenic seedlings. The inheritance of the multicopy inserts of the PPV-CP and PRV-CP transgenes is being analyzed. The combined effects of both transgenes on resistance to PPV and the stability of PPV resistance in the progeny of the resistant C5 transgenic line are currently under evaluation.
Zantedeschia aethiopica and Z. `Green Goddess' Responses to GA3 and Bonzi for Cut Flower Calla Lily Production in Florida
Authors: Reiser Ramona A.
Published: February 2019

Zantedeschia aethiopica, the large white calla lily, and Z. `Green Goddess', which is white with a unique green blush on the lip, are two cultivars popular in the floral cut flower trade. Both were treated with gibberellic acid (GA3) for increased flower development, a technique routinely successful for potted calla production but not previously reported effective on cut flowers. Two winter trials in successive years were replicated under Florida growing conditions. A preplant bulb dip of GA3 ranged from 100 to 250 ppm. Z. aethiopica control plants averaged 1.3 flowers per plant, which increased to 3.4 with GA3 in the first trial and from 1.6 to 2.5 in the second trial. `Green Goddess' went from 1.3 to 3.8 flowers per plant and 0.9 to 3.3, respectively. Bonzi was applied at either a short (10.2–12.7 cm) or tall (30.5–38.1 cm) height, with greater effect when shorter. A drench application of 2 mg a.i. per pot shortened foliage more than flower height with 32% reduction on foliage and 12% on flowers for Z. aethiopica and 44% and 33% respectively on `Green Goddess'. Results favor use of GA3 on cut flowers for increased flower production, but discourage Bonzi because shortened heights are normally undesirable for cut flowers.
Effects of Irridiance Levels during Flasking and Greenhouse Production on Growth and Flowering of the Phalaenopsis Orchid
Authors: Konow Elise A. , Wang Yin-Tung
Published: February 2019

Four-month-old, aseptically raised Phalaenopsis Atien Kaala `TSC 22' seedlings 1.0 cm in leaf spread were transferred (Nov. 1995) 25 per polycarbonate box to an agar medium and placed under 10, 20, 40, or 80 mol·–2·s–1 PPF from cool-white fluorescent tubes. In June 1996, plants grown under 40 or 80 mol·–2·s–1 PPF had greater mass, wider leaves, and more roots than those under the two lower PPF. Plants were then transplanted and grown in a greenhouse (GH) under 340, 170, or 85 mol·–2·s–1maximum PPF. In May 1997, plants previously produced under 40 mol·–2·s–1 PPF had longer, wider, and thicker leaves than those under 10 mol·–2·s–1 PPF when grown under the two higher GH PPF. Under the low GH PPF, however, plants were equally small, regardless of the previous flasking PPF levels. Plants under the high, medium, and low GH PPF had an average of 61, 37, and 17 g of fresh mass, respectively. By September 1997, plants had increasingly larger leaves and higher concentrations of malic acid, sugars, and starch as GH PPF increased. Each doubling in GH PPF resulted in more than a two-fold increase in plant fresh mass. Under the low GH PPF, plants previously produced under 80 mol·–2·s–1 PPF during flasking were 13% larger than those under 10 mol·–2·s–1 PPF. Plants grown under the high, medium, and low GH PPF had 100%, 79%, and 0% flowering, respectively. Those under the high GH PPF bloomed earlier and had longer inflorescences, bearing many more and larger flowers, than those under the medium GH PPF.
Phenological Aspects of Strawberry Growth Influencing Gray Mold Development in Annual Systems
Authors: Carver L.M. Butler , Fernandez G.E. , Louws F.J.
Published: February 2019

Strawberry (Fragaria xananassa) plant phenology was evaluated at two sites in North Carolina in order to assess the relationship of plant growth and the development of gray mold fruit rot (Botrytis cinerea). Site 1 consisted of three cultivars: Camarosa (CA), Chandler (CH), and Sweet Charlie (SC) from a single nursery; site 2 consisted of cultivar CH obtained from three distinct sources. Weekly records were kept of leaf senescence, leaf emergence, flowering, and fruit set, as well as a monthly whole-plant analysis. Leaf senescence and emergence was uniform for all treatments, with >90% of transplant foliage senescing between November and December. Analysis of leaf area and plant weights reveal an increase in dry mass beginning in February and continuing through April. Although first bloom appeared in December, primary floral development occurred in late February for cultivar SC and in March for cultivars CA and CH, with blooms continuing through late May. Marketable yield was lower in cultivar SC throughout harvest, with the exception of early fruit development in March. Non-marketable yield varied, with increases in gray mold following periods of heavy rainfall. Statistical analysis of all data shows no consistent differences in plant growth or disease among treatments. Analysis of foliage revealed latent infections on transplants as the primary source of gray mold inoculum. Patterns of plant growth and corresponding disease development found in this study provide tools necessary for phenology-based control practices for the integrated management of gray mold.
Effects of Drought and Post-drought Recovery on Katsura Tree
Authors: Dosmann Michael S. , Iles Jeffery K.
Published: February 2019

Katsura tree (Cercidiphyllum japonicum Sieb. & Zucc.) is appreciated because of its stately form and brilliant autumnal leaf color. One problem of the species, however, is its reputed intolerance to drought. While data either refuting or substantiating this claim are lacking, anecdotal references abound. To understand this issue better, a study was designed to measure the effect of drought and post-drought relief on growth and development of katsura. Two-year-old trees were container-grown in a greenhouse and subjected to one of three irrigation treatments (comprised of four irrigation phases) that simulated either drought or conditions where moisture was not limiting. In treatment one (control), plants in each phase were irrigated daily with the amount of water lost the previous 24 h. Plants in the second treatment experienced an initial drought phase (irrigation withheld until soil moisture content decreased to a predetermined level) followed by three non-drought phases. In the third treatment, plants were subjected to two drought phases, each followed by a non-drought phase. Destructive harvests were performed at the beginning of the study and at the conclusion of each phase. Due to abscission, trees subjected to one and two drought phases underwent a 38% and 63% reduction in lamina mass, respectively. Stem diameter in trees exposed to both drought phases was 16% less than that of controls. Net assimilation rates of trees within each treatment indicate that plants recovering from drought may be more efficient as assimilating systems than controls. Based upon our results, we find that katsura is a drought avoider, responding to drought by defoliating. Refoliation once water is available does occur and may lend itself to recovery.
Prohexadione-Ca—A New Plant Growth Regulator for Apple with Interesting Biochemical Features
Authors: Rademacher W. , Speakman J.B. , Evans R.R. , Evans J.R. , Roemmelt S. , Michalek S. , Lux-Endrich A. , Treutter D. , Iturriagagoitia-Bueno T. , John P.
Published: February 2019

Prohexadione-Ca is currently developed as an inhibitor of excessive vegetative growth in apple. In addition to the control of shoot growth, distinct effects on the incidence of fireblight are observed that are not due to any bactericidal effect of the compound. Further, the compound often causes a delay of senescence. It is known that prohexadione-Ca acts as a structural mimic of 2-oxoglutarate thereby inhibiting dioxygenases, which catalyze distinct steps in gibberellin (GA) biosynthesis. As a result, levels of growth-active GAs are lowered and, hence, longitudinal shoot growth is reduced. Prohexadione-Ca also induces changes in flavonoid metabolism, which may also be related to the inhibition of dioxygenases involved in this pathway. Preliminary evidence is available that this effect is related to a lowered susceptibility of apple tissue towards infection with fireblight. ACC oxidase, another dioxygenase, which catalyzes the conversion of aminocyclopropane-carboxylic acid into ethylene, is also affected by prohexadione-Ca and related compounds. Lowered levels of ethylene may account for a delay of senescence.
Light Absorption and Partitioning in Response to Nitrogen in Apple Leaves
Authors: Cheng Lailiang , Fuchigami Leslie H. , Breen Patrick J.
Published: February 2019

Bench-grafted Fuji/M26 apple trees were fertigated with different concentrations of nitrogen by using a modified Hoagland solution for 6 weeks, resulting in a range of leaf N from 1.0 to 4.3 g·m–2. Over this range, leaf absorptance increased curvilinearly from 75% to 92.5%. Under high light conditions (1500 (mol·m–2·s–1), the amount of absorbed light in excess of that required to saturate CO2 assimilation decreased with increasing leaf N. Chlorophyll fluorescence measurements revealed that the maximum photosystem II (PSII) efficiency of dark-adapted leaves was relatively constant over the leaf N range except for a slight drop at the lower end. As leaf N increased, non-photochemical quenching under high light declined and there was a corresponding increase in the efficiency with which the absorbed photons were delivered to open PSII centers. Photochemical quenching coefficient decreased significantly at the lower end of the leaf N range. Actual PSII efficiency increased curvilinearly with increasing leaf N, and was highly correlated with light-saturated CO2 assimilation. The fraction of absorbed light potentially used for free radical formation was estimated to be about 10% regardless of the leaf N status. It was concluded that increased thermal dissipation protected leaves from photo-oxidation as leaf N declined.
Molecular Marker Linked to High Solanine/Chaconin (Nil/Low Leptin) in Solanum chacoense, and Implications for Leptine Biosynthesis
Authors: Ronning C.M. , Stommel J.R. , Sanford L.L. , Kowalski S.P.
Published: February 2019

Solanum chacoense, a wild relative of the cultivated potato, contains several glycoalkaloids, including solanine, chaconine, and leptine. The foliar-specific leptine glycoalkaloids are believed to confer resistance to the Colorado Potato Beetle (CPB). Data from segregating F1 populations developed from crosses of high × nil and high × high leptine producers were consistent with control of leptine production by a single recessive gene; however, data from subsequent generations strongly suggests the presence of additional factors affecting the inheritance and expression of leptine glycoalkaloids in this population of S. chacoense. Using two bulked DNA samples composed of high- and low-percent leptine individuals from a segregating F1 population of S. chacoense, a 1500-bp RAPD product, UBC370-1500, was identified that is closely linked to high percent solanine+chaconine, and conversely to low percent leptine. This marker mapped to the end of the short arm of potato chromosome 1, near the location of a previously mapped major QTL for solanidine. The observed distribution of the UBC370-1500 marker, in conjunction with these QTL data, suggest that hydroxylation of a common precursor to form leptinidine occurs prior to formation of the solanidine aglycone. Implications of these findings for the development of CPB-resistant potato varieties will be discussed.
Effect of Red Polyethylene Mulch on Yield of Fresh-market Tomatoes
Authors: Olson Stephen M.
Published: February 2019

Trials were conducted during the spring production seasons of 1995 and 1996 comparing tomato (Lycoperisicon esculentum Mill.) Production on red polyethylene mulch with black (standard) polyethylene mulch. `Colonial' was used in 1995 and `Mountain Spring' in 1996. In 1995, fruit was harvested as a mixture of color and mature greens while in 1996 fruit were harvested as pinks only. In 1995, mulch color did not affect early, late, or seasonal yields of medium, large, extra-large, or combined grades of fruit. Mulch color also did not affect fruit size or percentage of fruit that were marketable. In 1996, six harvests were made and there were no differences in yield (medium, large, extra-large, or combined grades), fruit weight of percent marketable fruit at each harvest date or for total season. From the results of these studies there was no benefit from using the red mulch, especially since the cost is higher.
Physiology of Fruit Set and Abscission
Authors: Dennis Frank G.
Published: February 2019

Thinning, whether mechanical or chemical, prevents the development of some fruits, allowing the remainder to become larger and more marketable. Chemicals used for thinning either prevent fruit set or increase the proportion of fruits that fall in the “June drop”; some, however, are effective even after this drop. The mechanisms involved in blossom thinning are straightforward. Either pollination is prevented, or some of the flowers are injured, causing their abscission. The mechanisms involved in fruit thinning are more complex; physiologists continue to debate the effects of thinning agents on phloem transport, endogenous hormone content/production, seed development, and other physiological processes. The effects of ethephon in thinning have led to the suggestion that the response to applied hormones is mediated by their effects in stimulating ethylene biosynthesis. Hypotheses as the mechanisms of action of thinning agents will be reviewed, emphasizing those most often invoked today.
Application of Photoperiodic Manipulation in Vegetative Specialty Floral Crop Propagation and Flowering
Authors: Williams Millie S. , Starman Terri Woods
Published: February 2019

Photoperiod requirements are important for optimum flower development, decreasing production time, year-round flowering, and/or for increasing vegetative growth necessary in stock plant production. The photoperiodic responses were determined for 24 vegetatively propagated specialty floral crops. Each plant species was grown at 8-, 10-, 12-, 14-, and 16-h photoperiods. Photoperiods were provided by 8 h of sunlight, then pulling black cloth and providing daylength extension with incandescent bulbs. Data collected included time to flower, flower number, and vegetative characteristics. Evolvulus nuttallianus `Blue Daze', Heliotropium arborescens `Fragrant Delight', and Orthosiphon stamineus `Lavender' were facultative short-day plants with respect to flowering. Time to flower increased as photoperiod increased. Duranta repens `Blue', Verbena hybrid `Tapien Lavender', and Verbena peruviana `Trailing Katie' were facultative long day plants with respect to flowering. Days to visible bud and first open flower decreased as photoperiod increased. Argeranthemum frutescens `Sugar Baby', Scaevola aemula `Fancy Fan Falls', and Portulaca hybrid `Apricot' had increased flower number as photoperiod increased from 8- to 16-h, although time to first flower initiation was not affected. Abutilon hybrid `Apricot', Duranta repens `Blue', Evolvulus nuttallianus `Blue Daze', Lotus berthelotii `Parrot's Beak', Lysimachia nummularia `Aurea Creeping Golden', Rhodanthe anthemoides `Milkyway', and Scaevola aemula `Fancy Fan Falls' had increased vegetative growth as photoperiod increased. All other species studied were day-neutral with regard to flowering and vegetative parameters.
The Effect of Thiols and Rhizopon on the Rooting of Woody Stem Cutting of Punica granatum L.
Authors: LaFaver Carol , Ching Alejandro
Published: February 2019

A research study was established to determine the effect of thiol compounds glutathione (GSH) and dithiothreitol (DTT) to induce rooting and root growth of woody stem cuttings from Punica granatum L., either alone or in combination with rhizopon. Woody cuttings of P. granatum 10 cm long were collected from 5-year-old potted greenhouse grown plants. No leaves were left attached on the cuttings. The proximal end of cuttings were dipped for 10 sec in 0.05 and 0.1 mM of GSH; 0.6, 1, and 2 mM of DTT followed by a 5-min rest, and immediately dipped in a solution of 1500 ppm of Rhizopon for 10 sec. Untreated cuttings were used as control as well as cuttings dipped only in 1500 ppm of Rhizopon for 10 sec. Rooting was continuous with bottom heating at 24 °C under greenhouse conditions. The experimental data was analyzed statistically using a completely randomized block design with five replications. The average total number of roots was increased when the cuttings were treated with the thiol compounds and Rhizopon, 52 days after treatment. However, DTT at 1.0 mM increased more significantly the average total number of roots than GSH at any concentration. The presence of DTT alone at 1.0 mM or with 1500 ppm of Rhizopon increased the average number of roots to 10.04 and 10.99, respectively. No significant difference was found for the treatment of 0.05 mM GSH and 1500 ppm Rhizopon showing average number of 12.11 roots. Significant average total root length was detected in cuttings treated with 1500 ppm Rhizopon compared to control, GSH at 0.1 mM, and DTT at 0.6 mM and 1.0 mM.
Potential for Recyclable Plastic Film for Vegetable Production
Authors: Boozer Robert , Simonne Eric , Pitts Jim
Published: February 2019

A clear polyester plastic was evaluated to determine if its physical properties were suitable for vegetable plasticulture. Integrity of the clear plastic was greatly reduced if edges were damaged or torn, resulting in ripping during the mulch lading process. All six punching devices evaluated for planting holes performed well on the black plastic. Flame burner rated highest for the clear plastic and the lowest rating was achieved with the standard transplanter wheel punch. Clear plastic deteriorated quickly and by 78 days after laying was brittle. Where paint treatments provided adequate coverage, deterioration was greatly reduced. Weed growth under clear plastic was a problem early, but weeds soon died due to heat accumulation under the clear plastic. Despite a lower cost, limited agricultural use could be made of this material.
Do Cell Size and Age Influence Growth and Yield of Containerized Onion Transplants?
Authors: Leskovar Daniel I. , Vavrina Charles S.
Published: February 2019

The effect of cell volume and age of `Texas Grano 1015Y' onion transplants on survival, growth, and yield were evaluated. Transplant ages and cell volume were 5, 7, 9, and 11 weeks (W) and 6.5 cm3 and 20.0 cm3 in Florida; and 6, 8, 10, and 12W, and 4.0 and 7.1 cm3 in Texas. In Florida, total yields were unaffected by transplant age and cell volume, but jumbo size bulbs increased with increasing age from 5 to 9W in 6.5 cm3 cells. Bulb size increased significantly for 11W transplants only in 20.0 cm3 cells. In Texas, survival was reduced for 6W compared to ≥8W transplants. At planting, root count increased linearly with age. Cell volume did not affect root count, plant height, or leaf number, but shoot dry weight was greater in 7.1 cm3 compared to 4.0 cm3. Total jumbo and large size yields were highest for ≥10W in 7. 1 cm3 and ≥8W in 4.0 cm3 cells. Total yields were unaffected by cell size but seedlings in 4.0 cm3 had a 16% decrease of jumbo size compared to 7.1 cm3. The use of 10 and 12W transplants produced in small cell sizes may be viable for onion establishment.
Evaluation of Southernpea Breeding Lines and Varietie for Earliness, Yield, and Maturity
Authors: Brandenberger L.P. , Weidenfeld R.P. , Lopez J. , Mercado R.
Published: February 2019

Evaluation of new southernpea cultivars and advanced breeding lines for spring and fall cropping is important for both producers and processors of this crop in South Texas. The spring trial included three commercially available cultivars and 17 advanced breeding lines from the Univ. of Arkansas breeding program. Foliage color ratings taken in the spring correlate with similar ratings taken in 1995 and indicate that Arkansas 435-87-68 may be tolerant to high pH soils that caused yellowing in several other cultivars. The highest producing varieties, Arkansas 87-435-68 and Arkansas 92-552, produced net yields > 1000 lb/acre. The fall trial included the same material as the spring trial plus four more commercially available cultivars. Maturity ratings taken in early October varied widely between cultivars and breeding lines. Recorded ratings represented growth stages ranging from cultivars with no flowering to those that had set pods that were filling. The most mature types included Arkansas breeding lines 96-593, 95-368, 96-556, and 95-301, which had maturity ratings of 3.8, 3.5, 3.5, and 3.3, respectively. Net yields varied widely among cultivars in the fall trial. Yields ranged from 23.8 to 522.8 lb/acre. Those with the highest net yields included 'Early Scarlet', Arkansas 91-285, Arkansas Blackeye #1, and Arkansas 95-368, with yields of 522.8,402.2, 401.2 and 400.5 pounds per acre, respectively. Although yields in the trial were considerably lower than expected, several cultivars produced 400 or more pounds of peas per acre compared to many commercial fields that were not harvested.
Gas Exchange Characteristics of Apple at Various Light Intensities under Two Levels of European Red Mite Damage
Authors: Kugler-Quinn Krista L. , Rom Curt R. , Johnson Donn T.
Published: February 2019

Single leaf gas exchange measurements were taken at a range of light intensities from 20 to 1500 μmol·m-2·s-1 PAR under greenhouse conditions on `Washington Spur'/EMLA seven potted apple trees subjected to either 1500 cumulative mite days (CMD) European Red mite (ERM) damage or no mite damage. 1500 CMD ERM damage significantly reduced assimilation (A) over all light intensities for leaves present during mite damage at 6 days after the mite population had reached the 1500 CMD level and the mites were killed. Mite damage did not significantly affect A of either leaves present during mite damage or leaves produced after the mites were killed on any other sampling date. However, a trend of reduced A of leaves present during mite infestation on the mite-damaged trees was apparent on all sampling dates after the mites were killed. Evapotranspiration (E) was not affected by mite damage. The mite damage by light intensity interaction did not have a significant effect on A or E on any sampling date.
Selective Inhibition of Flowering on `Braeburn' Apple Trees with Gibberellins
Authors: McArtney Steven J. , Li Shao-Hua
Published: February 2019

`Braeburn' apple trees were treated with GA3 or GA7 at either 100, 200, or 400 mg·L-1, 2 years after being grafted onto 4-year-old `Royal Gala'/MM.106 trees in order to evaluate their effects on flower bud formation. Inhibition of flowering was observed on 1-year wood only and not on spurs in response to GA treatments applied later than 6 weeks after bloom. GA7 was a more potent inhibitor of flowering than GA3. These results indicate that GA treatments may provide a useful technology for the selective removal of flowers from 1-year wood in apple and may also provide a useful tool for overcoming biennial bearing in apple by inhibiting flower bud formation when applied in the light-cropping year of the biennial cycle.
Phosphate Starter Fertilizer Temporarily Enhances Soil Arsenic Uptake by Apple Trees Grown under Field Conditions
Authors: Peryea F.J.
Published: February 2019

Monoammonium phosphate (MAP) is a popular starter fertilizer in Pacific Northwest tree fruit orchards; however, its use on soils contaminated with lead arsenate pesticide residues can enhance As solubility, thereby increasing As phytoavailability. `Fuji'/EMLA.26 apple trees (Malus ×domestica Borkh.) were planted in Mar. 1992 on a lead arsenate—contaminated Cashmont gravelly sandy loam soil (HCl-extractable soil As range: 60-222 mg·kg-1) using in-hole starter fertilizer application of either MAP or ammonium sulfate at equivalent N and anion rates. In ensuing years, all trees received identical applications of ammonium nitrate only. Relative trunk cross-sectional area was inversely related to soil As concentration in the year of planting but not in subsequent years, and was independent of starter fertilizer treatment. Leaf and fruit As were positively related to soil As in all years. Leaf As was initially higher in the MAP-treated trees; however, this effect diminished over time and disappeared by 1995. Fruit As was independent of starter fertilizer treatment, and was substantially lower than the tolerance established for As in fresh produce. The experimental results indicate that MAP starter fertilizer can increase soil As phytoavailability to apple trees grown under field conditions; however, the effects on tree growth and food safety are insignificant.
Ploidy Determination in Musa Germplasm Using Pollen and Chloroplast Characteristics
Authors: Tenkouano A. , Crouch J.H. , Crouch H.K. , Vuylsteke D.
Published: February 2019

We attempted to determine ploidy level in the gametophyte and the sporophyte of Musa using pollen and chloroplast characteristics, respectively. In the gametophyte, interploidy differences accounted for 63.8% of the genetic variance for pollen diameter and 87.5% for pollen stainability, the remainder being attributable to intraploidy differences among clones. While pollen count and stainability effectively separated triploid accessions from diploids or tetraploids, they did not discriminate between diploids and tetraploids. In the sporophyte, the relative contributions of interploidy and intraploidy differences to genetic variation in the number of chloroplasts in stomatal guard cells were 70.8% and 29.2%, respectively. Although pollen diameter and chloroplast number increased with ploidy, the use of the sporophytic parameter appears to provide a more satisfactory means of estimating ploidy status in Musa.
Evaluation of Oriental Trellis Cucumbers for Production in North Carolina
Authors: Shetty Nischit V. , Wehner Todd C.
Published: February 2019

Eighteen cucumber (Cucumis sativus L.) cultivars (15 oriental trellis and three standard American slicers) were grown on trellis and flat-bed production systems during the spring and summer seasons of 1995. Vine, flower, fruit quality, keeping ability, and yield traits were measured. Vine length, incidence of powdery mildew, fruit shape, fruit quality, fruit firmness, yield of Fancy plus No. 1 grade slicer fruits, marketable yield, and percentage of culled fruits were all higher when cultivars were grown on trellis support. Anthracnose damage, fruit length, fruit diameter, average fruit mass, fruit color, overall impression, fruit shriveling, seedcell size, branch number, percentage of staminate nodes, and total yield were not significantly affected by production system. The best cultivars for marketable yield (mass of Fancy, No. 1 and 2 grade slicers) were `Summer Top', `Tasty Bright', and `Sprint 440' on trellis support and `Sprint 440' and `Poinsett 76' on flat bed. The cultivars with the best fruit quality were `Tasty Bright', `Summer Top', and `Sprint 440' on trellis and `Poinsett 76', `Sprint 440', and `Tasty Bright' on flat bed. The best cultivars overall on the trellis production system were `Sprint 440', `Summer Top', `Tasty Bright', and `89-211', and the worst were `Sky Horse', `Hongzhou Green 55', and `Fengyan'. The best cultivars overall on the flat bed were `Poinsett 76', `Sprint 440', and `89-211', while the worst cultivars were `Sky Horse' and `Hongzhou Green 55'.
Annual Applications of N, P, and K for Four Years Moderately Increase Nut Production in Black Walnut
Authors: Ponder Felix , Jones James E. , Haines Joan
Published: February 2019

Annual applications of N, P, and K fertilizers were broadcast for 4 years around black walnut trees (Juglans nigra L.) in an upland plantation to determine their effect on nut production and foliar nutrient levels. Fertilization significantly (P = 0.05) increased nut production, treatments containing P with N and/or K being most effective. Doubling the rate of application did not produce a corresponding yield in nuts. Increases in leaf concentrations of N, P, and K were associated with increasing treatment levels of these elements. Levels of all elements tested, except P, were above deficiency levels. The modest gain in production suggests that soil fertility was not a major factor limiting nut production for trees in this study.
Influence of Pine Bark on the Efficacy of Different Growth Retardants Applied as a Drench
Authors: Million Jeff B. , Barrett James E. , Nell Terril A. , Clark David G.
Published: February 2019

Dendranthema×grandiflorum (Ramat.) were grown in either a peat-based or pine bark—based medium and drenched with growth retardants at a range of concentrations to generate dose : response curves. The effect of ancymidol, paclobutrazol, and uniconazole on stem elongation was less in the pine bark—based than in the peat-based medium. Generally, the concentrations required to achieve the same response were 3- to 4-fold as high in the pine bark—based medium as in the peat-based medium. However, chlormequat was slightly more active in the pine bark—based medium than in the peat-based medium. Chemical names used: α-cyclopropyl-α—(4-methoxyphenyl)-5-pyrimidinemethanol (ancymidol); (±)-(R*,R*)-β-[(4-chlorophenyl)methyl]-α-(1,1-di methyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol); (E)-(RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pent -l-en-3-ol (uniconazole); 2-chloroethyltrimethylammonium chloride (chlormequat).
Relative Susceptibility of Peach and Plum Germplasm to Armillaria Root Rot
Authors: Beckman T.G. , Okie W.R. , Nyczepir A.P. , Pusey P.L. , Reilly C.C.
Published: February 2019

Nearly 5000 seedling trees representing more than 100 peach [Prunus persica (L.) Batsch.] and plum (Prunus spp.) lines were planted at a 4 × 0.6-m spacing in Jan. 1983, on a site with a known history of peach tree short life (PTSL) and Armillaria root rot (ARR). Trees were arranged in a randomized complete-block with eight replicates of six trees each. Beginning in Spring 1984 and each year thereafter the cause of tree death was determined. At the end of 9 years, 50% of the trees had succumbed to PTSL and 35% had been killed by ARR apparently caused by Armillaria tabescens. Analysis of the data for trees killed by ARR showed a wide range in mortality, some peach lines appeared significantly more tolerant to ARR than others. Plum lines derived from native North American species also appeared to be a potential source of improved tolerance. We did not establish whether ARR tolerance is affected by PTSL.