bluuebunny/crossref_metadata_2025 huggingface dataset:
Development and Evaluation of a Portable, Handheld Mechanical Shaker to Study Fruit Detachment in Blueberry
Authors: Malladi Anish , Vashisth Tripti , NeSmith Scott
Published: February 2019

A portable, handheld, mechanical shaking device was developed and its effects on fruit detachment in rabbiteye bluebbery (Vaccinium ashei Reade) and southern highbush blueberry (hybrids of mostly Vaccinium corymbosum L. and Vaccinium darrowi Camp.) were evaluated. The instrument facilitated effective detachment of fruit within a branch, especially in rabbiteye blueberry (greater than 75%). Approximately 3 to 4 seconds of shaking was sufficient to detach the majority of the fruit. Differences in the extent of fruit detachment were observed across the genotypes, especially among southern highbush blueberry genotypes. The majority of fruit detachment in rabbiteye blueberry and most of the southern highbush blueberry genotypes occurred at the point of attachment of the pedicel to the berry, although a significant portion detached with the stem intact, resulting in stemmy fruit. Although only a small proportion of the detached fruit was immature in the rabbiteye blueberry genotypes, up to 23% of the detached fruit was immature in the southern highbush blueberry genotypes. Application of the abscission agents methyl jasmonate (MeJa; 20 mm) and ethephon (1000 mg·L−1) reduced the time required for fruit detachment on mechanical shaking by up to 5-fold. Together, these data indicate that the mechanical shaking device developed here is an effective tool for studying fruit detachment in blueberry. This instrument has potential applications in blueberry research programs evaluating fruit production. It can be used in breeding programs to aid in the selection of genotypes with fruit detachment characteristics that are potentially better suited for mechanical harvesting, and also in programs involving the screening and evaluation of abscission agents in blueberry.
Production of Amphidiploids of the Hybrids between Solanum macrocarpon and Eggplant
Authors: Mizanur Rahim Khan Md. , Hasnunnahar Mst. , Isshiki S.
Published: February 2019

To restore fertility of the F1 between Solanum macrocarpon and eggplant, amphidiploids were produced through doubling of chromosomes by colchicine treatment. Shoot tips and axillary buds of F1 plants were kept for 2 and 4 days in liquid Murashige and Skoog (MS) media with 0.05% colchicine. As a result of colchicine treatment, two amphidiploids were identified by observing root tip cell chromosome number, stomatal guard cell size, and pollen characteristics. The amphidiploids contained 48 chromosomes, twice the normal diploid number of 24. Stomata size and pollen diameter were significantly larger in amphidiploids than F1. Flower diameter and length and width of anther, petal, and sepal were significantly larger in the amphidiploids than in F1. Pollen stainability was 40% in amphidiploids but only 0.86% in the diploid F1. The amphidiploids, after selfing and backcrossing with S. macrocarpon, set fruits with healthy seeds. Therefore, production of amphidiploids by colchicine treatment restored the pollen and seed fertility of F1 between S. macrocarpon and eggplant. The amphidiploids produced in this study would be very useful in future breeding programs of eggplant.
Optimum Plot Size for Field Trials of Taro (Colocasia esculenta)
Authors: Miyasaka Susan C. , McCulloch Charles E. , Fogg Graham E. , Hollyer James R.
Published: February 2019

Taro (Colocasia esculenta L. Schott) is a root crop widely grown in the Tropics. To determine the optimum plot size for taro field trials, fresh and dry weights of individual corms were collected from two field trials conducted under flooded culture and two conducted under upland culture. For a given maximum test plot with a single border row surrounding inner measured plants, all possible combinations of smaller plot sizes were investigated. A plot size was defined as a given number of adjacent plants. A strong linear relationship was found between the natural logarithm of variance of yield and the natural logarithm of plot size. Expressed on the non-log-transformed scale, the point of maximum curvature in this relationship indicates a sudden decrease in advantage to larger plot sizes and is taken as optimum. Calculating maximum curvature mathematically, optimum plot size was 21 inner plants (5.7 m2) for the second flooded trial and 18 inner plants (4.9 m2) for the second upland trial. Another method of estimating optimum plot size minimized the cost per unit of research data by using the index of degree of correlation between neighboring plots. In three of four trials, the optimum plot size ranged from 16 to 24 inner plants (4.3 to 6.5 m2). In this second method, we calculated a non-linear relationship between plot size and outer border plants to estimate the fixed and per-unit cost of a single border row surrounding the inner measured plants. Both methods of calculating optimal plot size sometimes resulted in estimates that exceeded the maximum test plot size for particular field trials, indicating limitations of each method and the importance of managing field trials to ensure uniformity across treatments. No evidence of spatial autocorrelation was found in the corm yield of taro, indicating that the two methods used were adequate in calculating optimum plot size. In addition, we conducted an analysis based on statistical power but found that plot size did not materially affect the power to detect differences between treatments. To our knowledge, this is the first report of optimum plot size for field trials of taro.
Effect of Foliar Application of Methyl Jasmonate and Extracts of Juniper and Sagebrush on Essential Oil Yield and Composition of ‘Native’ Spearmint
Authors: Zheljazkov Valtcho D. , Astatkie Tess , Jeliazkova Ekaterina
Published: February 2019

Spearmint (Mentha spicata L.) is a major essential oil crop in the United States. Developing means for increased biomass and oil yields and increased concentrations of carvone would be beneficial for the essential oil industry. A field experiment was conducted to study the effect of foliar application treatments [water (control), water + Tween20, sagebrush essential oil + Tween20, sagebrush water extract, juniper essential oil + Tween20, juniper water extract, and methyl jasmonate] on ‘Native’ spearmint essential oil content, shoot fresh weight, oil yield, and oil composition. The essential oil content was low in the water + Tween20 and in juniper essential oil (EO) + Tween20 treatments and high in the juniper water extract and in methyl jasmonate (MJ) treatments; however, neither of these were different from the water control or from the sagebrush EO + Tween20. Biomass fresh weight was lower in the sagebrush water extract (SWE) and in the juniper water extract (JWE) relative to the water control. The application of juniper EO + Tween20 reduced the concentration of carvone in the oil relative to the water control or to the water + Tween20 treatment. The sagebrush water extract, juniper EO + Tween20, juniper water extract, and MJ increased the concentrations of beta-caryophyllene relative to the water treatment. The concentration of trans-beta-farnesene was lower in the control water treatment and higher in all other treatments. Also, with the exception of sagebrush EO + Tween20, all treatments increased the concentration of germacrene D relative to the water control but not relative to water + Tween20. This study demonstrated that foliar application of sagebrush EO, sagebrush water extract, juniper EO, or juniper water extract to ‘Native’ spearmint may affect the essential oil profile of spearmint essential oil. Some of the treatments increased the concentrations of beta-caryophyllene, trans-beta-farnesene, and germacrene D in the essential oil; however, neither of the treatments increased the concentration of carvone, the main essential oil constituent of ‘Native’ spearmint oil.
Eastern Filbert Blight-resistant Hazelnuts from Russia, Ukraine, and Poland
Authors: Capik John M. , Muehlbauer Megan , Novy Ari , Honig Josh A. , Molnar Thomas J.
Published: February 2019

Stable genetic resistance to the fungal disease eastern filbert blight (EFB), caused by Anisogramma anomala, is vital for sustainable production of European hazelnut (Corylus avellana) in eastern North America. In this study, new hazelnut germplasm from the Russian Federation, Ukraine, and Poland (a total of 1844 trees from 66 seed lots) was subjected to A. anomala under field conditions over at least five years in New Jersey. Plants were then rated for the presence of EFB using an index of 0 (no disease) through 5 (all stems containing cankers). Nuts of the resistant trees were evaluated to identify plants with improved kernel characteristics. Genomic DNA of these trees was also screened with sequence-characterized amplified region (SCAR) markers generated by the primers BE-03, BE-33, and BE-68, which are closely linked to the single dominant R-gene of ‘Gasaway’, to assess the resistant seedlings for the presence of this well-known source of resistance. At final evaluation, 76 trees remained free of disease with nine expressing only minor symptoms (rating 1 or 2). The resistant trees spanned 24 different seed lots representing all three countries. The remaining trees ranged from moderately to severely infected with 81% of the total collection rating 5. Several of the resistant trees were found to produce commercial-sized (≈12 mm diameter), round kernels that blanched well. Although the results of the ‘Gasaway’ SCAR primers were inconclusive, the diverse collection origins and disease phenotypes provide evidence that novel sources of resistance were likely identified in this study. These new plants should broaden the genetic base of EFB-resistant C. avellana hazelnut germplasm available for breeding.
Effects of Preharvest Weather Conditions on Firmness of ‘McIntosh’ Apples at Harvest Time
Authors: Lachapelle Maude , Bourgeois Gaétan , DeEll Jennifer R.
Published: February 2019

Apple fruit firmness is one of the main attributes indicating fruit quality at harvest. It is affected by numerous factors during the entire growing season. The effects of weather conditions during apple development are often mentioned as a result of their impact on attributes linked to fruit firmness: fruit size, calcium concentration, water content, etc. In this study, the effects of weather conditions on ‘McIntosh’ apple (Malus ×domestica Borkh. cv. McIntosh) firmness at harvest time were analyzed. Fruit were harvested at nine sites in Quebec and Ontario over 15 years (1996–2011). For each case, weather parameters were analyzed from full bloom until harvest, either in monthly subperiods from May until September or in terms of days from full bloom (DFB) until harvest. Regression results highlighted the negative effect of lower air temperature conditions from 31 to 60 DFB, higher air temperature conditions and precipitations from 61 to 90 DFB, and higher temperature conditions from 91 DFB until harvest on ‘McIntosh’ apple firmness level at harvest. Precipitation from 61 to 90 DFB alone explained 39% of ‘McIntosh’ apple firmness variation at harvest time. The prediction of apple firmness at harvest time could be helpful for producers to adjust their marketing and storage strategies according to apple quality level.
Effect of Diagonal Cut Surface Length on Graft Success and Growth of Mangifera indica, Persia americana, and Prunus persica
Authors: Mng’omba Simon A. , du Toit Elsa S.
Published: February 2019

Grafting has been a common propagation method in many fruit trees to achieve fruiting precocity. Its success has depended on proper alignment of parenchymatous tissues of both scions and their respective rootstocks. Although grafting has been practiced for a long time, the right or ideal length of a diagonal cut surface that promotes proper alignment of vascular bundles of both graft partners to ensure fast graft-take and eventually graft success have not been investigated. An experiment was carried out on mango, avocado, and peach trees with an objective of establishing suitable or correct length of a diagonal cut surface when grafting (splice method) to improve graft success. Diagonal cut surface lengths applied to both scions and rootstocks included 5 mm, 10 mm, 20 mm, 40 mm, 60 mm, 80 mm, or 100 mm with at least three grafters treated as a random component. A significant difference (P < 0.0001) was found among the diagonal cut surface lengths and over 80% of graft success was obtained with 40- to 100-mm diagonal cut surface lengths, especially for mango. Significant differences (P < 0.0001) were also obtained in shoot length and stem diameter size (thickness) for all tree crops studied and also for number of leaves except for avocado plants. It is concluded that improved graft success can be achieved with a diagonal cut surface length of 40 mm long with the need for a few grafting strips.
Investigation of the Origin of Aronia mitschurinii using Amplified Fragment Length Polymorphism Analysis
Authors: Leonard Peter J. , Brand Mark H. , Connolly Bryan A. , Obae Samuel G.
Published: February 2019

Aronia Medik., commonly known as chokeberry, is a genus of deciduous, multistemmed, rosaceous shrubs native to eastern North America. Three species of chokeberry are commonly accepted, A. arbutifolia (L.) Pers., red chokeberry, A. melanocarpa (Michx.) Elliott, black chokeberry, and A. prunifolia (Marshall) Rehder, or purple chokeberry. In Europe, a fourth species of human origin is recognized as Aronia mitschurinii A.K.Skvortsov & Maitul. In North America this type of Aronia is described as cultivars of A. melanocarpa, including ‘Viking’, ‘Nero’, and ‘Aron’. This species is characterized by near homogeneity of the population, tetraploidy, and a distinct morphology with more robust stems, wider leaf blades, and larger fruits than wild populations of A. melanocarpa. It has been proposed that this genotype originated from Russian pomologist Ivan Michurin’s early 20th century experiments involving Aronia × Sorbus hybridization. In this study we used amplified fragment length polymorphic (AFLP) markers to elucidate the relationships of A. mitschurinii to wild North American Aronia, ×Sorbaronia C.K. Schneid, Sorbus L., and six additional genera from subtribe Pyrinae (Rosaceae). Data from seven primer combinations were interpreted by the NTSYSpc software package into a similarity matrix using Jaccard’s coefficient. Clustering of AFLP similarity data using the unweighted pair group method with arithmetic mean (UPGMA) identified A. mitschurinii as distinct from wild Aronia, grouping it close to ×Sorbaronia fallax C. K. Schneid. and ×Sorbaronia ‘Ivan’s Beauty’. Non-metric multidimensional scaling (nMDS) also demonstrated a relationship between A. mitschurinii, ×Sorbaronia fallax, a ×Sorbaronia × Aronia backcross and compound-leaved Sorbus.
Plant Growth-promoting Rhizobacteria Mitigate Deleterious Effects of Salt Stress on Strawberry Plants (Fragaria ×ananassa)
Authors: Karlidag Huseyin , Yildirim Ertan , Turan Metin , Pehluvan Mucahit , Donmez Figen
Published: February 2019

The effect of selected plant growth-promoting rhizobacteria (PGPR) on the growth, chlorophyll content, nutrient element content, and yield of strawberry plants under natural field salinity conditions stress was investigated. Field experiments were conducted using a randomized complete block design with five PGPRs (Bacillus subtilis EY2, Bacillus atrophaeus EY6, Bacillus spharicus GC subgroup B EY30, Staphylococcus kloosii EY37, and Kocuria erythromyxa EY43) and a control (no PGPR) in 2009 and 2010. PGPR inoculations significantly increased the growth, chlorophyll content, nutrient element content, and yield of strawberry plants. PGPR treatments lowered electrolyte leakage of plants under saline conditions. The leaf relative water content (LRWC) of plants rose with bacterial inoculation. All nutrient element contents of leaves and roots investigated were significantly increased with PGPR inoculations with the exception of sodium (Na) and chlorine (Cl). The highest efficiency to alleviate salinity stress on the yield and nutrient uptake of strawberry plants was obtained from EY43 (228 g per plant) and EY37 (225 g per plant) treatment and the yield increasing ratio of plants was 48% for EY43 and 46% for EY 37 compared with the control treatment (154 g per plant). The highest nitrogen (N), potassium (K), phosphorus (P), calcium (Ca), magnesium (Mg), sulfur (S), manganese (Mn), copper (Cu), and iron (Fe) concentrations were obtained from EY43 and followed by E6, E37, and E30, and increasing ratio of leaves and root N, P, K, Ca, Mg, S, Mn, Cu, and Fe contents were 22% to 33%, 34% to 8.8%, 89% to 11%, 11.0% to 7.2%, 5.1% to 6.2%, 97% to 65%, 120% to 140%, 300% to 15%, and 111% to 9.0%, respectively. The results of the study suggested that PGPR inoculations could alleviate the deleterious effects of salt stress conditions on the growth and yield of strawberry plants under salinity conditions.
Vegetative Compensation Response of a Procumbent Grapevine (Vitis vinifera cv. Syrah) Cultivar under Mechanical Canopy Management
Authors: Kurtural S. Kaan , Wessner Lydia F. , Dervishian Geoffrey
Published: February 2019

A trial in the San Joaquin Valley of California investigated how the interaction of pruning systems and mechanical shoot thinning affected canopy performance, yield components, fruit phenolic composition at harvest, and production efficiency of a procumbent cultivar in a warm climate grape-growing region. Two pruning systems and three shoot thinning treatments were arranged factorially in a randomized complete block design with four replications. The pruning methods were applied by either hand-pruning to a target of 25 nodes/m or mechanically hedging and retaining a 100-mm spur height. The shoot density treatments were applied mechanically at a modified Eichhorn-Lorenz scale, stage 17 to retain 40 or 45 shoots/m of a row, or left unthinned. The contribution of count shoots to total shoots increased when mechanical box pruning replaced spur pruning. The contribution of percent count shoots to total shoots was greatest with 40 shoots/m and unthinned treatments. The percent photosynthetically active radiation (PAR) transmission and percent canopy gaps increased with mechanical box pruning and also with the decrease in shoot density per meter of row. Berry and cluster size decreased with mechanical box pruning application. However, because mechanically box-pruned vines carried more clusters, yield per meter of row increased. There was a quadratic response to shoot thinning where berry skin phenolics, anthocyanins, and tannins decreased with the 45 shoots/m treatment when compared with 40 shoots/m and unthinned treatments. Pruning weight per meter of row and leaf area-to-fruit ratio decreased, whereas Ravaz Index (kg yield/kg pruning weight) increased with mechanical box pruning. Shoot thinning treatments did not affect pruning weight per meter of row or leaf area-to-fruit ratio. Increasing amount of PAR and percent canopy gaps by shoot thinning resulted in vegetative compensation from a sparsely populated grapevine canopy, thereby negating its purported effects. The 40 and 45 shoots/m treatments repopulated the canopy rapidly with non-count shoots thereby increasing the pruning weight per meter of row at the end of the season. In the absence of a physiological response, shoot thinning in a procumbent cultivar is not recommended. Mechanically box pruning to a 100-mm spur height and slowing down vegetative growth by irrigating to 50% of daily evapotranspiration (ETo) variance between fruit set and veraison have resulted in a Ravaz Index window (5 to 10 kg·kg−1) and is recommended for procumbent red wine grape cultivars for the region with similar or better berry skin phenolic accumulation than spur-pruned vines.
Irrigation and Rootstock Influence on Water Use, Tree Growth, Yield, and Fruit Quality at Harvest at Different Ages of Trees in ‘Pacific Gala’ Apple
Authors: Fallahi Esmaeil , Fallahi Bahar , Shafii Bahman
Published: February 2019

During various ages of tree between 2002 and 2007, the effects of four rootstocks and two irrigation systems using a crop evapotranspiration-based (ETc) water scheduling on water use, tree growth, yield, and fruit quality at harvest in ‘Pacific Gala’ apple [(Malus ×domestica) Borkh] were studied. The use of ETc when a precise crop coefficient value (Kc), modified by percentage of ground shade (GS) and tree canopy maturity (M) was used, provided a reliable tool for irrigation scheduling of ‘Pacific Gala’ apple. Young trees with a full sprinkler (FS) system received an average of 872.3 mm (5616.8 L/tree), whereas those with full drip (FD) received 448.9 mm (2921.1 L/tree). However, when trees were mature, trees with a FS system received an average of 994 mm (6461.7 L/tree), whereas trees with a FD received 614.1 mm (3996 L/tree) of irrigation water per growing season. Trees on ‘Budagovsky 9’ (‘B.9’) had smaller trunk cross-sectional area (TCA) and higher yield efficiency, whereas those on ‘Supporter4’ (‘Sup.4’) had larger TCA and lower yield efficiency than those on other rootstocks in all years of the study. Trees on ‘Nic.9’ (‘RN29’) always had higher yield per tree as compared with those on other rootstocks. Trees on ‘RN29’ often had higher but trees on ‘B.9’ had lower fruit weight than did those on other rootstocks. Trees on ‘Sup.4’, despite their lower yields, had smaller fruits than those on ‘RN29’ every year and thus were not suitable for planting. Fruit from trees on ‘B.9’ and ‘Cornell-Geneva30’ (‘G.30’) often had higher soluble solids concentration (SSC) and starch degradation pattern (SDP) than those other rootstocks. Fruits from trees on ‘G.30’ also had lower firmness and higher stem-end cracking, suggesting that this rootstock advances maturity in ‘Pacific Gala’ apple. Trees with FS irrigation had higher TCA than those with the FD system. Trees with the FD system were more precocious and had higher yield per tree, yield efficiency, and fruit weight than trees with the FS system when they were young. However, these differences were not significant when trees matured. ‘Pacific Gala’ fruit from trees with FS consistently had better color than those with the FD system every year. Fruits from young trees with the FD system often had higher SDP and lower firmness than those from FS irrigation.
Nitrogen Fertility Influences Growth and Susceptibility of Rhododendrons to Phytophthora ramorum
Authors: Hummel Rita L. , Elliott Marianne , Chastagner Gary , Riley Robert E. , Riley Kathy , DeBauw Annie
Published: February 2019

Growth and susceptibility of evergreen Rhododendron ‘English Roseum’, ‘Cunningham’s White’, and ‘Compact P.J.M.’ to Phytophthora ramorum in response to biweekly nitrogen (N) fertilizer application at rates of 25, 75, and 150 mg N per 11.4-L container was evaluated during two growing seasons. At the end of both growing seasons, horticultural evaluation of the different plants showed that 150 mg N-fertilized cultivars had superior shoot growth, visual quality, leaf color, and the highest leaf N concentration, whereas the 25-mg N cultivars were inferior for these characteristics. Plants fertilized with the 75-mg N rate were typically intermediate to the 150- and 25-mg N plants for the measured characteristics. During the first growing season, the number of flower buds on ‘Cunningham’s White’ and ‘English Roseum’ was not influenced by N rate but the second season bud numbers increased with increasing N fertilizer. Foliar susceptibility to P. ramorum was influenced by N fertilizer application rates in the most susceptible cultivars, ‘English Roseum’ and ‘Cunningham’s White’, in which lesion size and infection frequency both increased at higher N rates. The results were variable in ‘Compact P.J.M.’, the most resistant cultivar.
Hot Callusing for Propagation of American Beech by Grafting
Authors: Carey David W. , Mason Mary E. , Bloese Paul , Koch Jennifer L.
Published: February 2019

To increase grafting success rate, a hot callus grafting system was designed and implemented as part of a multiagency collaborative project to manage beech bark disease (BBD) through the establishment of regional BBD-resistant grafted seed orchards. Five years of data from over 2000 hot callus graft attempts were analyzed using a logistic regression model to determine which factors were important in graft success. Variables having the largest influence included scion genotype, technical problems, health issues (such as chlorosis or dwarfing), and contamination. Very few genotypes had significantly lower success compared with the average genotype, indicating that this method should be widely applicable. Comparison of the hot callus method with traditional grafting demonstrated that the odds of success using the hot callus method were 17 times greater than traditional grafting methods. Hot callus grafting is an efficient method for propagating American beech selections resistant to BBD for the establishment of seed orchards and superior clones with value as ornamentals.
Impacts of Aerated Compost Tea on Containerized Acer saccharum and Quercus macrocarpa Saplings and Soil Properties in Sand, Uncompacted Loam, and Compacted Loam Soils
Authors: Scharenbroch Bryant C.
Published: February 2019

Aerated compost teas (ACTs) are applied to soils with the intent of improving microbial properties and nutrient availability and stimulating plant growth. Anecdotal accounts of ACT for these purposes far outnumber controlled, replicated, and peer-viewed experiments that have examined the impacts of ACT on soil properties and plant growth responses. This research assessed the impacts of four rates of ACT compared with water on containerized Acer saccharum and Quercus macrocarpa saplings growing in loam, compacted loam, and sandy soils. No significant differences were found comparing water with ACT applied at rates of 2, 4, and 40 kL ACT/ha for any of the six tree responses and 21 soil responses. Microbial biomass nitrogen (N) and potassium (K) increased, and available N decreased, in soils treated with ACT at 400 kL·ha−1 compared with water. Shoot, root, total biomass, and the root/shoot ratio were significantly greater for Quercus macrocarpa trees growing in compact loam with the 400 kL ACT/ha treatment compared with water, but significant differences were not detected for this application rate compared with water in the other soil types and in no instances with Acer saccharum saplings. These results provide some support for claims of ACT being able to increase soil microbial biomass and K, but provide minimal support for ACT being able to increase tree growth across multiple species in a variety of soil types. An application rate of 400 kL ACT/ha may be attainable for trees in containers with limited soil volumes, but this application rate is likely cost-prohibitive, and not practical, in the landscape. At this application rate, ≈1000 L of ACT would be required to treat a typical, and relatively small, critical root zone of 25 m2.
Sustainable Production of Marigold and Calibrachoa with Organic Fertilizers
Authors: Eaton Touria E. , Cox Douglas A. , Barker Allen V.
Published: February 2019

Experiments were conducted to evaluate organic fertilizers in production of greenhouse-grown calibrachoa (Calibrachoa ×hybrida Llave & Lex) and marigold (Tagetes erecta L.) and nitrogen (N) leaching from containers during production. Calibrachoa was grown with five fertilizer treatments: one chemical, one organic-based, and three organic (liquid fish, oilseed extract, and a combination of oilseed extract and liquid fish). Marigold was grown with seven fertilizer treatments: one chemical and three organic (liquid fish, oilseed extract, and alfalfa pellets) used either alone or in combination. Chemical or organic-based fertilizers produced the best quality calibrachoa based on plant appearance and size. Liquid fish fertilizer produced healthy plants but smaller plants than those grown with chemical or organic-based fertilizers. Plants grown with oilseed extract were stunted and showed chlorosis. If oilseed extract was combined with liquid fish, the plants were similar to those grown with the chemical or organic-based fertilizers in size and quality. Chemical or liquid fish fertilizers produced the highest quality marigold based on plant appearance. Plants fertilized with alfalfa pellets were sparse and pale green. Oilseed extract produced the poorest growth and quality. If oilseed extract was combined with liquid fish or alfalfa, marigold plants were close in size and development to chemical-fertilized plants without nutrient deficiency and with some enhancement of nutrient levels in the leaves. The combination of alfalfa and liquid fish produced similar results. The highest N leaching resulted from plants fertilized by liquid fish, mostly in the form of ammonium nitrogen (NH4-N). Combining liquid fish with alfalfa or oilseed extract reduced the amount of N leached from the pots. The results suggest that organic fertilizers can be used successfully to grow commercial greenhouse crops but should be combined for good plant quality and environmental sustainability.
Fruit Quality in Induced Polyploids of Actinidia chinensis
Authors: Wu Jin-Hu , Ferguson A. Ross , Murray Brian G. , Duffy Alison M. , Jia Yilin , Cheng Canhong , Martin Philip J.
Published: February 2019

Fruit of colchicine-induced tetraploids of Actinidia chinensis were 50% to 60% larger than those of their diploid progenitors. In addition to fruit size, fruit quality is a key issue in any commercialization of these autotetraploids. We have made the first detailed study of the effects of chromosome doubling on fruit quality parameters other than size: these attributes include flesh firmness, color, soluble solid content (SSC), dry matter content (DM), vitamin C content, fruit skin thickness, and red pigmentation distribution in red-fleshed kiwifruit. Four selections from colchicine-induced tetraploids from the yellow-fleshed kiwifruit cultivar Hort16A were trialed for the stability of their fruit quality. Analysis of fruit at harvest over 3 years showed that fruit of the induced autotetraploids were significantly softer (lower flesh firmness), had lower DM, and had a less intense golden flesh color than fruit of their diploid progenitor. During development, SSC of fruit of the autotetraploid plants started to increase earlier than in the diploid ‘Hort16A’. This has been confirmed by replicated trials. No difference was found in vitamin C content between fruit of autotetraploids and diploids. Autotetraploids had significantly thicker skins than diploid ‘Hort16A’. Induced autotetraploids from three female genotypes of red-fleshed A. chinensis showed similar trends to autotetraploids of ‘Hort16A’ in fruit flesh firmness and outer pericarp flesh color, DM, SSC, and vitamin C. All the traits analyzed indicated that fruit of the autotetraploid plants matured earlier than those of their diploid progenitors. Furthermore, red pigmentation, one of the most important traits for red-fleshed kiwifruit breeding, showed a reduction in both intensity and distribution in the autotetraploids compared with their diploid progenitors. There was considerable variation among fruit of autotetraploid plants regenerated from each diploid progenitor. Therefore, selection among the regenerants may be required to achieve the best outcome after ploidy manipulation in kiwifruit breeding.
Physical Properties of Biocontainers Used to Grow Long-term Greenhouse Crops in an Ebb-and-flood Irrigation System
Authors: Beeks Stephanie A. , Evans Michael R.
Published: February 2019

The physical properties of new 15.2-cm plastic and comparably sized bioplastic, solid ricehull, slotted ricehull, paper, peat, dairy manure, wood fiber, rice straw, and coconut fiber containers were determined. Additionally, the physical properties of these containers were determined after being used to grow ‘Rainier Purple’ cyclamen (Cyclamen persicum L.) in ebb-and-flood benches for 15 weeks in a greenhouse environment. The punch strength of new coconut fiber containers was the highest of the containers. The used plastic containers had strengths of 228.0, 230.5, and 215.2 N for the bottom, middle, and top zones, respectively. The used peat, dairy manure, and wood fiber containers had strengths of less than 15 N for each zone. Tensile strength of all new containers was 10 kg. The plastic, bioplastic, solid ricehull, slotted ricehull, paper, and coconut fiber containers had used strengths that were similar to plastic containers. Total water used for wood fiber containers was higher than plastic containers. Irrigation intervals for plastic containers were similar to bioplastic, solid ricehull, slotted ricehull, paper, and coconut fiber containers. The irrigation interval for plastic containers was 1.32 days and the wood fiber container had the shortest irrigation interval at 0.61 day. Container absorption for coconut fiber containers was 255 mL and was higher than plastic containers. Wood fiber container absorption was 141 mL and lower than plastic containers. Plastic, bioplastic, solid ricehull, and slotted ricehull containers had no visible algal or fungal growth. The wood fiber containers had 79% of the container walls covered with algae or fungi and the bottom and middle zones had 100% algae or fungi coverage. The bottom zone of rice straw, dairy manure, and peat containers also had 100% algae or fungi coverage. The bioplastic, solid ricehull, and slotted ricehull containers in this study proved to be good substitutes for plastic containers. These containers retained high levels of punch and tensile strength, had no algal and fungal growth, and required a similar amount of solution as the plastic containers to grow a cyclamen crop. The peat, dairy manure, wood fiber, and rice straw containers proved not to be appropriate substitutes for plastic containers because of the low used strengths, high percentage of algal and fungal coverage, and shorter irrigation intervals as compared with plastic containers.
Naphthaleneacetic Acid and Ethephon Are Florigenic in the Biennial Apple Cultivars Golden Delicious and York Imperial
Authors: McArtney Steven , Greene Duane , Schmidt Tory , Yuan Rongcai
Published: February 2019

‘Golden Delicious’ and ‘York Imperial’ are apple cultivars that are prone to develop a biennial bearing habit. A successful chemical thinning program with carbaryl plus 6-benzyladenine applied at the 10-mm fruit diameter stage reduced cropload and increased return bloom of ‘York Imperial’, although the improvement in return bloom resulting from chemical thinning was insufficient to ensure a commercial cropload in the year after treatment (fewer than 10% of spurs developing flowers). A chemical thinning program with multiple applications of a naphthaleneacetic acid (NAA) and ethephon mixture during the period from 36 to 73 days after bloom increased return bloom of ‘York Imperial’ trees to commercially acceptable levels (25% or greater of spurs flowering). NAA applied during the period from 50 to 100 days after bloom (summer NAA program) or from 110 to 140 days after bloom (preharvest NAA program) increased return bloom of ‘Golden Delicious’. When aminoethoxyvinylglycine (AVG) was included with the first NAA spray in a summer program, the efficacy was reduced, indicating that ethylene may be partly involved in the florigenic activity of NAA. Dissection of ‘Golden Delicious’ buds sampled from three locations (Asheville, NC; Amherst, MA; Wenatchee, WA) at ≈14-day intervals beginning 50 days after bloom indicated that the time of floral transition (doming of the meristem apex) occurred during the period from 65 to 105 days after bloom at each location. Thus, NAA applications in a summer program for return bloom coincided with the period when floral determination normally occurred. Preharvest NAA programs effectively promoted return bloom in the experiments where a summer NAA program was also effective. These responses indicate that NAA can trigger floral development within vegetative buds relatively late in the summer and outside of the time period when it is generally believed possible to influence flower bud formation.
Hydrolyzed Organic Fish Fertilizer and Poultry Litter Influence Total Phenolics and Antioxidants Content but Not Yield of Amaranth, Celosia, Gboma, and Long Bean
Authors: Staley Loutrina , Mortley D.G. , Bonsi C.K. , Bovell-Benjamin A. , Gichuhi P.
Published: February 2019

Dietary intake of a variety of vegetables is very important for disease prevention and may help in the treatment of certain maladies. Experiments were conducted to evaluate yield and the content of antioxidants and phenolics of vegetable Amaranth (Amaranthus hybridus), Celosia (Celosia argentea), Gboma (Solanum macrocarpon), and Long Bean (Vigna unguiculata) in response to poultry litter (PL) and a hydrolyzed fish fertilizer [Megabloom (MB)]. The experiments were conducted as a randomized complete block design with a four × three factorial treatment and four replications. The treatments were applied based on soil test recommendations in a single band 15 to 20 cm away from the plants 1 week after transplanting. Plants were harvested sequentially during the season as foliage and fruits became physiologically mature and once over at the end of the season. Species were analyzed for vitamin C content, total phenolics, and β-carotene content as well as antioxidant capacity. Organic amendments did not significantly influence biomass production, whereas species impacted fresh and dry biomass. Amaranth, Celosia, and Long Bean produced greater fresh and dry biomass than did Gboma. Vitamin C content was highest among Amaranth and Celosia plants receiving nitrogen–phosphorus–potassium (NPK) compared with the other two treatments, whereas that of Gboma was higher among plants receiving MB.
Lateral Spread of Three Warm-season Turfgrass Species as Affected by Prior Summer Water Stress at Two Root Zone Depths
Authors: Steinke Kurt , Chalmers David R. , White Richard H. , Fontanier Charles H. , Thomas James C. , Wherley Benjamin G.
Published: February 2019

As a result of increasing demand for potable water, local and national initiatives to conserve municipal water supplies have been implemented. Many of these initiatives focus on reducing irrigation of turfgrass in urban landscapes and may totally ban irrigation during periods of severe water shortage. Proper selection of adapted turfgrass species and cultivars is vital to long-term water conservation initiatives. Turfgrasses that can survive and recover from extended hot and dry periods under limited to no irrigation would best meet water conservation objectives. The present study was conducted to evaluate the recuperative potential of transplanted plugs of 24 commonly grown cultivars of three warm-season turfgrass species after incremental increases in water stress imposed by withholding all water for up to 60 days. A 2-year field study was conducted consisting of eight blocks containing 25 plots each. Each block was planted with one plot each of eight cultivars of bermudagrass (Cynodon dactylon sp.), seven cultivars of st. augustinegrass (Stenotaphrum secundatum sp.), and nine cultivars of zoysiagrass (five of Zoysia japonica sp. and four of Zoysia matrella sp.). Four blocks were planted on native soil with no restriction to rooting, whereas the other four had an effective root zone of only 10 cm of soil. Cup cutter plugs were collected at predetermined intervals, transported to College Station, TX, replanted, and grown under well-watered conditions. Measurements of the lateral spread of the plugs were taken every 10 to 14 days for the first 60 to 70 days after planting (DAP). The lateral spread of plugs collected after 0 days of summer dry-down (DSD) was greatest for bermudagrass, intermediate for st. augustinegrass, and lowest for zoysiagrass. In most cases there were no consistent differences between cultivars within a species. All species grown on the 10-cm deep root zone were unable to survive the 60-day period without water and died within the first 40 days. For each species, lateral spread was increasingly delayed or reduced with increasing DSD. Although all three species grown on native soil were able to survive and recover from a 60-day period without water, the bermudagrass cultivars had the most rapid recovery rates measured as lateral spread of transplanted plugs.
Fifty Years of Citrus Developmental Research: A Perspective
Authors: Goldschmidt Eliezer E.
Published: February 2019

An overview of the conceptual and methodological changes in citrus developmental research during the past half century is provided. Beginning with the hormonal era, the extensive use of plant growth regulators (PGRs) is described and the presumed role of gibberellins in various stages of the reproductive processes is emphasized. Introduction of the source-sink concept opened the way for alternative, carbohydrate-mediated explanations of productivity and alternate bearing. The potential role of ethylene in citrus abscission and fruit ripening is reviewed. The recent adoption of genetic–molecular approaches paves the way for deeper understanding of citrus developmental enigmas.
Ploidy Levels and Relative Genome Sizes of Species, Hybrids, and Cultivars of Dogwood (Cornus spp.)
Authors: Shearer Kimberly , Ranney Thomas G.
Published: February 2019

Dogwoods (Cornus spp.) are valuable nursery crops grown as landscape plants throughout much of the world. Although there has been considerable work on breeding and selecting dogwoods, there is little information available on genome sizes (DNA content) and ploidy levels within the genus, particularly for specific clones and cultivars. Our objective was to conduct a survey of relative genome sizes and ploidy levels of dogwood taxa representative of the big-bracted, cornelian cherry, and dwarf dogwood clades. Flow cytometry was used to determine relative genome sizes and ploidy levels of 94 accessions of various species, hybrids, and cultivars. Traditional cytology was performed on root cells of representative taxa to calibrate genome sizes with ploidy level. All dogwood accessions tested were diploid with the exception of C. canadensis that was tetraploid and the hybrid cultivar C. KN30-8 that was triploid. Relative genome sizes varied by clade, subgenus, and species with 1Cx values ranging from 1.07 pg for C. canadensis to 5.08 pg for C. eydeana. Relative genome sizes were also valuable for confirming hybridity of interspecific crosses in cases in which parents varied substantially in relative genome size and hybrids were intermediate. A broad range of interspecific hybrids was documented including C. capitata × florida, C. capitata × kousa, C. elliptica × florida, C. hongkongensis × florida, C. kousa × elliptica, and C. kousa × florida. These results provide further insights into the cytogenetics, reproductive biology, crossability, and relative genome sizes of dogwoods.
Damage and Recovery of Cranberry Vines from Exposure to Handheld Flame Cultivators
Authors: Ghantous Katherine M. , Sandler Hilary A. , Autio Wesley R. , Jeranyama Peter
Published: February 2019

Damage and recovery responses of four cranberry varieties (‘Mullica Queen’, ‘Crimson Queen’, ‘Stevens’, and ‘Howes’) to handheld propane flame cultivation (FC) torches were evaluated. All combinations of four levels of exposure duration of three FC torches (open flame 0, 3, 6, and 9 seconds), infrared (IR) and IR with a 4.5-cm metal spike (0, 15, 30, and 45 seconds), were tested on rooted cranberry uprights (vertical stems) planted in clay pots. Pots were subjected to a single treatment from one FC torch at one exposure duration; a glyphosate wipe was also included as a treated control (industry standard). Treatments were replicated five times. All cranberry plants were damaged by all levels of exposure duration as evident by visual damage ratings, reduced net cumulative stem lengths, reduced number of uprights, and reduced proportion of reproductive uprights when compared with untreated plants. All cranberry plants treated with glyphosate had total mortality; all cranberry plants from all varieties treated with FC survived, and all had net positive stem growth in the year after treatment except for ‘Stevens’ treated with open flame and IR with spike. The non-fatal response of cranberry to FC indicates that FC will cause less damage than glyphosate to cranberry plants that are incidentally exposed during spot treatment of weeds and thus could be integrated into weed control in certain situations, including organic farming.
Efficacy of Preemergence and Postemergence Herbicides for Controlling Common Purslane
Authors: Proctor Christopher A. , Reicher Zachary J.
Published: February 2019

Common purslane (Portulaca oleracea L.) can be problematic in thin turf, along sidewalks and drives, and especially during turfgrass establishment. Little published research exists evaluating herbicides that will control purslane and are also labeled for turfgrass. Thus, our objective was to evaluate the efficacy of preemergence (PRE) or postemergence (POST) herbicides labeled for use in turf for controlling purslane. Experiments were conducted once in 2011 and twice in 2012 to evaluate nine PRE herbicides at one-half maximum and maximum label rates applied over immature perennial ryegrass (Lolium perenne L.). The PRE herbicides isoxaben and simazine consistently resulted in the best purslane control for all three PRE experiments. Experiments in 2011 and 2012 evaluated 25 POST herbicides at full label rates applied to mature purslane plants. The POST herbicides fluroxypyr, triclopyr, and metsulfuron-methyl were most effective in controlling purslane.
Carbohydrate and Nutritional Responses to Stem Girdling and Drought Stress with Respect to Understanding Symptoms of Huanglongbing in Citrus
Authors: Cimò Giuseppe , Lo Bianco Riccardo , Gonzalez Pedro , Bandaranayake Wije , Etxeberria Edgardo , Syvertsen James P.
Published: February 2019

The most important worldwide problem in citrus production is the bacterial disease Huanglongbing (HLB; citrus greening) caused by a phloem-limited bacterium Candidatus Liberibacter asiaticus. The earliest visible symptoms of HLB on leaves are vein yellowing and an asymmetrical chlorosis referred to as “blotchy mottle,” thought to be the result of starch accumulation. We tested the hypothesis that such visible symptoms are not unique to HLB by stem girdling 2-year-old seedlings of two citrus rootstocks with and without drought stress in the greenhouse. After 31 days, girdling had little effect on shoot growth but girdling increased the relative growth rate of shoots in drought-stressed trees. Starch content in woody roots of non-girdled trees was three to 19 times higher than in girdled trees. In non-girdled trees, drought stress induced some starch accumulation in roots, but there were no effects of drought stress on root starch or sucrose in girdled trees. Girdling induced a 4-fold greater starch content in leaves on well-watered trees but leaf sucrose content was unaffected. Girdling reduced leaf transpiration in well-watered trees but net assimilation of CO2 was unaffected by girdling or leaf starch accumulation. Leaves on girdled trees clearly had visible blotchy mottle symptoms but no symptoms developed on non-girdled trees. The increase in leaf starch, up to 50% dry weight (DW), resulted in an increase in leaf DW per leaf area (LA) and an artificial reduction of many leaf nutrients on a DW basis. Most of these differences disappeared when expressed on a LA basis. Leaf boron (B), however, was inversely related to leaf starch when both were expressed on a LA basis. In the absence of HLB, girdling increased leaf starch, decreased root starch, and duplicated the asymmetric blotchy mottled visual leaf symptoms that have been associated with HLB-infected trees. This supports our contention that such symptoms generally attributed to HLB are not uniquely related to HLB infection, but rather are directly related to starch accumulation and secondarily to nutrient deficiencies in leaves.