bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Reproductive Impairment of Most Developed Flowers on Fruit Set and Fruit Quality in Pear
Authors: Miranda Carlos , Santesteban Luis G. , Royo José B.
Published: February 2019

The lowest flower in the pear (Pyrus communis L.) cluster usually develops and blooms first and also has a greater sink potential. For this reason, resources are preferentially utilized by the lowest fruit, and this is also one of the reasons why most thinning practices tend to favor their set. However, it is not always possible to perform selective thinning. This study was undertaken to determine if hindering pollination in the most developed flowers in the cluster influences yield or quality compared to that obtained in a whole open-pollinated cluster. The treatments were made in `Blanquilla' (Spadona, Agua de Aranjuez) and `Conference' pear within a wide range of flower densities for each cultivar. Pollination was hindered by cutting off the flower styles. The factor tested was style removal intensity (SRI). Treatments consisted in removing the styles of two, four(always the most developed), or all flowers in each cluster. Flower density was used as a covariate in an analysis of covariance to account for differences in flower densities in response to SRI treatments. In all experiments the covariate was not significant; therefore, SRI effect was not affected by flower density. `Blanquilla' and `Conference' had similar responses to treatments, so that when at least three flowers are susceptible to be openly pollinated, fruit set, seed content, and cluster yield were similar to control clusters, therefore the growth potential of fruit from partially damaged clusters in their most developed flowers is similar to undamaged open pollinated clusters. The reduced set of parthenocarpic clusters implies yield reductions ranging between 40% and 60% in `Conference', and up to about 60% in `Blanquilla'.
Alternatives to Benomyl for Management of Cercospora Leaf Spot on Turnip Greens
Authors: Kahn Brian A. , Damicone John P. , Schatzer Raymond Joe
Published: February 2019

Benomyl was compared with copper hydroxide, azoxystrobin, tebuconazole, acibenzolar-S-methyl, and basic copper sulfate for efficacy of cercospora leaf spot [incited by Cercospora brassicicola P. Henn] management on turnip greens [Brassica rapa L. var. (DC.) Metzg. utilis]. Treatments included various application times and were evaluated in three field experiments over 2 years. The few yield effects that occurred were not consistent between years. Copper hydroxide and basic copper sulfate were not useful alternatives to benomyl due to a combination of phytotoxicity symptoms and ineffective disease control. Inconsistent results were observed with acibenzolar-S-methyl. A single, early application of tebuconazole greatly reduced cercospora leaf spot severity relative to the control in both years. Tebuconazole may be a good alternative to benomyl if a label can be obtained. Multiple (at least two) applications of azoxystrobin may be needed to achieve the same degree of cercospora leaf spot control as would result from a single properly timed application of benomyl. Although azoxystrobin is now labeled for turnip greens, grower costs will likely increase as a result of benomyl being discontinued. Chemical names used: methyl-1-[(butylamino)carbonyl]-H-benzimidazol-2-ylcarbamate (benomyl); methyl (E)-2-{2-[6-(2-cyanophenoxy)pyrimidin-4-yloxy]phenyl}-3-methoxyacrylate (azoxystrobin); alpha-[2-(4-chlorophenyl)ethyl]-alpha-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (tebuconazole); 1,2,3-benzothiadiazole-7-thiocarboxylic acid-S-methyl-ester (acibenzolar-S-methyl).
Impact of Cutting Pressure on Yield, Quality, Root Carbohydrates, and Survival of Spring-harvested or Summer-forced Asparagus
Authors: Dufault Robert J. , Ward Brian
Published: February 2019

Excessive cutting pressure (CP) early in the lifespan of an asparagus (Asparagus officinalis L.) plantation may weaken and reduce yields and quality. The objective of this research was to determine how increasing CP affects yield, quality, and survival of spring-harvested and summer-forced asparagus. `Jersey Gem' asparagus was harvested for 4 years (1999–2002) in spring or summer-forced on 1 Aug. using the following CP (weeks/year from 1st to 4th years, respectively): 2, 3, 4, 6 (low), 3, 4, 5, 7 (medium), and 4, 5, 8, 10 (high). In all harvest years, as CP increased, marketable number and weight increased. Yield in spring harvest seasons significantly increased with each increase in CP. In summer, yield significantly increased only when high CP was used with equivalent yields at low and medium CP. With summer forcing, there were 48% and 55% fewer large spears at medium and high CP, respectively, compared to the same CP used during spring harvest seasons. Stands tended to decrease with CP from 1997 to 2003, but these differences were not significant and not severe enough to kill the plants. Yearly root fructose concentrations (RFC) with all CP increased yearly from 1999 to 2001 and plateaued from 2002 to 2003. From 1999 to 2002, RFC increased 53%, 27%, 13%, and 13% in unharvested control, low, medium, and high CP, respectively, indicating that with a greater CP, RFC decreased. RFC in summer-forced asparagus was significantly less than spring-harvested in 83% of all sample months. RFC in spring-harvested asparagus was similar to unharvested asparagus in February, March, April, November, and December; however, in all other sample months, spring-harvested RFC was significantly lower than unharvested control plants. The highest CP scheme is appropriate for spring-harvested asparagus based on greatest marketable yields and acceptable cull losses. For summer-forced asparagus, the lowest CP scheme is more appropriate based on acceptable marketable yields and to avoid undue plant stress verified by unacceptably large cull losses mostly attributed to spindly spear size and lower RFC.
Human Response to Window Views and Indoor Plants in the Workplace
Authors: Chang Chen-Yen , Chen Ping-Kun
Published: February 2019

The purpose of this paper was to report the effects of window views and indoor plants on human psychophysiological response in workplace environments. The effects of window views and indoor plants were recorded by measuring participant's electromyography (EMG), electroencephalography (EEG), blood volume pulse (BVP), and stateanxiety. Photo Impact 5.0 was used to simulate the environment in an office, where six conditions were examined: 1) window with a view of a city, 2) window with a view of a city and indoor plants, 3) window with a view of nature, 4) window with a view of nature and indoor plants, 5) office without a window view, and 6) office without a window view and indoor plants. Participants were less nervous or anxious when watching a view of nature and/or when indoor plants were present. When neither the window view nor the indoor plants were shown, participants suffered the highest degree of tension and anxiety.
Effects of Particle Film Application on Leaf Gas Exchange, Water Relations, Nut Yield, and Insect Populations in Mature Pecan Trees
Authors: Lombardini Leonardo , Harris Marvin K. , Glenn D. Michael
Published: February 2019

Trials were conducted during summer months of 2002 and 2003 to evaluate the effects of a kaolin-based particle film (Surround WP, Engelhard Corp.) on gas exchange, nut quality, casebearer density and population of natural enemies (insects and arachnids) on pecan (Carya illinoinensis `Pawnee') trees. Film application was repeated for seven (2002) or nine (2003) times during the growing season. In both years, treated trees showed lower leaf temperature (up to 4 °C) than untreated trees. During the warmest hours of the day, kaolin-treated leaves were generally 0 to 2 °C cooler than air temperatures, compared to 4 to 6 °C for control leaves. Leaf net assimilation rate, stomatal conductance and stem water potential were not affected by film application. Nut size and quality did not differ between the two treatments. Shellout (percentage of nut consisting of kernel) was not affected by treatment and averaged about 55%. Crop grade distribution (fancy, choice, standard, and damaged) was also similar among treatments in both years. In both years, numbers of green lacewing eggs was less on kaolin-treated compared to control leaves. The density of common natural enemies (lady beetles, green lacewings, spiders) of pecan pests did not differ between treatments. The average number of developing nuts damaged by pecan nut casebearer (Acrobasis nuxvorella Neunzig) was significantly higher in kaolin-sprayed trees (24.2%) compared to control trees sprayed with conventional insecticides (9.3%). The results suggest that kaolin-based particle film may not be a viable alternative to conventional methods of controlling pecan pests. Also, under adequate irrigation conditions, carbon assimilation, water relations and productivity may not benefit from kaolin particle film application.
Sweet Corn Hybrid Responses to Thifensulfuron-methyl
Authors: Soltani Nader , Sikkema Peter H. , Robinson Darren E.
Published: February 2019

Limited information exists on sweet corn (Zea mays) tolerance to postemergence (POST) applications of thifensulfuron-methyl under Ontario growing conditions. Eight sweet corn hybrids were evaluated for tolerance to thifensulfuron-methyl in four field experiments conducted in 2003 and 2004. Thifensulfuron-methyl was applied POST at 6 and 12 g·ha–1 a.i., the registered and twice the registered rate for use in soybean in Ontario. Sweet corn hybrid responses to thifensulfuron-methyl varied. Delmonte 2038 was the most sensitive to thifensulfuron-methyl and had as much as 92% visual injury, 76% height reduction, and 98% yield reduction compared to the nontreated control. Empire, GH1861, GH2298, and GH2684 hybrids showed visual injury of 53%, 55%, 53%, and 61%, height reduction of 34%, 31%, 32%, and 26% and yield reduction of 77%, 68%, 68%, and 51%, respectively. GG214, GH2547, and GSS9299 sweet corn hybrids were not as sensitive to thifensulfuron-methyl. The initial sensitivity observed in these hybrids was minimal and transient with no effect on yield. Although thifensulfuron-methyl is safe for use on some sweet corn hybrids, it has the potential to cause severe crop injury and yield reduction in other hybrids and therefore it should not be recommended for weed management in sweet corn production in Ontario.
Variation in Leafhopper Species Abundance and Diversity among Elm Seedlings and Cultivars
Authors: Bentz Jo-Ann , Townsend Alden M.
Published: February 2019

A survey was conducted in the 2001 growing season to determine the leafhopper species composition, abundance, richness, diversity, and evenness among trees of three elm (Ulmus sp.) cultivars, two U.S. National Arboretum (USNA) seedling selections of U. szechuanica Fang, and two USNA seedling selections of U. bergmanniana Schneid. in a mixed stand. Yellow sticky traps were used to qualify and quantify the number of aerial leafhoppers from 1 May 2001 until 4 September 2001. A total of 4,523 individuals, belonging to 39 species within seven leafhopper subfamilies, were trapped. The weekly mean number of leafhoppers collected was significantly higher on traps from `Patriot', followed by `Frontier' and `Prospector', than on traps from the USNA seedling selections. Although the weekly mean species richness for `Prospector' was lower than the other two cultivars, the three cultivars had higher mean species richness than the USNA seedling selections of U. szechuanica and U. bergmanniana. Diversity among cultivars was higher than among the USNA seedling selections. Ulmus bergmanniana 68983 and U. szechuanica 68986 shared the highest percentage of species similarity, while `Frontier' and U. szechuanica 68991 were the most dissimilar. Of the species collected, Agallia quadripunctata, Empoasca fabae and Graphocephala versuta were the most abundant. The other species were mostly rare based on their low abundance. Scaphoideus luteolus, the only confirmed vector of elm yellows in North America, was found among the elm cultivars only. Yet, the Cicadellinae leafhoppers that are vectors of Xylella fastidiosa, the causal agent of bacterial leaf scorch, were found among both the cultivars and USNA seedling selections. Such data could allow for the screening and selection of elms resistant to economically important leafhoppers.
An Apple Chlorotic Leaf Spot Virus Isolate from Ornamental Dwarf Flowering Almond (Prunus glandulosa 'Sinensis'): Detection and Characterization
Authors: Spiegel Sara , Thompson Dan , Varga Aniko , James Delano
Published: February 2019

An apple chlorotic leaf spot virus (ACLSV) isolate was detected by TAS-ELISA and RT-PCR in an ornamental dwarf flowering almond (Prunus glandulosa Thunb.). This plant, maintained at the Centre for Plant Health, Sidney, B.C., Canada, has been showing transient leaf symptoms during the spring seasons. A 390-bp fragment and a 1,350-bp product, in the RNA polymerase and the coat protein viral coding regions, respectively, were amplified by RT-PCR from the infected plant. A sequence comparison of the 390-bp fragment of this ACLSV isolate (designated as AL1292) with other published isolates, revealed a similarity of 81% to 84% at the nucleotide level and 88% to 100% at the amino acid level. In contrast to other ACLSV isolates, AL1292 has an exceptionally narrow range of experimental herbaceous and woody hosts, as determined by mechanical and graft inoculation assays. These standard bioassays may not be effective for the detection of the AL1292 isolate because of its limited host range. The results we report in this paper confirm P. glandulosa as a natural host of this virus. Currently it is not known how ACLSV is spread, other than by bud-grafting and possibly by root grafts. The use of virus-tested source plants for the preparation of planting material will minimize its spread.
Tropaeolum Mosaic Potyvirus (TropMV) Reduces Yield of Andean Mashua (Tropaeolum tuberosum) Accessions
Authors: Guimarães Rejane L. , Flores Hector E.
Published: February 2019

Quechua farmers have cultivated mashua (Tropaeolum tuberosum Ruiz & Pavon) and other tuber crops for thousands of years. The practice of trading seed tubers may have contributed to dispersal of viral diseases, such as the tropaeolum mosaic virus (TropMV). We surveyed 17 accessions of mashua collected from Quechua farmers in the provinces of Cuzco and Ayacucho, Peru. Most cross-reacted with the TropMV antibody and showed viral disease symptoms. Significant differences were observed between accessions from Cuzco and Ayacucho, with respect to virus infection and tuber yield under greenhouse conditions. Of the accessions from Cuzco, 87% displayed viral symptoms, while only 22% from Ayacucho showed symptoms. Fewer tubers from Cuzco generated mature plants. In turn, those mature plants produced lower tuber yields. The practice of trading seed tubers may be advantageous for promoting crop diversity but can be harmful when diseased seed tubers are being traded. A program to generate and distribute virus-free seed tubers among Andean farmers would contribute to higher crop yields while preserving local customs and crop diversity.
Effects of the Bioregulators Aminoethoxyvinylglycine and Ethephon on Brix, Carbohydrate, Acid, and Mineral Concentrations in 'Scarletspur Delicious' Apple Juice
Authors: Drake S.R. , Eisele T.A. , Elfving D.C. , Drake M.A. , Drake S.L. , Visser D.B.
Published: February 2019

In a study conducted over three crop seasons, Ethrel (ETH) increased the Brix, sucrose, and sorbitol content of 'Scarletspur Delicious' apple juice while reducing the fructose content. Both longer preharvest exposure to, and higher concentrations of, ETH had a stronger influence than application closer to harvest and/or at lesser amounts. Time of ETH application tended to influence individual carbohydrates more so than amount of ETH applied. ETH reduced total acidity and also reduced apple juice individual acid (quinic and malic) contents with longer preharvest exposure or higher concentrations. Aminoethoxyvinylglycine [AVG (ReTain)] reduced both Brix and sucrose content of 'Scarletspur Delicious' apple juice, but had no influence on either total acidity or individual acid contents. Combinations of AVG with ETH tended to counteract the influence of either used alone on total Brix, carbohydrates, total acidity and individual acids. Mineral content of 'Scarletspur Delicious' apple juice was not strongly influenced by application of either ETH or AVG.
The Structure of Graft Unions in European Chestnut Using Different Grafting Methods
Authors: Serdar Umit , Kose Bulent , Yilmaz Fatma
Published: February 2019

We studied the anatomical structure of graft unions in European chestnut using several grafting methods. The work was done in the greenhouse during 2003–04. The grafting methods epicotyl, hypocotyl, and inverted radicle were used. The grafts were made with scions of clone SA 5-1 on clone SE 21-9 rootstock. The samples for examination were taken from the graft unions 2, 6, and 12 months after grafting, and fixed in a formalin–acetic acid–alcohol solution. The observation of the anatomical structure of the graft union area revealed that new cambium, xylem, and phloem tissues were formed in the samples two months after grafting. Further, it could be also observed that 6 months were necessary for continuous cambial connection.
Lettuce Response to Phosphorus Fertilization in High Phosphorus soils
Authors: Johnstone P.R. , Hartz T.K. , Cahn M.D. , Johnstone M.R.
Published: February 2019

Decades of heavy phosphorus (P) fertilization of vegetable crops in the Salinas Valley of California has increased soil test P (STP) levels, with bicarbonate-extractable P (Pbc) values >50 mg·kg–1 now common. To evaluate the response of lettuce (Lactuca sativa L.) to P fertilization in fields with elevated STP levels, 12 trials were conducted in commercial fields during 2002–03. Initial Pbc at the trial sites varied from 53 to 171 mg·kg–1. In each trial, four replicate plots receiving the growers' P application were compared with paired plots in which no P was applied. Leaf P was monitored at midseason and at harvest. At harvest, mean whole and marketable plant mass and percent of marketable plants were recorded. A significant increase in lettuce yield with P fertilization was achieved at only one trial site, a spring planting with 54 mg·kg–1 Pbc; at all other sites, including three with Pbc <60 mg·kg–1, P application resulted in no significant yield increase. Phosphorus application resulted in only a marginal increase in plant P uptake; in the nonresponsive fields leaf P concentration of nonfertilized plots was in excess of established sufficiency levels. In a laboratory study, the correlation of Pbc to bioavailable P (Pba) was evaluated using 30 representative Salinas Valley soils; Pbc varied among these soils from 15 to 177 mg·kg–1. Pba was estimated by P adsorption on an anion resin membrane during a 16 hour incubation. The effect of temperature on P bioavailability in six of these soils was estimated by conducting the Pba incubation at 5, 15, and 25 °C. Pba was highly correlated with Pbc (r = 0.89), and increased about 40% across soils with each 10 °C increase in soil temperature. Therefore, Pbc was determined to be an accurate reflection of bioavailable P in these soils, although the addition of a temperature correction factor in setting threshold values is desirable.
Response of Four Apple Cultivars to 1-Methylcyclopropene Treatment and Controlled Atmosphere Storage
Authors: Bai Jinhe , Baldwin Elizabeth A. , Goodner Kevin L. , Mattheis James P. , Brecht Jeffrey K.
Published: February 2019

Apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf. (`Gala', `Delicious', `Granny Smith' and `Fuji')], pretreated or nontreated with 1-methylcyclopropene (1-MCP, 0.6 to 1.0 μL·L–1 for 18 hours at 20 °C), were stored in controlled atmosphere (CA, 1 to 1.5 kPa O2; 1 to 2 kPa CO2) or in regular atmosphere (RA) for up to 8 months at 1 °C. Firmness, titratable acidity (TA), soluble solids content (SSC), and volatile abundance were analyzed every month directly or after transfer to air at 20 °C for 1 week to determine effect of 1-MCP, storage atmosphere and storage time on apple quality immediately after cold storage and after simulated marketing conditions at 20 °C. The 1-MCP ± CA treatments delayed ripening and prolonged storage life as indicated by delayed loss of firmness and TA in all four cultivars during storage. The 1-MCP ± CA also slightly delayed loss of SSC for `Gala' but had no effect on SSC levels for the other cultivars. There were differences among treatments for firmness and TA content [(1-MCP + RA) > CA] for `Gala', `Delicious', and `Granny Smith' apples, but not for `Fuji'. These differences were generally exacerbated after transfer of fruit to 20 °C for 1 week. A combination of 1-MCP + CA was generally best [(1-MCP + CA) > (1-MCP + RA) or CA] for maintaining `Delicious' firmness and TA. However, the treatments that were most effective at retaining TA and firmness also retained the least volatiles. The results indicate that the efficacy of 1-MCP and CA in maintaining apple quality factors is cultivar dependent and that 1-MCP + RA may be a viable alternative to CA for optimal eating quality for some cultivars.
Use of 1,3-Dichloropropene to Reduce Irrigation Requirements of Sting Nematode-infested Bermudagrass
Authors: Trenholm Laurie E. , Lickfeldt Darin W. , Crow William T.
Published: February 2019

This research was conducted to determine if application of 1,3-dichloropropene (1,3-D) could reduce turfgrass water requirements in soil infested with sting nematodes (Belonolaimus longicaudatus Rau). The effects of 1,3-D and fenamiphos were evaluated on quality and persistence of `Tifway 419' bermudagrass (Cynodon dactylon × C. transvaalensis Burtt-Davy) subjected to drought or deficit irrigation. The research consisted of two greenhouse studies in 2002 and 2003 where irrigation was either withheld or applied in deficit quantities, and one field study in 2003 where irrigation was withheld. In general, 1,3-D-treated turf maintained up to 40% higher quality during drought than other treatments and had up to 27% less leaf wilting. As drought severity increased, 1,3-D treatments had better spectral reflectance values, indicating better physiological functioning under stress. Results of this research suggest that application of 1,3-D in sting nematode-infested soils may increase bermudagrass drought survival.
Sources of Resistance to Two-spotted Spider Mite (Acari: Tetranychidae) in Citrullus spp.
Authors: López Rolando , Levi Amnon , Shepard B. Merle , Simmons Alvin M. , Jackson D. Michael
Published: February 2019

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), often causes serious damage to watermelon (Citrullus spp.), and there is a need to evaluate and identify watermelon germplasm resistant to T. urticae. Watermelon cultivars (Citrullus lanatus var. lanatus), and U.S. plant introduction (PI) accessions of C. lanatus var. citroides and C. colocynthis, were evaluated for preference by T. urticae (number of adults and eggs on leaves). In open-choice experiments in the greenhouse and in laboratory rearing cages, there was a significant preference by T. urticae for watermelon cultivars, Citrullus lanatus var. lanatus PIs, and C. lanatus var. citroides PIs over C. colocynthis PIs. All watermelon cultivars and PIs were infested, but the C. colocynthis PIs were significantly less infested with T. urticae. The C. colocynthis PIs may be useful sources for enhancing T. urticae resistance in cultivated watermelon.
Second Generation (F2) Hybrid Cultivars for Jalapeño Production
Authors: Bosland Paul W.
Published: February 2019

Chile pepper (Capsicum spp.) hybrids are normally produced by hand-emasculating the female parent and then pollinating the emasculated flower by hand. Increased yield has occurred with F1 hybrid seed, but the seed is considered too expensive by growers to be direct-seeded, a common production practice in the southwestern U.S. chile pepper industry. In ornamental flowers, when F2 hybrid seed is available, it is cheaper than F1 hybrid seed. If F2 hybrid chile pepper cultivars could manifest heterosis, and produce fruit quality acceptable to the chile pepper industry, then a less-costly alternative would be available to growers. A series of field trials with jalapeños was conducted to test F1 hybrid cultivars to their F2 progeny for yield and fruit quality. The results indicated that in some instances the F2 progeny can yield as well as the F1 hybrid parent. Therefore, F2 hybrid cultivars can be used in a commercial production system. However, if a male-sterility system is used to produce the F1 hybrid cultivar, the F2 progeny will have significantly lower yield than the F1 hybrid parent, as was the case in one accession in this trial. Nevertheless, F2 hybrid cultivars are an additional way to supply high yielding hybrid cultivars to growers.
Temporal Weed Interference with Young Pecan Trees
Authors: Smith Michael W. , Cheary Becky S. , Carroll Becky L.
Published: February 2019

Vegetation surrounding pecan (Carya illinoinensis Wangenh. C. Koch) trees in a 4.3 × 6 m area was either controlled with a nonresidual herbicide for the entire growing season, not controlled, or controlled at certain times during the growing season. After three growing seasons, trunk diameters were suppressed 54% when vegetation was not controlled, 47% when not controlled until 1 Aug., and 37% if not controlled after 1 June compared to entire growing season vegetation control. Trunk diameters were not significantly different from entire season vegetation control when vegetation was controlled from 1 June through fall frost or vegetation controlled from April until 1 Aug. Vegetation in the plots was typically dominated by cool season herbaceous dicots in May and June, and warm-season grasses during August and September.
Temperature and Cultivar Effects on Anthocyanin and Chlorophyll b Concentrations in Three Related Lollo Rosso Lettuce Cultivars
Authors: Gazula Aparna , Kleinhenz Matthew D. , Streeter John G. , Miller A. Raymond
Published: February 2019

Pigment concentrations in leaf tissue affect the visual and nutritional value-based indices of lettuce crop quality. To better discern the independent and interactive effects of temperature and cultivar on anthocyanin and chlorophyll b concentrations, three closely related Lolla Rosso lettuce cultivars (`Lotto', `Valeria', and `Impuls'), varying primarily in the number of genes controlling anthocyanin concentrations, were subjected to different air temperatures in controlled environments. Fifteen-day-old seedlings previously grown at 20 °C day/night (D/N) were transplanted into growth chambers maintained at 20 °C (D/N), 30/20 °C D/N and 30 °C D/N air temperatures. Twenty days later, leaf tissue was sampled for measures of pigment concentrations, calculated based on spectrophotometric absorbance readings taken at 530 nm (anthocyanin) and 660 nm (chlorophyll b) respectively. Although significant, the temperature × cultivar interaction resulted from differences in the magnitude (not direction) of the change in pigment concentrations among cultivars with changes in temperature. Regardless of cultivar, anthocyanin and chlorophyll b concentrations were highest, moderate and lowest after growth at 20 °C D/N, 30/20 °C D/N and 30 °C D/N respectively. Likewise, irrespective of temperature, anthocyanin and chlorophyll b concentrations followed the pattern `Impuls' (three genes) > `Valeria' (two genes) > `Lotto' (one gene). These data provide additional strong evidence that lettuce leaf pigment concentrations and growing temperatures are negatively related. The data also suggest that low temperatures during the dark phase may mitigate high temperature-driven reductions in lettuce leaf pigment levels.
Olive-mill Waste Compost as a Growth Medium Component for Foliage Potted Plants
Authors: Papafotiou M. , Kargas G. , Lytra I.
Published: February 2019

Research was carried out to evaluate composted olive-mill waste as a peat substitute in foliage potted plant production. Rooted cuttings of Codiaeum variegatum (L.) A. Juss and Syngonium podophyllum Schott were grown for 5 months and Ficus benjamina L. for 10 months in media containing olive-mill waste compost (OWC), sphagnum peat and perlite in 1:3:4, 1:1:2, and 3:1:4 ratio (by volume), respectively, and their foliage and root growth was determined and compared to a control medium of 1 peat: 1 perlite (by volume). When up to 75% of peat in the control medium was replaced by OWC, C. variegatum foliage and root growth were similar compared with the control, while a 50% peat replacement gave the best growth. Syngonium podophyllum was more sensitive to peat replacement compared to C. variegatum, as only 25% of peat could be replaced by OWC without any reduction in foliage growth. The dry weight of the roots was not affected in all media tested. In F. benjamina, peat could be replaced up to 75% without effects on plant height and lateral shoot number, while the length of the laterals was progressively reduced with increasing OWC level. However, only at the highest OWC level (75% peat replacement) the laterals were shorter compared with the control. There was also a progressive reduction of main stem diameter, foliage fresh weight, and root dry weight with increasing OWC level in the medium. Even the lowest OWC level (25% peat replacement) caused a decrease of foliage and root weight compared with the control, with no effect though on plant visual quality. Even a 25% peat replacement by OWC caused an increase in bulk density. A considerable decrease of total porosity and readily available water were measured in media where 50% or 75% of peat was replaced by OWC. The pH of the medium with the highest OWC level was high during the first 4 months of culture compared to the other media. The electrical conductivity initially related to OWC level, but it decreased to values similar to that in the control medium during the first month of culture.
The Effect of Seed Source, Light during Germination, and Cold-moist Stratification on Seed Germination in Three Species of Echinacea for Organic Production
Authors: Romero Fredy R. , Delate Kathleen , Hannapel David J.
Published: February 2019

Organic production of one of the most popular botanical supplements, Echinacea, continues to expand in the U.S. Echinacea seeds typically show a high degree of dormancy that can be broken by ethephon or gibberellic acid (GA), but these methods are currently disallowed in organic production. In order to determine the efficacy of nonchemical seed treatments, we evaluated the effect of varying seed source and supplying light, with and without cold-moist stratification, on seed germination of the three most important medicinal species of Echinacea, E. angustifolia DC, E. purpurea (L) Moench, and E. pallida (Nutt.) Nutt. Treatments included cold-moist stratification under 24 hours of light, 24 hours of dark, and 16/8 hours of light/dark to break seed dormancy. We found that germination was greater in the E. purpurea and E. pallida seeds from a commercial organic seed source compared to a public germplasm source. When seeds were not cold-moist stratified, 16 to 24 hours light increased germination in E. angustifolia only. Echinacea angustifolia, E. purpurea, and E. pallida seeds that were cold-moist stratified under 16 to 24 hours of light for 4 weeks had a significantly greater percentage and rate of germination compared to seeds germinated in the dark. Therefore, cold-moist stratification under light conditions is recommended as a method to break seed dormancy and increase germination rates in organic production of Echinacea.
Growth of Containerized Atlantic White Cedar Seedlings as Affected by Container Volume, Substrate, Fertilizer, and Irrigation
Authors: Derby Scott A. , Hinesley L. Eric
Published: February 2019

Germination and growth of atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] was evaluated in response to four container volumes (98 to 530 cm3), two substrates [North Carolina Forest Service (NCFS) container mix [3 canadian peat: 2 coarse vermiculite: 1.5 perlite (by volume), and 3 composted pine bark: 1 peat (by volume)], two controlled-release fertilizers [Osmocote 15N–4.0P–10.0K (15N–9P2O5–12K2O), 12- to 14-month southern formulation, with micros; and Polyon 18N–2.6P–10.0K (18N–6P2O5–12K2O) with micros, 9-month formulation], and three irrigation frequencies (2, 3, or 4 times daily). Although growth increased up to the maximum container volume (530 cm3), the optimum for 1-year-old seedlings appeared to be 164 to 262 cm3. The higher peat content and water holding capacity of the NCFS substrate yielded better growth than 3 bark: 1 peat. Osmocote yielded larger and heavier plants than Polyon, probably owing to more available phosphorus in the former. Irrigation three times daily was optimum. Suitable manipulation of container volume, substrate, fertilizer, and irrigation should yield high quality containerized atlantic white cedar seedlings.
Preharvest Application of Methyl Jasmonate to 'Fuji' Apples Enhances Red Coloration and Affects Fruit Size, Splitting, and Bitter Pit Incidence
Authors: Rudell David R. , Fellman John K. , Mattheis James P.
Published: February 2019

Repeated preharvest applications of methyl jasmonate (MJ) to 'Fuji' apple [Malus sylvestris var. domestica (Borkh.) Mansf.] fruit were evaluated for impacts on peel color, size, fruit finish, and maturation. MJ treatments at 2 week intervals began 48 days after full bloom (DAFB) (early season) or 119 DAFB (late season) and fruit were harvested 172 DAFB. MJ treatment stimulated significant increases in peel red color following the initial application and thereafter. Early season MJ treatment reduced fruit diameter and length to diameter ratio but slowed softening and starch hydrolysis. Fruit receiving late season MJ treatments had increased incidence of bitter pit and splitting, shorter green life, and slower softening. Results suggest preharvest application of MJ impacts apple color development and other aspects of fruit quality. Chemical name used: methyl 3-oxo-2-(2-pentenyl)cyclopentane-1-acetate (methyl jasmonate).
Application of CaCl2 Sprays Earlier in the Season May Reduce Bitter Pit Incidence in 'Braeburn' Apple
Authors: Neilsen Gerry , Neilsen Denise , Dong Shufu , Toivonen Peter , Peryea Frank
Published: February 2019

Calcium application trials were undertaken in a 'Braeburn' apple (Malus ×domestica Borkh.) orchard with a history of bitter pit development at harvest. In 2000, an early season calcium chloride application strategy was compared with the unsprayed control and a late season application strategy. From 2001–03, the assessment of timing of calcium chloride sprays was extended by comparing effects of five weekly sprays applied during the growing season either early, middle, or late season. Other Ca application strategies tested included sprays of acidified calcium carbonate suspensions and soil application of calcium thiosulphate. In the first experiment, early application of calcium chloride reduced the occurrence of bitter pit at harvest and after 3 months cold air storage, despite having low harvest fruit Ca concentrations. Late sprayed fruit had a higher incidence of bitter pit. In the second experiment, the later calcium chloride was sprayed in the growing season, the higher the fruit Ca concentration at harvest. Despite this, no bitter pit was measured at harvest for 2 years for early and midseason calcium chloride spray regimes. In 2003, when Ca disorders were severe and fruit large, bitter pit was observed despite early season calcium chloride sprays. Soil calcium thiosulphate application and foliar sprays of acidified calcium carbonate suspensions failed to meaningfully augment harvest fruit Ca concentrations and affect bitter pit incidence.
Foliar Damage and Flower Production of Landscape Plants Sprinkle Irrigated with Reuse Water
Authors: Devitt D.A. , Morris R.L. , Fenstermaker L.K. , Baghzouz M. , Neuman D.S.
Published: February 2019

Nineteen flowering landscape species were sprinkle irrigated with either reuse water or fresh water, with an additional treatment of reuse water plus shade (solar radiation reduced by 24%), for 113 days during late summer and early fall in southern Nevada. The species selected were common to mixed landscape areas on golf courses in southern Nevada transitioning to reuse water. An index of visual damage (IVD) was assessed, along with an assessment of flower production, canopy temperature, tissue ion analysis and spectral reflectance. The IVD values separated based on species (p < 0.001), treatment (p < 0.001) and by a species by treatment interaction (p < 0.001). Irrigating with reuse water plus shade reduced the IVD compared to the reuse without shade in 7 of the 19 species (p < 0.05). When IVD values were included for all species, 40% of the variation in the IVD values could be accounted for if N, B, Ca, Mg, Na, and Zn were included in the regression equation. Higher r2 values were obtained when individual species were isolated, with regression equations differing based on tissue ion combinations [e.g., ice plant (Mesembryanthemum crystallinum L.) r2 = 0.81 IVD↑, Na↓, Mn↑]. Three vegetation indices chlorophyll index (CHL), red/far red (R/FR) and water band index/normalized difference vegetation index (WBI/NDVI)) accounted for 51% of the variation in the IVD values. As much as 72% of the variation in vegetation indices could be accounted for based on tissue ion concentrations when separated based on treatment, with Na being the only common ion in all of the highest correlations. Flower production was highest in the reuse plus shade treatment in all 13 species flowering during the experimental period, with as much as 86% of the flower production variation driven by different tissue ion concentrations [purple cup (Nierembergia hippomanica), r2 = 0.86, flowers↑, Mn↑, Zn↓]. Nine of the nineteen species had acceptable levels of foliar damage (IVD < 2.0). We believe that if the spray irrigation can be minimized (bubblers/drip) and/or partial shade provided, through multi-story landscape designs, a more favorable response will be observed.
Biostimulant Influences on Turfgrass Microbial Communities and Creeping Bentgrass Putting Green Quality
Authors: Mueller S.R. , Kussow W.R.
Published: February 2019

Immature sand matrix golf putting greens are considered to be inhospitable environments for microorganisms as compared to native soils. Subsequently, turfgrass quality may suffer in the absence of beneficial microbe–plant interactions. The turfgrass industry has responded by marketing a wide array of biostimulant products that claim to improve putting green quality through influences on soil microbial activity. A field study was conducted to determine what influences five commercial biostimulants have on the root-zone microbial community and creeping bentgrass (Agrostis stolonifera L.) quality. A three year old U.S. Golf Association (USGA) specification sand-based putting green (e.g., 80% sand: 20% peat humus by volume) was the test site. Commercially available biostimulants and fertilizer were applied biweekly from May until August 2000. The soil microbial community was characterized using soil enzymes and substrate utilization profiles. Turfgrass quality was determined visually by evaluating color, percentage of localized dry spot (LDS), and overall uniformity. Nutrient uptake levels were monitored to ascertain if increases in quality related to plant health. Visual quality of the putting green was significantly improved (p < 0.05) by the commercial biostimulants. The positive response to biostimulants was not of a nutritional origin. The biostimulants did not effectively alter the putting green microbial community in terms of enzyme activity or substrate utilization. However, a seasonal decline was detected in cellulase activity, which prevailed over any treatment effect, suggesting the root-zone microbial community responded to summer decline of bentgrass roots and concomitant decreases in quantities of root exudates. Visual improvements in putting green quality during the period of summer stress were primarily associated with the incidence of LDS. Visual LDS ratings were significantly reduced (less LDS) by applications of the biostimulants on each observation date (p < 0.05) and over the entire course of the experiment (p < 0.10). Surfactant properties of the biostimulants therefore appeared to play a major role in the improvements in putting green quality. This does not negate the fact that the seaweed extracts and humic acids in the biostimulants may have improved the heat and moisture stress tolerance of the bentgrass once the LDS formed.
Genetic and Phenotypic Parameter Estimates for Yield and Fruit Quality Traits from a Single Wide Cross in Yellow Passion Fruit
Authors: de Moraes Michel Choairy , Geraldi Isaias Olívio , Matta Frederico de Pina , Vieira Maria Lucia Carneiro
Published: February 2019

The aim of this study was to estimate genetic and phenotypic parameters in a population of yellow passion fruit for determining its potential for genetic improvement, as well as to establish strategies for selection. The basic material comprises a sample of 100 F1 plants derived from a single cross between the accessions `IAPAR-06' and `IAPAR-123', which are genetically divergent. The experimental evaluation was performed in a 10 × 10 triple lattice design. At harvest, yield and number of fruit were evaluated, as well as other traits related to fruit quality. Results indicated that the population displays wide genetic variability, with coefficients of heritability on a genotype mean basis varying from 52.6% to 83.2%. High and positive genetic correlations were detected between yield and number of fruit and for combinations of the traits weight, length, and width of the fruit. Negative genetic correlations were found between the soluble solids content and the other traits. The relevance of the results from such a divergent cross to a commercial breeding program is discussed.
Identification of Genes Regulated by Low Temperature in Pachysandra terminalis Sieb. et Zucc Using cDNA Differential Display
Authors: Zhou Suping , Sauve Roger J. , Abdulah Abdulah
Published: February 2019

Complementary Deoxyribonucleic Acid (cDNA) differential display and reverse Northern dot blot were used to identify genes in Pachysandra terminalis Sieb. & Zucc., a cold-tolerant plant, that are regulated by low temperatures. Rooted cuttings were obtained from stock plants that had been maintained in a greenhouse at 24 °C. These cuttings were subjected to the following cold treatments: 2 weeks at 12 °C, 48 hours at 4 °C, 48 hours at 0 °C, and 4 hours at –1 °C. Following leaf tissue analysis of treated and control plants, some stress-related genes and many novel genes were identified. Northern blot hybridization demonstrated that all novel genes were regulated by the cold treatments.
A Novel Method to Quantify Transport of Self- and Cross-pollen by Bees in Blueberry Plantings
Authors: Brevis Patricio A. , NeSmith D. Scott , Seymour Lynne , Hausman Dorothy B.
Published: February 2019

Blueberry species (Vaccinium section Cyanococcus) benefit from cross-pollination. Outcrossing increases fruit set, berry size, and ripening rate. Although knowledge of pollen dispersal is essential for maximizing cross-pollination and achieving optimal planting designs, this process has not been quantified previously in blueberry plantings. A novel method was developed to estimate the proportion of self- and cross-pollen transported by blueberry pollinators. The proposed technique requires a consistent difference in pollen size between two cultivars to predict the composition of a pollen mixture based on frequency distributions of pollen diameter. Vaccinium ashei Reade `Brightwell' and `Climax' were chosen for this study because they produce pollen tetrads of different size. Tetrad diameter and number were analyzed with a particle counter. The technique was validated by predicting the proportion of `Brightwell' in pollen mixtures where the cultivar composition was known, and predicted and actual values were linearly correlated (r = 0.995, P < 0.0001). The technique was then applied to pollen samples extracted from the bodies of pollinators that were collected in a mixed `Brightwell' and `Climax' blueberry plot. Numbers of blueberry tetrads extracted per bumblebee (Bombus spp.) averaged 4595 and 797 in 2003 and 2004, respectively, which was considered adequate to make accurate predictions based on frequency distributions of tetrad diameter. The proportion of `Brightwell' pollen carried by bumblebees changed with the phenology of the crop following an expected pattern, indicating that the method performed well under field conditions. This technique could potentially be used to quantify the likelihood for outcrossing and establish the effect of cultivar arrangements on pollen dispersion, as well as to examine pollen collection and manipulation, and cultivar preference by bees.
Time of Aminoethoxyvinylglycine Application Influences Preharvest Drop and Fruit Quality of 'McIntosh' Apples
Authors: Greene Duane W.
Published: February 2019

AVG was applied as the ReTain formulation over three harvest seasons to determine the influence of time of application on drop control efficacy and its influence on fruit maturity of 'McIntosh' apples. Effective drop control was achieved through the commercial harvest season with application of AVG made from 1 to 6 weeks before the anticipated start of harvest for untreated fruit. Drop control extended beyond the normal harvest period when application was made either 2 weeks or 1 week before anticipated harvest. Application made between 6 and 4 weeks before anticipated harvest generally delayed parameters associated with ripening, such as softening, degradation of starch, and development of red color, more than applications made on later dates. While AVG consistently and effectively retarded abscission, the length of time it controlled drop varied from year to year, even when used on similar trees in the same block. Once applied, it required 10 to 14 days before AVG started to retard fruit abscission. AVG controlled drop linearly with increasing concentration. AVG was a superior drop control compound than NAA. Chemical names used: aminoethoxyvinylglycine (AVG), naphthaleneacetic acid (NAA).
Soil Mounding as a Control for Dogwood Borer in Apple
Authors: Gut Larry J. , McGhee Peter H. , Perry Ron
Published: February 2019

The relationship between the extent of burrknots on apple rootstocks and dogwood borer (DWB) [Synanthedon scitula Harris] infestation, and the efficacy of a cultural management strategy for this pest were studied in heavily infested plots at the Michigan State University Clarksville Horticulture Experiment Station. Spearman rank correlation Rho values of 0.85 and 0.75 in consecutive years of the study substantiated a strong positive correlation between the number of larvae present in the rootstock and the surface area of the rootstock covered by burrknots. Cultivar type affected the level of the DWB infestation in the rootstock. Larval densities were 8- to 10-times higher in Mark rootstocks when the grafted scion was `Idared' instead of `Liberty'. This cultivar related difference in larval infestation was associated with a greater number of burrknots on `Idared'/Mark compared to `Liberty'/Mark trees. Mounding of soil to cover the exposed rootstock was found to be a highly effective alternative to insecticides for DWB control. Under conditions of heavy pest pressure, this cultural control tactic provided 76% to 99% reductions in larval densities. These levels of control are comparable to or better than those reported for trunk sprays with chlorpyrifos, the most effective of currently available insecticides.