bluuebunny/crossref_metadata_2025 huggingface dataset:
HORTICULTURE INTERACTIVE VIDEO PROGRAMS IN VIRGINIA
Authors: Ness Carol , Bloom Leslye , Relf P. Diane , Miller Mary
Published: October 2019

Horticulture information is being placed at the fingertips of Virginia citizens through the use of Public Information Interactive Video Systems. A personal computer (with a touch-screen monitor) and laserdisc player work together to offer a multi-media delivery system. The user moves through programs by simply touching the screen to browse, skip ahead, back up, look up specific information, and print out needed information. A program on household plants contains photographs and information on 131 popular cut flowers and houseplants. A program on selecting landscape plants includes short video segments on the plant selection process, a plant sorter, picture album, and information on the 141 trees, shrubs, vines, and ground covers. Horticulture questions are among those answered in a section on questions most often asked of extension agents. This horticulture information program is one of the top two programs used in the Public Information Interactive Video System in Virginia.
ASPEN WOOD CHIP AND STONE MULCHES FOR ORNAMENTAL PLANTINGS IN INTERIOR, ALASKA
Authors: Holloway Patricia S.
Published: October 2019

Five woody ornamentals Rosa rugosa, Cotoneaster acutifolia, Malus baccata, Picea glauca and Pinus contorta var. latifolia, were grown for 4 seasons mulched with one of five treatments: 2.5 cm or 5 cm of crushed basaltic quarry stone, 5 cm or 10 cm of quaking aspen wood chips, and an unmulched control. Maximum soil temperatures at the 10 cm depth on the wood chip plots were decreased by as much as 8°C over control plots, and soil moisture was increased. Stone mulch plots showed a slight increase in both temperature and moisture. Soil minimum temperatures were lower on the wood chip plots than the other treatments early in the season, but were slightly higher in September. Soil pH and available N, P and K did not differ among mulch treatments. Weed growth was suppressed by all mulch treatments but was best controlled on the wood chip plots followed by the 5 cm stone plots. Plant growth for all species except Rosa rugosa was greatest on the stone mulch plots. Roses growing on the stone mulch plots and the control were subject to significant dieback from winter injury and did not show any difference in total growth after 4 years when compared with the wood chip plots. Plants grown on the wood chip plots exhibited varying degrees of nitrogen deficiency which may be related to reduced nutrient uptake in cooler soils or to a significant amount of rooting in the mulch-soil interface.
LEAF CHARACTERISTICS OF FRUITING AND DEFLOWERED RED RASPBERRY CANES OVER THE COURSE OF THE GROWING SEASON
Authors: Klauer Stephen F. , Chen Chuhe , Cameron J. Scott , Hartley Carol A.
Published: October 2019

In the early spring, 300 canes of `Meeker' red raspberry were tagged and 150 were deflowered at anthesis. During a 12-week period beginning at anthesis, leaves were sampled for anatomical sectioning and determination of chlorophyll content and dry weight per leaf unit area,

Comparisons of leaf cross-sections from fruiting (F) and deflowered (DF) canes demonstrated high levels of starch accumulation in the latter. This accumulation of starch was layered throughout the cross section, and size of starch crystals varied by location. Dry weight per leaf unit area increased in all leaves during the season, but was consistently greater in leaves of DF canes throughout the season.

Total leaf chlorophyll and chlorophyll a content increased until reaching a maximum three weeks after anthesis, Both decreased slightly until nine weeks after anthesis and sharply thereafter as leaves began to senesce. Chlorophyll b content remained nearly constant until eight weeks after anthesis at which time levels declined during the onset of senescence.
CHEMICAL THINNING OF `GRANNY SMITH' APPLE
Authors: Micke Warren C. , Grant Joseph A. , Norton Maxwell V. , Yeager James T.
Published: October 2019

Under California conditions `Granny Smith' apple does not “self-thin” sufficiently to promote good return bloom nor to provide fruit size desired for the fresh market. Preliminary studies conducted during 1985-87 indicated that 1-naphthyl N-methylcarbamate (carbaryl), 1-naphthaleneacetic Acid (NAA), and 1-naphthaleneacetamide (NAD) could be useful for thinning `Granny Smith'. Detailed studies conducted in 1988 and 89 using dilute handgun applications demonstrated that all 3 materials provided reasonable thinning as shown by fruit set counts. NAA and NAD tended to slow fruit growth as compared to carbaryl. Carbaryl tended to uniformly thin clusters while NAA and NAD were more likely to remove all the fruit from some clusters and few fruit from others, especially in 1988. Compared to the control, all materials applied in 1988 improved return bloom in 1989 with carbaryl having a slightly greater effect than NAA and NAD. As a result of these studies carbaryl at 1.7 to 2.2 kg (active ingredient) per ha as a dilute application is being suggested for grower trials in California.
IN VITRO PROPAGATION OF ALGERIAN IVY (HEDERA CANARIENSIS L.)
Authors: Al-Juboory Karim H. , Williams David J.
Published: October 2019

Shoot tip explants of Algerian Ivy Heder a canariensis were cultured on MS basal medium supplemented with a combination of salt strength and NAA and IBA. More roots per explant developed on full salt strength medium combined with NAA. The most roots per explant were obtained with a combination of IBA and 1/4 MS salt. There was an inverse relationship between an increase in IBA or NAA concentration and root length and number. Shoots proliferated better on full MS salt combined with NAA and IBA. The highest level of NAA (40 uM) and 0.1 uM TDZ produced the most shoots and roots, the longest roots, the highest rooting percentage, the largest plants with the most leaves and the best callus quality per explant. The leaves from in vitro were cultured on MS medium with varying levels of Thidiazuron (TDZ) and NAA in the presence of light produced the highest number of roots.
LONG-TERM CONTROL OF TREE GROWTH IN UTILITY RIGHTS OF WAY USING GROWTH REGULATORS
Authors: Klingaman Gerald L. , Wheeler G. Laurin
Published: October 2019

Twelve to 15 year old silver maple and wild cherry trees were top pruned severely to a height of 5m and then trunk injected with Prunit 20g/l at 0, 0.1, 0.5 or 1.0 g/inch of trunk diameter or were treated with a trunk pour of Prunit 50W at the rate of 0, 0.5 or 1.0 g/inch of trunk diameter. Treatment effects were not obvious on any trees until 12 months after treatment. After 36 months maples receiving the two highest rates had made less than 50 cm of growth above the pruned top of the tree whereas the untreated control had produced 3 m of new shoot growth. The 0.1 g rate produced less aesthetic disruption to the appearance of the tree and reduced growth to 1.2 m. Wild cherry trees responded similarly but the amount of regrowth following pruning was less. Maple trees receiving the trunk pour treatment exhibited a 50% reduction in new shoot growth 36 months after treatment.
PRUNE OVULE LONGEVITY: EFFECT OF CULTIVAR AND FALL-APPLIED ETHEPHON
Authors: Moreno Yerko M. , Miller Anita Nina
Published: October 2019

Some cultivars of prune (i.e. `Brooks') consistently set good crops while others (i.e. `Italian') are erratic bearers. Fall-applied ethephon increases fruit set. Ovule longevity has been hypothesized to be an important factor in fruit retention. The effects of the cultivar and fall ethephon application on ovule longevity were determined.

Ethephon (0 and 500 mg·l-1) was applied to `Italian' and `Brooks' prune trees at the 50% leaf drop stage. The following spring, flower buds were emasculated and covered to prevent pollination. Ten flowers were sampled every two days from anthesis until 20 days after anthesis (DAA). Flowers were fixed in FAP and ovule longevity determined using fluorescence microscopy. Ovule longevity was longer in `Brooks' than `Italian'. At 20 DAA, all of the `Brooks' flowers still had viable ovules. Only 40% of the `Italian' flowers had viable ovules. The `Italian' flowers excised from ethephon-treated trees had at least one non-senescent ovule at 17 DAA. Ethephon prolonged ovule longevity in `Italian' prune flowers. No effect of ethephon was observed on the ovule longevity of the `Brooks' prune.
SOIL TYPE AND POTTING MEDIUM INFLUENCE ON RUST PUSTULE GRADE (SIZE) ON DRY BEAN LEAVES (Phaseolus Vulgaris L.)
Authors: Zaiter Haytham Z. , Coyne Dermot P. , Clark Ralph B. , Steadman James R.
Published: October 2019

Nine bean cultivars/lines were grown in a Tripp sandy-clay loam (high pH), a Sharpsburg silty clay loam (neutral pH), and a potting mix (equal volume of sand, soil [Sharpsburg silty clay loam], vermiculite and moss pest) (low pH) in greenhouse (one experiment), growth chamber (two experiments), and field (two experiments) in Lincoln, NE, in order to evaluate the leaf reaction of the plants to a Nebraska rust (Uromyces appendiculatus var. appendiculatus) isolate US85-NP-10-1. A factorial arrangement of soil media and cultivars/lines in a randomized complete block design was used in the greenhouse and growth chamber experiments, while a split-plot design (soil media as main plots and cultivars/lines as sub-plots) was used in the field experiments. Significant differences were observed for rust pustule size of cultivars/lines grown on the three different soil media. Plants grown on potting mix medium showed significant Increases in rust pustule size compared with Tripp (high pH) or Sharpsburg silty clay loam soils (neutral pH). A significant interaction occurred between soil media and cultivars/lines for the rust reaction. A positive correlation (R= +0.5) was observed between the increased concentration of C1 and Mn,, and a negative correlation for lower K (R+ -0.44) and soil pH in the potting mix and larger rust pustule size of leaves. These results have implications for plant breeders and pathologists involved in evaluating bean progenies and lines for rust resistance.
USE OF TIME TEMPERATURE MONITORS FOR PREDICTING SHELF LIFE OF FRESH FRUITS AND VEGETABLES
Authors: Dean Bill B. , Kupferman Eugene M.
Published: October 2019

Shelf life of perishable commodities is a function of time by temperature effects on the composite kinetic reactions within each commodity. Empirical tests to approximate shelf life have limited value, particularly in long-distance shipment when less than ideal storage conditions occur, such as for the export market. Time temperature monitors (TTMs) have been developed for monitoring storage temperatures and predicting remaining shelf life. Kinetics curves for ripening of pears, yellow color development in broccoli and browning of mushrooms were compared to kinetics properties of available TTMs at 5, 10, and 20°C. Each commodity deteriorated or ripened at rates corresponding to a different TTM. At 20°C, broccoli kinetics were similar to TTM MC 60 or 67, pears to MC 74, and mushrooms MC 66. Customized TTMs and application of this technology will be discussed.
CHANGES IN GLUTATHIONE AND CATALASE ACTIVITY ASSOCIATED WITH BREAKING OF DORMANCY IN CHERRY SEEDS.
Authors: Siller-Cepeda Jorge H. , Fuchigami Leslie , Chen Tony H. H.
Published: October 2019

Many seeds of woody plants require low temperature or other treatments to overcome dormancy. Changes in catalase activity and glutathione has been proposed to be associated with the breaking of dormancy. We examined the level of glutathione and catalase activity of cherry seeds (Prunus mahaleb cv. Lambert) exposed to several dormancy breaking agents. Seeds imbibed in water for 24 hrs. were either stratified at 4°C or at 25°C for up to 12 weeks, or exposed to other dormancy breaking agents. Germination test, glutathione and catalase activity were determined weekly and/or after treatment. Analysis of levels and state of glutathione were performed by high pressure liquid chromatography (HPLC), and catalase activity was assayed spectrophotometrically. Total glutathione in dry and imbibed seeds were similar, but, ratio between the reduced and oxidized form were different. Low temperature stratification for 12 weeks increased the reduced form of glutathione six-fold, while percent germination increased up to 94%.
FRUIT QUALITY DEVELOPMENT OF `GRANNY SMITH' APPLES IN RESPONSE TO TREE CANOPY LIGHT MICROCLIMATE.
Authors: Izso Elena , Larsen Fenton
Published: October 2019

A preliminary study suggested light distribution (400-700nm) did not change from terminal bud set (July) to harvest (9/9/88). Therefore, limbs of 5-year-old trees were shaded the last 90 days of the season in 1988 and 7-year-old trees were shaded the last 60 days in 1989 with 30, 63, 95% or no shadecloth. Medium (63%) and heavy (95%) shade decreased fruit weight both years. Fruit soluble solids (SSC) decreased with increasing shade in 1988 but not in 1989 until after 60 days of storage. Fruit peel chlorophyll (chl) declined with time for all treatments. Apples from full sun and heavy shade treatments had the lowest chl and visually appeared the lightest. Evidence from both years suggested there was an optimal light level between 37-70% full sun for maximum fruit color and chl. Link of 7-year-old trees were shaded at intervals, light all season, mid-season and late season. Fruit weight and firmness were not affected by time of shading. SSC was liner for mid-season shaded fruit. Chl was highest for late season shaded fruit but differences evaporated by 90 days of storage.
ROOT HARDINESS OF GRAPE CULTIVARS
Authors: Ahmedullah M. , Rom C. R.
Published: October 2019

Roots of one year old grape cvs. Concord, White Riesling, Grenache and Semillon were frozen to 0, -5, -10, -15 and -20°C in a programmable freezer. The tops were protected from cold by insulating them. For survival test, 4 plants of each cv. were planted in the greenhouse and their growth observed. Differential thermal analysis (DTA), using a computer attached to a programmable freezer was performed on roots. To aid in the interpretation of DTA, triphenyltetrazolium chloride (TTC) was performed. Hardiness determinations were based on DTA, TTC and the survival tests. DTA patterns representing exothermic response showed an exotherm associated with extracellular free water in tissue which appeared at about the same temperature range for all cvs. This is not associated with hardiness. Additional minor exotherms related to hardiness appeared at lower temperatures than the extracellular water exotherm. Their location differed from one cv. to another. Based on these tests, Concord roots appear to be hardier than other cvs. with important but minor differences in the hardiness of other cvs.
IN VITRO ROOTING OF PINUS STROBUS AND THUJA OCCIDENTALIS `HETZ'S WINTERGREEN' AS INFLUENCED BY ANTIGIBBERELLIN COMPOUNDS (ANCYMIDOL AND FLURPRIMIDOL).
Authors: Burkhart Len , Meyer Martin , Dorner S.
Published: October 2019

Rooting of shoots from in vitro culture of most conifers can be difficult. An antigibberellin, ancymidol, has been shown to promote rooting of in vitro proliferated shoots of asparagus clones, but it has not been tested on conifers. Ancymidol and flurprimidol was tested for rooting on established cultures of Lake States white pine (Pinus strobus). Pulse treatments containing 5 uM ancymidol and 0.5 uM NAA gave 43% rooting, while pulse treatment with 0.5 uM NAA resulted in 7% root formation. Flurprimidol also stimulated root formation on white pine shoots, but was less than ancymidol. Thuja occidentalis `Hetz's Wintergreen' formed roots on 87% of in vitro proliferated shoots when given a pulse treatment with 5 uM ancymidol and 50 uM NAA. Shoots initiated an average of 10 roots after 60 days on vermiculite containing 1/2 liquid MCM medium.
FRAGARIA GERMPLASM FROM MINNESOTA AND WISCONSIN
Authors: Stabler Margaret M. , Luby J. J. , Ascher P. D.
Published: October 2019

Introgression of Fragaria vesca, the diploid wild strawberry, and F. × ananassa, the octoploid cultivated strawberry, into octoploid F. virginiana collected from Minnesota and Wisconsin was suggested by gynodioecy and cluster analysis. Nine morphological traits separated collections into two main clusters, one associated with the northern hardwoods, and the other in the prairie-forest floristic province. Under field conditions, wild female clones were rated similarly to check cultivars for fruit set and plant productivity but always significantly higher than wild hermaphrodites, Increases in yield might be gained by selecting female clones for incorporation into a breeding program. Breeders anticipating rapid transfer of traits from the wild might concentrate on collections from the prairie-forest floristic province, since these materials contain F. × ananassa traits. Maximum genetic diversity would be gained using collection from both floristic provinces.
PHOTOPERIODIC CONTROL OF DEVELOPMENTAL GROWTH IN BEGONIA × TUBERHYBRIDA
Authors: Karlsson Meriam G. , Werner Jeffrey W.
Published: October 2019

Plants of Begonia x tuberhybrida `NonStop Orange', `Clips Orange' and `Musical Orange' were exposed to 1, 2, 3 or 4 weeks of short days initiated at 4 stages of plant development (immediately upon germination, 5 weeks after germination, 10 weeks after germination and 15 weeks after germination). Prior to and succeeding short days, plants were exposed to a day length of 16 hours at 100 μmol·m-2s-1. Short days were 9 hours at an irradiance level of 180 μmol·m-2s-1 to give the same total daily irradiance (5.8 mol· m-2day-1) as long day conditions. The temperature was maintained at 21° ± 4°C during the day and 18° ± 2°C during night. The observed growth and development responses were similar among the studied cultivars. During the period of 4 to 8 weeks after germination, the seedling height increased at an average rate of 0.7 mm day-1 for plants grown under long days and 0.3 mm day-1 for short day plants. The photoperiodic conditions did not affect the number of emerging leaves. The root development was more proliferate on plants allowed to develop under long days compared to plants exposed to short days during early development.
THE EFFECTS OF PREHARVEST ENVIRONMENTAL FACTORS ON ENDOGENOUS ANTIOXIDANTS AND SCALD DEVELOPMENT IN APPLES
Authors: Barden Cynthia L. , Bramlage W. J.
Published: October 2019

Superficial scald development on apples is related to preharvest environmental conditions, perhaps through effects on endogenous antioxidant concentrations In 1989 we examined effects of maturity, light, and preharvest temperatures (< 10°C) on endogenous antioxidant levels in the fruit at harvest and on scald development after long-term storage in 0°C air. Cortland apple trees were sprayed with 500 ppm ethephon 1 month before normal harvest to create maturity differences. Fruit on other Cortland trees were bagged 1 month prior to harvest to reduce light interception. Samples also were harvested from other Cortland trees after exposures to different numbers of hours < 10°C, Hours < 10°C before harvest were negatively correlated to scald development. Ethephon treatment decreased scald incidence, and bagging increased it, The total lipid-soluble antioxidant activity increased with increasing hours < 10°C and with ethephon treatment, while bagging of fruit slightly decreased this antioxidant activity. To better understand the relationships between preharvest factors and antioxidant levels, individual antioxidants, including ascorbic acid, α tocopherol, anthocyanins and glutathione, are being analyzed.
SEASON OF SEED DEVELOPMENT AFFECTS GERMINATION OF LETTUCE SEED WITH HIGH TEMPERATURE
Authors: Mnichowicz Margaret , Coons Janice , McGrady John
Published: October 2019

Lettuce (Lactuca sativa L.) seed germination is inhibited at temperature higher than 25-30C. The extent of this inhibition varies between seed lots. Our objective was to determine how the season during which seed develops affects the ability of seeds to germinate and establish a stand at high temperatures. Lettuce seed, `Empire', was produced during 2 summers and 2 winters (1988 and 1989) in Yuma, AZ. These seeds were germinated at 20, 25, 30 or 35C in petri dishes or in growth pouches to determine percent germination or root lengths, respectively. Electrical conductivity of seed leachates was measured. Field emergence of seeds was tested with early fall plantings in Yuma, AZ. Percent seed germination was greater and root lengths were longer for the seeds produced in summer than in winter. Conductivity will be correlated with relative tolerance to high temperatures of the different seed lots. In the field, percent emergence of seed lots from summer and winter averaged 60% and 38%, respectively.
ESTABLISHING CULTURES FROM MATURE PECAN EMBRYO EXPLANTS ON MEDIA WITH LOW WATER AVAILABILITY
Authors: Obeidy Ahmed , Smith M. A. L.
Published: October 2019

Endophytic fungi associated with mature pecan nuts (cultivars `Smart', `Desirable' and `Owens') prevented successful, contaminant-free. in vitro culture of embryo explants, even after rigorous surface disinfestation of the nuts and careful aseptic shelling. Disinfestation with sodium hypochlorite after removing the shells was also unsuccessful, because even dilute concentrations which were ineffective against the fungal contaminants destroyed embryo viability. An alternative disinfestation technique is required to establish in vitro cultures from mature pecan explants. Explanting media with low water availability were developed to capitalize on the relatively stringent requirement of most fungal contaminants for free water. The explanting media were supplemented with 0.9-1.5% agar. Other media components were selectively included or omitted to test their influence on water activity and fungal growth. After four weeks of culture, the incidence of contamination was reduced to 30% or less on modified explanting media, compared to 100% loss to contamination on control medium (0.5% agar). The brief initial culture period effectively eliminated fungal contamination from cultures by plasmolyzing fungal hyphae or denaturing fungal protein, without effecting pecan embryo viability. Cultures remained contaminant-free after transfer to control medium. Axillary and adventitious bud development from disinfested embryo axes was subsequently induced in a medium with 18 μM BAP and 5 μM IBA, and regeneration from cotyledon explants was accomplished in a medium with 50 μM NAA. This disinfestation technique allows mature pecan embryo explants to be used in biotechnology.
EFFECTS OF GROUNDCOVER MANAGEMENT SYSTEMS AND WATER DEFICIT STRESS ON QUALITY OF APPLE
Authors: Russell Steven G. , Blankenship Sylvia M. , Skroch Walter A.
Published: October 2019

A field study was initiated in 1981 in western North Carolina to determine the influence of eight groundcover management systems on quality of `Redchief Red Delicious' apple (Malus domestica) grafted onto rootstock of M VIIA. Management systems included: bare soil, Secale cereale mulch, minimal cultivation, Festuca arundinacea, Dactylis glomerata, Poa pratensis, Muhlenbergia schreberi and Rubus sp. Thus far, fruit quality data indicate that fruits produced in plots of cool-season grasses are smaller and less mature than those produced in vegetation-free plots or plots of warm-season grasses. A negative correlation was noted between high fruit quality and water deficit stress as measured by water potential and stomatal conductance.
RFLP ANALYSES OF PHASEOLUS INTERSPECIFIC HYBRIDS
Authors: Guo Mei , Lightfoot David A. , Mok Machteld C. , Mok David W. S.
Published: October 2019

Interspecific hybridization between Phaseolus vulgaris and P. coccineus results in mature seeds or abnormal embryo formation depending on the direction of the cross. In addition, differential fertility and reversion to parental types occur in later progeny populations, accompanied by recurrence of various embryo types. Normal and abnormal embryos exhibited isozyme patterns resembling P. vulgaris and P. coccineus parents respectively, suggesting that developmental abnormalities may be associated with specific combinations of parental genes. RFLP between parental species was examined and probes were selected for analyses of F2 populations. Differential transmission of alleles occurred for some RFLP markers. Statistical analyses were applied to detect possible association between probes and abnormal developmental events. The high incidence of interspecific polymorphism will also facilitate the construction of a linkage map in Phaseolus.
THE INFLUENCE OF SOIL CALCIUM LEVEL ON GROWTH AND YIELD OF WATERMELON AND CALCIUM CONCENTRATION OF WATERMELON RIND TISSUE
Authors: Scott W.D. , McCraw B.D.
Published: October 2019

Three cultivars of watermelon (Citrullus lanatus), `Crimson Sweet', `Charleston Gray' and `Tri-X Seedless' were grown in combination with 4 levels of soil applied calcium (0, 280, 560, 1120 kg Ca/ha). Gypsum was incorporated into 6 m plots on 5 m centers then covered with black plastic mulch. Irrigation requirements were provided through a hi-wall drip system and soil water status monitored with tensiometers. Transplants were spaced 1.2 m apart in-row spacing allowing for 5 plants per plot and replicated 3 times. Melons were harvested at 7, 14, 21 days from anthesis and at full maturity. Rind tissue was analyzed for total and extractable Ca, Mg, K, Mn, Zn and Fe. Leaf samples were taken 6 weeks from transplanting for similar analysis, Yield, vine growth and the incidence of blossom-end rot were recorded. The study was conducted at 2 locations during the 1989 and 1990 growing seasons. Data will be presented at the meeting,
THE EFFECT OF DEFOLIATION ON STRAWBERRY FRUITING RESPONSE
Authors: Albregts E. E. , Howard C. M. , Chandler C. K.
Published: October 2019

During 2 seasons, defoliated and non-defoliated strawberry plants were evaluated for their fruiting response using the annual hill cultural system in Dover, FL. Partially dormant Canadian grown `Chandler' and non-dormant locally grown FL breeding line 79-1126 were grown the first season. Locally grown `Dover' was added the second season. Total yields of all clones were reduced with foliage removed. Monthly yields were reduced the first season with FL 79-1126 defoliated plants, but only the April yield of defoliated `Chandler' was reduced. December, January, March, and total yields of defoliated plants from all clones were reduced the second season. Average seasonal fruit weight was reduced the second season with locally grown defoliated plants. During the second season the percent marketable fruit of `Chandler' and FL 79-1126 was greater with the defoliated plants.
GAS EXCHANGE AND FERN WATER POTENTIALS OF WATER-STRESSED ASPARAGUS
Authors: Drost Daniel , Wilcox-Lee Darlene
Published: October 2019

Asparagus is considered a relatively drought tolerant plant, but few studies are available on the gas exchange response to soil moisture stress. Seedlings were grown in the greenhouse for six months before initiation of the water stress treatments. Soils were allowed to dry to matric potentials of -0.05, -0.3 and -0.5 MPa before rewatering to pot capacity. Gas exchange and fern water potentials were measured diurnally on asparagus plants when soil matric potentials reached their minima. Decreasing soil matric potentials decreased net carbon dioxide assimilation, stomatal conductance and fern water potential. Assimilation rates (6 am) were between 3 and 5 umols m-2 s-1 for all soil moisture treatments. Carbon assimilation rates of 10, 8, and 7 umols m-2 s-1 were recorded at 10 am for the -0.05, -0.3 and -0.5 MPa soil matric potentials, respectively. Assimilation rates decreased sharply over the remainder of the day. The diurnal pattern for conductance were similar to the assimilation rates. Fern water potentials were greater in the -0.05 MPa than in the -0.5 MPa treatment for all measurement periods with an intermediate response for soil matric potentials of -0.3 MPa. Fern water potentials were highest at 6 am (-0.2 to -0.6 MPa) before declining to their minima (-1.5 to -1.8 MPa) at 10 am. Water potentials remained at these low levels throughout the day before recovering slightly at 6 pm.
THIDIAZURON EFFECTS ON GROWTH INITIATION AND EXPRESSION IN MANGO (MANGIFERA INDICA L.)
Authors: Nunez-Elisea R. , Caldeira M. L. , Davenport T. L.
Published: October 2019

Thidiazuron (TDZ; N-phenyl-N-1,2,3-thiadiazol-5-ylurea) stimulates axillary bud break in some horticultural crops. We are exploring its ability to initiate bud growth in mango trees in order to manipulate vegetative and reproductive shoot initiation. Axillary buds on defoliated, decapitated shoots were treated in late October, 1989 (about two months before normal floral initiation), with 0, 125, or 1000 ppm TDZ. Although timing or percent of bud-break was unaffected by TDZ, the compound influenced growth expression. TDZ (125 ppm) produced morphologically typical panicles (mixed or purely floral), while at 1000 ppm purely floral panicles were produced which were abnormally compact (similar to panicles affected by mango malformation). Non-treated buds produced only vegetative shoots. Sprays of TDZ (25 to 200 ppm) on developing panicles produced morphological anomalies in panicles such as thickening of the central axis and secondary branches, increase in flower size, and sprouting of the most basal buds on the central axis. Effect during the vegetative flushing period will be discussed.
FLOODING TOLERANCE IN SPINACH (Spinacia oleracea L.)
Authors: Fiely M.B. , Morelock T.E.
Published: October 2019

Spinach (Spinacia oleracea L.) varies in tolerance to saturated soil conditions. Plant vigor was assessed for plants flooded in autoclaved and nonautoclaved field soil. Decline of vigor was more rapid for plants flooded in nonautoclaved field soil, indicating that flooding tolerance may be influenced by soil borne pathogens.
HIGH TEMPERATURE RESPONSE IN BEAN -BREEDING CONSIDERATIONS
Authors: Davis David W. , Sauter Karl J.
Published: October 2019

Attention has been given in recent literature to crop breeding for heat tolerance, but, as with certain other physiological traits, such as photosynthetic efficiency, practical gain has lagged. The question remains as to whether heat tolerance can be improved, and, if so, if it can most efficiently be improved by a holistic approach, as in breeding for yield following timely high temperature levels in the field environment, or whether the breeding for heat (and drought) tolerance components in the laboratory would be feasible. At issue is the identification and repeatability of key plant responses, such as cell membrane damage, heat shock protein formation, increased ethylene output and other responses, and the relevance, effectiveness and cost of screening for such traits. Results from our laboratory, and the work of others, will be reviewed.
BREEDING SWEETPOTATO FOR RESISTANCE TO MULTIPLE INSECT PESTS
Authors: Jones Alfred
Published: October 2019

Sweetpotato [Ipomoea batatas (L.) Lam.] cultivars with high levels of resistance to root damaging insects have been developed through the collaborative efforts of a multidisciplinary research team. These resistances were combined with other traits necessary for a successful cultivar such as: disease resistances; high yield; long storage life; prolific sprout production; marketable root size, shape and skin at tributes; and culinary excellence. Adpotion of quantitative genetic principles, development of a wide gene base, sequential selection schemes, use of effective selection criteria and appropriate susceptible standards contributed to the program's success. These achievements were made with, little prior knowledge about inheritance patterns, gene action, mechanisms of resistance or a complete knowledge of the insects concerned. The value of insect resistant cultivars has become better appreciated with the recent decrease in chemical alternatives.
Cell Size and Pretransplant Nutritional Conditioning Influences Early Vine Growth and Yield of Transplanted Watermelon
Authors: Graham Charles J.
Published: October 2019

Research is needed to better understand the influence of cell volume and fertility on watermelon transplant size and field performance in order to determine the most economic production practices. `Jubilee' watermelon transplants were grown using a 4 x 4 factorial experimental design consisting of 4 cell volumes (30.7, 65.5, 147.5, and 349.6 cm3) and 4 fertility rates (0, 1/4, 1/2, and full-strength Hoagland's solution). Transplant shoot dry weight significantly increased as cell volume and fertility increased. Increasing cell volume linearly increased watermelon number/ha and tons/ha for early and total harvest in 1995. The average weight per watermelon significantly increased for early-harvested fruit but not for total harvest as cell volume increased in 1995. Soluble solids concentration linearly increased with increasing cell volume for early and total harvests in 1995. Cell volume had no significant influence on the harvest parameters measured in 1997. In 1995, increasing fertility linearly increased watermelon number/ha and tons/ha for early harvests. Increasing fertility increased the soluble solids concentration linearly for early-harvested watermelons in 1997 but not in 1995. Fertility rate had no significant influence on any of the other harvest parameters measured in 1995 and 1997. The growing conditions and disease pressure in 1997 reduced melons/ha, yield, and soluble solids content when compared to 1995 values. The half-strength Hoagland's solution produced the greatest number of watermelons/ha, tons/ha, and the highest soluble solids concentration in 1995 and 1997. Pretransplant nutritional conditioning had no significant effect on total `Jubilee' watermelon production in Louisiana for 1995 and 1997.
Lab Screening of the Wild Tomato, Lycopersicon peruvianum, for Foliar Resistance to the Tomato Fruitworm, Helicoverpa Zea
Authors: Irvin Kelly M. , Lamb Elizabeth M.
Published: October 2019

A lab screening method has been devised to evaluate a diverse population of a heterogeneous wild tomato species for foliar resistance to tomato fruitworm. This method isolates neonate fruitworms on individual, 25-day-old plants. The larvae are allowed to consume the plant material for 4 days, after which they are removed from the plants, weights are taken and percent survival recorded. The trial is conducted in a growth chamber at a constant temperature of 28 °C with a 16-hour light cycle. The replications are set up as a complete randomized block design. Preliminary data reveal at least two plant introductions expressing strong foliar resistance to H. zea, showing a significant difference from the susceptible control, L. esculentum, and no significant difference from the resistant control, L. hirsutum f. glabratum.
Recycled Waste Paper Mulches Influence Moisture Retention in Greenhouse Containers
Authors: Edwards J.H. , Smith D.R. , Gilliam C.H. , Erbach D.C.
Published: October 2019

Excessive moisture is a problem in evaluating recycled paper products as mulch to replace other common mulch materials and in landscape and container uses. To isolate the water associated with soil and/or media, two recycled paper products, pellets or crumble, were used as mulches in trade gallon containers in a greenhouse. Pine bark, pellets, and crumble needed to obtain standard mulch depth were enclosed in plastic mesh. These mulches were placed in containers that contained 1 kg of a 7 pine bark : 1 sand media. All containers were saturated with tap water for 24 hours. Mulches were placed on each container and allowed to drain for 1 hour. Weights of media, mulch, and media and mulch were obtained every 24 hours for a total of 312 hours. Water content of the media was not influenced by any of the mulch treatments. Water content of the paper products was increased by a factor of two. Pine bark mulch water content was zero 96 hours after an initial dry down cycle began, while the water content of pellet and crumble were 100 and 90 cm of water. Total water content of the media plus the mulch was increased by 30% to 35% when compared to pine bark mulch alone. However, the increase was associated with the water content of the waste paper mulch.
Influence of Sweetpotato Resin Glycosides on the Life Cycle of the Diamondback Moth
Authors: Peterson J.K. , Jackson D.M.
Published: October 2019

Resin glycosides extracted from sweetpotato skins were bioassayed for their effects on survival, development, and fecundity of diamondback moths, Plutella xylostella (L.). Glycosides were incorporated into an artificial diet (Bio-Serv, Inc.) and fed to diamondback larvae. Neonatals were individually fed artificial diet with 0.00, 0.25, 0.50, 1.00, 1.50, and 2.00 mg·mL-1. There were highly significant negative correlations between glycoside levels and survival as well as weight of survivors after 6 days. A significant positive relationship existed between dosages and development time. Lifetime fecundity was negatively affected at sublethal doses. The glycosides are viewed as contributors to resistance to the wireworm, Diabrotica and Systena insect complex.
Economic Analysis of In-row Plant Spacing and Date of Harvest on `Beauregard' Sweetpotato
Authors: Schultheis Jonathon R. , Walters S. Alan , Estes Edmund A.
Published: October 2019

Yield in most crops can be increased with closer in-row spacing; however, the costs vs. benefits need to be assessed. A partial economic analysis was conducted at various plant spacings and harvest times to determine the best cultural management strategy. The effect of plant spacings (15.2, 22.9, 30.5, and 38.1 cm) and two dates of harvest (≈110 or 130 days after planting) were studied on `Beauregard' sweetpotato in one planting in 1991 and two planting locations in 1992. Weights were obtained for the U.S. Number 1, canner, jumbo, and cull grades. The 30.5-cm spacing interval was used as the standard comparison for economic analysis. Yields of sweetpotatoes increased as in-row spacing decreased. Based on economic analysis, the 38.1-cm spacing was always inferior to the 30.5-cm spacing. The preferred in-row spacing of `Beauregard' sweetpotato is 22.9 if a late harvest is anticipated, while the 15.2-cm spacing would be best if harvesting at ≈110 days after transplanting. As long as moisture is not limiting and planting is before mid-June, sweetpotato growers should place `Beauregard' plants at an in-row spacing of 15.2 or 22.9 cm, depending on projected date of harvest, to obtain the best yields with the highest marginal return on investment.
Shelf Life of Sweetpotatoes under Tropical Conditions: Effect of Storage Time on Sensory Properties and Importance of Water Loss
Authors: van Oirschot Quirien. E.A. , Rees Debbie , Aked Julia
Published: October 2019

Sweet potato is an important staple food crop in East Africa, but under local marketing conditions it has a shelf life of generally no longer than 2 weeks. As a result, the potential for marketing over longer distances is limited. The role of changes in sensory properties and weight loss as limiting factors for shelf-life were investigated. The important sensory attributes of five sweet potato cultivars were determined in discussion sessions with four taste panels and were: floury, sweet, chestnutty, grainy, smooth, soft, fibrous, discoloration, and moist. The sensory profiles of the five cultivars (KSP20, Kemb10, Yanshu 1, Pumpkin, and SPK004) differed significantly (P < 0.001). However, after 4 and 8 weeks under simulated tropical storage conditions (26 °C, 80% to 90% RH) no significant changes in the attributes were detected in most cases (P > 0.05). Changes in sensory properties were therefore not considered to limit shelf life. Shelf life experiments in Tanzania under simulated marketing conditions (26 + 5 °C, 50% to 60% RH) with 29 local cultivars revealed that roots with high rates of weight loss also rot rapidly. It was found that weight losses (primarily due to water loss) were high and varied significantly among cultivars (12% to 45% loss in 21 days). Further studies will investigate the structure and strength of the periderm as the main barrier to water loss to facilitate future cultivar selection.
Mulch Types Affect Fruit Quality and Composition of Two Strawberry Genotypes
Authors: Wang Shiow Y. , Galletta Gene J. , Camp Mary J. , Kasperbauer Michael J.
Published: October 2019

The influence of mulch types (black polyethylene, red polyethylene, and straw-vetch in raised bed hill culture) on the chemical composition of `Northeaster' and `Primetime' strawberry (Fragaria ×ananassa Duch.) fruit and plant parts was evaluated. Ascorbic acid (AA), malic acid, citric acid, and ellagic acid levels were higher in `Primetime' than in `Northeaster' fruits, while `Northeaster' had a higher soluble solids content (SSC). Fruit grown on straw-vetch had lower SSC than did those grown on the polyethylene mulches. The AA content in the fruit of either cultivar was not affected by the mulch treatment. Fruit grown on the straw-vetch mulch had less red surface and flesh color but higher pigment intensity than fruit grown on the polyethylene mulches. Strawberry plants grown on straw-vetch mulch had the largest leaf area and the highest chlorophyll content, while plants grown on red polyethylene mulch had the smallest leaf area and lowest chlorophyll content. There were significant mulch × cultivar interactions in fruit titratable acid (TA) and AA levels, sugars, citric and ellagic acid contents, leaf area and chlorophyll levels, and soluble carbohydrate and starch contents in leaves, petioles, crowns, crown-roots, and roots. TA was highest in `Northeaster' fruit when grown on red polyethylene, whereas TA was highest in `Primetime' fruit when grown on straw-vetch. The highest fruit citric acid levels were found in straw-vetch mulched plots of `Northeaster', and in black polyethylene mulched plots of `Primetime'. Ellagic acid accumulation was highest in `Northeaster' fruit grown on black polyethylene, and in `Primetime' fruit grown on red polyethylene or straw-vetch mulches. Fruit glucose content was highest in `Northeaster', but lowest in `Primetime', when grown on the straw-vetch mulch. There was a general tendency for soluble carbohydrate and starch levels in plant tissues to be lowest when the plants were grown in red polyethylene mulch and highest when grown in black polyethylene mulch. `Primetime' contained higher total carbohydrate levels than did `Northeaster' in all tissues tested.
Timing and Severity of Summer Pruning Affects Flower Initiation and Shoot Regrowth in Sweet Cherry
Authors: Guimond Charlotte M. , Lang Gregory A. , Andrews Preston K.
Published: October 2019

To examine the effect of timing and severity of summer pruning on flower bud initiation and vegetative growth, 4-year-old `Bing' cherry trees (Prunus avium L.) were pruned at 31, 34, 37, 38, or 45 days after full bloom (DAFB) with heading cuts 20 cm from the base of current-season lateral shoot growth, or at 38 DAFB by heading current-season lateral shoot growth at 15, 20, 25, or 30 cm from the base of the shoot. The influence of heading cut position between nodes also was examined by cutting at a point (≈20 cm from the shoot base) just above or below a node, or in the middle of an internode. Summer pruning influenced the number of both flower buds and lateral shoots subsequently formed on the shoots. All of the timings and pruning lengths significantly increased the number of both flower buds and lateral shoots, but differences between pruning times were not significant. There was significantly less regrowth when shoots were pruned just below a node or in the center of an internode, rather than just above a node, suggesting that the length of the remaining stub may inhibit regrowth somewhat. The coefficient of determination (r2) between flower bud number and regrowth ranged from -0.34 to -0.45. In young high-density sweet cherry plantings, summer pruning may be useful for increasing flower bud formation on current-season shoots. The time of pruning, length of the shoots after pruning, and location of the pruning cut can influence subsequent flower bud formation and vegetative regrowth.
A Recirculating Hydroponic System for Studying Peanut (Arachis hypogaea L.)
Authors: Mackowiak C.L. , Wheeler R.M. , Stutte G.W. , Yorio N.C. , Ruffe L.M.
Published: October 2019

Peanut (Arachis hypogaea L.) plants were grown hydroponically, using continuously recirculating nutrient solution. Two culture tray designs were tested; one tray design used only nutrient solution, while the other used a sphagnum-filled pod development compartment just beneath the cover and above the nutrient solution. Both trays were fitted with slotted covers to allow developing gynophores to reach the root zone. Peanut seed yields averaged 350 g·m-2 dry mass, regardless of tray design, suggesting that substrate is not required for hydroponic peanut production.
Long-term Effects of Rows per Bed and In-row Spacing on Yield and Spear Size of Asparagus
Authors: Sanders D.C. , Cure J.D. , Sperry W.J. , Gilsanz J.C. , Prince C.A. , Bandele O.
Published: October 2019

Three studies were conducted at Clinton, N.C., to investigate the relationship between number of rows per bed, in-row spacing, and spear yield of asparagus (Asparagus officinalis L.) over 11 to 13 years. In the first study, increasing plant densities from 21,550 to 43,100 plants/ha by doubling the number of rows/bed increased the cumulative yield from 64% to 80% for three hybrid lines (`UC 157', `WSU 1', and `WSU 2') but only 6% for `Rutgers Beacon'. The effects of doubling the plant density were still apparent 13 years later. In the second study, yields of `Princeville' (`Mary Washington' selection) crowns, grown at densities from 14,000 to 86,000 plants/ha, were also increased for 8 years by doubling rows at various in-row spacings. In a third study, in which densities ranged from 21,000 to 387,900 plants/ha, the magnitude of the response to rows/bed was dependent on in-row spacing. Efficient use of bed space and the avoidance of crowding exerted a larger influence on productivity than did average planting density. The yield response to rows/bed was greater and more persistent through the years for wider in-row spacings. Spear size was only marginally responsive to rows per bed and in-row spacing.
Photoperiod, Temperature, Gibberellin, and an Anti-gibberellin Affect Tuberization of Potato Stem Segments In Vitro
Authors: Escalante B.Z. , Langille Alan R.
Published: October 2019

`Katahdin' potato plants were grown under conditions that did not induce tuberization (noninducing conditions) and the foliage was sprayed with either a growth retardant (BAS-111) at 1000 mg·L-1 or distilled water. Other plants, grown under tuber-inducing conditions, received a foliar spray of gibberellic acid (GA3) at 100 mg·L-1 or distilled water. After 1 week, treatments were repeated. Two-node stem segments were excised from the apical, subapical, medial, and basal sections of each plant 72 hours after the second foliar treatment, disinfested, and inserted into flasks containing 50 mL of Murashige and Skoog medium (2% sucrose). After 3 weeks in a darkened incubator adjusted to 24 °C, tuberization response was evaluated. Orthogonal contrasts revealed significant differences between induced and noninduced controls for tuber number, diameter, and fresh mass. BAS-111 reduced rhizome length and increased tuber number, diameter, and fresh mass. GA3 increased rhizome length, but reduced tuber number, diameter, and fresh mass. Node location influenced tuber development, as basal explants produced significantly more and larger tubers, as well as longer rhizomes, than did apical explants, and subapical segments produced more and larger tubers than did apical segments. There were no significant differences between medial and basal nodal segments with respect to tuber number or tuber/rhizome size. Chemical names used: 1-phenoxy-5,5-dimethyl-3-(1,2,4-triazol-1-yl)-hexan-5-ol (BAS-111); 2,4a,7-trihydroxy-1-methyl-8-methylenegibb-3-ene-1,10-carboxylic acid 1->4 lactone (GA3).