bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Calcium Chloride and Ammonium Sulfate on Onion Bulb Quality at Harvest and During Storage
Authors: Coolong Timothy W. , Randle William M.
Published: February 2019

Sandy soils in the onion (Allium cepa L.) growing region of southeastern Georgia are generally low in calcium (Ca). Bulbs grown in these soils are often soft and susceptible to postharvest diseases. Preliminary greenhouse studies have indicated that supplemental calcium chloride (CaCl2) can improve bulb firmness. The effects of supplemental CaCl2 on the quality of field-grown onions were therefore investigated. Other preliminary studies indicated that CaCl2 may inhibit sulfur (S) uptake in onion and decrease bulb pungency. Thus, ammonium sulfate (NH4)2SO4 and CaCl2 levels were varied to determine if CaCl2 could improve flavor at different levels of nitrogen (N) and S fertility. Onions, cv Georgia Boy, were grown with 0, 250, and 500 kg·ha−1 (NH4)2SO4 and 0, 115, and 230 kg·ha−1 CaCl2 in a factorial combination in 2005 and 2006. Total bulb yield increased with increasing (NH4)2SO4, but was unaffected by CaCl2. The percentage of diseased bulbs increased during storage in both years, and was affected by (NH4)2SO4 fertility in 2006. Bulb scale firmness increased with supplemental CaCl2 fertility and decreased significantly during storage in both years. Fertility treatments had little effect on bulb pectin composition, although total pectin concentrations fell during storage in 2005 and 2006. In addition, bulb pungency decreased with additional CaCl2 in 2006. However, CaCl2 had a limited effect on flavor precursor concentrations. There were no interactions between fertility treatments, but there were CaCl2 and (NH4)2SO4 by storage duration interactions affecting firmness and disease incidence, respectively. With the exception of yield, differences among years in the parameters measured were generally small.
Influence of Growing Area, Year, Season, and Cultivar on the Composition of Myrtle Leaves and Infusions
Authors: Mulas Maurizio , Melis Rita A.M.
Published: February 2019

Leaves of five myrtle cultivars were analyzed for chlorophyll a and b, polyphenol, and tannin contents in two years (2000 and 2001), two seasons (spring and winter), and two growing areas (Alghero and Oristano, Sardinia, Italy). The hydroalcoholic leaf infusions obtained from the same cultivars were analyzed for the above-mentioned compounds and for their chromatic values as well. L* chromatic component ranged from 44.22 to 49.94, a* values ranged between −5.82 and −2.50, and b* values ranged between 10.74 and 18.40. The relationships between leaf and infusion characteristics were evaluated. Chlorophyll a content ranged from 1.9 to 4.7 mg·g−1 of dry weight in leaves and from 14.8 to 35.2 mg·L−1 in infusions. Chlorophyll b ranged between 0.3 and 2.9 mg·g−1 of dry weight in leaves and between 3.4 to 12.1 mg·L−1 in infusions. Polyphenols ranged between 6.8 and 15.3 g/100 g of dry weight in leaves and between 2.6 and 13.9 g·L−1 in hydroalcoholic infusions. Tannins ranged from 140 to 516 mg·g−1 of dry weight in leaves and from 57 to 291 mg·L−1 in infusions. Significant interactions among year, growing area, season, and cultivar effects occurred for all leaf and infusion parameters, except for leaf chlorophyll a. Strong correlations between leaf and infusion composition were not found. Because infusion quality was little influenced by the studied variables, to the best of our knowledge, winter harvest of myrtle leaves for white myrtle liqueur is feasible.
Effect and Empirical Models of Nitrogen Uptake Under Different Nitrogen Sources in Dieffenbachia amoena
Authors: Becker Silvia Jiménez , Lao Maria Teresa , Segura Mari Luz
Published: February 2019

Adjusting fertility programs according to peak demand periods will help prevent periodic nutrient disorders during crop growth, allowing enhanced use efficiency of water and fertilization. The objectives of this article were to investigate 1) the evolution of the changes in the concentration of nitrate and ammonium in the recycled solution with different N-NO3
–/N-NH4
+ ratios; 2) the influence of the N form supply (N-NO3
– or N-NH4
+) on the nitrogen uptake, the nitrogen:water uptake ratio, and nitrogen use and uptake efficiency; and 3) the development of empirical models that would allow the prediction of nitrogen nutritional needs of Dieffenbachia amoena to increase the N use efficiency in a recycled system. To achieve these aims, N uptake has been correlated to climate parameters such as temperature, vapor pressure deficit and global radiation, and growth parameters such as leaf area index. The trial was carried out with Dieffenbachia amoena plants growing in a recycled system with expanded clay as substrate. The crop was placed in an INSOLE (Buried Solar Greenhouse), the plants being supplied with equal amounts of N, differing in the percentage of the N form applied (NO3
–:NH4
+): TA (100:0), TB (50:50), and TC (0:100). The nitrogen form generated important changes in the pH and nitrate and ammonium concentration in nutritive solution during the recirculating solution. In N-NO3
– treatment, pH increased and nitrate concentration showed a tendency to drop slightly. N-NH4
+ treatment showed an abrupt N-NH4
+ concentration decrease, and N-NO3
– concentration increased along with a pH drop. Also, the nitrogen form applied to the Dieffenbachia amoena crop affects nitrogen uptake. Nitrogen uptake rates and nitrogen uptake concentration were higher in the plants supplied with N-NH4
+ or NO3
–+NH4
+ than in the plants provided with N-NO3
– alone. The supply of a combination of 50:50 NO3
–+NH4
+ improved the N use efficiency. The study also indicated the possibility of predicting the N uptake rate and N uptake concentration using the proposed models.
Effects of Foliar-applied Boron on Fruit Retention, Fruit Quality, and Tissue Boron Concentration of Pecan
Authors: Wells M. Lenny , Conner Patrick J. , Funderburk J. Frank , Price Jacob G.
Published: February 2019

Previous studies with a variety of tree species have demonstrated enhanced flowering, fruit set, and yield with foliar boron (B) applications. The effects of foliar-applied B on pecan [Carya illinoinensis (Wangenh.) K. Koch] in the southeastern United States are poorly understood. This study was undertaken to investigate the effect of foliar B application on leaf tissue B concentration, fruit retention, and kernel quality of pecan. Controlled pollination studies showed no effect of B on fruit retention of ‘Stuart’ pecan. Tissue B concentration, fruit retention, and percent kernel of ‘Desirable’ pecan were occasionally enhanced by both two and five B applications made before and through the pollination window in multiple studies over 3 years. As long as leaf B is within the recommended sufficiency range, timing of foliar B application during the critical prepollination period appears to be more valuable for pecan production than are increasing leaf B levels. Given the production enhancements observed here, and the low cost of B fertilizers, the practice of foliar B application merits consideration as a component of pecan orchard management when tank-mixed with normal prepollination pesticide or nutrient sprays.
Effect of Planting Date and Nitrogen Fertilization Rates on No-till Pumpkins
Authors: Harrelson E. Ryan , Hoyt Greg D. , Havlin John L. , Monks David W.
Published: February 2019

Vegetable growers in the Mountain region of North Carolina are faced with increased land prices resulting from urbanization and reduced farm income from low-commodity prices. Local consumer use of pumpkin (Cucurbita pepo) for jack-o-lanterns and baking provides a fall market for growers to increase production and profitability on-farm. Most soils in these regions are highly erodible and susceptible to drought during the growing season. Little information is available on cultural practices for no-till pumpkin production in this region. Field studies were established to evaluate the yield response of no-till pumpkin to planting date and nitrogen (N) fertilization. Experiments were conducted at the Mountain (MRS), Upper Mountain (UMRS), and the Mountain Horticultural Crops Research Stations (MHCRS) in Summer 2003 and 2004 using no-till cultural practices. Three planting dates were established at 2-week intervals and 0, 40, 80, and 120 kg·ha−1 N treatments were applied at each planting date in a randomized complete block design. The 80 and 120 kg·ha−1 N fertilization rates produced greater yields and larger fruit size than the 0 and 40 kg·ha−1 N rates. Pumpkins planted earliest produced the greatest marketable and total yields for all N rates at all three locations. The latest planting date (9 July) and highest N rate yielded more cull fruit compared with marketable pumpkins with the earlier planting date at the Upper Mountain Research Station. This location has a shorter growing season and cooler summer temperatures than the two other locations. Although the third planting date was late for pumpkin planting, higher N rate treatments at that timing produced marketable yields comparable to earlier planting dates at the two warmer summer locations (MRS and MHCRS). In these experiments, the highest rate applied (120 kg·ha−1 N) maximized pumpkin yield. This observation would indicate that higher yields might be possible with even greater N rates.
Annual Bloom-time Phosphorus Fertigation Affects Soil Phosphorus, Apple Tree Phosphorus Nutrition, Yield, and Fruit Quality
Authors: Neilsen Gerry H. , Neilsen Denise , Toivonen Peter , Herbert Linda
Published: February 2019

A randomized, complete block, split-plot experimental design with six replicates was established and maintained annually for the first five fruiting seasons (1999 to 2003) in a high-density apple [Malus sylvestris (L) Mill var. domestica (Borkh.) Mansf] orchard on M.9 rootstock planted in Apr. 1998. Main plot treatments involved eight different nutrient regimes, each containing three tree subplots of each of five different cultivars (Ambrosia, Cameo, Fuji, Gala, and Silken). This report compares a +phosphorus (P) treatment, involving annual fertigation at bloom time of 20 g P/tree as ammonium polyphosphate (10N–15P–0K), to a −P treatment. Both treatments also received nitrogen, potassium, and boron nutrients through fertigation. Drip fertigation of P increased 2 M KCl-extractable P to 0.4-m depth within 0.5-m distance of the drippers. Leaf and fruit P concentrations were consistently increased by the +P treatment with few differences among cultivars. P-fertigated trees also had a 20% increase in cumulative yield overall cultivars during the first five fruiting seasons. Standard fruit quality measurements, including fruit size, soluble solids concentration, titratable acidity, and red coloration were unaffected by P application. However, reductions in incidence of water core at harvest, increased resistance to browning, and elevated antioxidant content of harvested fruit measured in some years imply a role for P in apple membrane stability. The cumulative results indicate that applications of 20 g P as ammonium polyphosphate annually at bloom would be advantageous for apples receiving adequate fertigated applications of nitrogen, potassium, and boron. Best apple performance was associated with leaf P concentrations above 2.2 mg·g−1 dry weight and fruit P concentrations between 100 and 120 mg·kg−1 dry weight.
Chemical and Physical Properties of Soil Amended with Pecan Wood Chips
Authors: Tahboub Mohammed B. , Lindemann William C. , Murray Leigh
Published: February 2019

The pruning wood of pecan [Carya illinoinensis (Wangenh.) K. Koch] is often burned. Chipping and soil incorporation of pruning wood is becoming more popular as a result of environmental constraints on burning. The objective of our research was to determine how pecan wood incorporation into soil affects the soil chemical and physical properties. Pecan wood chips were incorporated into a silty clay soil at rates of 0, 4484, 8968, 13,452, and 17,936 kg·ha−1 in Summer 2002, 2003, and 2004. Some plots received nitrogen at a rate of 0, 15.2, 30.5, 45.7, and 61.0 kg·ha−1 to adjust the C : N ratio of trimmings to 30 : 1. Ammonium sulfate, as a nitrogen source to balance the C : N ratio of pecan wood chips, reduced soil pH. However, the wood chip amendments alone did not reduce soil pH. Soil salinity (as determined by electrical conductivity) and bulk density were unaffected by wood chip incorporation regardless of application rate or number of applications. Incorporation of pecan chips had little effect on soil moisture content, but the soil had an inherently high waterholding capacity. Pecan wood chip incorporation significantly increased soil organic matter content and aggregate stability, particularly at the higher application rates and with repeated amendment. The incorporation of pecan pruning wood into the soil appears to improve soil tilth and aggregation while providing growers with an environmentally acceptable means of disposal.
Selective Removal of Creeping Bentgrass from Kentucky Bluegrass with Sulfosulfuron
Authors: Jones Marcus A. , Christians Nick E. , Weisenberger Daniel , Reicher Zachary J.
Published: February 2019

Creeping bentgrass (Agrostis stolonifera L.) is well adapted to golf course greens, tees, and fairways but may become a weed in Kentucky bluegrass (Poa pratensis L.) roughs and lawns. The objectives of this study were to determine effects of sulfosulfuron rate and application date on control of creeping bentgrass and safety on Kentucky bluegrass. Field experiments were initiated in 2003 and 2004 in Ames, IA, and West Lafayette, IN. Single applications of sulfosulfuron at 0.011 or 0.022 kg·ha−1 were applied over a 9-week period during the fall of each year. Phytotoxicity on Kentucky bluegrass was recorded weekly and control of creeping bentgrass was determined in the spring after fall treatments. No treatment provided greater than 31% control, and there were few differences in control between the two rates of sulfosulfuron. In West Lafayette, late fall applications were the most effective providing up to 31% control of creeping bentgrass. Sulfosulfuron provided less than 18% control in Ames in either year. Kentucky bluegrass was tolerant of all sulfosulfuron applications. Late fall applications of sulfosulfuron may be useful in partially removing creeping bentgrass from a heavily contaminated sward of Kentucky bluegrass.

Chemical names used: 1-(4,6-dimethoxypyrimidin-2-yl)-3-(2-ethylsulfonylimidazo[1,2-a]pyridin-3-ylsulfonyl)urea (sulfosulfuron)
Inheritance of Resistance to Crown Rot Caused by Phytophthora capsici in Cucurbita
Authors: Padley Les D. , Kabelka Eileen A. , Roberts Pamela D.
Published: February 2019

The various disease syndromes caused by Phytopthora capsici Leonian can be devastating to squash (Cucurbita spp.) production areas of the United States. In some growing seasons, yield loss has been reported up to 100%. A recently developed University of Florida Cucurbita breeding line, #394-1-27-12, resistant to the crown rot syndrome of P. capsici, was used to determine the inheritance of resistance to this disease. Data from F1, F2, and backcross progeny from crosses of a P. capsici-susceptible butternut-type winter squash (C. moschata) with #394-1-27-12 indicated that resistance is conferred by three dominant genes. The introgression of P. capsici crown rot resistance from #394-1-27-12 into morphologically diverse domesticates within Cucurbita will aid in the management of this economically important pathogen.
Simple-sequence Repeat Marker Analysis of Genetic Relationships within Hydrangea paniculata
Authors: Reed Sandra M. , Rinehart Timothy A.
Published: February 2019

Genetic diversity studies using 26 simple-sequence repeat (SSR) markers were conducted with 36 cultivars, breeding lines, and wild-collected accessions of Hydrangea paniculata Sieb. The SSR markers were highly variable among the genotypes, producing a mean of 5.8 alleles per marker. Three cultivars (Boskoop, Compact Grandiflora, and Webb) were either identical to or sports of the popular cultivar Grandiflora. The name ‘Pee Wee’ appears to have been applied to two phenotypically different compact forms of H. paniculata, one of which seems to be a sport of ‘Tardiva’, whereas the other is likely derived from ‘Grandiflora’. No close genetic similarity was observed among several cultivars from a long-term Belgium breeding program, although many had one parent in common. Early-flowering genotypes clustered separately from genotypes that flower in midsummer, but close genetic relationships were not observed among early-flowering cultivars. Two genotypes from Taiwan were genetically similar but were distinctly different from the Japanese genotypes. These, along with the early-flowering genotypes and a new collection from Japan, may represent unexploited sources of germplasm for improvement of H. paniculata.
Development of 11 Polymorphic Microsatellite Loci from Primula amthystina Franchet. (Primulaceae)
Authors: Huang Yuan , Wang Xue-qin , Yang Chun-yan , Long Chun-lin
Published: February 2019

Primula amethystina Franchet. is a beautiful perennial herbaceous plant locally endemic to the alpine area in southwest China. We isolated and characterized 11 polymorphic microsatellite primer pairs from this species. The number of alleles ranged from two to five. The observed and expected heterozygosities (HO and HE) were 0.25 to 0.875 and 0.223 to 0.691, respectively. Six loci were significantly deviated from Hardy-Weinberg equilibrium as a result of the heterozygote deficiency. These markers will have great potential to reveal the genetic population structure and genetic diversity of P. amethystina.
Growth and Yield of Cultivated Grape with Native Perennial Grasses Nodding Needlegrass or California Barley as Cover Crops
Authors: Costello Michael J.
Published: February 2019

Two California native perennial grasses, nodding needlegrass [Nassella cernua (Stebbins & R.M. Love) Barkworth] and California barley [Hordeum brachyantherum Nevski ssp. californicum (Covas & Stebbins) Bothmer, N. Jacobsen & Seberg], were compared with a conventional grass cover crop, ‘Blando’ brome (Bromus hordeaceus L.), as well as resident (weedy) vegetation and a clean cultivated control for effects on growth and yield of cultivated grape (Vitis vinifera L. cv. Barbera). Statistical analyses did not reveal yield differences between treatments with floor vegetation (the native grasses, ‘Blando’ brome, and resident vegetation) and clean cultivation, the cover crop treatments (the native grasses and ‘Blando brome’) and clean cultivation, nor the native grass treatments versus treatments with non-native floor vegetation (‘Blando’ brome and resident vegetation). However, there was a significant difference between the two native grasses with the average yield of nodding needlegrass 26.2% higher than that of California barley. Treatments did not differ in °Brix, berry weight, or pruning weight. At the end of the study, vine trunk diameter was 7.1% higher under the cover crop treatments than resident vegetation. Given these results, in vineyards where a neutral effect on growth or yield is desired, nodding needlegrass would be suitable as a permanent cover crop, whereas California barley would not.
A Copper-based Fungicide Has Minimal Effects on Tart Cherry Fruit Quantity and Quality
Authors: Gruber Barrett R. , Davies Libby R.R. , McManus Patricia S.
Published: February 2019

Copper-based fungicides are effective for managing cherry leaf spot disease incited by Blumeriella jaapii (Rehm) Arx. However, their application has been associated with bronzing discoloration of tart cherry (Prunus cerasus L.) foliage. This work explored the consequences of foliar applications of a copper-based fungicide for tart cherry fruit quantity and quality. ‘Montmorency’ tart cherry trees were subjected to one of the following fungicide programs in 2007, 2008, and 2009: synthetic fungicides only, synthetic fungicides integrated with a copper-based fungicide, or not sprayed. Each year, the number of fruits per shoot and fruit fresh weight and soluble solids concentration (SSC) were measured three to six times during drupe development. Repeated measures indicated no collection date × fungicide program effect on the mean number of fruits (P ≥ 0.48) and SSC (P ≥ 0.14) in all years or on fresh weight in 2008 and 2009 (P ≥ 0.58). There was a collection date × fungicide program effect (P = 0.02) on mean fresh weight in 2007. On 6 July 2007, trees assigned to the integrated copper program were observed having 23% and 27% lower fruit fresh weights than trees assigned to the nonsprayed and synthetic programs, respectively. However, pairwise comparisons indicated no difference in fresh weight between the integrated copper and the nonsprayed programs (P = 0.26) and no difference between the integrated copper and synthetic programs (P = 0.25) on the final collection date of 2007. In 2007, fresh weight decreased slightly (slope = –0.08, P = 0.05) as leaf bronzing severity increased, whereas SSC increased slightly (slope = 0.31, P = 0.06). In 2008 and 2009, there was no relationship between bronzing severity and fresh weight or SSC (P ≥ 0.34). These results indicate that applied copper does not lead to fewer fruits per shoot or reductions in fresh weight or SSC of mature fruit and that the observed range of leaf bronzing severity had little to no influence on fresh weight and SSC.
Cooling Effect of Shade Trees with Different Characteristics in a Subtropical Urban Park
Authors: Lin Bau-Show , Lin Yann-Jou
Published: February 2019

The effect of shade trees on the air and surface-soil temperature reduction under the canopy was studied in a park in subtropical Taipei City, Taiwan. Ten species of trees and two species of bamboo, which had tightly clustered tall stems and spreading branches resembling trees in shape, were chosen for the study. In the summer of 2007, we measured leaf and canopy characteristics of each species. The microclimate conditions under the tree canopies and an unshaded open space were measured repeatedly at middays without precipitation. In comparison with the nearby unshaded open space, air temperatures under the canopies were 0.64 to 2.52 °C lower, whereas the surface-soil temperatures were 3.28 to 8.07 °C lower. Regression analysis revealed the relative contributions to air cooling effect by the plant's leaf color lightness, foliage density, leaf thickness, and leaf texture (surface roughness) in decreasing order. Foliage density had the greatest contribution to surface-soil cooling followed by leaf thickness, leaf texture, and leaf color lightness in that order. Regression analysis also revealed that solar radiation, wind velocity, and vapor pressure at the site had significant effects on temperature reduction attributable to shade trees or bamboo.
Regulated Deficit Irrigation of ‘Montmorency’ Tart Cherry
Authors: Papenfuss Kylara A. , Black Brent L.
Published: February 2019

Mature tart cherry (Prunus cerasus L. ‘Montmorency’) trees in a commercial orchard were subjected to irrigation deficits from pit hardening to harvest during the 2007 and 2008 seasons. Irrigation treatments ranged from 30% to 100% of a commercially managed application rate during the deficit period. Midday stem water potential measurements were significantly different among treatments before harvest. However, fresh weight yield at harvest did not differ significantly among irrigation treatments in either year (P = 0.64). In 2008, the amount of undersized fruit eliminated during packout was significantly higher in the treatments replacing 30% and 47% of the commercial irrigation level (P < 0.001), but only amounted to 2.0% and 1.4% of total yields, respectively. This small increase in undersized fruit did not significantly affect packout. Soluble solids concentration and chroma of intact fruit increased with the severity of the irrigation deficit and were inversely correlated with fruit water content.
The Stem Age Required for Floral Induction of Synchronized Mango Trees in the Tropics
Authors: Ramírez Fernando , Davenport Thomas L. , Fischer Gerhard , Augusto Pinzón Julio Cesar
Published: February 2019

The quantitative floral inductive role of the age of the last vegetative flush was investigated in replicated trials of two cultivars of mango (Mangifera indica L.), Keitt and Tommy Atkins, growing in tropical conditions of Cundinamarca State in Colombia. Empirical observations have indicated that stems must be in rest for sufficient time, generally 4 to 5 months, to be induced to flower in the absence of cool temperatures. Twelve trees per cultivar were tip-pruned to stimulate a synchronous flush of vegetative growth at the beginning of the experiments. The first of four sets, each consisting of three replicate trees among the 12, were sprayed with 4% potassium nitrate on a 2-week schedule beginning 2 months after the pruning date. Biweekly sprays continued in this first set until a growth response was observed, whereupon the set was retired from further observations, and the second set of three synchronized trees began receiving biweekly spray treatments until they initiated a growth flush. The schedule continued through the four successive sets of trees until the age of stems necessary to induce a flowering response was determined. Treatment applications were quantified using a one-m-square quadrate to determine the numbers of resting stems and vegetative and /or reproductive shoots contained within. KNO3 sprays applied 3 months after the pruning date stimulated initiation of vegetatively induced shoots in both ‘Keitt’ and ‘Tommy Atkins’ trees. Synchronous generative shoot initiation in ‘Keitt’ trees occurred in ≈75% and 100% of the stems after KNO3 sprays applied 5 and 6 months after the pruning date, respectively. Tommy Atkins, a cultivar that is more difficult to induce to flower than ‘Keitt’, had 18% of shoots flowering after the 5-month application and 100% flowering after the KNO3 application 6 months after the pruning date. None of the non-treated orchard trees flowered during this time. Stem age was the key factor correlated with flowering. The experimental trees, which were naturally habituated to experience two flowering periods per year, each within separate sections of tree canopy, were stimulated to produce one annual synchronized flowering event throughout the tree canopy as a result of the treatments.
Study of a Non-destructive Method for Estimating the Leaf Area Index in Vegetable Crops Using Digital Images
Authors: Campillo Carlos , García M.I. , Daza C. , Prieto M.H.
Published: February 2019

One estimate of a crop's ability to capture light energy is the leaf area index (LAI), which is defined as the proportion of leaf area per unit of land area. Direct methods of estimation involve determining the LAI in a significant area of cultivation and individually measuring the leaf surface, which is often tedious. The objective of this study was to develop a cheap and simple method for determining LAI based on the percentage of groundcover (PGC) measured in two vegetable crops with notable differences in leaf type and plant architecture using digital images obtained with a commercial camera and applying open-source software. The PGC values obtained from digital image analysis in cauliflower and tomato crops and the measurements of LAI obtained by destructive sampling (measured with a planimeter) allowed us to obtain a relationship between two variables (r2 > 0.88). In all cases, the extinction coefficients were obtained from comparisons of LAI and PGC with values ranging between 0.75 and 0.85 for processing tomato and 0.60 and 0.70 for cauliflower. The method used allows non-destructive estimations of LAI that are comparable with other more expensive indirect methods that require a skilled operator.
Landscape Coefficients for Single- and Mixed-species Landscapes
Authors: Pannkuk Tim R. , White Richard H. , Steinke Kurt , Aitkenhead-Peterson Jacqueline A. , Chalmers David R. , Thomas James C.
Published: February 2019

Urban landscape irrigation is becoming increasingly important from a resource management point of view. Significant water use savings may be achieved if landscape irrigation is based on reference evapotranspiration (ETo). This study measured landscape crop coefficients (KL) for landscapes that are comprised of different vegetation types and irrigation water quality differences affecting KL. The KL was determined from the ratio of actual evapotranspiration to the ETo calculated from the modified Penman-Monteith equation. Irrigation quantity was based on 100% replacement of ETo. The KL values were determined for the following landscape vegetation on a fine sandy loam: St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze.], a single shumard red oak (Quercus shumardii Buckl.), St. Augustinegrass plus red oak, native grasses [Muhlenbergia capillaries (Lam.) Trin. and Schizachyrium scoparium (Michx.) Nash], and native grasses plus Red Oak in both College Station (CS) and San Antonio (SA), TX. Soil was systematically placed into lysimeters containing a drainage system and soil moisture probes. Lysimeters (1136 L) were placed in-ground in a randomized complete block design with three blocks. Soil moisture measurements were made at 0- to 20-, 20- to 40-, and 40- to 60-cm depths. The KL was determined after a rainfall or irrigation event for periods of 2 to 5 days. During the combined growing seasons of 2007 and 2008, KL in SA increased from early, to mid, to late season. In CS, the KL was unaffected by plant treatment or season. The St. Augustinegrass treatment KL seasonally ranged from 0.45 to 0.62 in SA. In CS, soil sodium accumulation caused decreased KL. These results of KL for mixed-species landscapes on non-sodic sites trend toward seasonal values of 0.5 to 0.7 for irrigation decisions in southern Texas. Landscape coefficients can be used as a tool in irrigation decision-making, which could contribute to water savings in amenity landscapes.
Post-transplant Irrigation Scheduling for Two Native Deciduous Shrub Taxa
Authors: Griffin Abby B. , Wright Amy N. , Tilt Kenneth M. , Eakes D. Joseph
Published: February 2019

The effect of five irrigation scheduling treatments on shoot growth [growth index (GI)] and stem water potential (SWP) of Itea virginica L. ‘Henry's Garnet’ (‘Henry's Garnet’ sweetspire) and Rhododendron austrinum Rehd. (Florida flame azalea) were studied. Plants were transplanted on 13 Mar. 2008 at soil grade level under shade structures in field plots of sandy loam soil on the Auburn University campus in Auburn, AL. Matric potential was continuously measured 7.6 cm from the stem in the root ball and 20.3 cm from the stem in the soil backfill for three plants per treatment per taxa. Irrigation scheduling treatments included (in order of decreasing irrigation frequency): root ball and surrounding soil matric potential maintained at or above –25 kPa [well-watered (WW)]; root ball and surrounding soil rewatered when root ball matric potential dropped to either –50 kPa (50RB) or –75 kPa (75RB); and root ball and surrounding soil rewatered when surrounding soil matric potential dropped to either –25 kPa (25S) or –50 kPa (50S). In both taxa, GI increased linearly over time in all five irrigation treatments. For I. virginica ‘Henry's Garnet’, GI increased most in WW and 25S treatments followed by 50S, 50RB, and 75RB. Shoot growth of R. austrinum was similar among treatments. Both I. virginica ‘Henry's Garnet’ and R. austrinum had a larger increase in GI during the first growing season (2008). For I. virginica ‘Henry's Garnet’, SWP was higher in 50S and 75RB treatments than in 50RB, WW, and 25S. For R. austrinum, SWP was not different among treatments. Results indicate that although plant growth might be diminished slightly, irrigation frequency can be reduced without compromising plant visual quality or survival if root ball and soil matric potential is monitored. Additionally, until roots grow into the backfill soil, monitoring both backfill soil and root ball matric potential is important for scheduling and reducing post-transplant irrigation applications.
Variation in Phytoecdysteroid Accumulation in Seeds and Shoots of Spinacia oleracea L. Accessions
Authors: Cheng Diana M. , Yousef Gad G. , Lila Mary Ann
Published: February 2019

Spinach (Spinacea oleracea L.) is a valuable agricultural crop that accumulates phytoecdysteroids, polyhydroxylated triterpenoids, which may play a role in plant defense and have purported health benefits for human consumers. In this study, phytoecdysteroid accumulation was measured in seeds and shoots of 15 spinach accessions to determine whether phytoecdysteroid levels vary between spinach varieties and whether seed content could reliably predict relative levels in the edible foliage. Additionally, phytosterols, precursors to phytoecdysteroids, were examined to determine potential points of regulation of spinach phytoecdysteroid biosynthesis. Significant variations in phytoecdysteroid levels between accessions were observed (P < 0.05), suggesting the potential for genetic manipulation through traditional breeding or genetic engineering to increase phytoecdysteroid levels in spinach. However, results suggest that estimation of phytoecdysteroid levels in shoots may not be achieved by measuring levels in the seeds. Levels of phytoecdysteroids in spinach ranged from 19.9 to 44.1 μg per shoot, 0.7 to 1.2 μg·mg−1 dry mass shoot, 3.2 to 9.6 μg per seed, and 0.5 to 1.1 μg·mg−1 seed. Several phytosterols connected to the phytoecdysteroid biosynthetic pathway were identified by gas chromatography–mass spectroscopy, predominantly spinasterol, 5-dihydroergosterol, and 22-dihydrospinasterol, which comprised 79.8%, 6.3%, and 4.6% of the total phytosterol content, respectively. Detection of the phytosterols cycloartenol and lanosterol in spinach suggests that spinach may also have dual biosynthetic pathways to phytosterols that contribute to the production of phytoecdysteroids.
Chrysanthemum Production in Composted and Noncomposted Organic Waste Substrates Fertilized with Nitrogen at Two Rates Using Surface and Subirrigation
Authors: Krucker Michele , Hummel Rita L. , Cogger Craig
Published: February 2019

As nursery and greenhouse growers adopt more sustainable production practices, interest has grown in local, recycled organic materials (ROM) as partial or complete substitutes for peat in container substrates. Chrysanthemum ×morifolium Ramat. ‘Shasta’ was grown in substrates formulated from ROM: 1) 100% Groco, an anaerobically digested biosolids composted with sawdust; 2) 100% Tagro, a thermophilically digested class A biosolid mixed with sawdust and sand; 3) 100% dairy compost, the solids screened from dairy manure slurry and then composted; 4) 100% dairy fiber, the solids fraction from an anaerobic dairy manure digester; 5) 50% Groco:50% douglas-fir bark (mixed by volume); 6) 50% Tagro:50% bark; 7) 50% dairy compost:50% bark; 8) 50% dairy fiber:50% bark; and 9) the control, a commercial peat–perlite mixture. Soluble fertilizer [200 mg·L−1 nitrogen (N)] was applied every second day (high N) or every fourth day (low N). Water was applied through capillary mat subirrigation or overhead sprinkler surface irrigation. Surface irrigation and high N produced shoot dry weight, shoot growth index (SGI), quality, and flower bud counts similar to controls in all ROMs but Groco. Groco SGI was similar to the control but the other parameters were lower. Surface-irrigated, low N shoot dry weight, SGI, and flower buds in all ROM equaled or exceeded the control and quality was similar to or better than controls in all but dairy compost:bark. Subirrigated and high N substrate comparisons indicated that growth, quality, and flower bud measurements were similar to the control except for Groco in which performance was reduced. Low N rate subirrigation produced dry weight, SGI, quality, and flower buds similar to or better than the control in all but the Groco and dairy compost:bark substrates. The generally inferior performance in Groco is likely the result of its low water-holding capacity. In substrates with higher available N (Groco, Tagro, Tagro:bark, and dairy fiber), plant growth parameters generally did not respond to doubling the applied N; in the other substrates, including the control, growth generally increased in response to additional N. Measured differences in leaf color across treatments were not large. Root growth of plants in the experimental substrates was similar to the control in both irrigation systems. Substrate effects on leachate nitrate-N were small and inconsistent. When properly constituted, biosolids and dairy manure can be used as substrates under reduced fertilization with both surface and subirrigation systems.
Hyperhydricity and Flavonoid Content of Scutellaria Species In Vitro on Polyester-supported Liquid Culture Systems
Authors: Tascan Ayse , Adelberg Jeff , Tascan Mevlut , Rimando Agnes , Joshee Nirmal , Yadav Anand K.
Published: February 2019

Three Scutellaria species (Scutellaria lateriflora, S. costaricana, and S. baicalensis) were grown in different in vitro physical environments: agar, liquid culture, and liquid culture with fiber-supported paper (with initial media volumes of 20 mL and 30 mL). During an 8-week time course, tissue growth was assessed for each species by fresh weight (FW), dry weight (DW), percent DW, and multiplication ratio. Water use and hyperhydricity were also compared. Scutellaria lateriflora plantlets grown in liquid were hyperhydric despite the greatest accumulation of dry mass, but multiplication diminished with time as plants became hyperhydric. In contrast, S. costaricana and S. baicalensis plantlets had higher FW and DW on agar. With all Scutellaria species tested, plantlets grown on agar or fiber-supported paper were not hyperhydric, and fiber-supported paper with 20 mL initial volume yielded plants with the greatest percent DW. The lowered hyperhydricity was related to reduced water uptake. The flavonoids baicalin, baicalein, and wogonin were quantified in plants grown on fiber-supported paper culture. The baicalin concentrations in in vitro cultured S. lateriflora shoots was comparable to those of field-grown plants. The in vitro method presented a unique opportunity to enhance baicalein content and produce wogonin-rich roots. S. costaricana plantlets in vitro showed high levels of the three flavonoids compared with S. baicalensis and S. lateriflora. Growing non-hyperhydric tissues on fiber-supported paper, in vitro, allowed the clonal propagation of Scutellaria species with increased flavonoid content to proceed in a simple, controlled environment.
Spathe Color Variation in Anthurium andraeanum Hort. and Its Relationship to Vacuolar pH
Authors: Avila-Rostant Omaira , Lennon Adrian M. , Umaharan Pathmanathan
Published: February 2019

The relationship between vacuolar pH in Anthurium andraeanum (Hort.) and spathe color, cultivar, developmental stage, spathe location, spathe surface differences, and time after harvest was investigated with the overall long-term objective of developing a methodology for engineering blue-colored spathes. Chromospectral analysis of the pigmentation was also studied. Six experiments were conducted involving 23 cultivars of anthurium with each experiment arranged in a randomized complete block design with five replications. Spathe color was associated with vacuolar pH with the whites and greens having the highest pH (average 5.65) followed by corals (5.38), pinks (5.20), reds (5.10), and oranges (4.5). In general, there was correspondence between the lightness of the pigmentation (L*) and the pH values with the lighter colors having higher pH values. There were, however, significant differences among cultivars within the color groups. Whereas spathe pH decreased with aging, there was no difference in the spectral data, suggesting that factors other than anthocyanin content may be contributing to the pH difference. There were no differences in pH between locations sampled on the spathe nor between the spathe surfaces provided there were no differences in color intensity (L*). The pH increased with vase life in two of three cultivars tested with pH values showing an association with increases in a* and b* (chromospectral data) reflecting a bluing effect. The importance of the results to engineering blue-colored spathes in anthurium is discussed.
Can We Improve the Salinity Tolerance of Genotypes of Taxodium by Using Varietal and Hybrid Crosses?
Authors: Zhou Lijing , Creech David L. , Krauss Ken W. , Yunlong Yin , Kulhavy David L.
Published: February 2019

Taxodium distichum (L.) Rich. var. distichum [baldcypress (BC)], Taxodium distichum var. mexicanum Gordon [Montezuma cypress (MC)], and a Taxodium hybrid (‘Nanjing Beauty’: BC × MC cross, T302) were evaluated for salt tolerance in 2006 at Nacogdoches, TX. Plants were irrigated weekly with four levels of salinity [0, 1, 3.5, and 6 ppt (0, 17, 60, and 102 mol·m−3)] for 13 weeks and then 0, 2, 7, and 12 ppt (0, 34, 120, and 204 mol·m−3) for another 12 weeks. Salinity treatments did not have a significant effect on growth rate; however, there were significant differences in growth rate among the three genotypes. Genotype T302 produced the greatest wet weight, whereas MC had stronger apical dominance and exhibited the greatest increase in height over the course of study. As expected, sodium (Na) concentration in Taxodium leaves increased as sea salt concentrations increased but did not tilt Na/potassium (K) ratios to stressful disproportions. Of the three genotypes, BC exhibited the highest leaf content of Na, calcium (Ca), sulfur (S), and iron (Fe); MC had the lowest leaf content of Na, Ca, S, and Fe; and T302 was intermediate. The benefits of using a hybrid cross (T302) that maintains greater biomass than BC or MC across a range of salinities must be weighed against the potential additional pruning and training necessary for cutting-grown clones relative to BC and MC propagated from seed and flood tolerance relative to BC. Still, combining the best characteristics of different varieties of T. distichum should facilitate the production of favorable genotypes tolerant to a number of soil physical and chemical property fluctuations for arboricultural operations.
Blue Light-emitting Diode Light Irradiation of Seedlings Improves Seedling Quality and Growth after Transplanting in Red Leaf Lettuce
Authors: Johkan Masahumi , Shoji Kazuhiro , Goto Fumiyuki , Hashida Shin-nosuke , Yoshihara Toshihiro
Published: February 2019

In this study, we determined the effects of raising seedlings with different light spectra such as with blue, red, and blue + red light-emitting diode (LED) lights on seedling quality and yield of red leaf lettuce plants. The light treatments we used were applied for a period of 1 week and consisted of 100 μmol·m−2·s−1 of blue light, simultaneous irradiation with 50 μmol·m−2·s−1 of blue light and 50 μmol·m−2·s−1 of red light, and 100 μmol·m−2·s−1 of red light. At the end of the light treatment, that is 17 days after sowing (DAS), the leaf area and shoot fresh weight (FW) of the lettuce seedlings treated with red light increased by 33% and 25%, respectively, and the dry weight of the shoots and roots of the lettuce seedlings treated with blue-containing LED lights increased by greater than 29% and greater than 83% compared with seedlings grown under a white fluorescent lamp (FL). The shoot/root ratio and specific leaf area of plants irradiated with blue-containing LED lights decreased. At 45 DAS, higher leaf areas and FWs were obtained in lettuce plants treated with blue-containing LED lights. The total chlorophyll (Chl) contents in lettuce plants treated with blue-containing and red lights were less than that of lettuce plants treated with FL, but the Chl a/b ratio and carotenoid content increased under blue-containing LED lights. Polyphenol contents and the total antioxidant status (TAS) were greater in lettuce seedlings treated with blue-containing LED lights than in those treated with FL at 17 DAS. The higher polyphenol contents and TAS in lettuce seedlings at 17 DAS decreased in lettuce plants at 45 DAS. In conclusion, our results indicate that raising seedlings treated with blue light promoted the growth of lettuce plants after transplanting. This is likely because of high shoot and root biomasses, a high content of photosynthetic pigments, and high antioxidant activities in the lettuce seedlings before transplanting. The compact morphology of lettuce seedlings treated with blue LED light would be also useful for transplanting.
Intermittent Light from a Rotating High-pressure Sodium Lamp Promotes Flowering of Long-day Plants
Authors: Blanchard Matthew G. , Runkle Erik S.
Published: February 2019

A technology for long-day (LD) lighting was evaluated for commercial production of ornamentals using a stationary high-pressure sodium (HPS) lamp with an oscillating aluminum parabolic reflector (rotating HPS lamp). We performed an experiment with four LD species (Campanula carpatica Jacq., Coreopsis grandiflora Hogg ex Sweet, Petunia ×hybrida Vilm.-Andr., and Rudbeckia hirta L.) to compare the efficacy of a rotating HPS lamp in promoting flowering with night-interruption (NI) lighting using incandescent (INC) lamps. Seedlings were grown under natural short-day (SD) photoperiods (12 h or less) and NI treatments were delivered from a 600-W rotating HPS lamp mounted at one gable end of the greenhouse or from INC lamps that were illuminated continuously for 4 h or cyclically for 6 min every 30 min for 4 h. Plants were grown at lateral distances of 1, 4, 7, 10, or 13 m from the rotating HPS lamp, which provided a maximum photosynthetic photon flux of 25.4 μmol·m−2·s−1 (at 1 m) to 0.3 μmol·m−2·s−1 (at 13 m). Control plants were grown under an uninterrupted 15-h skotoperiod. Within 16 weeks, 80% or greater of the plants within each species that received NI lighting had a macroscopic visible flower bud or inflorescence, whereas all species but Petunia ×hybrida remained vegetative under the SD. Flowering of all species grown at 13 m from the rotating HPS lamp was delayed by 14 to 31 d compared with those under continuous INC. The weekly operational costs to provide NI lighting to a 139-m2 greenhouse with one 600-W rotating HPS lamp or a standard cyclic INC lamp installation was estimated to be 80% to 83% lower compared with INC lighting for the entire 4-h NI. These results indicate that a rotating HPS lamp can be used to efficiently deliver LD lighting, but flowering time was delayed and flower number reduced in some species when the maximum NI light intensity was less than 2.4 μmol·m−2·s−1.
Bispyribac–sodium, Sulfosulfuron, and Interseeding Creeping Bentgrass for Long-term Control of Roughstalk Bluegrass
Authors: Rutledge James M. , Morton Debbie E. , Weisenberger Daniel V. , Reicher Zachary J.
Published: February 2019

Roughstalk bluegrass (Poa trivialis L.) contamination is problematic on golf course fairways from the Midwest to the mid-Atlantic regions of the United States. Bispyribac–sodium and sulfosulfuron have potential to selectively control roughstalk bluegrass. Our objectives were to determine the most effective herbicide treatments for short- and long-term roughstalk bluegrass control and to determine if interseeding with creeping bentgrass (Agrostis stolonifera L.) after herbicide treatments will improve long-term control of roughstalk bluegrass or conversion to creeping bentgrass. Plots were treated with bispyribac–sodium or sulfosulfuron and then half of each plot was interseeded with creeping bentgrass in early August, 2 weeks after the final herbicide application in 2006, 2007, and 2008 in Indiana. Roughstalk bluegrass cover reduction was highest when treated with bispyribac–sodium at 56 or 74 g·ha−1 a.i. applied four times or sulfosulfuron at 27 g·ha−1 a.i. applied three times. Interseeding with creeping bentgrass improved long-term roughstalk bluegrass control and quickened conversion to creeping bentgrass. Furthermore, bispyribac–sodium and sulfosulfuron appeared to be more effective in the first 2 years of the study when seasonal heat stress was greater, which appeared to improve long-term roughstalk bluegrass control and promoted creeping bentgrass establishment. Chemical names used: {2,6-bis[(4,6-dimethoxypyrimidin-2-yl)oxy] benzoic acid} (bispyribac–sodium), {1-[4,6-dimethoxypyrimidin-2-yl]-3-[2-ethanesulfonyl-imidazo(1,2-a)pyridine-3-yl) sulfonyl]urea} (sulfosulfuron).