bluuebunny/crossref_metadata_2025 huggingface dataset:
Minimizing Irrigation and Fertilization in Greenhouse-grown Flowering Vinca
Authors: Panter Karen L. , Briggs Amy M. , Roll Michael J. , Newman Steven E.
Published: February 2019

The objective of this study was to determine which combination of three types of irrigation systems, three fertilization method, and four growing media produced optimum growth of flowering vinca, Catharanthus roseus. Irrigation systems used included ebb-and-fl ood, drip, and pulse; fertilization methods included slow release, prepackaged, and custom mixed; and the four growing media were peatmoss:perlite:vermiculite (1:1:1, by volume), peatmoss:rockwool (1:1, by volume), and 0.6-cm diameter shredded rubber or fabric from waste tires: vermiculite:peatmoss (1:1:2, by volume). Four replications of five plants each were used in each of the 36 treatment combinations. Plants were potted 29 and 30 May 1996 in 10-cm containers, grown for 10 weeks, and harvested 6 Aug. 1996. The drip-irrigated benches were irrigated once per day for 15 s. Pulse-irrigated benches were watered twice per day for 6 s. This resulted in the drip- and pulse-irrigated plants receiving a similar volume of water daily. Ebb-and-fl ood benches were filled once per day with drainage occurring 15 min after filling. Ending plant heights and dry weights indicated that those plants in the prepackaged fertilizer/drip or ebb-and-fl ood irrigation/shredded tire fiber growing medium were comparable to plants grown in the peatmoss:rockwool medium with the same fertilizer and irrigation methods.
Effect of Fertilizer Source on Fe, Mn, and Zn Leaching, Nutrient Distribution, and Geranium Growth
Authors: Frost Michael D. , Cole Janet C. , Dole John M.
Published: February 2019

Improving the quality of water released from containerized production nurseries and greenhouse operations is an increasing concern in many areas of the United States. The potential pollution threat to our ground and potable water reservoirs via the horticultural industry needs to receive attention from growers and researchers alike. `Orbit Red' geraniums were grown in 3:1 peat:perlite medium with microtube irrigation to study the effect of fertilizer source on geranium growth, micronutrient leaching, and nutrient distribution. Manufacturer's recommended rates of controlled-release (CRF) and water-soluble fertilizers (WSF) were used to fulfill the micronutrient requirement of the plants. Minimal differences in all growth parameters measured between WSF and CRF were determined. A greater percentage of Fe was leached from the WSF than CRF. In contrast, CRF had a greater percentage of Mn leached from the system than WRF during the experiment. Also, regardless of treatment, the upper and middle regions of the growing medium had a higher nutrient concentration than the lower region of medium.
Co-blended Composts for Production of Potted Poinsettia
Authors: Ku Catherine S.M. , Bouwkamp John C.
Published: February 2019

Production of `Top White', `Peterstar Pink', `Lilo Red', and `Red Success' poinsettias were evaluated in a treatment combinations that included 10 compost blends, three compost levels, and two commercial soilless substrates of Sunshine Mix 1 and Pro Gro 300S as controls. The compost feedstocks included PSG polymer dewatered biosolids (PSG), lime dewatered biosolids (CP), yard trimmings (YT), poultry litter (PL), and municipal solid waste (MSW Bedmininster). The PSG, PL, YT, and MSW were co-blended with CP on a 2:1 ratio (v/v), all other composts were co-blended on a 1:1 ratio (v/v). The compost levels of 33%, 50%, and 67% were mixed with peat:perlite (1:1, v/v). There were five replicates per treatment. Plants were fertilized once weekly with 200 mg·L–1 N from 21N–2.2P–16.6K. Sunshine mix produced control plants that had greater canopy diameter and plant grade than Pro Gro mix. Plant height was reduced as compost level increased from 33% to 67%. Blends of PSG:PL at the 33% and 50% levels and PSG:YT at the 33% level produced premium-quality plants. Good-quality plants, similar to those grown in Sunshine Mix, were produced with the PSG or PL compost blended with immature MSW at the 33% level; PSG:PL blend at a 67% level; PSG:YT blend at the 50% and 67% levels; and PL:YT blend at the 33% level.
Characterization of ENOD2 cDNAs in Maackia amurensis Rupr. & Maxim. (Amur Maackia)
Authors: Foster Carol M. , Graves William R. , Horner Harry T.
Published: February 2019

ENOD2 and other early nodulin genes are conserved among legumes studied to date and might function as markers for the potential of legumes to nodulate. Early nodulin genes have been characterized only among herbaceous legumes. We are interested in understanding the nature of ENOD2 in a nodulating, woody legume. A 561-bp MaENOD2 PCR fragment was used as a probe to screen a cDNA library from nodules ≈1 mm in diameter on roots of Amur maackia, the only temperate and horticulturally desirable leguminous tree species known to nodulate. Five cDNAs were selected for nucleotide sequence analysis. Sequences were determined by using automated dideoxy sequencing and analyzed for identity to other genes with the Genetics Computer Group (GCG) program. The cDNA clones show 68% to 74% identity at the nucleic acid level with ENOD2 genes of Sesbania rostrata Brem. & Oberm., Glycine max (L.) Merrill, and Lupinus luteus L. Southern and northern analyses are being conducted to investigate the possibility of a gene family and to show differential and temporal production of transcripts, respectively. These studies provide new information about nodulins of woody legumes and are being used to facilitate related research on molecular barriers to nodulation in the closely related, non-nodulating tree species Cladrastis kentukea (Dum.-Cours.) Rudd (American yellowwood) and Sophora japonica L. (Japanese pagodatree).
Does Enhanced Removal of Active Oxygen Species Contribute Resistance to Superficial Scald in Apple Fruits?
Authors: Mulpuri Rao V. , Watkins Chris B.
Published: February 2019

Apple fruits are highly susceptible to superficial scald, which is currently controlled by both chemical- and non-chemical-based technologies. The possible threat of withdrawal of diphenylamine (DPA) for the control of superficial scald has prompted us to investigate the biochemical and molecular aspects of scald resistance. We have selected genetic populations of a cross between `White Angel' and `Rome Beauty' that are resistant and susceptible to scald, and investigated whether the resistance of scald in these populations is due to the higher antioxidant-based defense systems. Cortical tissue of fruits (0–3 cm) was peeled and analyzed for conjugated trienes, H2O2, carbonyl groups, and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidases (POX). Scald-resistant fruits at harvest had higher antioxidant enzymes and low levels of conjugated trienes, carbonyl compounds, and H2O2 levels compared to fruits that are susceptible to scald. Further, H2O2 levels rose in scald-susceptible fruits stored under low temperature with a concomitant increase in the production of conjugated trienes and carbonyl compounds, while no major changes were observed in scald-resistant fruits. Enhanced levels of H2O2 in scald-susceptible populations could be related to enhanced SOD activities and decreased activities of H2O2 degrading enzymes, suggesting that an imbalance between /H2O2 may have occurred. These results indicate that a coordination between SOD and H2O2 degrading enzymes in scald resistant populations may have minimized the influence of AOS on the oxidation of α-farnesene, protein, and, thereby, on scald. Hence, we have hypothesized that enhancing the potential of apple fruit to metabolize AOS develops resistance to superficial scald. [Supported in part by USDA Specific Cooperative Agreement 58-1931-5-017.]
Temporal Relationship between Ethylene and Ester Production during Maturation of Apple Fruit
Authors: Mattheis J.P. , Buchanan D.A. , Fellman J.K.
Published: February 2019

Quantitative and qualitative changes in net production of volatile compounds by apples occurs during fruit development with a major transition to ester production occurring as fruit ripening begins. Ester production during fruit ripening is an ethylene-mediated response; however, differences in maturation patterns among apple cultivars led us to examine the relationship between ester production and onset of the ethylene climacteric in several commercial apple cultivars. Emission of volatile esters as a function of apple fruit development was evaluated for `Royal Gala', `Bisbee Delicious', `Granny Smith', and `Fuji' apple fruit during two harvest seasons. Apples were harvested weekly and analyses of harvest maturity were performed the day after harvest. Non-ethylene volatiles were collected from intact fruit using dynamic headspace sampling onto Tenax traps. Fruit from each harvest was stored at 1°C in air for 5 months (3 months for `Royal Gala') plus 7 days ripening at 20°C, then apples were evaluated for the development of disorders. The transition to ester production occurred after internal ethylene exceeded 0.1 μL for `Royal Gala', `Bisbee Delicious', and `Fuji'. Ester emission by `Granny Smith' apples remained low throughout the harvest period. Increased ester emission occurred after the optimum harvest date (as determined by the starch index and internal ethylene concentration) for controlled-atmosphere storage of `Bisbee Delicious' and prior to optimum maturity for `Royal Gala' and `Fuji'. A relationship between the potential for development of superficial scald and ester production at harvest was evident only for `Bisbee Delicious' apples.
Effect of Modified-atmosphere Packaging on Aroma Profiles of Whole Apple Fruit
Authors: Deng Weimin , Song Jun , Beaudry Randolph M.
Published: February 2019

The effect of polymers used in packaging on the aroma of the packaged product has been little explored. Using a package-in-a-jar system, we are able to simultaneously measure volatile production by plant organ (Malus domestica Borkh. cv. Golden Delicious) and the permeability of the packaging film to those volatiles. In this system, apple fruit were placed into a glass container or sealed in a low-density polyethylene(LDPE) package and subsequently placed into a glass container. Air or a modified atmosphere was slowly passed through the glass containers such that the O2 level in the package was similar to that in containers with no package. The package and jar head spaces were sampled for CO2, O2, ethylene, and aroma volatile analysis by gas chromatography/mass spectrometry. The effect of temperature, atmosphere and film presence to some major volatile compounds was determined. When storage temperature increased from 0°C to 22°C the production rate of hexylacetate and 2-methyl butylacetate increased 11.27- and 17.15-fold, respectively. At 0°C, as O2 decreased in concentration from 10% to 5% (v/v), hexylacetate and butylacetate declined significantly; however, 2-methyl butylacetate was not affected. This can be taken to indicate the production of 2-methyl butanol for 2-methyl butylacetate formation is not as O2 concentration dependent as straight-chain alcohols. At the same O2 concentration, non-packaged fruit evolved greater amounts of all volatiles than packaged fruit. The flux of α-farnesene, hexylacetate and 2-methyl butylacetate was 26.6-, 1.7-, and 1.4-fold higher, respectively, for fruit in glass container. The sorption of α-farnesene and some other volatiles into LDPE film is evidently considerable, altering the aroma profile of packaged produce relative to a flow-through system.
Using Hexanal Vapor to Inhibit Activity of Penicillium expansum in Inoculated Whole Apple Fruit
Authors: Fan Lihua , Song Jun , Beaudry Randolph
Published: February 2019

Hexanal vapor is a natural, metabolizable fungicide that inhibits fungal activity and enhances the aroma biosynthesis in sliced apple fruit. Whole apple fruit were inoculated at two points per fruit with Penicillium expansum at a concentration of 0.5 × 105 spore/ml and treated with hexanal vapors. Inoculated fruit were exposed to hexanal for 48 hr and kept for another 72 hr in hexanal-free air at 22°C. Treatments included 8.2–12.3 μmol·L–1 (200–300 ppm), 14.5-18.6 μmol·L–1 (350–450 ppm), and 24.8-28.9 μmol·L–1 (600–700 ppm), each with an air control. At a concentration of 200–300 ppm hexanal, there was no fungal growth during treatment, but lesion development was evident on 100% of the treated fruit following cessation of treatment. After 72 hr holding in air, lesion diameter was significantly smaller for treated fruit. When inoculated apple fruit were exposed to 350–450 ppm and 600–700 ppm hexanal vapors, the decay rate was 44.7% and 23.9%, respectively, while the decay rate of inoculated control apple fruit was 100% and 98%, respectively, after 72 hr holding in air. The development of aroma volatiles was investigated for both treated and untreated whole apple fruit. Hexanal was actively converted to aroma volatiles by `Golden Delicious' fruit and there was no detectable hexanal emanations. The amount of hexylacetate, hexylbutanoate, hexylhexanoate, hexylpropionate, butylhexanoate, and hexyl-2-methybutanoate were about 2- to 4-fold higher in treated apple fruit than in untreated apple fruit. `Mutsu' apple fruit were treated with 350–450 ppm hexanal for 48 hr and processed into apple sauce within 4 hr. An informal sensory evaluation for processed `Mutsu' apple revealed no apparent flavor difference between treated and control fruit sauce.
Effect of the Split Trellis on Growth and Yield of Red Raspberry (Rubus idaeus)
Authors: Klauer Stephen F. , Cameron J. Scott , Chen Chuhe
Published: February 2019

With the advent of new rotary-head mechanical harvesters, it is now possible to machine-harvest a wider raspberry canopy. In Spring 1996, a trial was established in a grower's field in Lynden, Wash., comparing raspberries trained to two top wires with a 70-cm spread (split trellis) to the conventional single top wire system. Within the split trellis, increases in leaf number per cane (97%), and leaf area per cane (55%) were not reflected in a concomitant increase in total leaf dry weight per cane (35%). Leaf dry weight per fruit weight was 11% less within the split trellis. These data suggest that the canopy is more efficient with this type of trellis. Increases in estimated yield per cane (49%) and projected yield per acre (50%) associated with the split trellis were due to increases in berry number per cane (47%). Fruit number per meter of lateral was 35% greater within the split trellis. Greatest enhancements to yield components were in the upper parts of the canopy where canes were tied over. Since there were no differences in lateral numbers or lateral lengths between the two systems, this increased productivity was due to increased floral expression, enhanced fruit set, increases through Spring bud initiation or any combination thereof. In both trellis systems, the longest laterals occurred on the middle third of the cane and decreased in length progressively towards the tip of the cane. Primocane lengths were shorter (20%) and diameters were smaller (10%) and more uniform in the split trellis system.
Field Assessment and Physiological Analysis of Cold Damage to the Red Raspberry Fruiting Cane and to Fruit Yield
Authors: Chen Chuhe , Cameron J. Scott , Klauer Stephen F.
Published: February 2019

Two sets of field experiments have been set up in Lynden, Wash., to evaluate cold damage to red raspberry `Meeker'. The locations represent newly established crops (fi eld 1) and a field that suffered reoccurring cold damages in recent years (fi eld 2), respectively. Temperature and moisture HOBOs were set up in the check and colddamaged treatments of both of the fields to record the air and soil temperatures and air moisture. The cold-damaged treatments in both fields had significantly higher cane dieback and dead buds. Cold injury significantly reduced berry yield in field 1, but not in field 2, through an steep drop in berry number per cane, mainly due to a significant reduction in lateral number/cane. Cold damage reduced primary lateral number/cane, and increased secondary lateral number/cane in both fields. Secondary laterals were shorter in length and had lower berry number/lateral than the primary ones. It proved that cold damage also delayed initiation and development of secondary laterals, and resulted in more yield loss to the plant. The cold-damaged fruiting cane had lower gas exchange rates, leaf and stomatal conductance, and transpiration rates during fruit development in both fields. It also significantly reduced fluorescence parameters Fo, Fm, Fv, T1/2, and Fq of the cold injury treatment in field 1. On a few cold days this spring, the HOBOs recorded a lower daily low temperature in the cold damaged area than in the check area.
Seasonal Frost Hardiness Changes in the Cranberry Plant
Authors: Workmaster Beth Ann A. , Palta Jiwan P. , Smith Jonathan D.
Published: February 2019

In Wisconsin, the cranberry plant (Vaccinium macrocarpon Ait.) is protected from freezing temperatures by flooding and sprinkle irrigation. Due to the high value of the crop, growers typically overprotect by taking action at relatively warm temperatures. Our goal is to provide recommendations for improved frost protection strategies by studying seasonal hardiness changes in different parts of the cranberry plant (leaves, stems, buds, flowers, fruit). Stages of bud growth were defined and utilized in the hardiness determinations. Samples were collected from mid-April to mid-Oct. 1996 and cuttings were subjected to a series of freezing temperatures in a circulating glycol bath. Damage to plant parts was assessed by visual scoring and observation, ion leakage, and evaluation of the capability to regrow. The following results were obtained: 1) Overwintering structures, such as leaves, stems, and buds, can survive temperatures <–18°C in early spring, and then deacclimate to hardinesses between 0 and –2°C by late spring. 2) In the terminal bud floral meristems are much more sensitive to freeze–thaw stress than are the vegetative meristems. 3) Deacclimation of various plant parts occurred within 1 week, when minimum canopy temperatures were above 0°C, and when the most numerous bud stage collected stayed the same (bud swell). 4) Fruits >75% blush can survive temperatures of –5°C for short durations. By collecting environmental data from the same location we are attempting to relate plant development, frost hardiness, and canopy temperatures (heat units).
Effect of Reduced Temperatures on Melon Transplant Subsequent Growth and Survival
Authors: Lange D.L.
Published: February 2019

Delays in transplanting vegetable seedlings are often a problem due to cold, wet spring weather. This results in the production of overgrown transplants, which are more difficult to transplant and often do not survive. The objective of this study was to find a non-chilling temperature at which to short-term-treat transplants in order to slow down vegetative growth. `Superstar' muskmelon and `Royal Jubilee' watermelon seedlings were greenhouse-grown at 20°C during Mar. 1996. Fifty-cell trays of transplants were grown to the first true leaf stage and then held in a dark cooler at 7.5 or 12.5°C for 4 to 8 days. Control plants were kept in the greenhouse. Transplants were repotted into larger pots after the treatment. Preliminary experiments revealed that 8 days of 7.5°C was too severe of a temperature for watermelon and cantaloupe transplants. Six days of 7.5°C was effective in significantly reducing stem and leaf area growth without seedling death for both types of melons. Shorter durations at 7.5°C or the same duration at 12.5°C was less effective in retarding stem elongation. Surface area of the transplant leaves, after the reduced temperature treatment and subsequent growth, was much more sensitive to a drop in temperature and the length of temperature treatment. In 1997, these treatments will be repeated in the greenhouse and also in the field.
Effect of Centrifugal Force on the Chilling Sensitivity of Cucumber Seedlings
Authors: Saltveit Mikal E.
Published: February 2019

The cessation of protoplasmic streaming is one of the first observable effects of chilling in sensitive plant tissue. If the lack of protoplasmic streaming contributes to the development of chilling injury, then impeding protoplasmic streaming at the chilling threshold temperature should induce chilling injury symptoms in tissue that would normally not exhibit symptoms at that temperature. A centrifuge was constructed to subject entire germinating cucumber (Cucumis sativus L., cv. Poinsett 76) seeds to centrifugal forces of up to 20 xg at 2.5, 10 and 12.5°C. Subjecting cucumber seeds with 5-mm-long radicles to high centrifugal forces (18 xg) at a marginal chilling temperature of 10°C for up to 3 days had no significant effect on subsequent radicle elongation of the entire population. In one experiment, spun seedlings were 7.4 ± 0.52 cm long, while the controls were 6.1 ± 4.3 cm long after 48 hr at 25°C. When analyzed by individual seed, the spinning treatments had no effect on high-vigor seedlings, while an 18 xg treatment significantly improved subsequent radicle elongation of low vigor seedlings. The effect of increased centrifugal forces on the respiration, metabolism and chilling sensitivity of cucumber seedlings will be discussed.
Duration of Composting Affects Compost Characteristics of Importance to Agriculture
Authors: Hartz T.K.
Published: February 2019

A recently enacted state law requiring California cities to reduce their solid waste flow to landfills has greatly increased the composting of yard and landscape wastes. Currently, much of this material is being composted for less than 16 weeks, some for as little as 4 weeks, before agricultural use. A study was conducted to document the effects of composting method and duration on the physiochemical and biological characteristics of green waste compost. At each of four commercial composting facilities, two windrows of municipal green waste were sampled at 3-week intervals over a 15-week composting period. Each sample was analyzed for pH, NH4-N, NO3-N, and total N and C. Phytotoxicity was measured by a tomato seed bioassay. N mineralization/immobilization behavior was evaluated in a 2-week aerobic incubation of a 10% compost/90% soil blend at 30°C. The growth of vinca plugs (Vinca minor cv. `Pink Cooler') in a 50% compost/50% perlite mix was also evaluated. At all sites, the initial green waste was similar, with 1.1–1.5% N and C/N ratio of 20–28. Rapid mineralization of carbon in the first 6- to 9-weeks reduced C/N ratios to 14–18, with little change thereafter. Phytotoxicity decreased through 9 to 12 weeks, then stabilized. Net N immobilization was observed throughout the compost period, but decreased with increased composting time. Vinca growth increased with increasing compost age, up to 9 to 12 weeks. In summary, at least 12 weeks of composting was required to produce material of sufficient quality for typical agricultural uses.
Integrating Watermelon and Forage Crops
Authors: Roberts Warren , Roe Nancy , Duthie Jim , Edelson Jonathan , Shrefler Jim , Cornforth Gerald , Enis Jim , Smith Steve
Published: February 2019

Watermelon growers are advised to grow melons in a given field no more than 1 year out of 4. Bermudagrass pastures are abundant in the southern U.S., but ranchers are reluctant to destroy a pasture for 1 year and plant it with melons if they must then re-establish a sod. A project was designed to develop a system for growing watermelon in a permanent pasture with only a minimal amount of tillage, and without destroying the established forages in the pasture. The approach is to compare and evaluate several techniques for growing watermelons in strip-tilled areas within a permanent pasture. These techniques include cultivation, plastic mulches, and herbicides applied to 2-m strips separated by untilled bermudagrass. Research was done in 1996 at two university research centers in Oklahoma and Texas. The treatments with greatest watermelon yields, in decreasing order, were black polyethylene mulch, hand-weeded control, photodegradable mulch, biodegradable mulch, cultivation plus sethoxydim, sethoxydim alone, cultivation alone, and the weedy check. At harvest, 63% of the area in the cultivation alone treatment, 40% of the area in the plastic mulch treatment, and 1% of the area in the sethoxydim treatment were covered with a regrowth of bermudagrass. Forage was also collected from row areas of plots. Forage amounts, in decreasing order, were from cultivation alone, weedy check, sethoxydim alone, photodegradable mulch, polyethylene mulch, biodegradable mulch, cultivation plus sethoxydim, and the clean control.
The NewCROP Electronic Network
Authors: Janick Jules , Simon James E. , Whipkey Anna , Alkire Ben
Published: February 2019

NewCROP (New Crops Resource On-line Program) is an Internet resource (http://www.hort.purdue.edu/newcrop) developed by the Indiana Center for New Crops and Plant Products to deliver instant topical information on the subject of fiber, energy, and specialty crops. NewCROP includes CropSEARCH (an index to food and feed crops of the world, including taxonomic information, uses, and economic importance), FactSHEETS (in-depth articles on selected crops), NewCROP Import–Export (importation permits, phytosanitation certificates, quarantine and inspection information), Organizations (listings of crop organizations, societies, and interest groups), FamineFOODS (includes about 1250 species that are consumed in times of food scarcity), and FarmMARKET (listing locations of United States farmers' markets). The web site also includes new crop bibliographies, directories of new crop researchers, announcements of pertinent up-coming symposia and crop conventions, the New Crop Center newsletters, and activities of the Indiana Center for New Crops. A search engine is provided for quick information retrieval from the system. An electronic bulletin board, NewCROP LISTSERV is maintained for posting queries and messages to subscribers. We are planning to incorporate material from three books (>1930 pages and 6000 index entries) derived from New Crops symposia and published as Advances in New Crops (1990), New Crops (1993), and Progress in New Crops (1996). The NewCROP digital information program is interlinked with FAO's EcoCROP system and the Australian New Crops Programme, as part of a developing world-wide crop information network.
NurseryWeb—An Information and Communication Page for the Nursery Industry
Authors: Michaels Tamela D. , Lea-Cox John D.
Published: February 2019

Electronic information systems that take advantage of new technological developments on the Web are a key towards fulfilling the mission of the extension educator; i.e., to help individuals, families and communities put research-based knowledge to work in improving their lives. Webpages are one key to achieving this goal, but vertical searches using search engines are tedious and inefficient. There is a need for a) rapid and easy access to verifiable information databases and b) the coordination of good information resources that are already available on the Web in an horizontal format. NurseryWeb was developed as an open information resource within a frames environment that enables users to gather information about a variety of nursery-related material; e.g., cultural information, diagnostic criteria for disease and pest identification, data on integrated pest management and marketing data. In addition, a password-protected communication resource within the page provides nurserymen with conferencing and direct email connections to nursery extension specialists through WebChat™, as well as providing time-sensitive data, alerts, and links to professional organizations. A number of critical issues remain unresolved—e.g., the integrity of information links, data and picture copyright issues, and software support. Nonetheless, the ease of use, availability of information in remote areas at relatively low cost, and 24-hr access assures that this type of information provision will become dominant in the future.
Isolates of Arbuscular Mycorrhizal (AM) Fungi Alter Citrus Leaf Gas Exchange during Soil Water Deficit Stress and Recovery
Authors: Fidelibus Matthew W. , Martin Chris A.
Published: February 2019

Four AM fungal isolates (Glomus sp.) from disparate edaphic conditions were screened for effects on leaf gas exchange of `Volkamer' lemon (Citrus volkameriana Ten. and Pasq.) plants of similar size under conditions of increased soil water deficit stress and recovery from stress. Mycorrhizal and non-mycorrhizal plants were grown in 8-L containers for 10 weeks under well-watered conditions in a glasshouse and then subjected to three consecutive soil-drying episodes of increased severity (mean soil water tension reached –0.02, –0.06, and –0.08 MPa, respectively). Gas exchange measurements were made on the last day of each soil-drying episode. Plants were irrigated after each soil-drying episode, and measurements were repeated on the following 2 recovery days, when soil remained moist. All measurements were made at mid-day with a LI-COR 6200 portable photosynthesis system. The effect of AM fungi on leaf gas exchange fluxes varied depending on the isolate and the intensity of soil water stress. Leaf gas exchange fluxes always were highest for plants colonized by Glomus mosseae (Nicol. & Gerde.) isolate 114C, except during the third soil-drying episode, when all mycorrhizal plants had similar, and lower, gas exchange fluxes compared with non-mycorrhizal plants. During recovery from the third soil-drying episode, Glomus mosseae isolate 51C had lower leaf gas exchange fluxes compared with all other plants. Our results show that AM fungi can alter leaf gas exchange fluxes of citrus, under conditions of optimal P nutrition, in an isolate-specific manner.
Phosphorus-induced Leaf Abscission in Olive and Citrus Explants
Authors: Goren Raphael , Huberman Moshe , Martin George C.
Published: February 2019

Previous studies, in which the role of phosphorus in abscission of olive leaves was examined in the presence of ethylene biosynthesis inhibitors, have suggested that phosphorus induces abscission directly, without involvement of ethylene. In the present study, this possibility was further explored by comparing the effects of an ethylene biosynthesis inhibitor, aminoethoxyvinylglycine (AVG), and an ethylene action inhibitor, 2,5-norbornadiene (NBD), in olive [Olea europaea (L) cv. Manzanillo] and citrus [Citrus sinensis (L.) Osbeck cv. Shamouti]. In olive, leaf abscission was always induced in the presence of KH2PO4, with or without AVG and NBD (alone or in combination), but was more pronounced when KH2PO4 was applied alone. In citrus, the effect of KH2PO4 alone on the induction of leaf abscission and ethylene production was much stronger than that observed in olive. However, in the presence of NBD, KH2PO4 did not induce leaf abscission in citrus during the first 60 hr. Similar results were obtained when NBD was replaced by AVG, but, in this case, abscission was inhibited for only 48 hr. In both cases, ethylene was detected after the inhibitory period had ended. The results obtained with citrus indicate that the observed effect of KH2PO4 on the ethylene-independent induction of leaf abscission in olive is not a general phenomenon and may differ in different species.
A Survey of Cold Protection Methods for Florida Citrus
Authors: Ferguson J.J. , Israel G.D.
Published: February 2019

During Summer 1996, a disproportionate systematic sampling procedure was used to obtain an initial sample of 955 citrus growers from the mailing lists of extension agents in 27 counties. Of these, 451 usable responses were returned (67% response rate), providing an expected error of ± 4.3% with a 95% confidence interval. Surveyed growers obtained weather information during the 1995–96 winter from multiple sources, including the National Weather Service (NWS) (48%), commercial radio/TV (48%), Extension offices (18%), private meteorologists (9%), and other sources (10%). After the NWS discontinued agricultural freeze forecasts in Apr. 1996, growers indicated they would rely on commercial radio/TV (72%); private meteorologists (20%), and their County Extension Office (32%) for weather reports. When deciding which cold protection method to use, respondents adopted Extension (35%) and consultants' recommendations (30%), assessed the costs and benefits of cold protection (32%), and assessed risks based on grove history (38%). Cold protection methods used by percent respondents included: flooding groves (22%); grove heaters (2%); wind machines (2%); permanent overhead irrigation systems (2%); ground microsprinklers (76%); in-tree microsprinklers (18%); tree wraps (13%); and tree wraps or covers with microsprinklers (6%). Seventy-three percent of growers reported that their cold protection methods were very effective for a freeze with minimum temperatures of –2°C for at least 4 hr, with 12% and 3% reporting cold protection measures being very effective at –7 and –9°C, respectively.
Developing Methodology for Evaluating Sweet Corn Tissues for Allelochemicals Restricting European Corn Borer Larval Development
Authors: Warnock Daniel F. , Davis David W. , Hutchison William D.
Published: February 2019

European corn borer, Ostrinia nubilalis Hübner, can severely affect sweet corn quality. Selection techniques in field experiments have improved ear feeding resistance associated with morphological features and/or allelochemicals. The isolation and identification of allelochemicals that detrimentally affect O. nubilalismay improve breeder selection for host plant resistance, thus reducing the need for insecticide application. A laboratory bioassay was used to detect chemical resistance factors in silk and kernel tissues of 10 variously resistant sweet corn genotypes. Ground lyophilized tissue from field-grown plants was added to a nutritionally complete larval diet before infestation with O. nubilalis neonates. Larval weights on a 10-day basis and time to pupation were recorded to estimate larval development. Tissue and genotype main effects affected (P ≤ 0.05) 10-day larval weight and time to pupation. Silk tissue (P ≤ 0.05) reduced 10-day larval weight and increased the time to pupation compared with kernel tissue and the cellulose control, which did not differ. Silk tissue reduced larval weight by 65% and increased time to pupation by 4.0 days compared with the cellulose control. Genotypes variously affected (P ≤ 0.05) larval growth and development, reducing 10-day larval weight up to 51% and increasing the time to pupation up to 4.2 days when comparing the best genotype for each developmental stage with the cellulose control. Silk tissue of some genotypes may contain allelochemicals that decrease the rate of larval growth and development. The status of allelochemical detection in silk tissue will be discussed.
Genomic Analysis of Chromosomal Regions Introgressed from Tepary Bean Associated with CBB Resistance in Phaseolus. vulgaris L.
Authors: Jung Geunhwa , Skroch Paul , Nienhuis James , Coyne Dermot
Published: February 2019

One of the highest levels of common bacterial blight (CBB) resistance identified in Phaseolus vulgaris is found in XAN-159, which was developed for leaf resistance to CBB through six generations of pedigree selection of progenies derived from the interspecific cross [(`Pinto UI 114' × PI 319441) × P. acutifolius PI 319443] × `Masterpiece'. A RAPD genetic linkage map was previously constructed in a recombinant inbred population derived from the common bean cross PC-50 × XAN-159 for identification of genomic regions associated with bacterial disease resistance in XAN-159. To confirm that chromosomal regions associated with CBB resistance in XAN-159 were introgressed from tepary bean, we investigated the parentage of each genomic interval in XAN-159 by studying the genomic constitutions of the four different parents involved in the pedigree. The results indicate that all genomic regions associated with CBB resistance contain intervals derived exclusively from tepary bean. The uniqueness of marker polymorphisms associated with resistance to CBB in XAN-159 will allow the application of marker assisted selection for these resistance genes in most populations of common bean.
A Management Strategy for Mango Production Beyond the Year 2000
Authors: Campbell R.J. , de B. Campbell C.
Published: February 2019

Mango (Mangifera indica L.) currently ranks fifth, along with apple, among fresh fruit imported by the United States, with more than 142,000 MT imported in 1995. Imports have doubled in the past 5 years and are projected to increase by 20% to 30% by the year 2000. Mexico supplied >80% of the imported volume in 1995, with the remaining 20% supplied by Brazil, Ecuador, Guatemala, Haiti, Nicaragua, Peru, and Venezuela. Individual production areas (countries) have traditionally controlled a market, defined by time of year, resulting in a near 12-month supply of mangos in the United States in the past few years. However, market share among producing countries is rapidly changing as individual producers and production regions extend their season through the use of different available microclimates, bloom manipulation, and new cultivars. With this extension of production season in each region, there is now significant market overlap and traditional regional windows have been shortened or eliminated. Producers in all regions must now make timely management decisions to assure their future profitability. A holistic management scheme involving attention to fruit quality, cultivar selection, volume consistency, and marketing is presented. Such a management plan is key to an individual region's success in establishing and holding a given market window.
Somatic Embryogenesis and Plant Regeneration from Roots of Punica granatum L.
Authors: Sinha Shailaja , Sharon Madhuri
Published: February 2019

Somatic embryogenesis from apical meristem, cell elongation zone, and cell differentiation zone of roots of Punica granatum L. var. Ganesh was obtained. The basal medium used was Gamborg's B5. 2, 4-D induced white globular callus in root tip explants, which on further subculture to medium containing 0.5 mg/L BAP, produced somatic embryos from the outer surface of the callus. Direct somatic embryogenesis occurred from all the three zones of the root in presence of 2 mg/L kinetin. BAP induced embryogenic callus in elongation and cell differentiation zone segments of the roots, which, on further subculture onto the same medium, produced somatic embryos. NAA caused rhizogenesis in all the three root segments. Differentiation of somatic embryos into plantlets took place on B5 medium supplemented with 0.01 mg/L NAA + 0.5 mg/l BAP + 2 mg/L kinetin.
The Effects of Three Nursery Production Methods on Tree Growth Rates
Authors: Waldo Amy Jo , Klett James E.
Published: February 2019

Ninety trees are being used and have been in the field since 1994. The three species studied include: Fraxinus pennsylvanica Patmore (Green Ash), Quercus macrocarpa (Bur Oak), and Pinus nigra (Austrian Pine); 30 of each species. Each species has been harvested in three different nursery production methods including balled and burlapped, plastic container, and fabric container. During the 1996 growing season, the following data was recorded for each tree, growth increments, caliper size, and tree heights. For the two deciduous species, both dry weights and leaf area were recorded. Some sap flow measurements were taken using a non-intrusive stem heat balance method, on the same tree species with varying production methods. All three species showed the greatest growth increments and heights for those trees planted in fabric containers. In regards to trunk caliper size, Pinus nigra showed that the balled and burlapped, and fabric containers had larger calipers than those planted in plastic containers. Fabric container trees were larger in caliper than plastic container trees, which was larger than the balled and burlapped on Quercus macrocarpa. The plastic container and balled and burlapped resulted in greater calipers on Fraxinus pennsylvanica than the fabric containers. Quercus macrocarpa also showed that both leaf area and dry weight were greatest for trees planted in fabric containers, followed by the other production methods. Trees in plastic containers exhibited the greatest leaf area and dry weight for Fraxinus pennsylvanica. Overall, the fabric container trees in all three species illustrated the highest-quality trees, followed by those planted in plastic containers, and then balled and burlapped. Minimal data was recorded for transpiration rates in 1996 and will be further investigated in 1997.
Monitoring Chemical Properties of Growing Media with Small Soil Solution Samplers
Authors: Cabrera Raul I. , Perdomo Pedro
Published: February 2019

Hydrophilic polymer tubes (2.5 mm OD, 1.4 mm ID, 10-cm length, 0.1-mm pore diameter) attached to PVC hose were used to extract solution from soilless media at container capacity and analyzed for pH, EC, NO3-N and NH4-N. Media chemical properties were also analyzed by the Saturated Media Extract (SME) and Pour-Through (PT) methods. Extraction and analyses were conducted in peat: vermiculite (PV) and peat: perlite (PP) media irrigated for 1 week with Hoagland solution at 0.25, 0.5, 1, 2 and 4x. A 10-mL syringe was used as the vacuum source (48.1 ± 0.5 kPa) for the solution samplers (SS), yielding ≈2–5 mL of solution over a 3-min period. Simple correlation coefficients for EC, NO3-N and NH4-N between SS and SME and PT were high (>0.99). When measured by PT, these chemical properties were similar to SS (within 1% to 6%), whereas SME values were much lower than SS (12% to 15% and 35% to 38% in PV and PP media, respectively). Correlation coefficients for pH were lower than in other chemical properties, particularly in the PV medium. With an estimated life of ≈6 months in soil, SS are excellent monitoring tools for mineral nutrition research and horticultural crop production.
Multiple Shoot Formation from Somatic Embryo Explants of Eastern Redbud (Cercis canadensis L.)
Authors: Distabanjong Karsedis , Geneve Robert L.
Published: February 2019

Somatic embryos from Eastern redbud show a high degree of malformation during development and a low conversion rate to seedlings. This problem is common with somatic embryo systems, especially with legume species. A procedure for multiple shoot formation from somatic embryo explants of Eastern redbud was developed that bypasses the need for germination to recover plantlets. Somatic embryo explants cultured on DKW medium containing benzyladenine (BA) and thidiazuron (TDZ) produced more shoots than either treatment alone. The highest number of shoots (3.3 to 3.4 shoots per explant) was obtained from partially desiccated and wounded explants treated with a combination of 5 or 10 M BA and 0.5 or 1.0 M TDZ for 20 days before being transferred to the same medium without TDZ. The number of shoots formed was increased from 1.5 to 3.2 shoots per explant by cutting through the cotyledonary node prior to culture. In addition, the frequency of explants forming shoots was increased by desiccation of somatic embryo explants to ≈50% moisture and by using somatic embryos with two well-formed cotyledons as explants.
Water Management and Citrus Tree Response to a Humid Climate
Authors: Parsons L.R. , Wheaton T.A.
Published: February 2019

Four decades ago, irrigation in much of the southeastern U.S. was considered not sensible economically because of normal rainfall in excess of 1200 mm in some areas. More-recent research has shown that irrigation makes definite economic sense because it can increase production substantially. This is especially true in Florida citrus, where irrigation can increase yield by up to 60%. Drip and microsprinkler irrigation have become popular, and these methods of partial root-zone coverage affect tree water potential and yield. Growing environmental concerns about possible nitrate and pesticide leaching to the groundwater have led to greater emphasis on irrigation management in an area of highly variable rainfall. Rapidly growing population has brought about increased competition for water and greater restrictions on agricultural water use. Reclaimed water, once considered a disposal problem, is now being promoted as a partial solution for periodic water shortages. Discussion will focus on tree response to different irrigation management systems and how agriculture is dealing with greater irrigation restrictions.
Rescuing Irrigated Desert Agriculture
Authors: Clemings Russell
Published: February 2019

From its birth in British India in 1847, modern irrigated desert agriculture has grown in just more than a century to produce one-third of the world's crops. Until the techniques of civil engineering were wedded to the ancient art of irrigation on the plains of the Punjab, most crops were rain-fed, except in areas such as the Nile Valley, where reliable seasonal floods made irrigation practical. Today, in contrast, we have made the desert bloom, giving ourselves fresh produce yearround and making the difference between survival and starvation in much of the developing world. Without irrigation, it would not have been possible to farm the high-yielding seeds of the Green Revolution, which greatly reduced the threat of famine in Asia and Latin America. But now, after a century of heavy irrigation, serious side effects are beginning to appear. Soils are becoming salinized by the cycles of wetting and drying in an arid climate, and wildlife has been poisoned by toxic drainage pumped from beneath irrigated fields where it has built up over time. These side effects have caused some to predict that the bounty of modern desert agriculture may not be sustainable, but others see hope of reducing the side effects through vastly improved water management.
Effects of Water Stress on Vegetative Growth and Productivity of Fruit Trees
Authors: Johnson R. Scott , Phene Claude J. , Handley Dale
Published: February 2019

Generally, water stress reduces yield in annual crops. However, for mature fruit trees, this relationship may not hold in many situations, thus providing the opportunity for saving water without losing production. Indeed, even an increase in productivity may be achieved as we better learn how to manipulate processes within the tree through moderate water stress. Several areas of research have shown promising results. The reduction of irrigation after harvest of early maturing peaches and plums has demonstrated substantial savings of water with no loss of production. Peaches can suffer fruit quality problems such as doubling and deep suturing, but these can be overcome with well-timed irrigations in the previous late summer. Water stress imposed before harvest has also shown some promise. Reports from Australia have demonstrated significant increases in yield and fruit size in peach and pear, although researchers in other locations have generally been unable to replicate these results. The timing and/or rate of stress development appear to be critical factors. Under the right conditions, stress can alter the allocation of resources between vegetative and fruit growth. Before implementation of these practices can be achieved, further research will need to focus on developing good tools for measuring stress in the trees, obtaining a better understanding of adaptation of trees to rapidand slow-developing stress, documenting the effects of stress on vegetative and fruit growth during different times of the season, and understanding the interaction of stress with other factors such as fruit load.