bluuebunny/crossref_metadata_2025 huggingface dataset:
Greenhouse Rose Yield and Ion Accumulation Responses to Salt Stress as Modulated by Rootstock Selection
Authors: Cabrera Raúl I. , Solís-Pérez Alma R. , Sloan John J.
Published: February 2019

Greenhouse rose (Rosa × spp. L.) production is facing the use of poor-quality irrigation waters and regulatory pressures to recycle runoff and drainage effluents. Two experiments (were conducted to evaluate the yield and quality and ion accumulation responses of roses grafted on various rootstocks to increasing salinity stress. In Expt. 1, the scion ‘Bridal White’ grafted on ‘Manetti’, R. odorata (Andr.), ‘Natal Briar’, and ‘Dr. Huey’ were irrigated over four flowering cycles with complete nutrient solutions supplemented with NaCl at 0, 5, and 30 mm. In Expt. 2, plants of ‘Red France’ on ‘Manetti’ and ‘Natal Briar’ were irrigated over six flowering cycles with complete nutrient solutions supplemented with NaCl + CaCl2 (2:1 m ratio) at 0, 1.5, 3, 6, 12, and 24 mm. Salt concentration increases significantly and negatively affected the biomass, cut flower production, and foliage quality of the roses in both experiments, but the responses were modulated by rootstock selection. ‘Manetti’ plants in general sustained better absolute and relative biomass and flower yields, accumulated less Na+ and Cl− in its tissues, and showed less toxicity symptoms with increasing salinity than the others. ‘Natal Briar’ also had similar absolute productivity responses as ‘Manetti’ but were afflicted by a significantly different mineral nutrient profile, including higher accumulations and toxicities with Na+ and Cl− that led to lower foliage visual ratings. Conversely, the relative yields of plants on ‘Dr. Huey’ and R. odorata were similarly reduced by increasing salinity, but the former had lower Na+ and Cl− concentrations in its tissues and better visual scores than the latter, which fared as the worst. A combined analysis of the results suggests that on a productivity basis (biomass and flower yields), greenhouse roses could withstand overall maximum electrical conductivities (i.e., osmotic effects) of applied fertigation solutions of 3.0 ± 0.5 dS·m−1. On the other hand, and considering the aesthetic responses (visual scores) of on-plant and harvested foliage (cut flower shoots), greenhouse rose tolerance to applied Na+ and Cl− concentrations (ion-specific effects) could range up to 10 ± 2 mm.
Identification of Sterile, Noninvasive Cultivars of Japanese Spirea
Authors: Wilson Rhiannon L. , Hoch William A.
Published: February 2019

Japanese spirea (Spiraea japonica L. f.), a popular landscape shrub, has shown the potential to become an invasive weed in both North America and Europe. Twenty commonly available S. japonica cultivars were evaluated for fertility using pollen and seed germination. Clones were grown in a randomized, replicated field plot, and additional seed samples were obtained from commercial nurseries and hand-pollinations in the greenhouse. Three sterile cultivars were identified: ‘Crispa’, ‘Dart's Red’, and ‘Neon Flash’. These cultivars demonstrated poor anther dehiscence and very low mean pollen germination, 2.7%, 3.0%, and 1.3%, respectively, which often produced abnormal pollen tubes. None of these three cultivars produced viable seed in the field plot, at commercial nurseries, or when hand-pollinated in the greenhouse, whereas seed germination from fertile clones ranged from 91.5% to 100%. The other 17 cultivars tested, which should be treated as entirely fertile for the purposes of invasive plant management, were ‘Albiflora’, ‘Anthony Waterer’, ‘Candlelight’, ‘Dakota Goldcharm’, var. alpina ‘Daphne’, ‘Flaming Mound’, ‘Flowering Choice’, ‘Froebelii’, ‘Golden Princess’, ‘Goldflame’, ‘Goldmound’, ‘Gumball’, ‘Lemon Princess’, ‘Little Princess’, ‘Magic Carpet’, ‘Norman’, and ‘Shibori’. Measurements of DNA content indicated that all tested clones are diploid; therefore, the observed sterility was not related to polyploidy. The identification of these three sterile cultivars can help reduce the use of fertile varieties in areas where Japanese spirea has shown the potential to become invasive.
Water Uptake Threshold of Rabbiteye (Vaccinium ashei) Blueberries and Its Influence on Fruit Splitting
Authors: Marshall Donna A. , Spiers James M. , Curry Kenneth J.
Published: February 2019

Split-resistant and split-susceptible rabbiteye blueberry fruit were evaluated at all stages of development to determine “water uptake thresholds” by soaking in distilled water. Weight increase after soaking was measured, and percent weight gain was calculated to take into consideration the weight increase of the fruit from development. The ratio of percent increase in volume to weight increase resulting from water uptake was calculated. Ratios of percent water uptake to weight increase between split-susceptible ‘Tifblue’ and split-resistant ‘Premier’ blueberries were found to be similar. The split-susceptible ‘Tifblue’ had a 1.6 g/50 fruit increase with a 1.7% water uptake and a ratio of 1.08. ‘Premier’ had a higher weight increase with 3.3 g/50 fruit and also a higher percentage of water uptake at 3.6% providing a ratio of 1.09. Although both absorbed water at a constant rate shown by a linear increase of weight increase over time, ‘Premier’ absorbed a significantly greater amount of water than did ‘Tifblue’ yet remained intact and did not split.
Pepper Accession LS2341 Is Highly Resistant to Ralstonia solanacearum Strains from Japan
Authors: Mimura Yutaka , Yoshikawa Masami , Hirai Masashi
Published: February 2019

Bacterial wilt caused by Ralstonia solanacearum is one of the most serious diseases in pepper (Capsicum annuum) crops in warm-temperate, subtropical, and tropical areas, including Japan. Resistant lines are a prerequisite for breeding resistant cultivars but are not well studied. Eight pepper accessions previously described as resistant to the pathogen were selected and inoculated with a highly virulent strain, KP9547. Among them, Malaysian accession LS2341 exhibited the highest resistance. Accession LS2341 was then challenged with 14 virulent strains collected from various areas in Japan. The strains cover biovars 2T, 3, and 4 and include isolates from the host plants of tomato, eggplant, and pepper. Results indicated that accession LS2341 had the highest level of resistance to all the strains of R. solanacearum examined. Therefore, accession LS2341 was confirmed as an appropriate source for the breeding of resistant cultivars of pepper in Japan and is a candidate for a potential source of resistance in other areas.
Stem Tissue Dimensions Correlate with Vulnerability to Injury for Six Cycas Species
Authors: Marler Thomas E. , Lindström Anders , Fisher Jack B.
Published: February 2019

Dimensions of pith, vascular tissue, cortex, live leaf bases, and periderm layers comprising the diameter of the stems of six Cycas species were measured at the standardized stem height where two vascular cylinders existed. The six species represent a range in susceptibility to injuries that occur in routine horticultural operations. We assigned a subjective numeric ranking from 1 for difficult to 10 for easy and then determined if this ranking correlated with any of the dimension characteristics. Pith diameter and cortex width differed among the species with the highly sensitive C. macrocarpa Griff. exhibiting the widest pith and most narrow cortex. Width of tissues peripheral to the vascular tissue (cortex, leaf base, and periderm layers) also differed among the species as did the proportion of total stem diameter occupied by these peripheral tissues. The sensitive C. macrocarpa exhibited the smallest values for these two variables. Simple correlation and multiple regression analyses indicated cortex width, total stem diameter, absolute width of peripheral tissues, and the relative proportion of these peripheral tissues in relation to stem diameter were positively correlated with susceptibility ranking. Of these, the relative proportion of peripheral tissues emerged as the variable with the most significant association with susceptibility ranking. Among these six representative species, the species that tend to be least susceptible to injuries during horticultural operations protect the youngest vascular tissues within a relatively wide zone of peripheral tissue. In contrast, the sensitive species exhibit a narrow zone of protective peripheral tissues.
Comparing Spray Gun and Spray Boom Applications in Two Ivy Crops with Different Crop Densities
Authors: Foqué Dieter , Pieters Jan G. , Nuyttens David
Published: February 2019

Flemish greenhouse growers predominantly use handheld spray guns and lances for their crop protection purposes despite the heavy workload and high risk for operator exposure associated with these techniques. These spray application techniques have also shown to be less effective than spray boom equipment under many conditions. Handheld spraying techniques are less expensive, however, and they are more flexible in practical use. Many growers also erroneously believe that high spray volumes and pressures are needed to assure good plant protection. The aim of this work was to evaluate the spray deposition, penetration, and uniformity between a manually pulled horizontal spray boom as compared with a spray gun under controlled laboratory conditions. In this study, we evaluated six spray application techniques, i.e., three spray boom and three spray gun techniques. In general, the deposition results were comparable between the spray boom and the spray gun applications. The spray boom applications, however, resulted in a more uniform spray distribution. At the plant level, the spray distribution was not uniform for any of the techniques used; the highest deposits were observed on the upper (or adaxial) side of the top leaves. Using spray guns at a higher spray pressure did not improve spray penetration in the canopy or deposition on the bottom (or abaxial) side of the leaves. Of the different nozzle types tested on the spray boom, the extended range flat fan XR 8003 gave the best results. Crop density clearly affected crop penetration and deposition on the bottom side of the leaves.
Rye Living Mulch Effects on Soil Moisture and Weeds in Asparagus
Authors: Brainard Daniel C. , Bakker John , Noyes D. Corey , Myers Norm
Published: February 2019

Living mulches growing below asparagus (Asparagus officinales) fern can improve soil health and suppress weeds but may also suppress asparagus through competition for water or nutrients. The central objective of this research was to test whether cereal rye (Secale cereale) living mulch, in combination with overhead irrigation, could provide comparable weed suppression to standard residual herbicides without reducing asparagus yields. A field experiment was conducted from 2008 to 2010 in a mature asparagus planting on sandy soils in western Michigan to evaluate the effects of irrigation (none vs. overhead) and weed management systems (standard herbicides vs. rye living mulch) on weed suppression, soil moisture content, and asparagus yield. Rye living mulch and herbicide treatments were established immediately after asparagus harvest in late June of each year. Rye living mulch reduced soil-available water in early August by 26% to 52% compared with herbicide treatments but had no detectable effect on asparagus yields. Compared with herbicide treatments, rye living mulch reduced fall-germinating weed emergence and resulted in lower densities of horseweed (Conyza canadensis) during asparagus harvest. However, in 2 of 3 years, the living mulch system resulted in higher densities of summer annual weeds—including Powell amaranth (Amaranthus powellii) and longspine sandbur (Cenchrus longispinus)—during the fern growth period compared with herbicide treatments. After 3 years, the density of summer annual weeds was more than 10-fold greater in rye living mulch treatments compared with standard residual herbicides treatments. Our results suggest that 1) soil-improving rye cover crops can partially suppress weeds but may also compete with asparagus for soil moisture in dry years unless irrigation is used; and 2) successful use of rye living mulches for weed management will depend on identification of complementary weed management practices to avoid build-up of the summer annual weed seedbank.
Posidonia-based Compost as a Peat Substitute for Lettuce Transplant Production
Authors: Mininni Carlo , Santamaria Pietro , Abdelrahman Hamada M. , Cocozza Claudio , Miano Teodoro , Montesano Francesco , Parente Angelo
Published: February 2019

Posidonia [Posidonia oceanica (L.) Delile] is a marine phanerogam endemic of the Mediterranean Sea that grows all along the coast forming extensive underwater meadows. Senescent posidonia leaves, together with fibers (residues of rhizomes and decomposed leaves), periodically accumulate along Mediterranean beaches, covering vast areas of coast. Removal and disposal of these large volumes of plant biomasses represent a high cost for local administrations. Therefore, in this experiment, beached residues of posidonia were composted with olive pruning and green wastes with the objective to assess the efficacy of posidonia-based compost (63% on a volume basis) as a peat replacement. The compost was then mixed with a peat-based commercial substrate at rates of 0% (C0, pure peat-based commercial substrate tested as control), 25% (C25), 50% (C50), 75% (C75), and 100% (C100, pure posidonia-based compost) v/v. Mixtures were used as growing media to produce lettuce seedlings for transplant. Two lettuce cultivars (8511RZ and Satine) were tested. Main physical and chemical properties of the five growing media, shoot and root fresh and dry weight, leaf area, root morphology, and elemental leaf tissue composition were studied. Growing media containing posidonia-based compost, C25 and C50 in particular, showed good physical properties. Increasing compost proportions in the mixtures resulted in enhanced: 1) availability of macro- and micronutrients in the growing media; and 2) overall growth parameters of lettuce seedlings, in particular for the cultivar Satine. In conclusion, posidonia-based compost shows a considerable potential as a peat substitute in horticultural substrates; posidonia residues are a low-cost renewable material. In growing media for lettuce seedlings production, posidonia-based compost could be used as a complement to peat at a rate of 25% or 50% to obtain optimal physical properties and to limit the negative effects of high B content, which are typical of posidonia residues.
Strip Tillage and Oat Cover Crops Increase Soil Moisture and Influence N Mineralization Patterns in Cabbage
Authors: Haramoto Erin R. , Brainard Daniel C.
Published: February 2019

Strip tillage (ST) is a form of conservation tillage in which disturbance is limited to the crop rows while the rest of the soil remains undisturbed. Compared with conventional, full-width tillage (CT), ST may reduce tillage costs, protect soil from erosion, and benefit cool-season crops including cabbage (Brassica oleracea L. var. ‘capitata’) by improving water retention, reducing soil temperatures, and improving the synchrony of inorganic nitrogen (IN) supply with crop demand. Field experiments were conducted in 2010 and 2011 in central Michigan to assess the effects of tillage (CT vs. ST) and a preceding cover crop (none vs. oats, Avena sativa L. var. ‘Ida’) on soil temperature, moisture, N dynamics, and yields in transplanted cabbage. Oats were sown in April and terminated 2 to 3 weeks before cabbage transplanting in early July. In-row (IR) soil moisture, temperature, and IN content were assessed from transplanting until cabbage harvest in October. In 2010, IR soil moisture was higher season-long in ST compared with CT and in oat compared with non-oat treatments, but these effects were not detected in 2011. Tillage and oat residue had little or no effect on IR soil temperature. Shortly after tillage in both years, soil IN availability was greater in CT treatments without oats compared with both ST treatments and CT with oats. However, these differences dissipated after 3 to 4 weeks, and hypothesized improvements in N release patterns under ST were not observed. No differences in cabbage marketable yield were detected in either year, although the proportion of plants that produced a marketable head was lower in cover-cropped plots in 2010. These findings suggest that soil conservation and input savings potentially associated with ST production systems may be attained without a yield penalty. More research is needed to understand and optimize cover crop management in ST systems to realize potential benefits in N use efficiency, moisture retention, and soil temperature moderation.
Chilling Requirements to Break Dormancy of Veratrum californicum
Authors: Sun Youping , White Sarah A. , Mann David , Adelberg Jeffrey
Published: February 2019

Veratrum californicum, a native of the western United States, has long been used in herbal medicine and now also has potential pharmaceutical uses. As a result of a projected increasing demand for V. californicum biomass for pharmaceutical purposes, the development of a chilling protocol for enhanced cultivation efficiency is needed. To study the effects of chilling on the growth of V. californicum, field-collected rhizomes with attached bulbs and roots were potted, stored at 10 °C for 2 weeks, and subsequently chilled at 5 °C for 30 to 180 days before transfer to a greenhouse or growth room. Twenty plants were transferred to the greenhouse every 30 days to observe growth. Ten plants were harvested at shoot emergence and the remaining 10 when leaves were fully expanded. In addition, 10 plants were transferred from 5 °C to a growth room every 30 days where net photosynthetic rates were measured. Longer chilling duration correlated with a reduction in days to shoot emergence and leaf expansion. The net photosynthetic rates of V. californicum plants chilled for 120, 150, or 180 days were higher than those of plants chilled for only 30, 60, or 90 days. Plants exposed to longer chilling durations were taller and had larger, more numerous leaves. Interestingly, V. californicum shoot emergence was also observed in the dark at 5 °C after the bulbs had been stored for 210 days. Growth of the root systems of plants was also observed during chilling. In conclusion, chilling was necessary at 5 °C for a minimum of 120 days to force early emergence and vigorous growth of V. californicum.
Foliar Nickel Application Can Increase the Incidence of Peach Tree Short Life and Consequent Peach Tree Mortality
Authors: Nyczepir Andrew P. , Wood Bruce W.
Published: February 2019

Peach tree short life (PTSL) is associated with the presence of ring nematode, Mesocriconema xenoplax, and poor orchard management practices. The ability of postplant nickel (Ni) foliar application to suppress M. xenoplax population density and thereby prolong survival of peach trees on a PTSL site infested with M. xenoplax was investigated from 2004 to 2011. For this study, the site was divided into plots, which received the following treatments: 1) Ni (foliar-applied); 2) methyl bromide fumigation (MBr); and 3) an untreated control. Peach trees were planted into all plots in Mar. 2005 and the foliar Ni treatment was applied three times in 2005 and 2006. Nickel did not detectably suppress M. xenoplax populations as compared with MBr fumigation. The protective effect of MBr fumigation in suppressing M. xenoplax population density persisted for 27 months after orchard establishment. Trees receiving multiple foliar Ni applications at 0.45 g·L−1 over 2 years, while exposed to M. xenoplax, exhibited greater PTSL mortality than trees growing in untreated or MBr-fumigated plots. These results suggest that foliar applications of Ni to peach trees, growing on a PTSL site, should be used with caution in commercial orchards because these treatments can deleteriously disrupt tree metabolic/physiological processes sufficient to increase the incidence of PTSL tree mortality.
Genotypic Variation of Total Phenol and Oleuropein Concentration and Antioxidant Activity of 11 Greek Olive Cultivars (Olea europaea L.)
Authors: Petridis Antonios , Therios Ioannis , Samouris Georgios
Published: February 2019

The chemical and biochemical composition of olives relies on some agronomical factors, one of which is the cultivar. In this study, fruits and leaves of 11 Greek olive cultivars were examined concerning their phenol and oleuropein concentrations. Fruit antioxidant activity was determined as well. The obtained results showed that significant differences existed among cultivars regardless of the tissue or the measured parameter. In general, leaves had higher total phenol and oleuropein concentrations than fruits. Finally, the highest oleuropein concentration in fruits was recorded in ‘Pikrolia Kerkiras’ followed by ‘Romeiki’, ‘Megaritiki’, ‘Kothreiki’, and ‘Kalamon’. These cultivars may constitute the raw material in the industrial production of oleuropein.
Assessing Nitrogen Status in Potted Geranium through Discriminant Analysis of Ground-based Spectral Reflectance Data
Authors: Wang Yun-wen , Dunn Bruce L. , Arnall Daryl B.
Published: February 2019

Nitrogen (N) deficiencies can significantly reduce plant growth as well as flower quantity and quality. However, excessive N application leads to increased production costs and may cause water contamination as a result of runoff. Ground-based remote sensing of plant chlorophyll content offers the possibility to rapidly and inexpensively estimate crop N status. The objective of this study was to test the reliability of three different Normalized Difference Vegetation Index (NDVI) measuring methods and Soil-Plant Analyses Development (SPAD) chlorophyll meter values as indicators of geranium (Pelargonium ×hortorum L.H. Bailey) N status. Two potted geranium cultivars, Rocky Mountain White and Rocky Mountain Dark Red, were supplied with N at 0, 50, 100, and 200 mg·L−1 levels, respectively. NDVI readings were measured at 45 cm above the canopy or media of individual plants or 45 cm above the canopy of a group of plants (four plants treated with the same N rate were placed together). Significant correlations existed between indirect chlorophyll content measurements of SPAD values and NDVI readings regardless of four-pot group or single-pot measurements with N application rates and leaf N concentration. Using a cross-validation technique in discriminant analysis, 70.8% to 79.2% of sample cases were correctly categorized to the corresponding N statuses including very deficient, deficient, and sufficient. Therefore, ground-based, non-destructive measurements of a chlorophyll meter and pocket NDVI unit were able to indicate N status. Considering that flower color can interfere with NDVI measurements, the chlorophyll meter may better determine N content when flowers are present.
Fruit Phosphorous and Nitrogen Deficiencies Affect ‘Grand Pearl’ Nectarine Flesh Browning
Authors: Olivos Andrés , Johnson Scott , Xiaoqiong Qin , Crisosto Carlos H.
Published: February 2019

Fruit flesh browning (FB) is a major component of cold storage disorders that limits fresh and fresh cut fruit consumption. Using fertigation, nutrient deficiencies were imposed on ‘Grand Pearl’ nectarines (Prunus persica var. nectarina) grown in sand culture for 8 years and postharvest flesh browning was studied over 2 years. Antioxidant activity, polyphenol oxidase activity, total phenolics, and fruit FB potential were evaluated. Nutrient deficiencies did not always result in leaf or fruit tissue deficiency, indicating complex interactions among nutrients during uptake and use in the plant and its fruit. Low phosphorus and nitrogen fruit concentrations were associated with biochemical browning reactions in fruit flesh at harvest and with fruit FB during storage, signs of a shorter market life and lower consumer quality. Currently recommended leaf and fruit nutrient critical values are based only on production and do not address postharvest quality. Further research is needed to determine new recommended leaf and fruit nutrient values suitable for both production and maintaining fruit quality during storage.
Removal of Bunches or Spikelets Is Not Effective for the Control of Aceria guerreronis
Authors: Melo José Wagner S. , Domingos Cleiton A. , Pallini Angelo , Oliveira José Eudes M. , Gondim Manoel G.C.
Published: February 2019

Worldwide, there remains a reliance on repeated chemical applications as a control strategy for the coconut mite, but these are impractical, not economical, and environmentally hazardous. In this study, the damage severity of Aceria guerreronis on coconut fruits was studied under different conditions to investigate the effects of bunch management on the amount of damage to newly produced bunches. The damage was evaluated using a diagrammatic scale under four different conditions: 1) plants with bunches removed; 2) bunches with the distal portion of the spikelet removed; 3) bunches sprayed monthly with abamectin (9 g a.i./ha); and 4) control plants. For each treatment, two fruits from bunches 1 to 6 (counted from the last open inflorescence) from 10 plants were randomly collected every month for 4 months. The removal of the distal portion of the spikelets had no effect on the damage level of new bunches but delayed the damage severity by ≈1 month. After the removal of all of the bunches, the damage severity was restored within 2 months to the newly produced bunches, whereas the chemical control with abamectin kept the A. guerreronis damage intensity at a low level. Thus, the removal of bunches or the distal portion of spikelets is not an effective practice for the control of A. guerreronis in areas with high levels of infestation.
Using New Gas Exchange Methods to Estimate Mesophyll Conductance and Non-stomatal Inhibition of Photosynthesis Caused by Water Deficits
Authors: Bunce James
Published: February 2019

Soil water deficits remain one of the most important factors reducing the yield of crop plants and may become even more limiting with changes in the global climate and competition for fresh water resources. Soil water deficits reduce plant growth partly by reducing photosynthesis. However, it remains unclear how important non-stomatal factors are in limiting photosynthesis under moderate water stress and whether rising atmospheric carbon dioxide may alter which processes limit photosynthesis under water stress. The conductance to CO2 from the substomatal air space to the site of carboxylation inside chloroplasts in C3 plants is now termed mesophyll conductance. Because of the competition between CO2 and O2 for RuBisco, the carbon dioxide concentration at the chloroplast can be estimated from the O2 sensitivity of photosynthesis, providing a new method of estimating mesophyll conductance. It has also recently been realized that partial stomatal closure resulting from water stress can often be reversed by exposing leaves to low CO2. This provides a new means of assessing the non-stomatal component of the inhibition of photosynthesis by water stress. These methods were applied to four C3 species and revealed that mesophyll conductance decreased substantially with water stress in two of the four species and that reopening of stomata did not eliminate the reduction in photosynthesis caused by moderate water stress at either the current ambient or elevated CO2 concentrations.
Magnitude of Genotype × Environment Interactions Affecting Tomato Fruit Quality
Authors: Panthee Dilip R. , Cao Chunxue , Debenport Spencer J. , Rodríguez Gustavo R. , Labate Joanne A. , Robertson Larry D. , Breksa Andrew P. , van der Knaap Esther , McSpadden Gardener Brian B.
Published: February 2019

There is a growing interest by consumers to purchase fresh tomatoes with improved quality traits including lycopene, total soluble solids (TSS), vitamin C, and total titratable acid (TTA) content. As a result, there are considerable efforts by tomato breeders to improve tomato for these traits. However, suitable varieties developed for one location may not perform the same in different locations. This causes a problem for plant breeders because it is too labor-intensive to develop varieties for each specific location. The objective of this study was to determine the extent of genotype × environment (G×E) interaction that influences tomato fruit quality. To achieve this objective, we grew a set of 42 diverse tomato genotypes with different fruit shapes in replicated trials in three locations: North Carolina, New York, and Ohio. Fruits were harvested at the red ripe stage and analyzed for lycopene, TSS, vitamin C, and TTA. Analysis of variance (ANOVA) revealed that there were significant differences (P < 0.05) among tomato genotypes, locations, and their interaction. Further analysis of quality traits from individual locations revealed that there was as much as 211% change in performance of some genotypes in a certain location compared with the average performance of a genotype. Lycopene was found to be most influenced by the environment, whereas TTA was the least influenced. This was in agreement with heritability estimates observed in the study for these quality traits, because heritability estimate for lycopene was 16%, whereas that for TTA was 87%. The extent of G×E interaction found for the fruit quality traits in the tomato varieties included in this study may be useful in identifying optimal locations for future field trials by tomato breeders aiming to improve tomato fruit quality.
Improving Growth and Productivity of Early-season High-tunnel Tomatoes with Targeted Temperature Additions
Authors: Hunter Britney , Drost Dan , Black Brent , Ward Ruby
Published: February 2019

In northern climates where the growing season is shortened by cool spring conditions, high tunnels make it possible to plant and produce tomatoes (Solanum lycopersicum L.) at least 1 month earlier than in the field. However, limited high-tunnel research has been performed in arid high-elevation regions that experience extreme diurnal temperature fluctuations. High tunnels are designed to be passively heated; therefore, additional protection from frost may be warranted if growers wish to plant significantly earlier than normal. Low tunnels built within a high tunnel reduce the energy requirement by concentrating heat around the plants, particularly when a heat source is placed inside the low tunnel. ‘Sunbrite’ tomatoes were transplanted through black plastic mulch in four high tunnels in North Logan, UT (lat. 41.73° N, long. 111.83° W, 1382 m elevation) on 17 Mar., 30 Mar., and 7 Apr. in 2009 and on 19 Mar., 30 Mar., and 9 Apr. in 2010. Low tunnels were constructed over each row, and three supplemental heat treatments (unheated, soil-warming cables, and soil-warming cables plus 40-W incandescent lights) were tested to improve plant performance. The highest total marketable yield was achieved for earliest planting dates in both 2009 and 2010. In 2009, early-season yield was significantly greater when both the soil + air were heated, but only for the earliest planting date. In 2010, soil heat alone and in conjunction with air heat significantly improved early-season yield. Information gathered in this study on planting dates, yield, and energy costs provides valuable production and economic information to growers in arid high-elevation climates who desire the benefits of growing early-season tomatoes in high tunnels.
Evaluation of ‘Miniverde’ Bermudagrass and ‘Diamond’ Zoysiagrass Putting Green Establishment using Granular Fertilizer Applications
Authors: Briscoe Kyle , Miller Grady , Brinton Scott , Bowman Dan , Peacock Charles
Published: February 2019

‘Miniverde’ bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis (Burtt-Davy)] and ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.] are becoming more widely used on putting greens in the transition zone. Field studies were conducted from June through Aug. 2008 and 2009 in Raleigh, NC, and in Jackson Springs, NC, respectively. The objective was to determine the influence of granular fertilizer programs consisting of various nitrogen (N) sources and rates on the establishment of ‘Miniverde’ and ‘Diamond’ from sprigs. In 2008, the experimental area consisted of a putting green built to U.S. Golf Association (USGA) recommendations [85 sand:15 peat (v/v)]. A native sandy-soil putting green was used in 2009. Fertilizer programs consisting of stabilized urea, polymer-coated urea, and a combination of stabilized urea and activated sewage sludge were initiated 1 week after planting (WAP). Nitrogen rates ranged from 12 to 48 kg·ha−1/week. Nitrogen source and rate differentially influenced turf color and establishment. The combination program increased color of both grasses to an acceptable level earlier than other programs. Coverage rates of both grasses under the combination program were significantly higher than other programs across both years. Despite having the most total N applied, the polymer-coated urea program did not significantly enhance bermudagrass and zoysiagrass color or establishment compared with other programs. Increasing the N rate of stabilized urea from 12 to 24 kg·ha−1/week did not increase establishment for either grass. This research indicates that ‘Miniverde’ bermudagrass and ‘Diamond’ zoysiagrass planted in the summer can be completely established from sprigs in the transition zone using granular fertilizer. However, turfgrass color and coverage may vary depending on N sources and rates within the fertilizer program.
Growing Degree-day Models for Predicting Lowbush Blueberry (Vaccinium angustifolium Ait.) Ramet Emergence, Tip Dieback, and Flowering in Nova Scotia, Canada
Authors: White Scott N. , Boyd Nathan S. , Van Acker Rene C.
Published: February 2019

Experiments were established to evaluate the suitability of growing degree-day (GDD, Tbase = 0 °C) models for predicting emergence, tip dieback, and flowering of lowbush blueberry ramets in Nova Scotia, Canada. Data for model development were collected from quadrats established in several non-bearing and bearing blueberry fields throughout the dominant blueberry production areas in northern and central Nova Scotia. Blueberry ramets emerged between 222 and 265 GDD (6 May to 14 May) and reached 90% emergence between 619 and 917 GDD (7 June to 5 July). Emergence continued to slowly increase until late summer or early fall. Tip dieback began between 598 and 792 GDD (14 June to 21 June) and duration of this phase depended on whether late-emerging ramets developed to tip dieback. A four-parameter Weibull and a three-parameter Gompertz equation adequately explained cumulative blueberry ramet emergence and cumulative ramets at tip dieback as functions of GDD in the non-bearing year, respectively. The four-parameter Weibull function also explained the relationship between cumulative flowering ramets and GDD in the bearing year. Flowering ramets were first observed between 376 and 409 GDD (19 May to 30 May) in the bearing year. Model predictions for initiation of emergence, tip dieback, and flowering were 243, 692, and 389 GDD, respectively. Models were validated with independent data sets collected throughout northern and central Nova Scotia. The relationship between the percentage of open flowers on individual ramets and GDD in the bearing year was well described by a Gaussian model at two sites with a predicted peak number of open flowers between 552 and 565 GDD.
Mammoth™ ‘Twilight Pink Daisy’ Garden Chrysanthemum
Authors: Anderson Neil O. , Gesick Esther , Ascher Peter D. , Poppe Steven , Yao Shengrui , Wildung David , Johnson Patricia , Fritz Vincent , Rohwer Charlie , Klossner Lee , Eash Neal , Liedl Barbara E. , Reith-Rozelle Judith
Published: February 2019

Mammoth™ ‘Twilight Pink Daisy’ (U.S. Plant Patent 14,455; Canadian Plant Breeders’ Rights Certificate No. 4192) is an interspecific garden chrysanthemum cultivar, Chrysanthemum ×hybridum Anderson (= Dendranthema ×hybrida Anderson) with common names of hardy mum, chrysanthemum, and garden mum. It is a new and distinct form of shrub-type garden mums in the Mammoth™ series with rosy-pink ray florets, a dark “eye” color in the center of the disc florets, frost-tolerant flower petals, and self-pinching growth. This cultivar is a butterfly attractant in the garden. Mammoth™ ‘Twilight Pink Daisy’ is a winter-hardy herbaceous perennial in USDA Z3b–Z9 (Southeast)/Zone 10 (West) with its cushion growth form displaying extreme hybrid vigor, increasing in plant height from 0.46 m in its first year to a shrub of 0.76 to 1.22 m in the second year and thereafter with greater than 3000 leaves/plant. Flowering is prolific, covering the entire plant at full flowering with as many as greater than 3500 flowers in the second year. Chemical abbreviations: ethanol (EtOH), indole-3-butyric acid (IBA).
A Study of Morphophysiological Descriptors of Cultivated Anthurium andraeanum Hort.
Authors: Elibox Winston , Umaharan Pathmanathan
Published: February 2019

Sixteen morphophysiological parameters of horticultural importance were investigated in 82 anthurium accessions grown in the Caribbean. The spathe colors included red, pink, white, green, orange, purple, coral, and brown and obake types with red, pink, and white spathe colors accounting for 63.4% of the accessions. There was wider variation in spadix color combinations than spathe color. There was wide variation for the cut flower and leaf parameters evaluated with productivity and peduncle length having the smallest and largest range, respectively. The frequency distributions were skewed to the right for spathe length, spathe width, spathe size, spadix length, spadix diameter, leaf width, leaf size, and productivity and was normal for leaf length, spadix angle, peduncle length, petiole length, and spathe showiness. Accessions with wider leaves had longer leaves and longer petioles; those with longer spathes had wider spathes; and those with longer peduncles had correspondingly longer petioles. Peduncle length also showed moderate, weak correlations with other leaf measurements and spathe parameters, respectively. Spadix diameter showed moderate correlations with leaf parameters. Spathe showiness showed moderate, weak correlations with spathe measurements and productivity, respectively. Principal component analysis of the 13 quantitative parameters showed that the first three principal components explained 75% of the variation in the accessions. Leaf length, leaf width, leaf size, petiole length, peduncle length, and spadix diameter; spathe length, spathe width, spathe size, and spathe showiness; and productivity loaded on the first, second, and third component, respectively. Hence, one leaf and one spathe size parameter, spathe showiness, petiole length, peduncle length, spadix length, spadix angle, spadix diameter, and productivity as well as spathe, spadix, peduncle, and petiole colors can be used as descriptors for anthurium. Based on these results and market information, an Anthurium ideotype adapted to the humid tropics is described.
Temperature-induced Glucosinolate Accumulation Is Associated with Expression of BrMYB Transcription Factors
Authors: Justen Veronica L. , Fritz Vincent A.
Published: February 2019

Turnips (Brassica rapa. subsp. rapa L.) produce glucosinolates (GSLs), thioglucosides whose hydrolyzed derivatives have been shown to provide chemopreventive benefits. Two cultivars of turnips [‘Just Right’ (JR) and ‘Scarlet Queen’ (SQ)] were grown under three different temperature regimes to assess the role of temperature on GSL production in roots and shoots. When compared with low-temperature treatments, high-temperature treatments increased total and individual GSLs in a tissue- and genotype-specific manner. When compared with low-temperature treatments, total GSLs were ≈70% and 130% higher in JR shoots and roots, respectively, grown at high-temperature treatments. High temperatures also increased total GSLs in SQ shoots and roots by ≈80% and 85%, respectively, when compared with low temperatures. Gluconasturtiin (GNS, 2-phenylethyl GSL) concentration was inversely correlated with temperature with high-temperature treatments resulting in 20% and 48% less GNS than low-temperature treatments in JR and SQ roots, respectively. The indolic GSL, 1-methoxyglucobrassicin (1MGB; 1-methoxy-3-ylmethyl GSL), was the root GSL most elevated by increased temperature resulting in a 1000% increase on average in both cultivars between the low- and high-temperature treatments. These results show promise for the use of temperature to enhance the health-promoting properties of turnip because 1MGB has potent chemopreventive effects. Gene expression analysis suggests that some BrMYB transcription factor expression levels are associated with temperature-dependent changes in GSL accumulation; however, this association varies between cultivar and tissue type.
Evaluating Paradox Walnut Rootstocks for Resistance to Armillaria Root Disease
Authors: Baumgartner Kendra , Fujiyoshi Phillip , Browne Greg T. , Leslie Chuck , Kluepfel Daniel A.
Published: February 2019

The most common rootstock for Juglans regia (Persian or “English” walnut) in California is Paradox, typically a hybrid of J. hindsii (Northern California black walnut) × J. regia. Unfortunately, Paradox is very susceptible to Armillaria root disease. The relative resistance to Armillaria mellea of six clonally propagated Paradox rootstocks (AX1, Px1, RR4 11A, RX1, Vlach, VX211) was evaluated and compared with that of clonally propagated J. hindsii rootstock selection W17, J. regia scion cultivar Chandler, and Pterocarya stenoptera (Chinese wingnut). In a growth-chamber assay, plants were micropropagated and rooted in vitro before inoculating the culture medium with A. mellea. At two months post-inoculation, the most resistant and susceptible Paradox rootstocks were AX1 and VX211, respectively, with 9% vs. 70% mortality, and this finding was consistent across three isolates of A. mellea and three replicate experiments. This broad range of resistance within Paradox is consistent with past field trials that tested other genotypes. Our finding of similarly high susceptibility of ‘Chandler’ and W17 (61% vs. 69% mortality) is in contrast to two field trials, in which other J. regia genotypes were more susceptible than those of J. hindsii. A third trial, however, identified some J. regia genotypes as more resistant than those of J. hindsii. Therefore, it is possible that W17, which was not previously tested, is an Armillaria-susceptible genotype of J. hindsii. Based on our findings of repeatable mortality levels across three isolates of A. mellea and three replicate experiments, the growth-chamber assay has promise, albeit with confirmed resistant and susceptible controls, for identifying putative resistant rootstocks (e.g., AX1) in preparation for a field trial with controlled inoculations.
Early-season Soil Moisture Deficit Reduces Sweetpotato Storage Root Initiation and Development
Authors: Gajanayake Bandara , Reddy K. Raja , Shankle Mark W. , Arancibia Ramon A.
Published: February 2019

Sweetpotato [Ipomoea batatas (L.) Lam.] storage root formation is a complex developmental process. Little quantitative information is available on storage root initiation in response to a wide range of soil moisture levels. This study aimed to quantify the effects of different levels of soil moisture on sweetpotato storage root initiation and to develop functional relationships for crop modeling. Five levels of soil moisture, 0.256, 0.216, 0.164, 0.107, and 0.058 m3·m−3 soil, were maintained using sensor-based soil moisture monitoring and semiautomated programmed irrigation. Two commercial sweetpotato cultivars, Beauregard and Evangeline, were grown in pots under greenhouse conditions and treatments were imposed from transplanting to 50 days. Identification of storage roots was based on anatomical, using cross-sections of adventitious roots, and visual features harvested at 5-day intervals from 14 to 50 days after transplanting (DAT). Recorded time-series storage root numbers exhibited sigmoidal responses at all soil moisture levels in both cultivars. Time to 50% storage root initiation and maximum storage root numbers were estimated from those curves. Rate of storage root development was determined as a reciprocal of time to 50% storage root formation data. Time to 50% storage root initiation declined quadratically from 0.05 to 0.15 m3·m−3 soil moisture and increased slightly at the higher soil moisture levels in both the cultivars. Cultivars differed in time to 50% storage root initiation and the storage root developmental rate. Soil moisture optima for storage root initiation were 0.168 and 0.199 m3·m−3 soil, equivalent to 63% and 75% field capacity for cultivars Beauregard and Evangeline, respectively. The data and the inferences derived from the functional algorithms developed in this study could be used to advise growers to schedule irrigation more precisely, make planting decisions based on available soil moisture, and to develop sweetpotato crop models for field applications.
Planting Configuration and Plasticulture Effects on Growth, Physiology, and Yield of Globe Artichoke
Authors: Leskovar Daniel I. , Xu Chenping , Agehara Shinsuke
Published: February 2019

Globe artichoke is typically grown in Mediterranean and coastal areas. Because of the high profitability as a specialty crop, demand to develop production systems optimized for other semiarid and water-limited regions is rising. Field experiments were conducted over three seasons (2008–09, 2010–11, and 2011–12) in southwest Texas to investigate plant growth, physiology, and yield of artichoke grown as an annual system. Three strategies were evaluated: planting configuration (single and double lines per bed), plasticulture (bare soil and black plastic mulch), and cultivars differing in maturity (‘Imperial Star’, early; ‘Green Globe Improved’, late). Each fall, transplants were established in the field at 2.03 m between rows and 0.90 m between plants (single line) or 4.06 m between rows and 0.90 m between plants (double line). In both cultivars, black plastic mulch enhanced plant growth (leaf number, plant height and width) and increased early yield; however, its effect on total yield and yield components was not consistent. Single line per bed significantly increased head number of jumbo and large size per plant as compared with double line in the 2009 season. Chlorophyll index was unaffected by either planting configuration or plastic mulch. Comparing cultivars, ‘Green Globe Improved’ had lower marketable yield but bigger head size than ‘Imperial Star’ in one and two seasons, respectively. Our results indicate that single line with black plastic mulch can be recommended to improve earliness and water savings as compared with the bare soil system for annual artichoke production.
Do Phytotoxic Compounds in Soils after Scale-infested Cycas micronesica Litter Deposits Explain Reduced Plant Growth?
Authors: Marler Thomas E. , Dongol Nirmala
Published: February 2019

We used activated charcoal methods to test for the presence of phytotoxic substances in soils that had received inputs of decomposing Cycas micronesica K.D. Hill leaves and stems that were heavily infested with the armored scale Aulacaspis yasumatsui Takagi. Velocity of Momordica charantia Descourt. and Carica papaya L. seedling emergence was increased by the addition of charcoal to these soils. Furthermore, M. charantia and C. papaya seedling height and dry weight were among the response variables that were increased by the addition of charcoal. Legacy effects of scale-infested C. micronesica plant litter deposited in these soils resulted in phytotoxic compounds that inhibited seedling emergence and plant growth. Scale-infested Cycas leaves should not be used as mulch or in compost until phytotoxic causal mechanisms are more fully understood.