bluuebunny/crossref_metadata_2025 huggingface dataset:
Preplant Storage and Greenhouse Temperature Influence Flowering of Ornithogalum
Authors: Lee Judy , Miller William B.
Published: February 2019

We determined the effects of preplant storage temperature and duration and greenhouse growing temperature on the growth and flowering of four cultivars of potted Ornithogalum representing Ornithogalum dubium (three cultivars) and Ornithogalum thyrsoides (one cultivar) originating from Israeli breeding. Bulbs were stored at five temperatures for 1 to 4 weeks before planting. Within the range of 9 to 27 °C, lower preplant storage temperature resulted in earlier flowering and taller plants, and for one cultivar, increased bulb respiration measured after storage. When bulbs were stored at 9 °C for 3 weeks, plants flowered at least 12 days earlier compared with controls stored at 27 °C. At 9 °C, as preplant bulb storage duration increased from 0 to 4 weeks, plants flowered more quickly and were taller. Within the range of 13 to 21 °C, 17 to 18 °C forcing temperatures gave the best combination of forcing time and plant quality.
Effective Bioassays for Evaluating Boxwood Blight Susceptibility Using Detached Stem Inoculations
Authors: Guo Yonghong , Olsen Richard T. , Kramer Matthew , Pooler Margaret
Published: February 2019

Two simple and rapid in vitro bioassays using detached stems were developed for evaluating the susceptibility of boxwood genotypes to the blight disease caused by Calonectria pseudonaviculata (Crous et al.) L. Lombard et al. Individual leaves were inoculated on detached stems or entire detached stems were sprayed to assess susceptibility. Both assay systems were optimized for inoculum concentration and disease rating time. The assay methods described here require minimal plant material and inoculum, especially the leaf inoculation assay, which uses as few as six leaves per stem and 500 spores per leaf for inoculation. The stem spray inoculation produced less variable results and was easier for quantifying susceptibility but required more inoculum than the leaf inoculation assay. No differences between the assays were found for the cultivars tested. The leaf inoculation assay is best used when limited plant material or inoculum is available; the spray inoculation of detached stems is suitable when larger plants are available.
Rhizometer: An Apparatus to Observe and Measure Root Growth and Its Effect on Container Substrate Physical Properties Over Time
Authors: Judd Lesley A. , Jackson Brian E. , Fonteno William C.
Published: February 2019

Container production of plants use substrates that are formulated to have adequate physical properties to sustain optimal plant growth; however, these properties can change over time as a result of substrate settling and root growth of the growing plant in the container. An apparatus (rhizometer) was developed that measures the changes caused by plant roots on physical properties of substrates during crop production in containers. The design of the rhizometer included a clear core, which allowed for observing and measuring a range of root system characteristics in situ, including total root length visible along the rhizometer. Physical properties of planted and fallow rhizometers were measured, and the effect of four species on substrate physical properties was determined. There was a general decrease in substrate total porosity and air space (AS) over time with both fallow and planted rhizometers as a result of both settling of the substrate and root growth into the substrate. Container capacity did not change over time with or without roots. Plants with large root systems such as Begonia ×hybrida acut. decreased AS over time, whereas plants of Rudbeckia hirta L. with a smaller root system did not have the same effect. Measured total root length was highly correlated to the total dry root mass of Tagetes erecta L. and Zinnia marylandica D.M. Spooner, Stimart & T. Boyle plants. This may allow tracing and measuring root lengths to be another (alternative) method to measure root systems. Planted rhizometers also allowed easy access for viewing the root system non-destructively, providing the ability to observe and measure root growth.
Groundcover Management System and Nutrient Source Impacts on Soil Quality Indicators in an Organically Managed Apple (Malus ×domestica Borkh.) Orchard in the Ozark Highlands
Authors: Mays Neal , Rom Curt Richard , Brye Kristofor R. , Savin Mary C. , Garcia M. Elena
Published: February 2019

The highly weathered, mineral, and often eroded and acidic soils of the Ozark Highlands region of northwest Arkansas generally have low soil organic matter (SOM) concentrations as a result of rapid organic matter turnover rates in the warm, moist climate. Orchard management practices that can improve SOM may also improve other soil quality-related variables for sustained production, which is an explicit goal for the National Organic Program (NOP). Therefore, beginning in Mar. 2006 and continuing for seven seasons, annual applications of municipal green compost, shredded office paper, wood chips, and mow-blow grass mulch groundcover management systems (GMS) in combination with composted poultry litter, commercial organic fertilizer, or a non-fertilized control as a nutrient source were implemented to evaluate their ability to alter near-surface soil quality in a newly established, organically managed apple orchard in the Ozark Highlands region of northwest Arkansas. The SOM concentration in the top 10 cm averaged 1.5% across all treatments at orchard establishment in 2006, but by 2012, SOM concentration had increased in all GMS and more than doubled to 5.6% under green compost. Similarly, soil bulk density in the top 6 cm, which averaged 1.34 g·cm−3 among treatment combinations in 2006, decreased in all GMS by 2012. Either green compost or shredded paper had the largest concentration of total water-stable aggregates across all aggregate size classes in the top 7.5 cm, whereas no differences among GMS were observed in the 7.5- to 15-cm soil depth. Green compost applied alone or in combination with commercial fertilizer had the largest estimated plant-available water (17.9% v/v) among all treatment combinations. Many soil quality-related variables measured in the various organic GMS had numerically greater values compared with an adjacent conventionally managed orchard on the same soils. Implementation of these GMS appears to provide apple producers in the Ozark Highlands and similar regions a tangible means of meeting NOP requirements for improving soil quality concurrent with production of certified organic crops. The findings also have implications for conventionally managed orchards, which have maintaining or improving soil quality as a management goal.
Pollen Effects on Fruit Set, Seed Weight, and Shriveling of ‘73-S-20’ Litchi- with Special Reference to Artificial Induction of Parthenocarpy
Authors: Chu Yu-Chun , Lin Tzong-Shyan , Chang Jer-Chia
Published: February 2019

In this study, we documented whether pollen parents are required for fruiting and their effects on fruit set and seed characteristics in field-grown ‘73-S-20’ litchi (Litchi chinensis Sonn.). The effects of preventing female (F) flower pollination to induce parthenocarpy, selfing, and outcrossing with ‘Haak Yip’ and open-pollinated (OP) fruits derived from F flowers and the second wave of the male (M2) flowers of ‘Haak Yip’ blooming in synchrony were assessed. The correlation between the percentage of fruit set and shriveled seed/seed weight in self-crossed and outcrossed fruits was calculated. At harvest, the absence of pollination induced a high proportion of parthenocarpic fruit without seed, although the fruit weighed only 4.2 g. Fruit set with outcrossing was greater than that with selfing and the percentage of shriveled seed obtained in self-crossed fruits was much greater than that in outcrossed fruits but not different from that in OP fruits, suggesting that outcrossing increased but selfing decreased the cluster yield and seed weight. However, 33.3% and 23.0% of seed contained embryos in selfed and OP fruits, respectively. No positive correlation between the percentage of fruit set and shriveled seed/seed weight was found, indicating that seed abortion during development was not the key factor leading to low yield. We concluded that tiny parthenocarpic fruit could be obtained but that pollination is essential for the good yield of ‘73-S-20’. Outcrossing markedly increased fruit set and seed weight and decreased the percentage of shriveled seed. Factors other than the pollen parents may be involved in the seed development of ‘73-S-20’.
Effect of Plant Growth Regulators on Growth, Yield, and Quality of Sweet Pepper Plants Grown Hydroponically
Authors: Maboko Martin Makgose , Du Plooy Christian Phillipus
Published: February 2019

A 2-year study (2012–13 and 2013–14) was conducted to evaluate the effect of plant growth regulator’s (PGRs) on plant growth, yield, and quality of hydroponically grown sweet peppers. In 2012–13, sweet pepper plants were subjected to two levels of gibberellic acid (GA3) (10 and 15 mg·L−1), two levels of naphthalene acetic acid (NAA) (15 and 30 mg·L−1), and four combinations of NAA and GA3 (10 mg·L−1 GA3 + 15 mg·L−1 NAA, 10 mg·L−1 GA3 + 30 mg·L−1 NAA, 15 mg·L−1 GA3 + 15 mg·L−1 NAA, and 15 mg·L−1 GA3 + 30 mg·L−1 NAA) applied to plants at flower initiation in a non-temperature-controlled tunnel. This PGR application was repeated 60 days after transplanting (DAT). In 2013–14, in addition to previously mentioned treatments, two levels of 4-chlorophenoxyacetic acid (4-CPA), at 30 and 45 mg·L−1, were applied at flower initiation followed by three additional applications of the latter treatments at 20-day intervals in a temperature-controlled tunnel. Marketable and total yield were markedly reduced by application of 4-CPA at 30 and 45 mg·L−1. Plant height was increased by application of GA3, and GA3 in combination with NAA, compared with application of 4-CPA, 30 mg·L−1 NAA, and the control. Results also showed that application of GA3 at 10 and 15 mg·L−1 or in combination with NAA increased plant fresh and dry mass as well; however, this had no beneficial effect on the yield of sweet pepper fruit. The application methods and concentrations of various PGRs needs further investigation under different growing conditions on sweet pepper cultivars.
Economic Evaluation of Implementing Strawberry Season Extension Production Technologies in the U.S. Intermountain West
Authors: Maughan Tiffany L. , Curtis Kynda R. , Black Brent L. , Drost Daniel T.
Published: February 2019

Strawberry production in the U.S. Intermountain West is limited by harsh climatic conditions and competition from domestic producers and imports. Using season extension methods to combat climatic conditions may be effective but generally increases production costs. This study evaluates the economic returns to implementing high tunnels, low tunnels, and in-ground supplemental heating to strawberry production (Seascape and Chandler cultivars) in northern Utah. The high tunnel provided a net return of $1,943.57 or $15,548.56 per hectare assuming eight high tunnels per hectare. The addition of low tunnels within the high tunnel led to a positive increase in net returns for ‘Seascape’ but not for ‘Chandler’ production. Supplemental in-ground heating increased net returns by up to 50% for both cultivars, primarily as a result of higher pre-season yield and market pricing. Study results find that season extension technologies can successfully increase net returns to strawberry production through early and increased yields, when strawberries are sold primarily through local direct markets.
Willingness-to-pay Comparisons for Flats of Groundcover Plants in Plantable Containers: Consumers versus Commercial Buyers in Kentucky
Authors: Ingram Dewayne L. , Woods Timothy A. , Hu Wuyang , Nambuthiri Susmitha S.
Published: February 2019

Increasing demand for groundcover plants and increasing consumer preference for more sustainable products encourage nursery crop producers and landscape management companies to assess efficiency and sustainable practices. Ajuga reptans ‘Bronze Beauty’ and Sedum kamtschaticum ‘Variegatum’ were grown in standard plastic containers or plantable containers (Ellepot and SoilWrap) and 12- or 18-count flats. These production alternatives were presented in personal surveys of commercial industry personnel and consumers to determine their willingness to pay for these attributes. A conjoint analysis revealed an affinity for both groups to purchase flats of groundcovers and preferred sedum over ajuga. Commercial buyers from larger companies were more likely to purchase plantable containers than those from smaller firms. Generally, flats of Ellepots were preferred over flats of SoilWraps and 18-count over 12-count flats by commercial buyers. Price had a negative impact on consumer willingness to pay. Consumers revealed no specific preference for the plantable containers, although preference for plastic containers declined with age and presence of children at home.
Hot Water Combined with Calcium Treatment Improves Physical and Physicochemical Attributes of Kiwifruit (Actinidia deliciosa cv. Hayward) during Storage
Authors: Shahkoomahally Shirin , Ramezanian Asghar
Published: February 2019

Kiwifruit has a short storage life and encounters severe disorders during maintenance mainly as a result of its climacteric behavior. The role of calcium and heat treatment in delaying degenerative processes during storage has been revealed. This study investigated the effects of hot water combined with calcium (Ca) dips on the quality of kiwifruit (Actinidia deliciosa cv. Hayward). Whole fruits were treated with hot water for 5, 10, and 15 minutes at 47 °C, therefore dipped in CaCl2 solution (2% w/v) and stored at 0 °C for up to 120 days. During storage, fruit were sampled at 0, 30, 60, 90, and 120 days for postharvest quality evaluation. Postharvest evaluations included chromatic parameters (L*, a*, b*, hue, and chroma), firmness, and physiological parameters [phenolic content and polyphenol oxidase (PPO)]. Heating combined with Ca dips significantly reduced PPO activity. The results showed that mild heat treatments in combination with CaCl2 maintained chromatic parameters for kiwifruits compared with control and hot water or CaCl2 treatments solely. In addition, the levels of total phenolic compounds remained significantly higher for hot water combined with CaCl2-treated fruit as compared with control or untreated fruits. According to the results, hot water treatments had a significant firming effect, whereas CaCl2 dips solely had less effect on chromatic parameters. However, the influence of hot water treatments was dependent on application time with (treatment that showed significant results) showing significant improved kiwifruit postharvest qualities. Overall, with this simple and non-contaminant technology, after long-term storage, quality of kiwifruit could be even greater than in recently harvested fruits.
Floor Management Systems in an Organic Apple Orchard Affect Fruit Quality and Storage Life
Authors: Tahir Ibrahim I. , Svensson Sven-Erik , Hansson David
Published: February 2019

In an organic apple orchard, standard mechanical cultivation was compared with four different orchard floor management systems (OFMS): acetic acid (V), living mulch (L), a sandwich system during the growing season (SSS), and a sandwich system during the whole year (SSW). The effects of these OFMS on weed management, soil conditions, tree growth, tree yield, fruit quality, and fruit storage potential in a cool climate were evaluated. Acetic acid treatment showed good weed suppression without any amendatory effect on soil conditions, fruit quality, or tree performance. The L and SSS systems increased soil respiration, decreased tree vigor, and improved fruit quality, but had no sufficient influence on weed competition and thus decreased fruit yield. Only SSW gave better weed control, higher soil respiration, and acceptable tree growth with no yield reduction. Fruit from this system also showed better quality at harvest than fruit from other OFMS and maintained this good quality during storage. A 6-week weed-free period from late May to mid-July gave the highest apple yield in two OFMS (SSW and V).
Seasonal Variation in Mineral Nutrient Content of Primocane-fruiting Blackberry Leaves
Authors: Strik Bernadine C.
Published: February 2019

Primocane-fruiting blackberry (Rubus L. subgenus Rubus, Watson) cultivars, Prime-Jan® and Prime-Jim®, grown only for a primocane crop, were studied for 2 years to evaluate whether this type of blackberry should be sampled at a certain stage of development or time of season to best evaluate plant nutrient status. Leaves were sampled every 2 weeks from a primocane height of ≈0.75 m in spring through fruit harvest in autumn and were analyzed to determine concentration of macro- and micronutrients. Primocanes were summer pruned at 1.4 m, by hedging to a height of 1.0 m, to induce branching, a standard commercial practice. Leaf nutrient concentration was related to stage of primocane growth and development and whether the leaves originated on the main cane or on the branches that resulted from summer pruning. Nutrient concentration of leaves sampled on the main primocane from early growth in spring until early branch growth in summer was significantly affected by cultivar, year, and week for most nutrients. When leaf sampling occurred on the older leaves of the main cane (for 4 weeks after hedging), the concentration of Ca, Mg, B, Fe, Mn, and Al increased, likely a result of the relative immobility of most of these nutrients. When samples were taken on primocane branches, leaf N, Mg, S, B (2009 only), Fe, Mn, Cu (2009 only), Zn, and Al concentrations did not differ between samples taken 6–8 weeks after summer pruning or hedging. Leaf K and Ca were more stable when sampling was done from weeks 8 to 10 (early bloom to green/early red fruit). There was a significant difference in leaf P among all weeks sampled during this period. A sample date corresponding to early green fruit stage (week 8) would thus likely provide the best compromise for assessing plant nutrient status in this crop. During this stage of development the nutrient concentrations measured for both cultivars and years, were within the present recommended nutrient sufficiency levels for other blackberry and raspberry crops for all except leaf K and P which were below current standards. The results suggest leaf sampling primocane-fruiting blackberry at the early green fruit stage (about 8 weeks after summer pruning) rather than a particular calendar date. The present leaf sufficiency range for P and K may need to be lowered for this crop. In addition, sampling cultivars separately for tissue analysis would still be advised to better manage nutrient programs.
Preemergence Herbicide Efficacy for Crabgrass (Digitaria spp.) Control in Common Bermudagrass Managed under Different Mowing Heights
Authors: Gannon Travis W. , Jeffries Matthew D. , Brosnan James T. , Breeden Gregory K. , Tucker Kevin A. , Henry Gerald M.
Published: February 2019

Research was conducted at multiple locations throughout the southeastern United States during 2012 and 2013 to assist turf managers in developing integrated programs for managing crabgrass in common bermudagrass turf. Our objective was to determine the effect of mowing height on the efficacy of several pre-emergent (PRE) herbicides labeled for crabgrass control in bermudagrass turf. Plots were established in Raleigh, NC (NCSU), Knoxville, TN (ETREC), and Winder, GA (UGA) and treated with a factorial combination of two mowing heights (1.5 or 3.8 cm), two application regimes [single or split application (initial and an 8-week sequential)], and six preemergent herbicides (dithiopyr, indaziflam, oxadiazon, pendimethalin, prodiamine, and prodiamine + sulfentrazone). In 2012, all herbicides provided greater crabgrass control on plots maintained at 3.8 cm compared with 1.5 cm. This response was not detected in 2013, potentially as a result of above-average rainfall at two of the three trial locations. Analysis revealed mowing height did not affect pendimethalin soil residue, whereas prodiamine concentrations from bermudagrass maintained at 1.5 cm were greater than bermudagrass maintained at 3.8 cm. Therefore, differences in crabgrass control in bermudagrass maintained under different mowing heights may be the result of plant growth, reduced photosynthetically active radiation (PAR) at the soil surface, among other reasons, and not solely differential degradation of applied herbicides at the 1.5- and 3.8-cm mowing heights. Future research should explore effects of increasing bermudagrass mowing height on PAR required for crabgrass germination and growth.
Evaluation of Onion Genotypes for Resistance to Stunting Caused by Rhizoctonia solani AG 8
Authors: Sharma-Poudyal Dipak , Paulitz Timothy C. , du Toit Lindsey J.
Published: February 2019

Thirty-five onion genotypes were evaluated for resistance to stunting caused by Rhizoctonia solani anastomosis group 8 (AG 8) in a growth chamber set at 15 ± 1 °C. The trial was repeated. Resistance to R. solani AG 8 was defined as a lack of significant difference in plant height, root length, and/or total dry biomass between inoculated and noninoculated plants of the same genotype. Plant height was not reduced significantly by R. solani AG 8 for 14 and 7 of the 35 genotypes in Trials 1 and 2, respectively. In Trial 1, plant height reduction caused by R. solani ranged from 24% for the cv. Lasalle to 62% for the experimental line R14882, and in Trial 2 plant height reduction ranged from 22% for the experimental line PX07713218 to 53% for the cv. Montblanc. However, the extent of reduction in plant height caused by R. solani did not differ significantly among genotypes in either trial. Onion root length was not reduced by R. solani AG 8 for 26 and 18 of the 35 genotypes in Trials 1 and 2, respectively. The degree of reduction in root length ranged from 9% (R14889) to 76% (Sterling and SN232) in Trial 1, and 14% (SN325) to 74% (Sterling) in Trial 2. Onion dry biomass was not reduced by R. solani AG 8 for 19 and 7 of the 35 genotypes in Trials 1 and 2, respectively, and ranged from 18% (Elbrus) to 69% (Sterling) in Trial 1, and 29% (SN232) to 79% (Sterling) in Trial 2. The reduction in onion root length and total biomass did not differ significantly among onion genotypes in Trial 1, but differed among genotypes in Trial 2. Of the 35 genotypes evaluated, 3, 16, and 3 demonstrated partial resistance to R. solani AG 8 for plant height, root length, and total biomass, respectively, in both trials. Only four genotypes displayed partial resistance to R. solani AG 8 for at least two of the three growth parameters: plant height, root length, and biomass of PX07713218 were unaffected by the fungus in either trial; and R14885, R14888, and SN307 displayed partial resistance in both trials for two of the three parameters, and in one of the two trials for the third parameter. These four genotypes could be used in onion breeding programs to develop cultivars partially resistant to stunting caused by R. solani AG 8.
Soaking, Temperature, and Seed Placement Affect Seed Germination and Seedling Emergence of Litchi chinensis
Authors: Zhang Chunyang , Wu Jiefang , Fu Danwen , Wang Limin , Chen Jiezhen , Cai Changhe , Ou Liangxi
Published: February 2019

To find efficient ways to increase the percentage of seed germination and seedling emergence in litchi (Litchi chinensis Sonn.), we investigated the effects of soaking and high temperature on seed germination, as well as the influence of seed placement (orientation and burial depth) on seedling emergence. Seeds of most tested litchi cultivars soaked in water had a better germination performance than seeds without soaking. More than 90% germination of tested litchi seeds was obtained when the soaking times were 26–54 hours. During presprouting, short-term high temperatures (37–44 °C) exerted a negative effect on seed germination rate, but did not influence the germination percentage. In addition, high temperatures (>42 °C) compromised the further growth of sprouted litchi seeds. Burial depth and seed orientation both significantly influenced the seedling recruitment. There was a reduction in seedling emergence with an increase in burial depth. Seeds at the depth of 2 cm showed the best seedling emergence with an average percentage of 90%. Litchi seedling emergence was greatest and most rapid when seeds were sown 2 cm deep, positioned flat, on their sides, and with the radicle oriented downward.
Systemic Acquired Resistance Induced by Agrobacterium tumefaciens in Peach and Differential Expression of PR1 Genes
Authors: Hao Fengge , Wang Lirong , Cao Ke , Wang Xinwei , Fang Weichao , Zhu Gengrui , Chen Changwen
Published: February 2019

Crown gall disease caused by Agrobacterium tumefaciens affects a wide range of horticultural plants, and has no effective treatment. During the evaluation of crown gall resistance of peach germplasm resources, we observed enhanced resistance to subsequent invasion that was activated by virulence of A. tumefaciens in two peach cultivars. To further verify the phenotype observed in field experiments, systemic acquired resistance (SAR)-related salicylic acid (SA) and PR1 genes were investigated. The levels of SA were elevated in two cultivars, and these high levels were maintained for 35 days postinoculation. Compared with mock-inoculated controls, eight of the 22 candidate PpPR1 genes in A. tumefaciens-inoculated samples were significantly upregulated and three were downregulated in response to inoculation with A. tumefaciens. These data suggested that SA-induced SAR was activated in two peach cultivars by virulent A. tumefaciens infection. In addition, the eight induced PpPR1 genes can be used as molecular markers in defense studies in peach.
Synchrotron X-ray Fluorescence Microtomography Profiling of Malus xiaojinensis Provides Insights into Mechanisms of Divalent Metals Transport Subjected to Iron Deficiency
Authors: Zhang Meiling , Chen Ming , Wang Zhen , Wu Ting , Wang Yi , Zhang Xinzhong , Han Zhenhai
Published: February 2019

Grafting has been widely used in orchard management because the rootstock can make the tree more tolerant to environmental stresses. Iron deficiency is one of the major limiting environmental factor in apple production worldwide. Systematic research has been made about iron-deficiency adaptive responses in the level of organs, cells, and subcells, whereas the interactions between Fe and other divalent cations in tissue level are little known. Synchrotron radiation X-ray fluorescence (SR-μXRF) was used to map the location of selected elements Fe, Zn, Mn, Ni, and Co in the longitudinal and latitudinal root samples of Malus xiaojinensis. Iron deficiency induced a significant increase in the relative contents of five micronutrients in epidermis and cortex. The ratio of element contents of roots under Fe-deficient condition and Fe-sufficient condition at same position increased obviously in the section of 1000- to 2000-μm distance from the root tip in xylem. Expression analysis of iron absorption- and transport-related genes in roots showed that MdNramp3 and MxCS1 increased significantly. These results indicated that iron deficiency promoted the long-distance transport of micronutrients in xylem, and MdNramp3 and MxCS1 might play an important role in this process. Importantly, this study directly provides visual divalent metals distribution in tissue level for an improved understanding of metal absorption process in apple rootstock.
A Review of Weed Control Practices in Landscape Planting Beds: Part II—Chemical Weed Control Methods
Authors: Marble S. Christopher , Koeser Andrew K. , Hasing Gitta
Published: February 2019

Use of preemergence and postemergence herbicides is the most effective and economical method of weed control in landscape planting beds. When used correctly, herbicides can provide satisfactory weed control, reduce labor costs, and cause little or no negative environmental impacts. Major factors in herbicide efficacy include choosing the correct herbicide for the weed species present, following proper calibration procedures, and applying herbicides at the correct timing. The objective of this review is to provide a comprehensive analysis of the research pertaining to herbicide use in landscape planting beds and present 1) the advantages and disadvantages of common chemical weed control strategies, 2) the most effective preemergence and postemergence herbicides in various landscape scenarios, 3) potential environmental concerns pertaining to improper application of herbicides, and 4) highlight knowledge gaps where additional research is needed or improvements could be made.
In Pursuit of the Perfect Peach: Consumer-assisted Selection of Peach Fruit Traits
Authors: Olmstead Mercy A. , Gilbert Jessica L. , Colquhoun Thomas A. , Clark David G. , Kluson Robert , Moskowitz Howard R.
Published: February 2019

Despite production of the first domestically produced peach of the calendar year in the United States, the subtropical peach industry faces marketing challenges, particularly with small fruit size. Although important, size is only one aspect of fruit quality, and not inclusive of all possible fruit quality attributes. Thus, this research asked consumers to identify an “ideal” peach given a combination of possible peach fruit quality attributes to help determine their influence on consumer purchase. These attributes were verified with farmers’ market intercept studies. The top attributes that fostered purchase likelihood included flavor, texture, size, and firmness. Psychophysics studies showed that consumers preferred peaches that were sweet, juicy, round, with freestone or semifreestone characteristics, whereas consumers were less likely to purchase peaches with mealy, dry, or meaty textures. Young consumers (ages 18–24) preferred crisp, firm peaches with good flavor, whereas older consumers (ages 51–65) preferred sweet, melting-texture peaches. Farmers’ market intercept studies found consumers (ages 45–65) preferred melting-texture peaches with good flavor that led to increased overall liking. In addition, in the farmers’ market studies, aroma and flavor were important attributes and were highly correlated with overall liking. Objective measurements of total soluble solids (TSS) were not correlated with overall liking, indicating that although the nationwide experiment found consumers desired sweet peaches, other attributes may contribute more favorably to overall liking.
Total Anthocyanin Content in Intact Açaí (Euterpe oleracea Mart.) and Juçara (Euterpe edulis Mart.) Fruit Predicted by Near Infrared Spectroscopy
Authors: Teixeira Gustavo H. de A. , Lopes Valquiria G. , Júnior Luís C. Cunha , Pessoa José D.C.
Published: February 2019

Açaí (Euterpe oleraceae Mart.) and juçara (Euterpe edulis Mart.) palms are native to Brazil and these species are rich in anthocynanins. The methods applied to determine anthocyanins are time-consuming, generate chemical residues, and do not fit in modern on-line grading machines. As near infrared (NIR) spectroscopy has been used as a nondestructive method to determine anthocyanin, the objective of this study was to use NIR spectroscopy to predict total anthocyanin (TA) in intact açaí and juçara fruits. Spectra were collected using a Fourier transform (FT)-NIR spectrophotometer in the diffuse reflectance (4,000–10,000 cm−1) and TA reference data were obtained using the Association of Official Analytical Chemists (AOAC) method. Different treatments were applied to spectra and spectral data sets were correlated with TA by using partial least squares (PLSs) regression algorithm. The global-PLS model obtained with açaí and juçara spectra resulted in a root mean standard error of prediction (RMSEP) of 10.05 g·kg−1. However, this model was not adequate for TA levels found in açaí fruits, therefore individual models were developed. The açaí-PLS model proved to be more adequate, as RMSEP was reduced to 3.56 g·kg−1. On the other hand, the RMSEP obtained with the juçara-PLS model (6.59 g·kg−1) was almost the same of the global model. NIR spectroscopy can be used to adequately predict TA content in intact açaí and juçara fruits and this method could be used as an analytical procedure to monitor their quality.
Physiological Responses of Greenhouse-grown Drip-irrigated Chile Pepper under Partial Root Zone Drying
Authors: Sharma Harmandeep , Shukla Manoj K. , Bosland Paul W. , Steiner Robert L.
Published: February 2019

Water saving, productivity, and quality of the chile pepper were evaluated under three irrigation treatments. Three drip irrigation treatments used were 1) control, where water was applied at the surface using two drip emitters; 2) partial root-zone drying vertically (PRDv), where subsurface irrigation was applied at 20 cm depth from soil surface; and 3) partial root-zone drying compartment (PRDc), where roots were divided into two compartments and irrigation was applied to one of the compartments on every alternate-day cycle for 15 days. Continuous measurements of soil water content were carried out during the growing seasons of 2013 and 2014, respectively. During both growing seasons, the stomatal conductance (gS) and net photosynthetic rates (Pn) were similar among all treatments including the control. In both PRD treatments, a higher rooting depth and root length density (RLD) than the control likely compensated for the water stress in dry soil zones by taking up more water from the water available parts of the root-soil system. In PRDc and PRDv treatments, 30% less water was applied than control without significant changes to plant stress expressed by stem water potential, plant height, capsaicinoid concentration, and yield. The increased irrigation water use efficiency (IWUE) demonstrated water saving potential of both PRD techniques for chile pepper production in water-limited arid environments.
Academic Research Perspective of LEDs for the Horticulture Industry
Authors: Mitchell Cary A.
Published: February 2019

Following is the invited perspective of an academic researcher and director of a multi-institutional research and education project tasked to test the feasibility of adopting light-emitting diode (LED) technology for application by the commercial horticulture industry. Academics researching basic specialty-crop responses to spectra, intensities, and durations of lighting with LEDs often find technical queries from growers, vendors, and entrepreneurs to go beyond the capabilities and scope of systematic research to answer definitively. Differences between commercial and academic research approaches to LED technology development are noted, including legal obstacles to open collaboration. Early generation commercial LED technology for horticultural applications is based on research begun >20 years ago. The basis for selection of various LED wavebands for inclusion in LED plant growth arrays is presented for both commercial as well as research applications. Advantages of light distribution from LED sources for different crop applications are presented, especially including close-canopy and intracanopy lighting, both of which contribute substantially to energy savings. Challenges to providing accurate LED light prescriptions for different crops are discussed, including those for supplemental lighting as well as for sole-source lighting applications. Anticipated trends are projected for horticultural applications of LED technology, including multispectral, individually adjustable, high-intensity arrays; increasing electrical efficacy of future LEDs; and reduced costs of mass production for particular applications.
Detection of Gene Expression Changes in Capsicum annuum L. Foliar Blight Caused by Phytophthora capsici Leon. Using qRT-PCR and Leaf Discs
Authors: Jones Rhiana F. , Bosland Paul W. , Steiner Robert L. , Jones Richard W. , O’Connell Mary A.
Published: February 2019

Phytophthora capsici is responsible for multiple disease syndromes of Capsicum annuum but the resistance mechanism is still unknown. Evaluating gene expression during foliar blight can be used to identify expression patterns associated with resistance in Capsicum species. This study reports a direct comparison of gene expression changes during the foliar blight syndrome using two different races of P. capsici on C. annuum host plants with resistant and susceptible phenotypes to those races. Four genes were evaluated for differential expression following leaf inoculation with P. capsici. RNA isolated from leaves at three time points was used to quantify gene expression by quantitative real-time polymerase chain reaction (qRT-PCR). Of four genes tested, two had differential expression in response to P. capsici at 72 hours postinoculation, a xyloglucan-specific endo-β-1,4-glucanase inhibitor protein (XEGIP2) in susceptible cultivar New Mexico Heritage 6-4 (NMH6-4), and a C. annuum cell wall protein (CWP) in resistant Criollo de Morelos 334 (CM334). Both genes had a 5-fold increase in transcription in leaves over the control. These results suggest that both genes are playing a role in disease resistance to foliar blight.
Profitability of Artichoke Growing in the Mediterranean Area
Authors: Sgroi Filippo , Foderà Mario , Di Trapani Anna Maria , Tudisca Salvatore , Testa Riccardo
Published: February 2019

Cultivation of artichokes for production is significant in the Mediterranean Basin. Italy represents an important productive hub and in this context, Sicily has been one of the foremost production areas. Artichoke production is a stable element of either specialized or mixed production systems in the region. However, due to the economic recession and increasing imports of artichokes from North African countries, many companies are undergoing crisis, with concerns for the negative impact on the socioeconomic fabric, in terms of the rising unemployment an eventual collapse of this specific activity would determine. According to the theory of economic development, a prerequisite of a territory’s development is that its economic enterprises be competitive. Ensuing from this hypothesis, this article analyzes the profitability of artichoke production in the Mediterranean. The study was conducted in Sicily, an island in the heart of the Mediterranean, where its cultivation is a long-standing tradition. Our results showed a low profitability for artichoke cultivation in relation to the unfavorably high production costs, whereas the low market prices also reflect the competition from countries of North Africa.
Genetic Diversity of South African Bottle Gourd [Lagenaria siceraria (Molina) Standl.] Landraces Revealed by Simple Sequence Repeat Markers
Authors: Mashilo Jacob , Shimelis Hussein , Odindo Alfred , Amelework Beyene
Published: February 2019

Bottle gourd [Lagenaria siceraria (Molina) Standl.] landraces are widely grown in South Africa, and genetic diversity analysis is necessary to identify promising genotypes for breeding or systematic conservation. Sixty-seven diverse bottle gourd landraces were genotyped using 14 selected simple sequence repeat (SSR) markers. The number of alleles detected per marker ranged from 4 to 11, with a total of 86 putative alleles being amplified. Allele sizes ranged from 145 to 330 base pair (bp). Number of effective alleles (Ne) ranged from 1.58 to 6.14 with a mean of 3.10. Allelic richness varied from 3.00 to 8.90 with a mean of 5.23. Expected heterozygosity (He) values ranged from 0.37 to 0.84 with a mean of 0.65. The mean polymorphic information content (PIC) was 0.57. Jaccard’s coefficient of similarity values ranged from 0.00 to 1.00, with a mean of 0.63. Analysis of molecular variance (AMOVA) revealed that 79%, 17%, and 4% of the variation in bottle gourd landraces was attributable to among landraces, within landraces, and between populations, respectively. The study established the existence of considerable genetic diversity among South African bottle gourd landraces. Unique landraces such as BG-4, BG-6, BG-8, BG-9, and BG-15 from cluster I; BG-55, BG-42, BG-57, and BG-58 from cluster II; BG-28, BG-23, BG-29, and BG-34 from cluster III were selected based on their highest dissimilarity index. These could be useful for bottle gourd breeding and systematic conservation.
Oxidative Metabolism in ‘Valencia’ Sweet Orange (Citrus sinensis Osbeck) Abscission Zone Tissue Treated with the Abscission Agent 5-Chloro-3-Methyl-4-Nitro-1H-Pyrazole
Authors: Kumar Naveen , Ebel Robert C.
Published: February 2019

5-Chloro-3-methyl-4-nitro-1H-pyrazole (CMNP) is an abscission agent, standardized for the mechanical harvesting of late season ‘Valencia’ sweet oranges in Florida. This work was conducted to investigate the role of CMNP to induce oxidative stress in the abscission zone (AZ) of ‘Valencia’ sweet orange. Fully mature ‘Valencia’ sweet orange trees in a commercial grove were sprayed with 2.0 mm of CMNP. The experiment was repeated three times during the Apr.–May 2013 harvest season. Fruit were harvested at 0, 1, 2, and 3 days after CMNP application. Hydrogen peroxide (H2O2) concentration and malonic dialdehyde (MDA) concentration, as well as superoxide dismutase (SOD), ascorbate peroxidase (APOD), glutathione reductase (GR), peroxidase (POD), and lipoxygenase (LOX) specific activities were measured 0, 1, 2, and 3 days after CMNP treatment (DAT). Rate of lipid peroxidation remains unchanged throughout the abscission period. However, LOX activity increased 1 DAT in AZ of treated fruit, which might produce jasmonic acid (JA), known to promote abscission in citrus. Levels of H2O2 were similar in the AZ of control and treated fruit except at 3 DAT. The specific activity of SOD declined at 2 DAT, which showed compromised SOD defense against superoxide radicals (O·−). APOD activity declined sharply at 3 DAT. Interestingly, GR activity was 1.9-fold higher in CMNP-treated fruit at 3 DAT. Higher GR and low APOD activity reflects limited functioning of the APOD/GR cycle (e.g., APOD and GR) in scavenging of H2O2 at 3 DAT. Guaiacol POD activity transiently increased at 1 DAT and then declined. POD plays an important role in cell wall lignification and indole acetic acid (IAA) oxidation. The decline in POD activity may cause a decrease in lignification while higher activity made the AZ sensitive to ethylene and thus promote abscission in citrus fruit. This work also showed that CMNP-induced abscission is a collaborative effort of oxidative metabolism in flavedo tissue (FT) and AZ.
Effects of Salinity and Irrigation Management on Growth and Nutrient Concentrations in Poinsettia
Authors: Gent Martin P.N. , Elmer Wade H. , Macherla Kranti , McAvoy Richard J.
Published: February 2019

Can regulated deficit irrigation in an ebb and flow system alleviate the effects of salinity stress on poinsettia? Two cultivars of poinsettia (Euphorbia pulcherrima Willd ex Klotzsch) were grown under partial- or full-saturation irrigation using a standard fertilizer solution, with or without the addition of 0.5 g·L−1 NaCl. The volumetric water content of the medium averaged 0.25 and 0.33 L·L−1 before irrigation, and 0.5 and 0.67 L·L−1 following irrigation, for partial- or full-saturation regimes, respectively. Plants had lower fresh weight with partial than full saturation. Sodium concentrations in bract, leaf, and stem tissues were higher (P ≤ 0.05) in plants exposed to salinity, and these plants accumulated less K in stems and less P in bracts. Eight cultivars were grown in a second study with or without salinity of 1.2 g·L−1 NaCl under drip or ebb and flow watering. Cultivar and watering had effects on plant fresh weight, but salinity did not. Of the cultivars tested, ‘DaVinci’, ‘Premium Picasso’, and ‘Prestige Red’ had the highest sodium in bracts under salinity with drip irrigation, whereas ‘Snowcap’ had the least. ‘Ruby Frost’ had the most sodium in stems, whereas ‘Snowcap’ had the least. For all cultivars, added salinity resulted in lower K in leaves and stem. Snowcap was the cultivar with the least sodium in stems and bracts under saline irrigation, with either drip or ebb and flow. Our research demonstrates that regulated deficit irrigation resulting in partial saturation of the growing medium is an effective water management option, when control of plant height and overall crop growth are desirable, and it limits the accumulation of sodium when raw water contains elevated salinity.
Cool-season Turfgrass Color and Growth Habit Response to Elevated Levels of Ultraviolet-B Radiation
Authors: Nangle Edward J. , Gardner David S. , Metzger James D. , Petrella Dominic P. , Danneberger Tom K. , Rodriguez-Saona Luis , Cisar John L.
Published: February 2019

Ultraviolet (UV) radiation poses a potential stress for plant growth and development due to its effect on photosynthesis and plant productivity. In the northern hemisphere, peak UV radiation exposure is predicted to occur from 2010 to 2020, with reduced color from UV-related injury, a possibility for turfgrasses. The objective of this study was to investigate the effects of ultraviolet-B (UV-B) light on turfgrass growth and morphology in three cool-season grasses. Cultivars Barvado tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.], Penncross and L-93 creeping bentgrass (Agrostis stolonifera L.), and Barlenium perennial ryegrass (Lolium perenne L.), were selected because of limited information on their growth and development in elevated UV conditions at heights of cut above 10 cm. The impact of UV-B light treatment on color, relative growth rate, and tillering was measured over a 4-week period in repeated experiments. Ultraviolet-B radiation levels were measured at 16 kJ·m−2·d−1 biologically effective UV-B light in growth chambers programmed for a day/night regime of 14/10 hours. Chamber temperatures were maintained at 20 °C day/17 °C night. Ultraviolet-B light significantly inhibited tiller production in the first experiment in all grasses except PR, whereas no grasses were inhibited in the second experiment. Relative growth rates in all grasses were significantly lower in UV-B conditions 3 weeks after treatment initiation. Turfgrasses exposed to this level of UV-B light at typical lawn heights-of-cut had lower color ratings compared with the non-UV-B-treated control at 2 weeks after treatment initiation. The experiments demonstrated that exposure to UV-B resulted in a decline of growth rate and color in cool-season turfgrasses within a timeframe of 2 weeks. Coarse-textured turfgrasses [tall fescue (TF)/perennial ryegrass (PR)] may be more adapted to higher UV-B conditions due to morphological differences compared with the finer textured varieties [creeping bentgrass (CB)].