bluuebunny/crossref_metadata_2025 huggingface dataset:
240 Fruit Removal Effects on Growth and Carbon Allocation in Young Citrus Trees
Authors: Ferguson J.J. , Koch K.E. , Huang T.B.
Published: February 2019

Fruit were removed 8, 16, and 24 weeks after peak bloom from 3- and 4-year-old, `Hamlin' orange [Citrus sinensis (L.) Osbeck] trees on `Carrizo' citrange root-stock [C. sinensis (L.) Osbeck ×Poncirus trifoliata (L.) Raf.], planted as bare root or containerized trees, to determine if fruit removal enhanced vegetative growth. Bare-root trees had a greater stem diameter and tree height than containerized trees at planting and after years 3 and 4. Fruit of bare-root trees had lower fresh and dry weights, refixed less of their respiratory CO2 during development, and lost water less rapidly after harvest. In addition, fruit removal treatments did not increase growth of either bare-root or containerized trees relative to trees from which no fruit had been removed. In fact, tree diameters were slightly higher when fruit were not harvested. Carbon cost of fruit production may have been countered by other factors under field conditions, such as known enhancement of photosynthetic rates by fruit load and/or diurnal contributions by fruit to leaf water demands.
241 Estimating Optimal Sample Size for Sweet Orange Fruit Quality Experiments
Authors: Barry Graham H. , Castle William S. , Davies Frederick S. , Littell Ramon C.
Published: February 2019

Variability in fruit quality of citrus occurs among and within trees due to an interaction of several factors, e.g., fruit position, leaf: fruit ratio, and fruit size. By determining variability in fruit quality among i) fruit, ii) trees, iii) orchards, and iv) geographic locations where citrus is produced in Florida, optimal sample size for fruit quality experiments can be estimated. To estimate within-tree variability, five trees were randomly selected from each of three `Valencia' orange orchards in four geographic locations in Florida. Six fruit were harvested from each of two tree canopy positions, southwest top and northeast bottom; fruit were not selected or graded according to fruit size. °Brix and titratable acidity of juice samples were determined, and the °Brix: acid ratio was calculated. Statistical analysis of fruit quality variables was done using a crossed-nested design. The number of trees to sample and the number of fruit per sample were calculated. To estimate between-tree variability, 10 trees were randomly selected from each of three `Valencia' orange orchards from four geographic locations in Florida. Fifty-fruit composite samples were picked from around the tree canopy (0.9 to 1.8 m). Juice content, SSC, acid content, and ratio were determined. Using a nested design, the number of orchards and number of trees to sample were determined. There was greater variability in fruit quality among trees than within trees for a given canopy position; the optimal sample size when taking individual fruit samples from a given location and canopy position is four fruit from 20 trees. There was less variability in fruit quality when 50-fruit composite samples were used, resulting in an optimal sample size of five samples from three orchards within each location.
248 Sunlight Penetration within the Tree Canopy after Tree Removal in Crowded Pecan Orchards
Authors: Herrera Esteban A. , Arreola Jesus
Published: February 2019

This study was conducted during 1996 and 1997 in a mature pecan orchard gradually thinned over 3 years. Twenty-five percent of the trees were first removed in 1993, 1994, or 1995. The orchard thinned in 1994 was further thinned to 50% in 1995. Diffuse photon flux density of photosynthetic active radiation (PAR) was measured within the tree canopy before and after tree thinning. Sunlight penetration measurements were taken on eight tree sides as follows (N, S, E, W, NE, SE, NW, NE), 24 readings were taken on each tree side three times a day. As expected, penetration of PAR inside the tree canopy increased as thinning reduced tree density. PAR levels recorded at 9, 12 or 15 daytime hours within the tree canopy increased as the solar time increased. Lower light values were found in the north side of the tree canopy compared to other tree sections.
254 Study of Regular and High Applications of Water with Drip Irrigation in Small `Manzanillo' Olives
Authors: Fontes Adán Fimbres , Contreras Raúl Leonel Grijalva , de Jesus Valenzuela Ruiz Manuel
Published: February 2019

The area of olives in the region of Caborca has been increasing in the last years to 4500 ha. Olives in other regions do not need the application of water, at Caborca evaporation is greater than rainfall. Because of that situation, an experiment was conducted in 1998 to determine the optimum water requirements and the crop coefficient for `Manzanillo' olives (2 years of planted) under drip irrigation and microsprinkler in a sandy loam soil. The results indicated no difference between treatments (50%, 75%, and 100% of ET estimated in a pan evaporation). The water applied to each treatment was 13.32, 19.98, and 26.64 cm.
261 Effect of SMP and Brushing on Gourd Seed Germination at Different Temperatures
Authors: Bang Hae-Jeen , Hwang Soo-Jung , Ham Hyun-Sook , Lee Jung-Myung
Published: February 2019

The effectiveness of solid matrix priming (SMP) and seed brushing was further evaluated by using an thermo-gradient table (Seed Processing, Holland) set at 10 different temperatures from 12 to 30 °C. Intact or brushed seeds of gourd (Lagenaria siceraria) were primed with Micorocel E (Celite Corp.) at 25 °C for 3 days in the mixture of 10 seed: 1 Microcel E: 3 water, by weight, and the primed seeds were dried again for long-term storage. SMP treatment significantly increased earlier seed germination at all temperatures. However, the difference in seed germination rate between intact and SMP-treated seeds was most pronounced at somewhat lower temperatures of 18-22 °C. SMP-treated seed showed about 20% final germination rate at 12 °C, whereas intact seeds did not germinate at all. Seed brushing treatment itself did not influenced the germination rate. However, brushing treatment before SMP treatment significantly increased the SMP effect. Combined use of chemicals in solution further increased the early germination. Details of various seed treatment methods will be presented.
268 Nursery Irrigation Effects on Postplanting Root Dynamics of Limonium cossonianum O. Kuntze in Semi-arid Conditions
Authors: Franco J.A. , GarcÌa M.J. , Cros V.
Published: February 2019

A study was conducted with Limonium cossonianum O. Kuntze to analyze the influence of irrigation regime in nursery on the dynamics of root development after being transplanted with minimum management conditions. Plants were potgrown in a greenhouse. Each plant was potted into 625-mL plastic pot filled with a 1 silica sand medium: 1 peat mixture (v/v) amended with osmocote plus (3.7 g•kg-1 substrate). Drip irrigation was used with a 2-L•h-1 emitter per plant. Two irrigation treatments were used: T3, plants watered 6 days a week at the water-holding capacity (leaching 20% of the applied water) and T1, plants watered twice a week, receiving an amount of water at 30% of T3 plants troughout the nursery period (45 days). After nursery period, plants were transplanted in the open air at the southeast Mediterranean coast of Spain (37°47′N, 0°′54′W), and just one establishment irrigation was applied (50 mm). There were three replications. Plant root and top growth were measured weekly for 13 months. For the root dynamics study, minirhizotrons were used. Acrylic tubes, 2 m long and 80 mm in outside diameter, were placed at a inclination of 24°, reaching a total depth of 160 cm. The evolution of the root length density (RLD) was measured by seven 23-cm-deep soil layers. Results indicate that those plants that were less watered in nursery showed a greater RLD for the whole soil profile. Plants root growth for the top 46 cm of soil were not significantly affected by irrigation treatments; between 46 and 115 cm deep, T1 plants showed greater RLD than T3 (average values of 0.6 vs. 0.3 cm•cm-3); and under 115-cm deep (where root growth was more limited), there were not significant differences. For the first 6 months, a important plant top growth was observed, there being no significant differences among irrigation treatments. Research suported by CICYT grant AGF-96-1136-C02-02.
270 Root, Stem, and Fruit Growth of `Tainung 1' Papaya Plants following Defoliation
Authors: Marler Thomas E. , Stushnoff Cecil
Published: February 2019

The influence of plant size on recovery following defoliation of `Tainung 1' papaya was used to study the role of respiratory sink size relative to photosynthetic surface area and the carbohydrate pool size available for remobilization. Defoliated (D) plants at three different ages: oldest, 24 weeks posttransplant (PT), supporting ≈8 weeks of fruit set; intermediate, 10 weeks PT, ≈2 weeks from initial flowering; and youngest, 4 weeks PT, were compared to an equal number of control plants. The oldest plants abscised all fruit <5.5 cm in diameter as a result of defoliation. Increase in stem height and basal circumference ceased on all plants and increase in fruit circumference ceased on the oldest plants following defoliation. Increase in stem height of D plants began again 3 weeks postdefoliation (PD) and returned to that of control plants by 6 weeks PD. Increase in basal circumference of D plants began again 6 weeks PD. Root density was observed on observation windows, and fine roots completely disappeared within 1 week PD. Root density returned to that of control plants by 6 weeks for the youngest and intermediate plants and by 8 weeks for the oldest plants. Increase in fruit circumference of pre-existing fruit for the oldest D plants never returned to that for control plants. These plants began setting fruit again ≈8 weeks PD. Defoliation delayed initial flowering of the intermediate plants 6.5 weeks and of the youngest plants ≈2 weeks. Thus, the greatest impact of defoliation on reproductive growth occurred with the two oldest age groups.
283 Response of Forbs to Grass Herbicides, Fire, and Mowing in Mid-successional Tallgrass Prairies of Central Missouri
Authors: Sharma Jyotsna
Published: February 2019

Because of thousands of years of adaptation to the native climate, prairie forbs (“wildflowers”) present a large potential for their use in beautification projects along roadsides, in large backyards, and in nature centers. Vegetation in abandoned, naturally revegetated, grass-dominated areas can be managed to encourage a forb-dominated stage. Two grass herbicides [sethoxydim (PoastTM) and fluazifop (Ornamec-170TM)], three burning treatments (winter, early spring, and late spring), and two mowing treatments (fall and late spring) were tested to determine their effect on forb cover and species diversity in a mid-successional tallgrass prairie. One application of either of the herbicides, at the time of recommended growth stage of target grasses, changed species composition significantly (80% forbs vs. 46% forbs in control plots; P < 0.05) in favor of showy forbs. Species diversity of sprayed plots was relatively low, however. Burning was the next best alternative (averaging 63% forbs) that also resulted in highest species diversity. Fall and late spring mowing reduced cover of forbs (32%) and species diversity to levels lower than those found in control plots. Cover of Solidago canadensis (tall goldenrod) in sethoxydim-treated plots increased to 22.8% compared to 2.5% in control plots. Cirsium discolor (pasture thistle) and Rudbeckia hirta (black-eyed susan) also increased significantly in response to herbicide treatments.
286 Plant Life Form Frequency, Diversity, and Irrigation Application in Urban Residential Landscapes
Authors: Peterson Cathleen A. , McDowell L. Brooke , Martin Chris A.
Published: February 2019

Heightened awareness of ecological concerns have prompted many municipalities to promote water conservation through landscape design. In central Arizona, urban residential landscapes containing desert-adapted plant species are termed xeriscapes, while those containing temperate or tropical species and turf are termed mesoscapes. Research was conducted to ascertain landscape plant species diversity, tree, shrub, and ground cover frequency; landscape canopy area coverage; and monthly irrigation application volumes for xeric and mesic urban residential landscapes. The residential urban landscapes were located in Tempe and Phoenix, Ariz., and all were installed initially between 1985 and 1995. Although species composition of xeric and mesic landscapes was generally dissimilar, both landscape types had comparable species diversity. Mesoscapes had significantly more trees and shrubs and about 2.3 times more canopy area coverage per landscaped area than xeriscapes. Monthly irrigation application volumes per landscaped surface area were higher for xeriscapes. Even though human preference for xeric landscape plants may be ecological in principle, use of desert-adapted species in central Arizona urban residential landscape settings might not result in less landscape water use compared with mesic landscapes.
288 Effects of Foliar Urea on Reserve Nitrogen and Carbohydrates in Young Apple Trees with Different Nitrogen Background
Authors: Cheng Lailiang , Guak Sunghee , Dong Shufu , Fuchigami Leslie H.
Published: February 2019

Bench-grafted Fuji/M26 plants were fertigated with seven nitrogen concentrations (0, 2.5, 5.0, 7.5, 10, 15, and 20 mM) by using a modified Hoagland solution from 30 June to 1 Sept. In mid-October, half of the fertigated trees were sprayed with 3% urea twice at weekly intervals, while the other half were left as controls. The plants were harvested after natural leaf fall, stored at 2 °C, and then destructively sampled in January for reserve N and carbohydrate analysis. As N concentration used in fertigation increased, whole-plant reserve N content increased progressively with a corresponding decrease in reserve carbohydrate concentration. Foliar urea application increased whole-plant N content and decreased reserve carbohydrate concentration. The effect of foliar urea on whole-plant reserve N content and carbohydrate concentration was dependent on the N status of the plant, with low-N plants being more responsive than high-N plants. There was a linear relationship between the increase in N content and decrease in carbohydrate concentration caused by foliar urea, suggesting that part of the reserve carbohydrates was used to assimilate N from foliar urea. Regardless of the difference in tree size caused by N fertigation, the increase in the total amount of reserve N by foliar urea application was the same on a whole-tree basis, indicating that plants with low-N background were more effective in using N from urea spray than plants with high-N background.
295 The Effect of Cultivar, GA4+7, and Number of Fruit per Spur on Flower Initiation in Apple
Authors: Hoover Emily , McArtney S. , Tustin S. , White M. , Hirst P.
Published: February 2019

Experiments were initiated to document the effect of cultivar, GA4+7, and number of fruit/spur on appendage number and flower bud initiation in apple. `Pacific Rose' is strongly biennial, `Braeburn' and `Fuji' are moderately biennial, and `Royal Gala' is not biennial. In the cultivar study, buds were sampled every 18 days starting at 50 days after full bloom and continuing through until leaf fall to determine the rate of appendage formation and appendage number in relation to doming. Because of the tendency for `Pacific Rose' to exhibit biennial bearing, the rate of appendage formation and the timing of doming were compared on nonfruiting trees, trees carrying a commercial crop, and trees sprayed with 300 PPM GA4+7 applied 14 days after full bloom. Number of appendages for the treatments were similar up to 100 days after full bloom. Presence of fruit on a spur has been demonstrated to inhibit flowering of apple. Spurs of `Pacific Rose', `Splendor', and `Royal Gala' were labeled with zero, one, two, and three fruit per spur and sampled three times during the season. As buds were harvested to count appendage number, the number of fruit per spur and the number of total seeds per spur were recorded. Correlation between number of seeds per spur and rate of appendage formation were done.
298 Root Restriction and Fertilizer Effects on Young Peach Trees
Authors: Daw T. , Tworkoski T.J. , Glenn D.M.
Published: February 2019

Shoot growth of peach trees can be managed by manipulating edaphic conditions such as root volume and soil fertility. In this experiment, 2-year-old peach trees (Prunus persica L. cv. Sentry on `Lovell' rootstock) were planted in pots with a split root design, so that half the roots were not treated and the other half received one of four treatments: root volume restricted with polypropylene nonwoven fabric (FAB), fertilizer alone (FER), FAB + FER, and untreated control (UTC). Total shoot growth and root growth were measured, and root growth in the split halves was compared. FER increased leaf number and weight by 48% and 60%, respectively, but not stem growth. Leaf nitrogen concentration and photosynthesis were greatest in FER treatment. FAB did not affect shoot weight or reduce total root weight or length, although roots did not grow past the fabric barrier. FER increased root weight and length (116% and 57%, respectively, compared to UTC) on the treated half but did not affect root growth on the untreated half. Greatest root growth occurred in the root half that received FAB + FER, particularly in the 5-cm soil segment proximal to the fabric (4.6 cm•cm-3 compared to 0.8 cm.cm-3 in UTC). Shoot length was greater in FAB + FER than FAB. Thus, fertilizer applied near fabric increased root growth and the combination of fertilizer and fabric may be used to regulate shoot growth. Specific root length (root length per gram dry weight) was highest in trees with no treatment, suggesting root acclimation to low nutrient soil conditions. Lower specific root length resulted in soils that were fertilized. The results indicate that nonwoven fabric restricts root growth in peach trees and reduces shoot elongation. The combined effect of fabric plus selected application of fertilizer may be used to regulate growth of peach trees.
299 Response of Mature Peach Trees to Grass Competition
Authors: Tworkoski T.J. , Glenn D.M.
Published: February 2019

Peach tree size has been restricted when trees were grown continuously with grass after tree planting. However, control of excess vegetative growth of fruit trees was inconsistent when grass was planted beneath mature trees. This research determined the effect of seven grasses on growth, leaf nitrogen concentration, and yield of 8-year-old peach trees and on weed abundance. Two cultivars (`Loring' and `Redhaven') of peach [Prunus persica (L.) Batsch] trees were planted in separate orchards in 1987 in a split-plot design with grass as a main effect and time as the subplot. Nine treatments were installed as ground covers beneath peach trees in 1995: Festuca arundinacea, Lolium perenne var Manhattan II; L. perenne var. Linn; Agrostis gigantea, Dactylis glomerata, Phleum pratense, Bromus carintus, weedy control, and herbicide control (simazine, glyphosate). In general, grasses reduced vegetative growth and yield in `Loring' and `Redhaven'. For example, compared to herbicide treatments, orchardgrass reduced sprout length by 27% in `Loring' and by 15% in `Redhaven'. Fruit-bearing branch length was reduced with orchardgrass by 30% in `Loring' and 19% in `Redhaven'. Orchardgrass affected fruit yield more than vegetative growth, reducing yield by 37% and 24% in `Loring' (predominantly in the 2- to 2.5-inch size class) and `Redhaven' (predominantly in the >2.5-inch size class), respectively. All grasses were not equally competitive, `Linn' perennial ryegrass never significantly affected growth or yield. Weedy treatments also did not differ from herbicide treatments in peach tree growth and yield. Grasses and weeds consistently reduced peach tree leaf nitrogen by 17% compared to herbicide treatment, but weed density was not correlated with reductions in yield and vegetative growth. The results indicate that peach cultivars respond differently to grass competition but the relative competitiveness of grass species was similar for both cultivars. Grass competition can reduce growth of mature peach trees but this reduction did not translate to reduced pruning time per tree.
306 Implications for Biogenic Hydrocarbon Inventory Development from Leafmass Measurements of Urban Trees
Authors: Karlik John F. , Winer Arthur M.
Published: February 2019

More than 70 biogenic hydrocarbon (BHC) compounds are known to be emitted by plants, but only a few are emitted in relatively large quantities. The magnitude of BHC emissions from individual trees is affected by ambient light and temperature, species-specific emissions rates, and leafmass. Like other volatile organic compounds (VOC), BHC emissions react with oxides of nitrogen (NOx) to form ozone and, thus, can contribute to urban air pollution. On average, BHC emissions are as reactive or more reactive than the VOC emissions from automobiles and can have higher ozone-forming potential. An accurate estimate of the overall magnitude of BHC contributions is important in formulating strategies to reduce peak ozone concentrations because an effective strategy will take into account the relative strengths of NOx and VOC emissions. The choice between NOx and VOC controls is crucial since an incorrect emphasis may result in non-attainment of ozone-reduction goals and control measures for either NOx or VOC involve enormous costs. As part of a program to develop a reliable BHC emission inventory for the Central Valley of California, a quantitative investigation of the leafmass of urban trees was conducted. Twenty-one trees in Bakersfield, Calif., were harvested and leaves removed, dried, and weighed. Leaf masses per tree ranged from 1.5 to 89.6 kg. Leaf mass densities (dry leaf mass per area of crown projection) ranged from 150 to 3200 g·m-2, as much as eight times greater than leaf mass densities for deciduous forests and more than twice those for coniferous forests. These data suggest the BHC contributions of urban trees may be underestimated if their foliar masses are calculated using forest-based leaf mass density data.
312 Composition of Leafy Greens as Affected by Season and Conventional or Organic Fertilization
Authors: Gent Martin P.N.
Published: February 2019

Nutrient availability may depend on method of fertilization particularly when the root medium is cool. The salad greens, arugula, lettuce, and spinach, were grown in spring, fall, and winter using organic or conventional fertilization to test this hypothesis. Field plots were mineral soil fertilized with 10N-10P-10K, or soil was amended with leaf compost and cotton-seed meal. Unheated high-tunnel plantings plots contained either perlite fertilized with a complete soluble fertilizer or a 1 leaf compost: 1 perlite mixture fertilized with cotton-seed meal. There was no consistent difference in growth due to the method of fertilization, either in the field or in high tunnels. Over all plantings in field and high-tunnel plots, concentrations of nitrogen and phosphorus were higher in leaves of plants grown with leaf compost. The time of year did not affect the difference in composition between plants grown in compost and perlite in a manner that could be related to the environment or rate of growth. Although relative growth rates were only 5% per day in high tunnels in winter compared to 10% to 18% per day in other seasons, the difference in reduced nitrogen among plants grown in compost and perlite was similar in winter and summer. The changes in composition due to method of fertilization were similar in all three plant species under study.
328 Long-term Impact of Cold Damage on Physiological Performance and Yield Efficiency in Red Raspberry
Authors: Chen Chuhe , Klauer Stephen F. , Cameron J. Scott
Published: February 2019

Two test sites pairing perennially cold-damaged portions of fields vs. controls for a 3rd year were assessed. Winter 1997-1998 was very mild and produced less winter injury than the previous winters. We evaluated continued recovery of the raspberry canopy and cane productivity. In contrast to the last 2 years, the previously cold-damaged plots did not show higher levels of cane dieback, percentage of cane dieback, number of dead or dormant buds per cane, and percentage of dead buds at either site. Very few secondary laterals were produced at either site, which supports previous observations that raspberry compensates for winter injury with increased production of secondary laterals. For the first time, the damaged plots actually produced higher yields mainly through a significantly increased berry number per cane at both sites. Floricane leaves in the damaged plots showed higher photosynthetic rates at the green fruit stage and after harvest at site 2. Cane size was similar across sites, although the previously cold-damaged plants had higher berry numbers per lateral. It seems the newly recovered plants in the previously damaged plots had a renewed vigor, working harder to achieve a higher yield. No differences between treatments was detected in leaf nitrogen for a third year, suggesting this may not be a factor in winter injury here. A high population of weevils was observed at one injured site, suggesting a possible interaction with cold damage.
542 Influence of Sowing Time and Temperature on Growth and Flowering of Platycodon grandiflorus (Jacq.) A. DC. `Sentimental Blue'
Authors: Zhang Donglin , Armitage A.M. , Affolter J.M. , Dirr M.A.
Published: February 2019

Platycodon grandiflorus (Jacq.) A. DC. `Sentimental Blue' can be used as a pot plant and garden perennial. Plants can be grown year-round in a greenhouse as cutting flowers if supplemental heat is provided in the winter. Sowing time did not affect plant growth and flowering. Seeds took 10 to 20 days to germinate at 20–25 °C day/15–20 °C night temperatures. As the day/night temperature decreased, time to germination increased and germination rate decreased. Temperature also influenced shoot proliferation and number of basal branches increased as temperature decreased. Plants reached reproductive growth about 20 days after transplanting and took another 20 days to reach full bloom. Open flowers lasted 3–7 days. Cold treatment was not necessary for flowering, but plants were forced into dormancy when provided with 5 °C for 4 or more weeks. Plants began to emerge 2 to 3 months later and two growth forms, “rosette” and “dwarf”, occurred in the second growth cycle. The dwarf form produced one or two stems with six to eight clustered flowers per stem while the rosette form produced an average of 10 stems with one or two flower per stem. For the “rosette” form, each stem could be divided as a new plant.
544 Photoperiod and Juvenility Affect Campanula and Lupinus Flowering Response and Cut Stem Quality
Authors: Cavins Todd J. , Dole John M.
Published: February 2019

Campanula medium L. `Champion Blue' (CB) and `Champion Pink' (CP) and Lupinus hartwegii Lindl. `Bright Gems' (LH) were grown in 8- or 16-h initial photoperiods, transplanted when two–three, five–six, or eight–nine nodes developed and placed under 8-, 12-, or 16-h final photoperiods. Greatest flowering percentage (100%) for CB and CP occurred when plants with two–three nodes were grown in the 16-h final photoperiod. The lowest flowering percentage for CB (3.3%) and CP (15.7%) resulted from plants grown in the 8-h photoperiod continuously (initial and final). CB and CP stem lengths (49.8 cm) were longest when grown in the 8-h photoperiod continuously and shortest with the 16-h initial and 8-h final photoperiods for CB (26.5 cm) and the 16-h photoperiod continuously for CP (25.4 cm). Fewest days to anthesis, 134 days for CB and 145 days for CP, resulted from the 16-h photoperiod continuously and greatest (216 days) from the 8-h photoperiod continuously. LH plants had a high flowering percentage (99.6%) regardless of photoperiod or transplant stage. Stem lengths were longest (60.1 cm) for LH plants exposed to the 16-h photoperiod continuously and shortest (46.2 cm) when exposed to the 8-h photoperiod continuously. LH exhibited a curvilinear response for days to anthesis with the 16-h final photoperiod producing the shortest crop time (166 days) and the 12-h final photoperiod producing the longest crop time (182 days). The experiment was repeated in 1998/1999 with high intensity discharge (HID) lighting during the initial photoperiod which increased plant quality.
584 The Effects of IBA Hormone Concentration, Cutting Type, and Media on Rooting of Local Hazelnut Cuttings
Authors: Talaie A , Nejatie M.R.
Published: February 2019

This work was conducted for the purpose of propagation of hazelnut cuttings, using hard-, semi-hard-, and softwood cuttings produced from 1-year-old suckers of local varieties of hazelnuts from the Alamout-Qazvin area of Iran. The research was carried out in a greenhouse with a mist system at the Faculty of Agriculture of Tarbiat Modarres University. This experiment was based on the complete randomized-block design with a factorial framework and resulted in two levels of 5% + 1% according to the Duncan test. The effect of rooting media (sand and pumice), cutting type (hard-, semi-hard-, and softwood), and use of a hormone with five concentrations (control, 1500, 3000, 4500, and 6000 ppm IBA) were investigated. The cuttings, being wounded and treated with hormones on certain beds, were kept in a greenhouse with a mist system. After 4 months, the number of rooted cuttings, mean number of roots per rooted cuttings, total length of roots, mean length of one root, average of dry weights, and average of young shoots were evaluated. The results indicate that the rooting medium and hormone are considerably effective for rooting of the cuttings and is considered as a significant facture. The general conclusion is that the most favorable result is reached with pumice and 4500 ppp IBA. The interaction between rooting medium and hormone on the rooting process was significant, and finally, it was found that there is not a significant relation between callusing and rooting in hazelnut. Also, the wounding is an effective factor for rooting of hazelnut cuttings.
589 Summer Pruning Effects on Leaf and Whole Canopy Gas Exchange in Apple Trees
Authors: Li Kuo-Tan , Lakso Alan N.
Published: February 2019

Summer pruning is primarily used in apples to increase the light penetration into inner canopy to improve fruit color. However, summer pruning may reduce fruit size. We hypothesize that removing healthy exterior shoots reduces the whole-tree carbon supply in relation to pruning severity. If the crop load (i.e., demand) is high, fruit size and quality will be reduced. The effects of summer pruning on photosynthetic activity and recovery of shaded leaves after re-exposure were monitored on a range of exposures in canopies of `Empire' apple trees. The photosynthetic ability of leaves was positively related to its prepruning exposure. There was little recovery of photosynthetic activity of shade leaves until late growing season, indicating the re-exposure of shade leaves after summer pruning cannot replace the role of exterior leaves removed by pruning. Whole canopy net CO2 exchange (NCER) was measured on `Empire'/M9 trees with a commercial range of pruning severity. Reductions in NCER were approximately proportional to pruning severity and % leaf area removed and were as great as 60% in the most severe pruning. Canopy light interception decreased slightly. The effects on canopy NCER thus appeared to be primarily related to reduced photosynthetic efficiency and secondarily to reduced light interception.
591 Potential Use of Infrared Thermometry for the Detection of Water Stress on Apple Trees
Authors: Giuliani Rita , Flore James A.
Published: February 2019

Infrared thermometry was applied to estimate the canopy temperature of apple trees with the aim to detect a water stress condition early by remote sensing. The measurements were taken in Michigan during Summer 1998 in a 4-year-old apple orchard. Digital thermo-images of the canopy were taken using a IR imaging radiometer on well-watered trees and trees in a water shortage condition. The images were taken considering the geometrical relationship among camera position, canopy, and sun position. During the measurements, environmental (air and soil) conditions were also monitored. A software program was developed to analyze the thermal data, to show the thermal frequency distribution and to estimate the statistical parameters, which are able to represent the physiological condition of the trees. An increase of the canopy surface temperature (connected to the partial stomatal closure that is affecting the leaf energy balance) was detected early in the non-irrigated plants, compared to the well-irrigated trees, already when physiological responses as photosynthetic activity and fruit growth were not yet negatively affected by water deficit. The study confirms that there are the theoretical basis to use infrared thermometry and digital image processing to early detect the water stress on fruit trees.
616 Rootstock, Strain, Ground, and Fertigated Nitrogen Effects on Tree Growth and Development, Nutrition, and Fruit Quality of `Fuji' Apple
Authors: Fallahi Esmaeil , Chun Ik-Jo
Published: February 2019

Effects of rootstock and ground and fertigated applied nitrogen on productivity and fruit quality of `Fuji' apple was studied. In the fertigation portion of this project, treatments were as follows: 1) 22.4 kg N/ha per year, 2) 89.7 kg N/ha per year, 3) 89.7 kg N/ha per year plus 78.5 kg K/ha per year; 4) 156.9 kg N/ha per year; 5) 156.9 kg N/ha per year plus 78.5 kg K/ha per year. Fruit had optimum quality when leaf N concentrations were approximately between 1.9% to 2.15% dwt during light-cropping years and approximately between 2.12% to 2.40% during heavy-cropping years. Cross-sectional areas of `Nagafu-6 Fuji' trees were slightly smaller than those in `BC-2 Fuji' trees. Preliminary data also showed that mineral concentrations of leaves from various strains of `Fuji' do not significantly vary. In 1998, trees from 22.4 kg N/ha zone had lower leaf N, resulting in lower leaf area and lower photosynthesis but better fruit color than those with higher N applications. In 1998, trees on Ottawa-3 had higher yield than those on B.9, M.26, and M.7. Trees on B9 had lower leaf N and smaller fruit than those on other rootstocks. Fruit on M.7 rootstock were larger, but had the worst color among all rootstocks. Fruit on M.9 had better color than those other rootstocks. Trees with 2.43-m in-row spacing had significantly higher photosynthesis than those of 1.22-m spacing.
631 Interaction of Genotype and Temperature on the Floral Initiation of Pelargonium ×domesticum
Authors: Anderson Laurel L. , Wakefield Laura M.
Published: February 2019

Pelargonium ×domesticum has great potential as a flowering potted plant. Low-temperature requirements for floral initiation create an obstacle for mass production, and precise temperature requirements for floral initiation vary among cultivars. Our objective was to determine optimum temperature for floral initiation of six cultivars: Dandy, Debutante, Empress, Enchantment, Imperial, and Rapture. Four complete experiments were conducted at 1-month intervals beginning Oct. 1998. In each experiment, 120 culture-virus-indexed rooted cuttings were obtained commercially and planted into 15-cm plastic pots. After 1 week, terminals were removed and plants were allowed to grow for an additional 3 weeks. Plants then were subjected to three floral initiation treatments at 12, 15, and 18° C for 4 weeks under 16-h photoperiods in growth chambers. A control group was initiated in the greenhouse. Following initiation treatments, all plants were finished under standard greenhouse conditions, supplemented with HID light. On flowering, plants were evaluated for time to anthesis, number and size of inflorescences, and overall plant quality. The 15° C treatment consistently produced the highest quality plants, while the 12° C treatment scored lowest with regard to flowering and overall quality. Differences among the cultivars were observed for time to anthesis. `Imperial' and `Rapture' flowered earliest, followed by `Enchantment' and `Empress', with `Dandy' and `Debutante' requiring the most time.
632 Introduction to the Colloquium Genetic Stability of Transgenes under Field Conditions
Authors: Grosser Jude W.
Published: February 2019

The genetic engineering of horticultural crops to improve disease/insect resistance, cultivar quality, or other characteristics has become a primary area of focus for many research programs. The technique is attractive because a single beneficial trait can be added to an already successful cultivar without otherwise altering cultivar integrity. However, little information has been available regarding the performance of such transgenic plants in the field, particularly regarding woody perennial crops. The purpose of this colloquium is to provide the latest available information regarding the performance of transgenic plants in the field, covering a wide range of crops including vegetables, woody fruit trees, woody nut trees, and forest trees. Focus will be on the long-term expression of transgenes and promoter efficiency. The information provided should be particularly useful to researchers who are currently designing or performing experiments to improve horticultural crops by genetic engineering.
641 Consumer Demand for Organic Foods
Authors: Thompson Gary
Published: February 2019

Sales of organic foods at retail have grown at rates from 20% to 35% in many countries throughout Europe, Asia, and the Americas during the 1990s. Yet market shares of organic foods remain quite small, less than 5%of retail value in all countries throughout the world. As mainstream retail outlets have begun to carry and promote organic foods, lack of availability of organic foods has become less of an impediment to consumer demand. The major impediment to continued growth in organic food demand is high price premiums for organic foods over conventional food counterparts. Some of the highest price premiums at retail are displayed by fresh and frozen vegetables and fruit; premiums as high as 250% for frozen green peas in the United States have been recorded. Indirect evidence in the form willingness-to-pay studies and retail pricing experiments indicate that the majority of consumers will not pay such high price premiums for organic fruit and vegetables. Small market shares at retail tend to corroborate consumers' willingness to pay such high prices. How much prices of organic fruit and vegetables would have to be reduced relative to conventional produce in order to increase market shares of organic produce is not clear.
646 Applications of Site-Specific Management for Tree Fruit Production
Authors: Righetti Tim
Published: February 2019

Our efforts are concentrated on quantifying spatial variability for tree vigor, yield, fruit quality, and profit. We use aerial photography to quantify tree vigor. For mechanically harvested hazelnuts, a prototype weight based yield monitor has been evaluated. This approach may also work for quantifying yield in mechanically harvested sweet cherries. For perishable hand-harvested crops, the GPS locations for individual bar-coded bins can be used to calculate bin density and estimate yield. Bar codes can also be used to track quality in the packing-house. Since profit depends on yield, size, and packout, it is not always intuitively obvious which areas of an orchard are most profitable. Defining which areas are most profitable, and identifying the problems associated with low-profit areas (poor yield, small size, storage loss, bruising, culls, etc) is an important step. Identifying areas producing fruit that stores poorly is a high priority. An evaluation of low- and high-profit areas may lead to alternate management plans. Anything from investing in more supervision of harvest labor and initiating different pruning regimes to attempts to obtain more uniform tree vigor can be evaluated. By delineating test areas with GPS boundaries, profit data in future years can quantify the success of different management approaches. For example, concentrating expensive inputs on the portion of trees (30% of total) that may produce the majority of gross returns, while not even harvesting fruit from regions (1% to 5% of total) that consistently produce poor quality fruit may be a sound strategy.
648 Practical Applications of Site-specific Management—An Industry Perspective
Authors: LeBoeuf John
Published: February 2019

The initial surge of interest in precision agriculture technologies exhibited by innovators and early adopters involved in crop production appears to have crossed over an important threshold and made a significant development. As valuable field experience increases and learning by doing advances, successful applications of management practices are being identified. Access to accurate information pertaining to practical applications of site-specific management would be expected to motivate more producers to incorporate technology uses with crop production. This next group of producers has been watching technology developments as they preferred to avoid risk and wait for identifiable benefits. Waiting for detailed case studies involving high value fruit and vegetables may be the wrong approach to take. Fierce competition and strict confidentiality are expected, especially in the fresh-market industry that places quality attributes high on the list of desired features. Practical applications of technology that pertain to manageable factors will be the impetus to implementation of site-specific management. High resolution remote sensing imagery from digital aerial and satellite sensors has been used to identify plant stress, direct plant tissue and soil sampling efforts to identifiable soil variability, and provide valuable information for analysis and interpretation of crop growth. Examples of remote sensing imagery that has provided valuable in season progress reports will be identified. Imagery can then be used in a geographic information system along with field maps based on soil properties and physical characteristics determined by on-the-go tractors using various sensors. The focus will be on practice, not theory, as seen from an industry perspective.
651 Important Genes that Have Been Transferred or Are Available for Transfer
Authors: Tricoli D.M. , Carney K.J. , Nea L.J. , Palys J.M. , Reynolds J.F. , Green C.E.
Published: February 2019

Many seed companies are using plant biotechnology as a valuable extension of conventional plant breeding with the goal of providing breeders with novel biological traits. The application of biotechnology allows scientists and breeders to make precise changes during the process of germplasm improvement. Many of the first improvements achieved using transgenic plants have involved the transfer of input traits. Some of these traits include, insect resistance, nematode resistance, disease resistance, and herbicide tolerance. For example, the insertion of a gene that produces the crystalline toxin from Bacillus thuringeinsis has led to the production of transgenic plants that are resistant to insects from the Order Lepidoptera. The transfer of coat protein genes from plant viruses has lead to the development of transgenic crops that are resistant to the virus from which the gene or genes were isolated. Various strategies have been developed that allow transgenic plants to tolerate applications of herbicides that allows for improved weed control. In addition to input traits, other strategies are now being used that are directed at improving output traits. These include such traits as enhanced shelf life, ripening control, altered oils, and superior processing characteristics. At Seminis Vegetable Seed Co., we are currently developing transgenic plants with enhanced input as well as output traits. We have an active program using pathogen derived genes to develop virus resistance cultivars in a range of crops including, tomato, cucurbits, and peppers. Using this approach, we have been able to develop plants with multiple virus resistance by transforming germplasm with constructs containing stacked genes. Seminis is currently marketing a hybrid squash variety with resistance to two major virus pathogens. Another major goal for Seminis is implementing biotechnology to improve various aspects of fruit quality including viscosity, color, softening, and shelf life. Through our collaboration with Zeneca we have developed a high viscosity tomato, which was produced by suppressing endogenous levels of polyglacturonase. This processed food product is currently on the market in the United Kingdom.
Pruning and Training Affect Yield but Not Machine Harvest Efficiency of `Meeker' Red Raspberry
Authors: Strik Bernadine C. , Cahn Helen K.
Published: February 2019

`Meeker' red raspberry (Rubus idaeus L.) cane densities of 5, 10, or 15 canes/hill in a hill system, with canes topped at 2 m or the entire cane length retained and looped, were compared with a 15- or 30-cm-wide hedgerow with canes topped at 2 m from 1995 to 1997. Cane density among all treatments ranged from 2.2 to 9.9 canes/m2 during the study. Plots were harvested by machine every 2 days. Within the hill system, total yield increased with cane density in all years. Looped treatments produced a higher yield/plot than did topped ones in all years except 1996, when the yield difference was insignificant because looped canes had greater winter injury. Weight per fruit ranged from 5.4% to 9.7% less on looped than on topped canes. Hedgerow systems had a lower yield than hill systems in 1996, but a higher yield in 1997. Losses due to machine harvest were not affected by pruning (cane density or topping) or production system (hill system or hedgerow) and averaged 16.2% of total yield in 1997. Thirty-five percent of the loss due to machine harvest occurred between harvests.
Winter Greenhouse Strawberry Production Using Conditioned Plug Plants
Authors: Durner Edward F.
Published: February 2019

Two- to three-week-old `Sweet Charlie' strawberry (Fragaria ×ananassa Duch.) plug plants were conditioned [seven 9-hour short days without chilling (21 °C day/21 °C night) followed by seven 9-hour short days with chilling during the nyctoperiod (21 °C/12 °C night)] in September, then planted in a vertical hydroponic system for winter greenhouse production. Conditioned plugs produced significantly more fruit than did nonconditioned control plugs in January and February, but the difference was nonsignificant in March and April. Fruit yield increased linearly with height in the column (≈40 g/plant for every 30-cm increase in column height), probably because of increasing light level. When productivity is considered on an area basis (kg·m–2) and the column height effect on yield is accounted for, productivity over a 4.5-month period was 4.8 kg·m–2 for controls and 7.8 kg·m–2 for conditioned plugs. Conditioned plug plants offer the potential for increasing strawberry productivity and therefore the profitability of a winter greenhouse production system.