bluuebunny/crossref_metadata_2025 huggingface dataset:
Pollen Competition Improves Performance and Reproductive Output of the Common Zucchini Squash Under Field Conditions
Authors: Davis Lynette E. , Stephenson Andrew G. , Winsor Janies A.
Published: August 2022

The objective of this study was to examine the effects of pollen competition on offspring quality in the common zucchini squash (Cucurbita pepo L.). In a controlled field study, we compared the performance of seeds that were produced under conditions of pollen competition (high pollen loads) to seeds produced under conditions of little or no pollen competition (low pollen loads). We found that seeds from high pollen loads were more likely to emerge and emerge more rapidly than seeds from low pollen loads. The high pollen load seedlings also tended to produce more flowers and fruits than the low pollen load seedlings. On a per-plant basis, the high pollen load progeny had significantly greater fruit volume, seed numbers, and total seed weight than the low pollen load progeny. We conclude that in zucchini, seeds produced under conditions of pollen competition are “superior” to seeds produced when pollen competition is minimal or absent. The significance of these results is considered in light of a previous study revealing nonrandom patterns of fruit abortion in this species.
Effect of Polyethylene Mulches, Irrigation Method, and Row Covers on Soil and Air Temperature and Yield of Muskmelon
Authors: Bonanno A. Richard , Lamont William J.
Published: August 2022

Field studies were conducted in 1984 and 1985 to document the effects of plastic mulches and row covers on soil and air temperatures and yield of muskmelons (Cucumis melo L.) in North Carolina. Treatments included bare ground, black plastic, and clear plastic, each with and without a slitted clear plastic row cover. In addition, both trickle and overhead sprinkler irrigation were evaluated. Soil temperatures were increased by plastic mulches, with clear polyethylene resulting in the highest soil temperatures. Air temperatures were increased by row covers. In 1984, total and early yields were increased over bare ground plots with the use of either clear or black polyethylene mulches. Row covers did not influence yields. In 1985, a warmer year than 1984, no total yield increases resulted from use of either row covers or mulches; however, row covers and clear plastic mulch increased early yield. Trickle irrigation used less water than did overhead irrigation, but did not increase yields.
Effects of Planting Densities, Irrigation, and Hornworm Larvae on Yields in Experimental Intercrops of Tomatoes and Cucumbers
Authors: Schultz Brian , McGuinness Hugh , Horwith Bruce , Vandermeer John , Phillips Cruz , Perfecto Ivett , Rosset Peter , Ambrose Robert , Hansen Michael
Published: August 2022

In experiments conducted near Ann Arbor, Mich. in 1981 and 1982, yield responses of intercrops of tomatoes (Lycopersicon esculentum Mill.) and cucumbers (Cucumis sativus L.) were compared to monocultures of each crop with respect to several variables affecting yields. In 1981, the effects of two levels of irrigation (irrigation and no irrigation) and three levels of artificially manipulated numbers of hornworm (Manduca spp.) larvae were compared in intercrops and monocultural controls planted at three different cucumber densities and one tomato density. In 1982, two levels of irrigation were compared across two densities of cucumbers and two densities of tomatoes. Intercrops of tomatoes and cucumbers showed relatively greater increases in yields than monocultures when water availability was greatest and at higher levels of pest (hornworm) attack. Irrigation seemed to relax competition between crop species, and cucumbers may have compensated for tomato defoliation by hornworms.
Restricted Root Zone Volume: Influence on Growth and Development of Tomato
Authors: Ruff Miriam S. , Krizek Donald T. , Mirecki Roman M. , Inouye David W.
Published: August 2022

‘Better Bush’ tomato (Lycopersicon esculentum Mill.) plants were grown in small- (450-cm3) or large-(13,500-cm3) volume plastic containers and harvested every 2 weeks from time of planting until 12 weeks, at which time ripe fruits had developed. Plants were fertilized three to six times daily to prevent drought and nutrient stress. After only 2 weeks, there were significant reductions in total height, node number, leaf area, and dry weight of leaves. By 4 weeks, dry weights of stems and roots were also significantly less in small pots than in large pots. These differences were maintained for the next 10 weeks. Root restriction also generally caused an increase in root : shoot ratio. Roots in small-volume containers formed a highly branched mat, whereas those in large-volume containers had long taproots and showed little branching. Root restriction also significantly reduced the total number and fresh and dry weight of mature fruits. Despite these differences, both groups of plants had nearly 41% of the total photosynthate in the reproductive portion of the plant after 12 weeks of treatment. During weeks 6–8, the mean relative growth rate of plants in small pots was twice that in large pots but thereafter was only half as much. Restricting root volume had little or no effect on net assimilation rate. These data suggest that, for a given growing area, a culture system using small containers would be more efficient in producing fruit for a given weight and size of plant than one using large containers. These findings have important implications for growers and researchers involved in growing plants in confined spaces such as in a phytotron or controlled ecological life support system (CELSS).
Ca2+ in Cell Walls of Ripening Tomato and Peach
Authors: Burns Jacqueline K. , Pressey Russell
Published: August 2022

Ca2+ content in cell wall-middle lamella (CW–ML) areas of outer and inner pericarp, placenta, and gel parenchyma of ripening tomato (Lycopersicon esculentum Mill. cvs. Celebrity and Jumbo) and mesocarp of ripening peach [Prunus persica (L.) Batsch cv. Georgia Belle] was determined by energy dispersive (EDS) X-ray microanalysis. Ca2+ increased from 1.50 to 6.95 mg·g–1 dry weight in CW–ML of outer pericarp and 0.98 to 2.60 mg·g–1 dry weight in CW–ML of inner pericarp during ripening. Ca2+ content remained constant in tomato placenta and peach mesocarp, and was undetectable in tomato gel parenchyma throughout ripening. CW–ML of peach mesocarp had lower Ca2+ content than tomato pericarp and placenta at all ripening stages, but total peach uronic acid content was 2.5 times greater. Pectin methylesterase (PME) activity increased in tomato pericarp as fruit ripened, but remained low and unchanged in placenta and gel parenchyma. PME treatment of pericarp increased amounts of CW–ML Ca2+ in the breaker stage but not in the green mature stage. The results indicate that increased amounts of Ca2+ are bound to CW–ML of tomato pericarp as ripening occurs but not in placenta or peach mesocarp. Pectin deesterification and wall softening during ripening may in part be factors that control the presence and amount of CW–ML Ca2+.
Vitamins C, B1, and B2 Contents of Stored Fruits and Vegetables as Determined by High Performance Liquid Chromatography
Authors: Watada Alley E. , Tran Tony T.
Published: August 2022

A high performance liquid chromatography (HPLC) method was developed for analyzing vitamin B1, and the method was used with other HPLC methods to monitor vitamins C, B1, and B2 of fresh fruits and vegetables stored at different temperatures. Ascorbic acid content of most commodities either dropped after being placed in storage or decreased during storage. Thiamine increased during storage of ‘Tendergreen’ beans and decreased in ‘BelRus’ potatoes; whereas riboflavin decreased in ‘Tendergreen’ beans and increased in ‘Superior’ potatoes. The changes in other cultivars or commodities were not significant.
Changes in Tannin Cell Morphology with Growth and Development of Japanese Persimmon Fruit
Authors: Yonemori Keizo , Matsushima Jiro
Published: August 2022

Morphological changes in tannin cells were observed in ‘Fuyu’ [pollination-constant and nonastringent (PCNA)] and ‘Hiratanenashi’ [pollination-variant and astringent (PVA)], two of the four types of Japanese persimmon fruit (Diospyros kaki L.). Pores in the tannin cell walls of ‘Fuyu’ started to occlude on 24 July when cell enlargement had ceased. This occlusion coincided with cessation of tannin accumulation, as determined by soluble tannin content and fresh weight of fruit. The pores were almost completely occluded on 7 Aug. Pore occlusion preceded the coagulation of tannins. In ‘Hiratanenashi’, pores in the tannin cell walls expanded until 7 Aug. When enlargement of tannin cells ceased on 14 Aug., occlusion of the pores in the cell walls was initiated. This event also nearly coincided with cessation of tannin accumulation. The process of occlusion was much slower than in ‘Fuyu’ and was about complete on 16 Oct. Thus, the pores in the tannin cell walls appear to be involved in tannin accumulation.
In Vitro Propagation of Dry Bean from Seedling Shoot Tips
Authors: Saam Mary M. , Hosfield G.L. , Saunders J.W.
Published: August 2022

A protocol for in vitro propagation was developed with two dry bean (Phaseolus vulgaris L.) cultivars. Shoot cultures were initiated by placing seedling shoot tips (1.0 to 1.5 cm) on Murashige and Skoog (MS) medium in which the effects of kinetin and BA alone or in combination with IAA or NAA were examined with regard to shoot multiplication and root or basal callus formation. The combination of BA (3.0 mg liter–1) and NAA (0.1 mg·liter–1) was most effective in shoot multiplication. At high concentrations of BA or kinetin (>10 mg·liter–1), shoot production and internode elongation decreased markedly and rosette-like cultures with multiple buds developed. Shoots were rooted on basal MS medium. Ramets grew to maturity in the greenhouse or field and produced fertile flowers, pods, and seeds. Chemical names used: N-(2-furanylmethyl)-1H-purin-6-amine (kinetin); N-(phenylmethyl)-1H-purin-6-amine (BA); 1H-indole-3-acetic acid (IAA); 1-naphthaleneacetic acid (NAA).
Interspecific Differences in the Percentage of Anthocyanins, Aglycones, and Aglycone-sugars in the Fruit of Seven Species of Blueberries
Authors: Ballington J.R. , Ballinger W.E. , Maness E.P.
Published: August 2022

HPLC analysis of seven blueberry species, V. ashei Read (2n = 6x = 72), V. constablaei Gray (2n = 6x = 72), V. corymbosum L. (2n = 2X = 24 and 2n = 4X = 48), V. elliotti Chap. (2n = 2X = 24), V. pallidum Ait. (2n = 2X 24 and 2n = 4X = 48), V. simulatum Small (2n = 4X = 48), and V. tenellum Ait. (2n = 2X = 24), identified the 3-monoarabinosides, 3-monogalactosides, and 3-monoglucosides of cyanidin, delphinidin, malvidin, peonidin, and petunidin in each species. Differences in relative percent of individual anthocyanins in some instances were useful in distinguishing among both species and ploidy levels. Differences in percent aglycones were also useful in distinguishing among species. Evidence presented does not support grouping V. elliotti, V. simulatum, and V. constablaei into a single “highbush” species (i.e., V. corymbosum). Percent cyanidin-3-galactoside appeared useful in distinguishing ploidy levels in V. pallidum and between 4X V. pallidum and the “palloid” phase of V. constablaei (6X).
Anthocyanin Content of Fruit, Stem, Tendril, Leaf, and Leaf Petioles in Muscadine Grape
Authors: Goldy R.G. , Ballinger W.E. , Maness E.P. , Swallow W.H.
Published: August 2022

Fruit, stems, tendrils, leaves, and leaf petioles of4Noble’ muscadine grape (Vitis rotundifolia Michx.) were analyzed using high performance liquid chromatography (HPLC) techniques. All five of the known 3,5-diglucoside forms of delphinidin (Dp), cyanidin (Cy), petunidin (Pt), peonidin (Pn), and malvidin (Mv) present in fruit of muscadine grape were detected in all sampled tissues except leaves, which contained only Dp, Cy, and Pt in detectable quantities. A sixth unknown pigment was detected in the fruit, and Dp 3-monoglucoside was detected in the leaves. Correlations were calculated to explore pigment relationships between fruit and vegetative tissues. Use of tendrils was best for predicting fruit Cy (r = 0.60), Mv (r = 0.57), Pn (r = 0.66), and Pt (r = 0.87). Use of stem tissue was best for predicting fruit Dp (r = 0.66). Prediction equations are given, and prediction of Cy could be improved by using both tendril and leaf measurements in a multiple regression (r = 0.80).
Pigment Correlations Between Fruit and Vegetative Tissue in 10 Selections of Muscadine Grape
Authors: Goldy R.G. , Ballinger W.E. , Maness E.P. , Swallow W.H.
Published: August 2022

Fruit, stem, tendril, leaf, and leaf petioles of 10 selections of muscadine grape (Vitis rotundifolia Michx.) were evaluated for pigment quantity and quality using high performance liquid chromatography (HPLC). All five of the 3,5-diglucoside pigments present in the fruit were present in detectable levels in the other four tissues of at least one selection except for leaves, which lacked peonidin (Pn) in all cases. Eight selections lacked detectable quantities of malvidin (Mv) in the leaves, one lacked Pn in stems, and six lacked Pn in leaf petioles. A sixth unknown pigment was detected in the fruit of two selections, and delphinidin (Dp) 3-monoglucoside was detected in leaves of all 10 selections. Fruit to vegetative tissue correlation and significance values were calculated across genotypes, with r ranging from 0 for fruit to leaf Mv to 0.53 for fruit to leaf petiole Dp. Stepwise regression analysis determined that leaf petiole and leaf tissue measurements together could predict fruit Dp better than could leaf petiole measurements alone (R = 0.80, significant at Ρ = 0.03; and R = 0.53, significant at Ρ = 0.11, respectively), and fruit petunidin (Pt) could be predicted from leaf petiole and stem measurements better than from leaf petiole measurements alone (R = 0.68, significant at Ρ = 0.12; and R = 0.40, significant at Ρ = 0.25, respectively).
Identification of Differential Responses of Cabbage Cultivars to Copper Toxicity in Solution Culture
Authors: Rousos Penelope A. , Harrison Helen C.
Published: August 2022

Eighty-four cabbage cultivars Brassica oleracea L., Capitata group, (tested in groups of nine) were germinated and supported on a fabric-lined growing panel over Hoagland's solution (0.03 mg·liter−1 Cu++ as CuSO4) for 2 weeks and then transferred intact to treatments (1.5 and 2.0 mg·liter−1 Cu++) and control 0.03 mg·liter−1 Cu++) vats for 1 week. Based on relative growth (percent of control), ‘Wisconsin All Seasons’ was identified as more tolerant to high Cu++ levels than ‘Globe King’. The two cultivars were compared for growth and Cu concentration in roots and shoots at 0-, 2-, 4-, and 6-day intervals during exposure to Cu++ levels of 0.03, 1.5, and 2.0 mg·liter−1. Although there were no cultivar differences, Cu treatments did significantly affect root Cu concentrations. Copper uptake into the shoots of both cultivars was linear over time. However, the less-tolerant cultivar Globe King had significantly higher shoot Cu levels than the more-tolerant cultivar Wisconsin All Seasons. Although in both cultivars Cu concentrations were lower in the shoot than roots, the higher Cu concentration in the shoot of the less-tolerant cultivar Globe King may be responsible for its reduced growth.
Vegetation Management: Its Influence on Survival and Early Growth of Fraser Fir and Norway Spruce
Authors: Warren Stuart L. , Skroch Walter A. , Perry Katharine B. , Monaco Thomas J.
Published: August 2022

Seven vegetation management programs ranging from 100% cover of grass-dominated vegetation to bare soil were created on opposing north and south aspects. After 3 years, fraser fir [Abies fraseri (Pursh) Poir.] survival had decreased when grown in bare soil, compared to survival in the other management programs. Norway spruce [Picea abies (L.) Karst.] survival was not affected by the management programs. Maximum stem diameter and root growth of Norway spruce were obtained with a bare row regardless of the interrow vegetation. Root growth in fraser fir was similar to spruce, but bare soil was required for maximum stem diameter growth. Height growth in both species was affected little by treatment. Stem diameter and root growth were negatively correlated with above-ground herbaceous biomass in the row. Forbs interfered less than grasses with fraser fir and Norway spruce diameter growth. Norway spruce growth was not affected by aspect, but fraser fir was larger (height and stem diameter) on the south aspect when grown in bare soil.
High Root-zone Temperatures, Mycorrhizal Fungi, Water Relations, and Root Hydraulic Conductivity of Container-grown Woody Plants
Authors: Newman S.E. , Davies F.T.
Published: August 2022

High root-zone temperatures can stress container-grown plants and ultimately reduce nursery productivity in the southern United States. Water relations of glasshouse-grown Berberis thunbergii DC ‘Atropurpurea’ Buxus microphylla Seibold and Zucc japonica and Pittosporum tobira, (Thunb.) Ait. ‘Wheeler’ were studied under high-temperature root-stress conditions using container-grown plants that were either colonized with vesicular arbuscular mycorrhizal fungi (VAM) or noncolonized. Predawn xylem water potential in stems (ψstem) increased initially (more positive) in response to high root-zone temperatures (40° to 45°C), and then decreased over a 5-day period. Stomatal conductance (gs) and evapotranspiration (ET) were reduced incrementally over time in response to high root-zone temperatures. Root damage occurred, as indicated by reductions in root quality and gs at 35° and 40° for B. thunbergii and P. tobira, and at 40° and 45° for the more high-temperature-resistant B. microphylla. Colonization increased gs and ET of B. microphylla at ambient (25°) and high temperatures (45°) and increased ET of B. thunbergii at 25°. Colonized plants had lower (more negative) ψshoot with initial exposure to increased root-zone temperatures; however, throughout the remainder of the study period there was little reduction in plant stress with the mycorrhizal isolates used. Root hydraulic conductivity (Lp) increased markedly in B. thunbergii compared to B. microphylla at 40° and 45°, indicating less high-temperature resistance in B. thunbergii roots. Mycorrhizal colonization did not moderate hydraulic conductivity at high root-zone temperatures of 40° and 45°. Of the two species, mycorrhizal B. thunbergii had lower Lp at 25° and B. microphylla had lower Lp at 35°.
Quantum Flux Density Effects on the Anatomy and Surface Morphology of in Vitro- and in Vivo-developed Sweetgum Leaves
Authors: Lee Ni , Wetzstein Hazel Y. , Sommer Harry E.
Published: August 2022

The anatomy of in vitro- and in vivo-developed leaves of sweetgum, Liquidambar styraciflua L., grown under three quantum fluxes (PPF), was evaluated using light and scanning electron microscopy. Leaf characteristics of both in vitro- and in vivo-developed plants were modified by light: high irradiance was associated with more compact mesophyll and larger cells than low irradiance. However, when compared to plants grown in vivo under corresponding irradiance levels, all plants grown in vitro had smaller, thinner leaves and smaller mesophyll cells lacking extensive vacuolar components. Leaves developed in vitro had larger, raised stomata regardless of light level and, except at the highest irradiance, exhibited significantly greater stomatal densities than in vivo-developed leaves.
Blueberry Response to NH4-N and NO3-N
Authors: Peterson L.A. , Stang E.J. , Dana M.N.
Published: August 2022

Rooted cuttings of blueberries (Vaccinium corymbosum L.) were grown in nutrient solutions containing different levels and combinations of NH4-N and NO3-N. Disappearance rate of the two forms from the nutrient solutions as determined by periodic analysis indicated that the plants absorbed the NH4-N more rapidly than NO3-N. Although both forms produced healthy plants, the plants receiving NH4-N were twice the size and dry matter yield of the NO3 plants after 15 weeks. Shoot N concentrations ranged from 0.99% to 1.29% for the N forms except where the blueberry plants had depleted the solutions of NH4-N before termination of the experiment. The N forms had a significant affect on the concentration of other plant nutrients, notably very low concentrations of Ca and Mg in roots with NH4-N and very high concentrations of Mn and Fe in roots with NO3-N plants. Expected levels of Mn and Fe and light brown roots were found with NH4-N plants.
Electrolyte Leakage as an Indicator of High-temperature Injury to Harvested Mature Green Tomatoes
Authors: Inaba Makoto , Crandall Philip G.
Published: August 2022

Newly harvested tomatoes are often exposed to short periods of high temperatures. To simulate harvest conditions, mature green (MG) tomatoes (Lycopersicon esculentum Mill., cv. 908) were exposed to direct solar radiation until their mean temperatures became 45°, 50°, or 55°C. When fruit temperatures were > 50°, heat injury was obvious. Once exposed, tomatoes remained at these high temperatures for ≈ 1 hr, even after being transferred to shade. The interaction between high temperature and exposure time on tomato thermostability was studied in the laboratory. MG ‘908’ tomatoes were exposed to temperatures ranging from 25° to 65° for 30 to 180 min; the damage was then measured by determining the amount of electrolyte leakage. A mathematical model describing the interaction of temperature and time was used to predict the critical high temperature and exposure time. Critical exposure times calculated for ‘908’ tomatoes were 34, 105, and 166 min for exposure to 55°, 50°, and 45°, respectively. For practical field applications, this high-temperature stress may decrease the quality by causing the destruction of fruit cellular tissue and physiological disorders.
Effects of Duration of Flower and Runner Removal on Productivity of Three Photoperiodic Types of Strawberries
Authors: Pritts Marvin P. , Worden Kathleen A.
Published: August 2022

The effects of duration of strawberry (Fragaria × ananassa Duchesne) flower and runner removal on first- and second-year yields were determined for two day-neutral cultivars (‘Tribute’ and ‘Brighton’), an everbearing cultivar (‘Ozark Beauty’), and a Junebearing cultivar (‘Scott’). For ‘Tribute’ and ‘Brighton’, flower removal until 1 July of the planting year resulted in maximum first-year yields, with continued flower removal positively associated with second-year yields. There was no effect of first-year fruiting on second-year production in ‘Scott’. Runner removal resulted in decreased cumulative yields per plot for all cultivars, but the effect was greatest for ‘Scott’. Second year fruit production of ‘Brighton’, ‘Tribute’, and ‘Ozark Beauty’ was synchronous and bimodal, with differences in yield occurring only in the later peak. Treatment had no effect on the periodicity of the fruiting cycle for any cultivar. ‘Tribute’ had the highest yield of the four cultivars in both years, whereas ‘Ozark Beauty’ had the smallest 2-year cumulative yield.
A Saline Irrigation Regime for Improving Tomato Fruit Quality Without Reducing Yield
Authors: Mizrahi Y. , Taleisnik E. , Kagan-Zur V. , Zohar Y. , Offenbach R. , Matan E. , Golan R.
Published: August 2022

Tomato (Lycopersicon esculentum Mill ‘FC111’) plants were dripirrigated with two different concentrations of diluted seawater (3 or 6 dS·m−1) applied at appearance of the first true leaf (early) or at first breaker fruit (late) stages of plant development. In general, salinity improved flavor and increased percent total soluble solids and sugar concentration. It also reduced color flaws, thus improving the overall quality of fruit. Shelf life was not affected by saline treatments, whereas the yield and fruit size were generally lower than those of fruit from the control treatment. The most important findings were that the overall yield of plants irrigated with the low concentration of saline water at the late stage of development was not significantly different from that of control plants; export quality yield was the same, while fruit quality was still significantly better than that of the control. The use of saline water for quality improvement of tomato fruit grown on sand dunes under glasshouse conditions is thus feasible.
Effects of Fertilization on Stability of Yield and Yield Components of Sweet Potato Clones
Authors: Bacusmo Jose L. , Collins Wanda W. , Jones Alfred
Published: August 2022

Fourteen sweet potato [Ipomoea batatas (L.) Lam.] clones were grown in fertilized and unfertilized tests at four locations during 2 years. Significant effects of genotype-environment interactions on yield components of sweet potato were found. Yields were generally higher in fertilized than in unfertilized tests, and number of roots was higher in fertilized tests for most grades except for canners and total number of roots. Rank correlations of stability of clones in fertilized and unfertilized tests were low for all traits measured. Implications of the results on testing and selection of sweet potato are discussed.
Heritability of Tomato Early Blight Resistance Derived from Lycopersicon hirsutum P.I. 126445
Authors: Nash Allan F. , Gardner Randolph G.
Published: August 2022

Early blight resistance was estimated in field plots for parents and F1, F2, and backcross progenies of crosses with NC EBR-1, a line derived from Lycopersicon hirsutum P.I. 126445. Areas under the disease progress curve (AUDPC) showed that resistance from NC EBR-1 was heritable and quantitative in nature. generation means in two families were intermediate to those of NC EBR-1 and susceptible parents. The distribution of AUDPC means for the different generations in both families indicated the presence of epistasis or gene linkage. Lack of fitness tests for curve-linearity confirmed this in one family. A, B, and C scaling tests showed similar results. A joint three-factor model and subsequently a six-factor model displayed the presence of epistasis in both families. Ignoring epistatic effects, narrow-sense heritability (h2) was 0.49 in one family and 0.40 in the other. By regressing F3 progeny AUDPC means on selected F2 plant values, h2 was 0.25 and 0.17, respectively.
Radiation in Controlled Environments: Influence of Lamp Type and Filter Material
Authors: Bubenheim David L. , Bugbee Bruce , Salisbury Frank B.
Published: August 2022

Radiation in controlled environments was characterized using fluorescent and various high-intensity-discharge (HID) lamps, including metal halide, low-pressure sodium, and high-pressure sodium as the radiation source. The effects of water, glass, or Plexiglas filters on radiation were determined. Photosynthetic photon flux (PPF, 400 to 700 nm), spectra (400 to 1000 nm), shortwave radiation (285 to 2800 nm), and total radiation (300 to 100,000 nm) were measured, and photosynthetically active radiation (PAR, 400 to 700 nm) and longwave radiation (2800 to 100,000 nm) were calculated. Measurement of PPF alone was not an adequate characterization of the radiation environment. Total radiant flux varied among lamp types at equal PPF. HID lamps provided a lower percentage of longwave radiation than fluorescent lamps, but, when HID lamps provided PPF levels greater than that possible with fluorescent lamps, the amount of longwave radiation was high. Water was the most effective longwave radiation filter. Glass and Plexiglas similarly filtered longwave more than shortwave radiation, but transmission of nonphotosynthetic shortwave radiation was less with Plexiglas than glass. The filter materials tested would not be expected to influence photomorphogenesis because radiation in the action spectrum of phytochrome was not altered, but this may not be the only pigment involved.
Periodic and Seasonal Flooding Effects on Survival, Growth, and Stomatal Conductance of Young Rabbiteye Blueberry Plants
Authors: Crane Jonathan H. , Davies Frederick S.
Published: August 2022

The response of 2- to 3-year-old ‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade) plants to periodic flooding of different durations and seasons was studied under field conditions in 1985 and 1986. Soil redox potentials (Eh) decreased to between 0 and −300 mV within 2 days of flooding and recovered to preflood levels (200 to 300 mV) within 8 to 10 days after flooding release. Plants survived 2-day (four periods) and 7-day (two periods) spring flooding treatments, whereas losses of 17% to 100% occurred after two 2- to 15-day summer flooding episodes. Most (83%) plants survived 106 to 117 days of spring flooding, while 33% and 0% survived 78 and 90 days of summer flooding, respectively. Generally, leaf area, percent fruit set, and yields decreased after two 7-day spring flooding periods, whereas the number of flower buds formed decreased by 38% to 70% with as little as two 2-day summer flooding periods. Stomatal conductance and transpiration decreased after the onset and increased after the release of the two 2- and 7-day summer flooding treatments, but remained low for the 15-day (two periods) and 78-day treatments. The effects of periodic flooding on plant survival, stomatal conductance, and the number of flower buds formed were similar to those found for continuously flooded plants in a previous study.
Influence of Cultivars, Ground Covers, and Trickle Irrigation on Early Growth, Yield, and Cold Hardiness of Peaches on Fox Sand
Authors: Layne Richard E.C. , Tan Chin S.
Published: August 2022

Three cultivars (early, midseason, late), two ground covers (clean cultivation followed by temporary cover vs. permanent sod strips), and trickle vs. no irrigation were studied in a high-density (633 trees/ha) experimental peach orchard established in 1980 on Fox sand. Growth rate in the first 5 years was similar for all three cultivars. It was retarded up to 12% by permanent sod relative to temporary cover and enhanced up to 30% by trickle irrigation vs. no irrigation. Total marketable yields and that of large-sized fruit (>6.3 cm) were significantly influenced by cultivars in the first and second, but not the third year of production. Ground cover treatments did not influence total marketable yields, but did affect the yield of large fruit in one year. Irrigation increased total marketable yields each year and also increased the yield of large fruit. Yields were up to 30.7% higher in trickle vs. non-irrigated plots. Cold hardiness of flower buds and shoot xylem in 1982 was significantly influenced by cultivar and irrigation treatments, but not by ground cover treatments; In 1984, each of these factors affected cold hardiness. Foliation in 1984 was affected by ground cover and irrigation treatments but not by cultivars. The best treatment combination across cultivars for management of the orchard floor consisted of permanent sod strips of creeping red fescue (Festuca rubra L.) in the row middles combined with trickle irrigation in the tree row.
Endomycorrhizal Status of Certified Strawberry Nursery Stock
Authors: Robertson William J. , Boyle C. David , Brown Heidi L.
Published: August 2022

Roots of several cultivars of strawberry (Fragaria × ananassa Duchesne) were examined for mycorrhizae at the various stages required to produce nursery stock. First-year screenhouse plants were always non-mycorrhizal, but colonization of plants growing in fumigated foundation (2nd year) and certified (3rd year) fields was highly variable. As a result, certified stock being sold from Nova Scotia is often non-mycorrhizal. When present, mycorrhizae appeared to correlate with the presence of viable propagules in the soils after fumigation. In a greenhouse inoculation trial, all cultivars tested, including those with resistance to red stele disease (Phytophthora fragariae Hickman), became equally infected. Since mycorrhizae were also responsible for significant increases in growth and fruit production, inoculation of strawberry plants at the screenhouse stage is being considered.
Cation Exchange Properties of Pine Bark Growing Media as Influenced by pH, Particle Size, and Cation Species
Authors: Daniels W.L. , Wright R.D.
Published: August 2022

Pine bark cation exchange capacity (CEC) (by Ba/Mg exchange on four particle size fractions) increased regularly from 38 to 98 meq/100 g between pH 4 and 7. Decreasing particle size from <2.38 to <0.05 mm did not result in the expected large increases in bark CEC. The Ba/Mg CEC of unsieved bark samples was less than that determined by the weighted average of component size fractions. Monovalent/monovalent-determined CEC was higher than Ba/Mg, indicating that a number of differing charge-specific sites are involved. The pH-dependent CEC increase between pH 4 and 7 was greater for divalent exchange than for monovalent. Ammonium/K CEC was higher than K/NH4 CEC, probably due to enhanced NH4 adsorption by carboxyl groups. Infrared analysis of pine bark revealed that surface functional group composition is similar to soil organic matter. The accurate measurement of CEC in pine bark is complicated by solution pH and ionic strength, as well as by the cations employed for exchange.
Measuring Internal Gases and Lenticel Resistance to Gas Diffusion in Potato Tubers
Authors: Banks Nigel H. , Kays Stanley J.
Published: August 2022

The testing of a simple, non-invasive method for internal atmosphere determination of potato tubers (Solanum tuberosum L.), which also can be used to determine individual lenticel resistance to gas diffusion, is described. The method involved sampling from a 0.34-ml chamber fixed over a lenticel following equilibration of its contents with the tuber's internal atmosphere. Equilibration time and the lenticel's resistance to gas diffusion were estimated from oxygen or carbon dioxide contents taken at two or more time intervals using first-order rate equations. In mature ‘King Edward’ tubers harvested in 1984 and kept at 5°C and 80% RH for 4 weeks, the mean 99.9% equilibration time of CO2 content was 4.4 ± 0.75 hr. In a second experiment on mature ‘King Edward’ tubers harvested in 1985 and stored for up to 12 weeks at 4° and 80% RH, the mean 99.9% equilibration time for O2 content was 6.0 ± 1.17 hr. Repeated rapid sampling from single chambers on tubers increased sample CO2 contents but had no measurable effect on O2 contents. Sealing areas of periderm around sampling chambers demonstrated that potato tuber flesh has a significant resistance to gas diffusion, which can give rise to measurable O2 gradients within undamaged tissue.
Evaluation of Rubus Germplasm for Reaction to Root Rot Caused by Phytophthora erythroseptica
Authors: Bristow P.R. , Daubeny A. , Sjulin T.M. , Pepin S. , Nestby R. , Windom G.E.
Published: August 2022

Seedlings from open-pollinated Rubus spp. were screened for resistance to the root rotting fungus, Phytophthora erythroseptica Pethybr., in greenhouse tests. A mycelial suspension was injected into the soil surrounding roots of seedlings and symptoms usually began to appear within 10 days after inoculation. Symptoms included stem and petiole discoloration, wilting, and often death. After 15 weeks, virtually all seedlings of the subtropical species R. glaucus Benth. and R. sumatranus Miq. survived; however, varying percentages of resistant seedlings were obtained from each of the other species or species hybrids, except R. leucodermis Dougl. A higher proportion of R. idaeus vulgatus Arrhem. seedlings survived in populations collected from wet sites than from dry sites. Similarly, populations of R. spectabilis Pursh. and R. parviflorus Nutt., which usually grow in wet locations, had higher survival rates. Resistance in R. idaeus strigosus Michx., R. idaeus vulgatus, and R. spectabilis may be more useful in breeding than that from more exotic Rubus spp. because they possess characteristics that are closer to commercial red raspberry cultivars.
Growth, Development, and Yield Potential of Short-internode Muskmelon
Authors: Knavel Dean E.
Published: August 2022

A short-internode (SI) muskmelon line was compared with a normal-internode (NI) cultivar in four seasons for growth and yield differences. Vines of both plant types were divided into leaves, petioles, and stems at 58, 72, and 86 days of age. Leaf dry weight and leaf area were generally the same for both plant types early in growth. NI plants had greater leaf and stem dry weights and leaf area at 72 days; however, only stem dry weights differed at 86 days. The leaf : stem and leaf area : leaf dry weight ratios were always greater for SI than for NI plants, but NI plants produced twice the number and weight of fruit as SI plants. Mean fruit weight for SI plants was slightly smaller than fruits of NI plants. Doubling the population of SI plants by either spacing plants 0.45 m within the row or planting two per hill reduced fruit number and total fruit weight per plant. Highest total fruit weight was obtained by spacing SI plants 0.90 m apart in a triangular fashion within double rows spaced 0.30 m apart on a mulch row. SI plants contained less K and more Mg in leaves and less N and Ca but more K in stems than NI plants. Both plant types had similar Mg levels in stems at each sampling. There were significant year effects and internode type × year interactions for fruit number, fruit weight, and elemental concentrations.
Pecan Phylloplane Chemicals Influence Germination of Pecan Scab Conidia
Authors: Wood Bruce W. , Gottwald Timothy R. , Reilly Charles C.
Published: August 2022

The high variability in physiologically different stages of leaves and susceptibility of pecan [Carya illinoensis (Wangenh.) C. Koch] cultivars to the pecan scab [Cladosporium caryigenum (Ell. et Lang) Gottwald] fungus prompted an evaluation of phylloplane-associated substances (PASs) that influence fungal conidia germination. Germination of conidia was evaluated in several TLC fractions derived from water or dichloromethane leachates of the phylloplane of pecan leaves. Reciprocal tests of pecan scab conidia isolated from ‘Schley’ and ‘Stuart’ against phylloplane leachates from both ‘Schley’ and ‘Stuart’ were conducted. Several PASs proved to have either inhibitory, neutral, or promotive effects on conidia germination. 5-hydroxy-1,4-napthoquinone (juglone) was identified as one such substance and was observed to be a strong inhibitor of conidia germination, but had no effect on colony growth or sporulation. The susceptibility of pecan foliage to pecan scab appears to be partially dependent on phylloplane composition.
Root Distribution of ‘Climax’ Rabbiteye Blueberry as Affected by Mulch and Irrigation Geometry
Authors: Patten Kim D. , Neuendorff Elizabeth W. , Peters Stan C.
Published: August 2022

We studied the horizontal and vertical root distribution of 3-year-old ‘Climax’ rabbiteye blueberry (Vaccinium ashei Reade) in a sandy loam soil. Root density decreased logarithmically in the horizontal direction from the crown and linearly with depth. Ninety percent of the roots were within 0 to 0.38 m from the crown and 0 to 0.45 m depth. Roots spread more within the rows than across rows. Sawdust mulch increased the radial spread of roots, but did not promote rooting in the top 0.15 m of soil. Compared to one or two drip emitters per plants, low-volume spray emitters increased radial spread of roots, but only in combination with mulching. Greatest vertical rooting occurred with a single emitter at the base of the plant without mulch. Emitters placed 0.46 m from the crown of the plant did not help the spread of roots towards these emitters.
Production of Snap Beans as Affected by Soil Tillage Method and Row Spacing
Authors: Mullins Charles A. , Straw R. Allen , Coffey David L.
Published: August 2022

Conventional tillage (CT), no-tillage (NT), and rotary strip-tillage (RT) methods were combined with row spacings of 0.46 m (28 plants/m2) and 0.92 m (56 plants/m2) in 1985 and 1986 snap bean (Phaseolus vulgaris L.) tests with a split-plot factorial arrangement of treatments. Yields were lowest with NT and 0.92-m row spacings both years, while plant stands were lowest with NT and RT. Plant lodging was lowest with NT and highest with CT each year. Pod clustering and broken pods following machine harvest were lowest with NT both years, while rotten pods and percentage no. 2 to 4 sieve-size pods were lowest with NT in 1986. Incidence of broken pods was higher with the 0.46-m row spacing than with the 0.92-m row spacing in 1985 and the incidence of rotten pods was greatest with the 0.46-m row spacing in 1986. The 0.46-m row spacing improved yields over the 0.92-m spacing, with minimal difference in pod quality. Weed control was less effective with NT than with CT and RT methods.
Putrescine Influences Ovule Senescence, Fertilization Time, and Fruit Set in ‘Comice’ Pear
Authors: Crisosto C.H. , Lombard P.B. , Sugar David , Polito V.S.
Published: August 2022

Putrescine at 10−5, 10−4, 10−3, and 10−2 m applied at anthesis increased fruit set of ‘Cornice’ pear (Pyrus communis L.) in 1985 and 1986. Ovule longevity and the effective pollination period were extended 2 days in 1985 and 5 days in 1986 by putrescine at 10−3 m. Pollen tubes reached the micropyle 2 days earlier in treated than in untreated flowers. High levels of evolved ethylene in flowers were related to pollination and fertilization and were unaffected by putrescine application. Increased ovule longevity and fruit set in treated flowers were associated with increased foliar and flower N and B levels after fertilization. Chemical name used: 1,4-diaminobutane dihydrochloride (putrescine).
Anthocyanin Biosynthesis and Maturity of ‘McIntosh’ Apples as Influenced by Ethylene-releasing Compounds
Authors: Murphey Anne Swindeman , Dilley David R.
Published: August 2022

Solvolytic fragmentation of (2-chloropropyI)phosphonic acid, ethephon, and 2-chloroethyl-methylbis-(phenylmethoxy)-silane (CGA 15281) was studied. Ethephon and CGA 15281 were applied 2 or 3 weeks before the onset of autogenous ethylene production in ‘McIntosh’ apple. Solvolytic fragmentation of the compounds and autocatalytic ethylene production, anthocyanin biosynthesis, and flesh firmness changes of the fruit were monitored. Ethephon at 2.0 mM (290 ppm) applied at either date degraded at a slow, constant rate accompanied by a significant increase in anthocyanin biosynthesis within 6 days of applying the chemical. This subsequently led to initiation of autocatalytic ethylene production and flesh softening. CGA 15281 generated ethylene within 3 hr of application. Ethylene levels of fruit treated 3 weeks before harvest with 1.0 mM CGA 15281 returned to low levels within 24 to 48 hr of application. Anthocyanin increased significantly within 6 days; this was not accompanied by autocatalytic ethylene production or accelerated flesh softening. Results suggest that anthocyanin biosynthesis may be enhanced in apples using ethylene-releasing compounds without necessarily inducing other ripening changes. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon); (2-chloroethyl)methylbis(phenylmethoxy)silane (CGA 15281).
Flux of Ethylene from Leaves Treated with a Polar or Non-polar Ethylene-releasing Compound
Authors: Beaudry Randolph M. , Kays Stanley J.
Published: August 2022

Flux of ethylene from adaxial applications of Ethrel and Silaid to amphi- and hemistomatous leaves was examined. Following application of Ethrel to amphistomatous leaves in the dark (i.e., closed stomata) or hemistomatous leaves in the light, steady-state ethylene evolution was almost entirely adaxial. When stomata of amphistomatous leaves were fully open, abaxial ethylene flux for Ethrel was about 45% of the total ethylene evolved. Abaxial ethylene flux could then be dramatically reduced by stomatal closure induced by low light levels. Steady-state abaxial flux of ethylene from Silaid on amphistomatous leaves in the dark or hemistomatous leaves in the light was usually equal to or greater than adaxial ethylene flux. When stomata of amphistomatous leaves were fully open, flux of ethylene from Silaid was invariably equal from both leaf surfaces. Flux of Silaid- or Ethrel-derived ethylene from one leaf surface was reduced by increasing air velocity on the opposite side of the leaf, but only on amphistomatous leaves following light-induced stomatal opening. For Ethrel, the effect of air velocity was greater when the side of the leaf to which Ethrel had been applied was exposed to the increased air flow. No similar effect was found for Silaid. Closure of stomata on amphistomatous leaves and use of hemistomatous leaf material prevented any air velocity effect. Data indicate little to no entry of Ethrel or Ethrel-derived ethylene into the side of a leaf that lacks stomata or whose stomata are tightly closed. Significant movement of Silaid into leaf tissues probably occurs regardless of stomatal status, resulting in considerable release of ethylene within the leaf. Chemical names used: (2-chloroethyl)phosphonic acid (Ethrel); (2-chloroethyl) methylbis(phenylmethoxy)silane (Silaid).
Modeling and Simulation of Tree Wraps and Microsprinkler Irrigation for Young Citrus Freeze Protection: I. Model Development and Validation
Authors: Rieger Mark , Smerage Glen H. , Davies Frederick S. , Jackson Larry K.
Published: August 2022

A dynamic heat transfer model was developed for simulation of freeze protection of young citrus trees by tree wraps and microsprinkler irrigation. Heat exchange at the surface of the tree wrap was a function of heat input from irrigation and heat losses to evaporation, radiation, and convection. A finite difference form of a transient heat conduction equation was used to calculate rates of trunk temperature change as a result of heat exchange at the wrap surface. Predicted trunk temperatures were generally within 1 SE of observed means when simulating the effects of tree wraps without irrigation, with high correlation (r = 0.99) between observed and predicted minimum temperatures. When simulating the effects of microsprinkler irrigation combined with tree wraps, however, predicted trunk temperatures were generally 1° to 3°C lower than observed means (r = 0.81). Under-prediction of trunk temperature was attributed to underestimation of sensible heat transfer from the irrigation water and/or inaccuracies in parameters associated with irrigation. The behavior of the real and model systems was qualitatively similar in a majority of validation trials. Thus, the simulation model could be used to analyze factors affecting freeze protection.
Vegetative and Reproductive Yield Components of Primocane-fruiting Red Raspberries
Authors: Hoover Emily , Luby James , Bedford David , Pritts Marvin
Published: August 2022

Selection criteria to identify primocane-fruiting red raspberry seedlings (Rubus idaeus L.) with high, early yield are desirable in regions with short growing seasons. To identify possible parents contributing these desirable characteristics, ‘Heritage’, ‘Redwing’, and two genotypes from the Minnesota breeding program were subjected to yield component analysis. In all genotypes, yield was determined by canes/meter of row, fruit per node, and fruit weight. Over the 3-year period, ‘Heritage’ had the highest yield/meter of row, yield per cane, fruit per cane, and number of fruit per fruiting node among all genotypes. Component compensation was highest for ‘Redwing’, while MN 652 had the greatest degree of independence among components. In selecting seedlings for early fruiting and high yield, high cane densities and/or large fruit size will be needed.