bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Stress, Storage Time, and Temperature Influence Cell Wall-degrading Enzymes, Firmness, and Ethylene Production by Cucumbers
Authors: Miller A. Raymond , Dalmasso Joseph P. , Kretchman Dale W.
Published: August 2022

Cucumber (Cucumis sativus L.) fruit (‘Heinz 3534’) subjected to mechanical stress followed by storage for 48 hr exhibited visible degeneration of the mesocarp and endocarp, which was accompanied by several-fold increases in the activity of the enzymes pectin methylesterase, peroxidase, polygalacturonase, and xylanase. The activity of all these enzymes increased in the endocarp, whereas only pectin methylesterase and polygalacturonase increased in the mesocarp, and pectin methylesterase, peroxidase, and polygalacturonase increased in the exocarp. Further, the increase in the activity of pectin methylesterase, peroxidase, and polygalacturonase was less when cucumbers were stored at 0° or 10°C vs. 25° or 38° after mechanical stress. Cucumbers stored for only 8 hr after mechanical stress, or not stressed, and stored for 8 or 48 hr showed no consistent significant increases in enzyme activity. Endocarp firmness of fruit stored at 25° or 38° for 8 hr after mechanical stress was lower than that of unstressed fruit, but this decrease was not evident after 48 hr of storage, and mesocarp firmness was not affected by mechanical stress regardless of storage temperature or time. Ethylene production was stimulated significantly by 8-hr storage at 0°, following mechanical stress, and by 48-hr storage at 0°, but was unaffected by all other treatment and storage regimes. These data indicate that mechanical stress induces biochemical and morphological changes in the major tissues of cucumber fruit, but tissue firmness and/or ethylene production will not serve as indicators of these changes. Moreover, the effects of mechanical stress do not appear to be mediated through the action of ethylene.
Genetic Variation for Quality Traits in an Advanced-cycle Breeding Population of Strawberries
Authors: Shaw Douglas V. , Bringhurst Royce S. , Voth Victor
Published: August 2022

Genetic variation for percent soluble solids, percent titratable acidity, and fruit firmness was analyzed for representative progenies from the California strawberry breeding population. Fruit samples were harvested from individual seedlings from 28 biparental crosses, organized in two factorial mating sets. Individual narrow-sense heritabilities were estimated as 0.07, 0.48, and 0.38 for solids, acids, and firmness, respectively. Broad-sense heritabilities were estimated as 0.35, 0.78, and 0.38 for the same traits, suggesting the presence of dominance variance for soluble solids and acidity, but not for firmness. Opportunities for genetic manipulation of traits with different additive-dominance genetic variation profiles are discussed.
Isozyme Inheritance, Polymorphism, and Stability of Malate Dehydrogenase and Phosphoglucose Isomerase in Pecan
Authors: Marquard Robert D.
Published: August 2022

Isozyme banding patterns of malate dehydrogenase (MDH) and phosphoglucose isomerase (PGI) were polymorphic in leaf and pollen extracts of pecan [Carya illinoensis (Wangenh.) C. Koch], Both enzyme systems produced two prominent anodal zones of activity with similar banding patterns expressed from leaves and pollen. The fast-migrating MDH region (Mdh-1) was polymorphic, with three banding patterns. Segregation ratios support a model that Mdh-1 is a dimer controlled by a dimorphic locus. The slow-migrating MDH region was monomorphic and produced five densely staining bands. The fast-migrating PGI zone also was fixed in all samples assayed. Six banding patterns were detectable in the less-anodal region (Pgi-2) and produced one of three single-handed or three triple-banded patterns in leaf extracts. Segregation ratios indicate Pgi-2 is controlled by three alleles at a single locus. Mdh-1 and Pgi-2 genotypes are included for 66 cultivars and based on Mdh-1 inheritance; ‘Kiowa’ has been incorrectly reported to be parented by a ‘Mahan’ × ‘Odom’ cross. Genes controlling Mdh-1 and Pgi-2 were not closely linked. Enzymes remained active and stable in pollen stored for 30 months at −20°C and in leaves stored at 4° for 45 days. Frozen enzyme extracts remained stable for 18-24 days and dimethyl sulfoxide [Me2SO (DMSO)] prolonged extract storability.
Microsporogenesis in Diploid and Tetraploid ‘Sherwood’ Daylily
Authors: Arisumi Toru
Published: August 2022

Comparisons between field-grown diploid and tetraploid cultivars of the daylily (Hemerocallis, cv. Sherwood) over two seasons showed significant differences in percentages of abnormal PMCs and nonsignificant differences in percentages of aborted pollen. Averages of abnormal PMCs in the two seasons were 1.0% and 3.7% in the diploid vs. 20.0% and 24.4% in the tetraploid. Percentages of aborted pollen at anthesis were 11.9% and 18.6% in the diploid vs. 17.0% and 22.2% in the tetraploid. With few exceptions, seasonal differences in abnormal PMCs and pollen abortion were not significant. Recurrent meiotic abnormalities included: a) chromosomes lying outside the equatorial plate in MI; b) precocious anaphase of some chromosomes in MI; c) nondisjunction and laggards in AI; and d) formation of micronuclei and small pollen grains in TII and tetrads. Pollen abortion in the diploid was attributed to genetic factors and, in the tetraploid, to deficiencies caused by chromosomal losses during irregular meiosis.
Nitrogen and Phosphorus Nutritional Influence on Bentgrass–Annual Bluegrass Community Composition
Authors: Dest William M. , Guillard K.
Published: August 2022

This study evaluated the effect of N and P fertilization on the change in species composition of a bentgrass (Agrostis spp.) and annual bluegrass (Poa annua L.) turf. Species composition was determined by a square grid method and visual estimate of percent bentgrass and plant separations. Bentgrass population significantly increased in those areas from which N was withheld for 3 years compared to areas that were fertilized with N. Phosphorus fertilizer treatments had no effect on species composition. Except for one of the three ratings made in 1982, turf quality was not significantly reduced by withholding N. Quality had begun to improve by 1984 on the no-N plots compared to the N-fertilized plots. This change was associated with increased bentgrass population. There was a significant correlation between the square grid and visual estimate method used to evaluate the change in species composition in 1982, 1983, and 1984 (r = 0.84, 0.87, and 0.88, respectively). Although the N content of the leaf tissue was greater in the bentgrass tissue compared with annual bluegrass, leaf tissue concentrations were within or above the sufficiency range for grasses. This study has shown that withholding N fertilization in some years under certain conditions gives bentgrass a competitive advantage over annual bluegrass without lessening turf quality.
Physiological Factors Associated with Yellow Shoulder Expression in Tomato Fruit
Authors: Picha David H.
Published: August 2022

Yellow shoulder (YS) expression was associated with differences in composition, respiration rate, and ethylene evolution between the yellow and normal red tissue in tomato (Lycopersicon esculentum Mill.) fruit. The YS tissue was higher in pH, dry matter, alcohol-insoluble solids (AIS), calcium content, respiration rate, and ethylene evolution than the red blossom-end tissue. The YS tissue had less phosphorus, potassium, citric acid, and a lower titratable acidity than the red tissue. Expression of YS was not associated with imbalances in fructose, glucose, malic acid, nitrogen, or magnesium concentration. Substantial YS development occurred in fruit of nonuniform ripening gene cultivars allowed to vine-ripen. Yellow shoulder was alleviated by harvesting fruit in the mature-green stage and room-ripening.
Seasonal Trends of Calcium and Iron Fractions in Sweet Cherry Leaves and Their Relationships
Authors: Sánchez-Alonso Francisco , Lachica Manuel
Published: August 2022

Calcium in cherry (Prunus avium L.) tree leaves was separated into four fractions at 2- to 4-week intervals during the season. Concentrations of all fractions increased, according to curvilinear equations. The organic insoluble fraction was the most important during the first half of the cycle, whereas the soluble fraction was the most important during the second half. Bound and inorganic insoluble Ca contribute little to the total content. Iron extracted by 1 n HCI is highly correlated with the total concentration and increased as a quadratic equation. Accumulation of Fe seems to be related to the accumulation of Ca in the leaf tissue.
Estimation of Diurnal Changes in Potato Leaf Water Potential Under Irrigated Conditions
Authors: Stark J.C. , Ojala J.C. , McCann I.R.
Published: August 2022

Regression models of potato (Solanum tuberosum L. cv. Russet Burbank) leaf water potential (ψleaf) were developed for irrigated conditions using concurrent measurements of total solar irradiance (Rs), air vapor pressure deficit (VPD), air temperature (Ta) and windspeed. Estimates of potential evaporation (Ep) also were related to ψleaf. The data were collected over a 3-year period from two locations in southern Idaho. Of the variables tested, Rs had the highest simple correlation with ψleaf (r = 0.93), although a slightly higher correlation was obtained for log-transformed values of VPD (1n VPD). Potato ψleaf was best described by the equation ψleaf = -0.3672 - 0.1959 In VPD – 0.0005 Rs, where ψleaf, VPD, and Rs are expressed in units of MPa, kPa and W·m–2, respectively. The model accounted for 95% of the variation in ψleaf for well-watered ‘Russet Burbank’ potatoes. When the model was tested on an independent data set, it estimated diurnal changes in ψleaf for several different cultivars to within ±0.1 MPa of the measured values. The relationship between ψleaf and Ep was nonlinear and was described by an exponential function. Estimates for the Ep model were nearly identical to those for the VPD Rs model when ψleaf values were below -0.3 MPa.
Kentucky Bluegrass Photosynthate Partitioning Following Scheduled Mowing
Authors: Hull Richard J.
Published: August 2022

The distribution of photosynthetically fixed carbon within a turfgrass sod was investigated following a routine mowing. The partitioning of 14C-labeled photosynthate was monitored in Kentucky bluegrass (Poa pratensis L. cvs. Baron and Merion) turf 2, 24, and 72 hr after mowing at 3.8 cm. Circles of turf (15 cm in diameter) were exposed to 14CO2 for 15 min, 10-cm-diameter plugs were removed 2 and 24 hr after exposure, and the plants were assayed for radioactivity. Experiments were conducted in late spring, midsummer, and early autumn for 2 years in field plots on a silt loam. Photosynthate translocation from leaf blades to leaf sheaths and crowns was reduced by as much as 25% within 2 hr after mowing but generally returned to a constant and greater rate within 24 hr. Midsummer mowing temporarily inhibited photosynthate transport more than mowing in spring or fall. Photosynthate distribution within turfgrass plants was influenced more by time of year and nutritional status than by mowing. Kentucky bluegrass maintained as closely mowed turf sustains only a slight and temporary disturbance in energy partitioning in response to mowing.
Influence of Leaf Age on the Upper and Lower Leaf Surface Features of Juvenile and Adult Pecan Leaves
Authors: Grauke L.J. , Storey J.B. , Emino E.R.
Published: August 2022

Adaxial and abaxial leaflet surfaces of juvenile and adult pecan [Carya illinoensis (Wang.) K. Koch] leaves were characterized in relation to leaf age. Three types of trichomes were found. Nonglandular hairs (acicular and fasciculate) were the most common trichome type on juvenile-phase leaves and reached their greatest density on the abaxial surface of immature leaves. Peltate scales were present in two forms: vesicular scales and concave scales. The two were distinguished on the basis of size and shape. Both types were more common on the abaxial than the adaxial surface. The vesicular scales were more common on immature than mature leaves, whereas the occurrence of concave scales were unaffected by leaf age. Capitate glands were observed on the veins of immature leaves in both juvenile and adult phase. Laminai stomata of two sizes and unusual veinal stomata were observed, the latter being confined to the abaxial surface of immature leaves.
In Vitro Propagation of Chinese Cabbage from Seedling Shoot Tips
Authors: Paek Kee Yoeup , Chandler Stephen F. , Thorpe Trevor A.
Published: August 2022

Shoot cultures were initiated from seedling shoot tips of Brassica campestris ssp. pekinensis (Lour.) Olsson (Chinese cabbage, cv. Kimjung) on Murashige–Skoog medium supplemented with 46.5 μm kinetin and 1.5 μm IBA. Proliferation was a result of growth from axillary buds. Adventitious shoots could not be induced on a wide range of culture media. The effects of cytokinin and auxin type and concentration, nitrate : ammonium ratio, sucrose concentration, and other additives on shoot multiplication and growth were determined. Only adenine sulfate was beneficial. Expiants were rooted on hormone-free medium, but addition of 2.5 or 5.0 μm IAA or IBA increased rooting and enhanced shoot growth. Regenerated plants were morphologically normal and exhibited flowering during both root initiation in vitro and after establishment in soil. Chemical names used: N-(2-furanylmethyl)-1H-purin-6-amine (kinetin); 1H-indole-3-butanoic acid (IBA); 1H-indole-3-acetic acid (IAA).
Inheritance of Compact Growth Habit in Rabbiteye Blueberry
Authors: Garvey E.J. , Lyrene P.M.
Published: August 2022

A vigorous, compact wild rabbiteye blueberry (Vaccinium ashei Reade) plant (FL78-66) found in northeast Florida had short internodes, small leaves, and low apical dominance. S1 plants after one growing season average 31 cm tall compared to 62 cm for S1 plants from the V. ashei cultivar ‘Premier’. FL78-66 was highly fertile when crossed as male or female with V. ashei cultivars. Most F1 plants were full-statured, but some resembled FL78-66. F2 plants obtained by intercrossing short-statured F1 plants ranged from full statured to much more compact than FL78-66.
Cytology and Morphology of Ovule Culture-derived Interspecific Impatiens Hybrids
Authors: Arisumi Toru
Published: August 2022

Hybrids among African, Indian, and New Guinea Impatiens were euploids and sterile. All but a few developed into normal mature plants. Classification of certain hybrid traits showed 115 mid-parental, 75 either seed- or pollen-parental, and 17 resembling neither parent. Data from phenotypic analysis of hybrids and parents suggested that the following phylogenetic trends could have been conditioned by dominant or partially dominant genes: from equal to unequal petals, flat to hooded dorsal petal, racemose to epedunculate inflorescence, nearly free to markedly fused lateral petals, and lower sepal and a filiform spur to bucciniform or saccate lower sepal. Spiral phyllotaxy was dominant over whorled. Crosses thought to be useful in ornamental breeding were I. auricoma × I. sultani ‘Elfin White’ or New Guinea species for yellow flowers, I. uguenensis × New Guinea or I. flaccida for drought tolerance, and I. flaccida × I. repens or ‘Elfin White’ for double flowers.
Translocation of Foliar-applied Urea 15N to Reproductive and Vegetative Sinks of Avocado and Its Effect on Initial Fruit Set
Authors: Zilkah Shmuel , Klein Isaac , Feigenbaum Salah , Weinbaum S. A.
Published: August 2022

Translocation of 15N from foliar-applied urea to vegetative and reproductive sinks of avocado (Persea americana Mill, cvs. Fuerte and Hass) was evaluated during inflorescence development and the early stages of fruit set. Urea (2%) increased the number and the total dry weight of the lateral inflorescence per shoot. The concentration of 15N in avocado inflorescences increased proportionately to the concentration of urea applied to the old leaf surface. The amount of 15N translocated was not affected by the proximity of the source leaf to the “terminal” inflorescence. 15N translocated to developing fruit and to new sprouting leaves in similar amount. Urea N was translocated basipetally from current flush leaves to developing fruit. Removing the vegetative sink reduced N influx to the reproductive tissue and increased initial fruit set by a factor of 1.7 to 2.1 in urea-treated and -untreated shoots, respectively. These data indicate that shoot growth does not limit fruit set in avocado via competition for N.
Microsprinkler Irrigation for Freeze Protection: Evaporative Cooling and Extent of Protection in an Advective Freeze
Authors: Parsons Lawrence R. , Wheaton T. Adair
Published: August 2022

Microsprinkler irrigation has proved effective in providing frost protection for young citrus trees, but there can be a risk of damaging trees during advective or windy freezes. The objectives of this study were to monitor evaporative cooling and to determine if height of young tree protection cold be increased to include the major scaffold branches. Microsprinklers were evaluated during a severely damaging advective freeze that occurred in central Florida in Jan. 1985. Trunk temperatures were measured at 15-, 30-, 45-, and 60-cm heights. By positioning the sprinkler at a 45° or higher angle, microsprinkler spray was aimed up into the young tree. This treatment was compared to the normal 15° low-angle spray pattern. Application rates on the wetted area were estimated to be 7 mm·hr−1 for high-angle treatment and 8.8 mm·hr−1 for low-angle treatment. With high-angle spray, trees were protected to a height of 85 cm, which was significantly higher than low-angle spray. Evaporative cooling below air temperature was not seen on irrigated trees. Continuous microsprinkler spray helped reduce evaporative cooling, but cooling did occur on a nearby tree that received only intermittent spray. Microsprinkler irrigation directed at an upward angle protected the trunk and scaffold branches of young trees in this particularly severe freeze and enhanced tree recovery.
Effects of Nitrogen Fertilization on Vegetative, Flowering, and Asexual Propagation Characteristics of Streptocarpus ×hybridus
Authors: Lyons R.E. , Booze-Daniels J.N. , Wright R.D.
Published: August 2022

The response of cape primrose (Streptocarpus) plants to external N application is dependent on growth media only in terms of response magnitude. A 2.0% to 2.9% tissue N level in either sand or bark media maximized shoot dry weight, the number of potential flowers, and the quantity and quality of plantlets regenerated during subsequent asexual propagation. In sand, 2.9% tissue N was below the level required for maximum leaf elongation and resulted in a desirable restriction of the primary leaf (phyllomorph). Tissue N levels that either exceeded or lagged behind the optima were often detrimental to plant aesthetics, and wasteful where luxuriant tissue levels did not affect the measured characteristics.
Effect of Soil Applications of Paclobutrazol on Vegetative Growth, Pruning Time, Flowering, Yield, and Quality of ‘Flavorcrest’ Peach
Authors: Martin George C. , Yoshikawa Frank , LaRue James H.
Published: August 2022

In each of three years, paclobutrazol was soil-injected at about a 15 cm depth and 1 m from the ‘Flavorcrest’ peach [Prunus persica (L.) Batsch] tree trunk. In the randomized complete block design, many significant differences between paclobutrazol-treated trees and controls were measured in the following categories: reduction of canopy growth, increased numbers of vegetative and floral buds in the lower portions of the tree, elimination of the need for summer pruning, increased hand fruit thinning time in two of three years, increased fruit yield and size, advanced fruit maturity, decreased leaf K, and increased leaf Ca. Paclobutrazol increased cumulative yield over controls from 30.1 to 41.8 t·ha−1 for the 3-year experimental period. This yield increase exceeded the controls by at least 22%, 71%, and 76% for 1984, 1985, and 1986, respectively, and occurred without measurable fruit quality loss, except for soluble solids, which were decreased in two of three years. Chemical name used: β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
Morphological Response of Flowering Annuals to Salinity
Authors: Devitt D.A. , Morris R.L.
Published: August 2022

Ten flowering annuals were greenhouse-grown and irrigated with four levels of saline water [electrical conductivities (EC) = 0.8, 1.5, 3.0, 4.5 dS·m−1] to determine their response to increased salinization. Twelve different parameters were monitored at the end of an 8-week period. All 10 species differed in their response to salinization. The relative number of flowers and the relative maximum flower diameter at harvest decreased significantly for six of ten and seven of nine species, respectively, with increased salinity. A salt tolerance scale was devised that best described their response to salinity. The parameters selected were dry weight, plant height, number of flowers, and maximum flower diameter. Cosmos (Cosmos bipinatus Cav. ‘Sunny Gold’) was rated very sensitive for all four parameters. Following Cosmos, the rating changed and so did the sequence, depending on the parameter being considered. Both petunias (Petunia hybrida Linn. ‘White Cascade’ and ‘Challenger White’) and dianthus (Dianthus chinensis Linn. ‘Princess White’) were the only species rated very tolerant for all four parameters.
Effect of Vegetation Management on Soil Nutrients and Nutrient Content of Herbaceous Vegetation
Authors: Warren Stuart L. , Monaco Thomas J. , Skroch Walter A.
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. Nutrient contents of the herbaceous vegetation and soil were effected significantly by management programs, location in the plot (row and interrow), and time. The presence or absence of vegetation influenced vegetative uptake and leaching losses, resulting in differences among the vegetation management programs. In general, the upper soil (0- to 15-cm depth) with 100% vegetative cover contained more exchangeable Mg and less NO3 and available P than under bare soil. Exchangeable Ca was not affected by the management programs. Differences in growth form (grass or forb), perennial or annual vegetation, and percent bare soil accounted for the majority of differences in the nutrient content of the noncrop vegetation. Aspect did not affect any of the plant and soil parameters measured.
Micropropagation and Phase Specificity in Mature, Elite Douglas fir
Authors: Gupta Pramod K. , Durzan Don J.
Published: August 2022

Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] plantlets, micropropagated from axillary buds of nodal segments from invigorated stems and adventitious buds from young needles of two 60-year-old trees, have been established in soil. Stem tips with half-pruned-back needles from the lower crown, when placed on DCR medium, sprouted buds in 90% of explants. Shoots from bud sprouts were plagiotropic when collected from explants of shoots with a horizontal and downward growth habit. By contrast, upright growth of micropropagated shoots was observed in all explants from branches with an upright habit. After four subcultures (3- to 4-week intervals on 0.5 mg·liter−1 BA in DCR), sprouted shoots of nodal segments from all expiant sources produced four to six multiple buds. With excised needles of sprouted buds, numerous (> 10) adventitious buds formed after 11 to 12 weeks on needle surfaces after the fifth subculture on DCR with 0.5 mg·liter BA. All adventitious and axillary buds elongated on 0.5 DCR lacking plant growth regulators. Rooting of the elongated shoots was induced in 20% of the explants with 0.2 mg·liter−1 each of NAA and IBA. In all instances, buds programmed for the development of female reproductive cones continued their phase-specific development even under conditions conducive to rejuvenation of vegetative tissues. Chemical names used: N-(phenylmethy)-1H-purin-6-amine (BA); 1-naphthaleneacetic acid (NAA); 1H-indole-3-butyric acid (IBA).
Discriminant Analysis for Kentucky Bluegrass Billbug Resistance Ratings
Authors: Bruneau A.H. , Parkhurst A.M. , Shearman R.C.
Published: August 2022

Four categories of billbug (Sphenophorus parvulus Gyllenhal) resistance were identified and contrasted in terms of anatomical, morphological, and physiological characteristics of 12 Kentucky bluegrass (Poa pratensis L.) cultivars. Discriminant analysis was used as a separatory procedure to determine the relative importance of these plant characteristics to observed billbug resistance and to construct a prediction procedure for potential billbug resistance classes. Variables measured from field-, controlled environment-, and greenhouse-grown plants were analyzed for the most biologically revealing characteristics of potential billbug resistance. Separatory discrimination indicated that cultivars exhibiting moderate and high billbug resistance had tougher tissue than tolerant or susceptible cultivars. Tolerant and highly resistant cultivars differed from those susceptible and moderately resistant by concealing billbug injury. Development of a predictive classification procedure was promising, with percent correct classification ranging from 67% to 94%, depending on number and type of discriminating variables analyzed.
Fertility of 4x × 5x and 5x × 4x Progenies Derived from Vaccinium ashei/corymbosum Pentaploid Hybrids
Authors: Vorsa Nicholi , Jelenkovic Gojko , Draper Arlen D. , Welker William V.
Published: August 2022

Percent fruit set, fruit size, total seeds/berry, developed seeds/berry, percent developed seeds/berry, and percent pollen stainability were examined in 4x × 5x and 5x × 4x progenies derived from Vaccinium ashei Reade/V. corymbosum L. pentaploid hybrids backcrossed to V. corymbosum. All fertility parameters indicated that the BC1 progenies were more fertile than the pentaploid hybrids. Pollen stainability indicated that the BC1 derivatives were less fertile than the parental species. All fertility parameters were significantly and negatively correlated with chromosome number, which ranged from the tetraploid (2n = 4x = 48) to pentaploid (2n = 5x = 60) levels within these progenies.
Identification and Performance of Citrus Trees on Nucellar and Zygotic Rootstocks
Authors: Roose M.L. , Traugh S.N.
Published: August 2022

Electrophoretic analysis of rootstock bark was used to identify citrus trees on zygotic rootstocks in five 9- to 19-year-old rootstock trials involving 24 rootstock cultivars, and in four additional 22- to 23-year-old rootstock trials involving 24 selections of trifoliate orange [Poncirus trifoliata (L.) Raf.]. The rootstock seedlings used to propagate the trees for these trials were rogued visually before budding. The theoretical probability of distinguishing between nucellar genotypes and zygotics resulting from self-pollination averaged ≈86% among the rootstocks studied. In cultivars other than trifoliate orange, only 17 of 899 rootstocks were detected to be zygotic: eight in Kikodaidai, four in H-56 tangor, two in C-32 citrange, and one each in three other rootstocks. Many of these zygotics resulted from cross-pollination. In trifoliate orange, 29 of 846 trees were identified to be on zygotic rootstocks, all apparently resulting from pollination by trifoliate orange. Some trees on zygotic rootstocks were smaller and lower-yielding than trees on nucellar genotypes of the same cultivar, but many were fairly similar to, and a few yielded significantly more than, trees on nucellars. Trees on zygotic rootstocks usually had bud unions that were either significantly more or less smooth than trees on nucellars of the same cultivar. Data from zygotics did not bias results of rootstock trials appreciably. Isozyme analysis of rootstocks in commercial groves or rootstock trials may allow preliminary identification of promising new genotypes resulting from open pollination.
Frequency and Characteristics of Nucellar and Zygotic Seedlings in Three Cultivars of Trifoliate Orange
Authors: Khan I.A. , Roose M.L.
Published: August 2022

Seedling populations of three cultivars of trifoliate orange [Poncirus trifoliata (L.) Raf.] were grown in a greenhouse from seed collected in three different years and four different locations. Starch gel electrophoresis of four heterozygous loci was used to distinguish nucellar (apomictic) seedlings from zygotic seedlings. Minimum estimates of the frequency of zygotics among 23 seed samples ranged from 0% to 76%, with an overall mean of 18%. All zygotics apparently originated from self-pollination or pollination by other trees of trifoliate orange. Samples collected from the same tree in different years had significantly different frequencies of zygotics. Differences among cultivars in frequency of zygotics were obscured by the large environmental effects. Samples stored for 8 months before planting generally did not differ in frequency of zygotics from those stored for 5 months. Mean height of zygotics was less than that of nucellars in all samples measured, significantly less in most samples. However, many zygotics were so similar to nucellars in height, leaf size, thorn length, petiole length, and stem diameter that they would be difficult to identify using these traits.
Role of Assimilate Translocation and Carbohydrate Accumulation in Fruit Set of Strawberry
Authors: Darnell Rebecca L. , Martin George C.
Published: August 2022

Soluble sugar and starch levels and translocation of 14C-Iabeled photoassimilates in receptacles of pollinated, nonpollinated, and auxin-treated strawberry flowers (Fragaria × ananassa Duch. ‘Fern’) were examined from 0 to 144 hr after anthesis and correlated with fruit set and initial growth. Receptacle dry weight of nonpollinated flowers increased very little during the experimental period, whereas receptacles of pollinated and auxin-treated flowers showed a gain in dry weight within 24 hr, which continued throughout the experimental period. However, 14C accumulation in flower receptacles did not reflect the initial differences in growth, indicating that recently fixed 14C-labeled photosynthate was not the source for the observed dry weight increases. Analysis of carbohydrate pool sizes in treated receptacles indicated no consistent correlation between pool sizes and fruit set and initial growth. Thus, fruit set and initial growth in strawberry is not limited by the capacity of receptacles either to mobilize current source leaf assimilates or accumulate carbohydrates.
Whole-fruit Ethylene Evolution and ACC Content of Peach Pericarp and Seeds During Development
Authors: Miller Anita Nina , Krizek Beth Allyn , Walsh Christopher S.
Published: August 2022

The rate of ethylene evolution of peach fruit (Prunus persica L. Batsch) and ACC content of peach pericarp/mesocarp and seeds was determined during development. Ethylene measurements of whole fruit began 18 days after anthesis (DAA), and ACC quantification was started 32 DAA. ACC levels and ethylene evolution followed similar patterns during stages I and II of fruit growth. At 39 DAA, there was an increase in ethylene evolution and extractable ACC concentration of both pericarp and seeds; however, variability was high at this time. Ethylene evolved by nondeveloping fruit of the “second wave” and “June drop” increased after senescence of the ovule was observed. By 49 DAA, ethylene production and ACC concentration reached a minimum that lasted until a 10-fold increase in ethylene evolution was detected in late stage III. This 10-fold increase in ethylene occurred in four different peach cultivars sampled at “firm-ripe” stage. Seeds excised at 67 DAA, which were incubated for 6 hr in ambient O2 conditions, evolved 400 nl·g−1·hr−1 ethylene and ACC concentration averaged 54 nmol·g−1 fresh weight. It is suggested that in split-pit fruits, ethylene generated by the seeds may accelerate fruit maturation and ripening. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).
Development of the Abscission Zone in Needles of Douglas-fir
Authors: Montano Jose M. , Proebsting William M.
Published: August 2022

The abscission zone of Douglas-fir (Pseudotsuga menziesii var. menziesii Mitb. Franco) was studied throughout needle development. A separation layer one cell thick developed at the needle base when extension growth ceased. Cells of this layer stained positively with safranin and slightly with toluidine blue. A protective layer, which developed in stem tissue adjacent to the separation layer, stained positively with safranin, periodic acid-Schiff's reagent, phloroglucinol-HCL and chlorine sulfite. Abscission was induced by drying cut trees to a water potential below −3.5 MPa. Water-stressed trees segregated into abscising and non-abscising needle groups. Walls of separation layer cells from trees with abscising needles were characterized by shrinkage followed by tearing. Walls of separation layer cells from trees with non-abscising needles were anatomically unaffected by water stress. Mechanical damage of cell walls in the separation layer occurred when water stress was −3.5 MPa or lower. Abscission could be prevented by maintaining a water potential above −3.5 MPa.
Micropropagation of Cherry Rootstocks: I. Response to Culture
Authors: Ranjit Makunda , Kester D.E. , Micke W.C.
Published: August 2022

Establishment, shoot proliferation, root induction, and transplanting stages were accomplished with Prunus avium × P. cerasus cv ‘Colt’, ‘Dwarf Mahaleb’ (P. mahaleb L) (both vegetatively propagated rootstock cultivars) and seedling Mazzard sweet cherry (P. avium L) ‘46-1 Mazzard’, (P. avium L.), a clonal rootstock seed tree, could be established and multiplied by the same procedure. However, no rooting was obtained. Limited rooting was possible with seedling Mazzard trees < 3 years in age. It was concluded that the limiting factor in ‘46-1 Mazzard’ rooting was the mature status of the source material.
Effects of Phenolic Compounds on Tobacco Callus and Blackberry Shoot Cultures
Authors: Compton Michael E. , Preece John E.
Published: August 2022

The effects of catechol, juglone, phloridzin, phloroglucinol, and tannic acid were tested on tobacco callus growth and on axillary shoot proliferation and rooting of blackberry. Juglone (500 μM) promoted tobacco (Nicotiana tabacum L. ‘McNair 944’) callus growth, whereas catechol and phloroglucinol (500 μM) increased adventitious shoot formation, but not callus growth. Tannic acid increased the frequency of vitreous shoots. No phenolic compounds stimulated axillary shoot proliferation in blackberry (Rubus sp. ‘Dirkson Thornless’), and phloroglucinol (1 mM) inhibited shoot elongation. Auxin increased rooting of blackberry shoots irrespective of the presence or absence of incorporated phenols. On shoots derived from proliferation media void of phenols, root number and percent rooting were greater if they were treated with the phenolic auxin P-ITB compared to IBA. In contrast, shoots originating from proliferation media containing phenols rooted the same with both auxins. Chemical names used: 1,2-benzenediol (catechol); 5-hydroxy-1,4-naphthalendedione (juglone); 1-[2-(β-D-glycopyranosloxy)-4,6-dihydroxyphenyl-3-[4-hydroxyphenyl)-1-propanone (phloridzin); 1,3,5-benzenetriol (phloroglucinol); 1H-indole-3-butanoic acid (IBA); N-(phenylmethyl)-1H-purin-6-amine (BA): phenyl indole-3-thiolobutyrate (P-ITB); (1α,2β,4aα,4bβ,10β)-2,4a,7-trihydroxy-1-methyl-8-methylenegibb-3-ene-1, 10-dicarboxylic acid 1,4a-Iactone (GA3).
Sensitivity of Peach Seedling Vegetative Growth to Paclobutrazol
Authors: Early J.D. , Martin G.C.
Published: August 2022

‘Nemaguard’ peach seedlings [Prunus persica (L.) Batsch] were grown for 21 days in nutrient solution cultures containing a range (0 to 3.4 μM) of paclobutrazol concentrations. Shoot growth rate and total extension growth were reduced by all paclobutrazol treatments. Within 2 days of treatment, paclobutrazol at 3.4 μM significantly reduced the growth rate, as did the 3.4 × 10−2 μM concentrations after 5 days. Increases in paclobutrazol concentrations decreased leaf area and leaf, stem, and shoot weights. However, specific leaf weight increased as paclobutrazol concentration increased. Leaf expansion was more sensitive to paclobutrazol treatments than stem elongation. As paclobutrazol concentration increased, root extension growth was reduced, but roots were thicker and produced more laterals near the tip. Compared with the control, paclobutrazol at 3.4 × 10−1 and 3.4 × 10−2 μM significantly increased the root: shoot ratio. Chemical name used: β-[(4-chIorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
Gradients in Maturity and Sugar Levels of Fruit Within Peach Trees
Authors: Dann Ian R. , Jerie Peter H.
Published: August 2022

Peach [Prunus perscia (L.) Batsch] flowers opened first at the base of young trees and last at the top. In contrast, fruit ripened first at the top of trees and at the tips of laterals. Dry weight and percentage dry weight (% dwt) of the mesocarp of fruit from the upper canopy were consistently greater throughout the season than for fruit from the lower canopy. These differences were large enough to have marketing significance and important implications for the future of mechanical harvesting.
Influence of Temperature and Plant Water Status on Pollen Viability in Beans
Authors: Weaver Merle L. , Timm H.
Published: August 2022

The effect of temperature, soil moisture, and diurnal variations in plant water content on pollen viability (PV) in bean (Phaseolus vulgaris L.) genotypes was investigated under field conditions in 1981 and 1982. Each year PV, relative water content (RWC), and leaf water potential (LWP) of each cultivar at mean soil moisture tensions (MSMT) of −0.05 and −0.10 MPa were reduced significantly between 0700 hr and 1400 hr. At a MSMT of −0.05 MPa, PV and RWC of both cultivars significantly increased between 1400 hr and 1900 hr. During the same period, the LWP of ‘California Light Red Kidney’ increased to the 0700-hr level, but remained at the 1400-hr level in ‘Gloria’. At a MSMT of −0.10 MPa, PV significantly increased in ‘Gloria’ but failed to increase in ‘California Light Red Kidney’ between 1400 hr and 1900 hr. RWC remained at the 1400-hr level in both cultivars. LWP of ‘California Light Red Kidney’ remained at the 1400-hr level, but continued to decline below the 1400-hr level in ‘Gloria’ during the same period. PV declined as both RWC and LWP decreased. A relative value for the simultaneous contribution of both high ambient temperature and the water status of bean plants to loss of PV was calculated.
Mulch and Irrigation Placement Effects on Soil Chemistry Properties and Rabbiteye Blueberry Plants Irrigated with Sodic Water
Authors: Patten K.D. , Neuendorff E.W. , Leonard A.T. , Haby V.A.
Published: August 2022

‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade) plants were grown for 3 years under a sodic irrigation regimen. Mulched and non-mulched plants were irrigated by one of three methods: one drip emitter at the base of the plant, two drip emitters on either side of the plant, or low-volume spray emitter (LVSE). There was a mulch × irrigation treatment interaction. Mulch increased the growth of drip-irrigated plants but not LVSE-irrigated plants. Salt-induced leaf chlorosis and necrosis was only evident on plants with no mulch and irrigated with two emitters. Under mulched soil, K, Na, Mg, Cl, electrical conductivity (ECe), and Na adsorption ratio (SAR) levels were several times lower and uniform throughout the soil profile compared to the non-mulched treatments. Maximum root-zone salinity was 3.7 dS·m−1 for two emitters without mulch and a minimum of 0.5 dS·m−1 for one emitter with mulch.
Quantifying Temperature-controlled Leaf Unfolding Rates in ‘Nellie White’ Easter Lily
Authors: Karlsson M.G. , Heins R.D. , Erwin J.E.
Published: August 2022

The rate of leaf unfolding was determined for Easter lily (Lilium longiflorum Thunb.) ‘Nellie White’ grown at day and night temperatures ranging from 14° to 30°C. In this temperature range, rate of leaf unfolding was a linear function of average daily temperature; i.e., the effect on rate of leaf unfolding for day temperature was the same as for night temperature. The function determined was: leaves unfolded per day = −0.1052 + (0.0940 × average daily temperature). Isopleth plots were developed to describe day and night temperatures required for specific rates of leaf unfolding under 8-, 10-, and 12-hr day temperature periods.
Influence of Photoperiod and Growth Regulators on Flowering of Rhipsalidopsis gaertneri
Authors: Boyle Thomas H. , Jacques Daniel J. , Stimart Dennis P.
Published: August 2022

Plants of Rhipsalidopsis gaertneri [Regel] Moran ‘Crimson Giant’ were given continuous 14-hr long-days (LD), provided by 8-hr daylight plus 6-hr incandescent (Inc) irradiation; continuous 8-hr short-days (SD), provided by daylight; 2, 4, 6, or 8 weeks SD, then LD; or 2, 4, 6, 8 weeks LD, then SD. All plants receiving continuous LD or 2, 4, 6, or 8 weeks SD then LD flowered, whereas some or all plants in other photoperiod regimes failed to flower. Earliest and most prolific flowering occurred in response to 4, 6, or 8 weeks SD then LD. In a second experiment, plants previously given 8 weeks of 8-hr daylight (SD) were transferred to one of the following photoperiods: 12-, 14-, 16-, or 20-hr (8 hr daylight plus = to 12-hr Inc irradiation); 8-hr daylight plus 4-hr Inc night interruption (NI); or 8-hr daylight (SD). All plants receiving photoperiods of 12 to 20 hr or 4-hr NI flowered. Days from start of photoperiod treatments to visible flower buds was inversely related to duration of the Inc irradiation period, with a 4-hr NI comparable to 16-hr day. Days required for visible flower buds to complete development (flower expansion) were largely unaffected by duration or timing of Inc irradiation. Application of BA delayed flowering but more than doubled the number of flower buds per flowering apical phylloclade. Flower bud abortion was increased and both flower fresh weight and flower diameter were diminished by BA. Application of STS did not reduce flower bud abortion on BA-treated plants, but increased the percentage of apical phylloclades flowering. Chemical name used: N-(phenylmethyl)-lH-purin-6-amine (BA), silver thiosulfate (STS).
Studies on Octylphenoxy Surfactants: V. Toxicity to Cowpea Leaves and Effects of Spray Application Parameters
Authors: Lownds N.K. , Bukovac M.J.
Published: August 2022

Surfactant toxicity was examined following application of octylphenol and linear alcohol surfactants to the adaxial surface of 10-day-old cowpea [Vigna unguiculata (L.) Walp. subsp. unguiculata ‘Dixielee’] leaves. Leaf damage first appeared as isolated discolored areas at the periphery of the droplet area, developed toward the center, and, when most severe, the entire droplet area was necrotic. Epidermal cells beneath the droplet area became discolored, lost structural integrity and collapsed. Similar changes were observed in the palisade layer and spongy parenchyma. In addition, walls of damaged cells were preferentially stained with Safranin O. For a given surfactant dose, phytotoxicity increased with increasing concentration, droplet volume, and temperature and decreased with increasing humidity. In general, phytotoxicity was inversely related to the length of the ethoxy (EO) chain for both the octylphenol (Triton X) and C12-15 linear alcohol (Neodol 25) surfactant series. Tissue did not recover after injury. Chemical names used: octylphenoxypoly(ethoxy)ethanol (Triton X-100), linear alcohol ethoxylate (Neodol 25-9).
Longevity of Pistachio Pollen Determined by in Vitro Germination
Authors: Polito Vito S. , Luza Juvenal G.
Published: August 2022

Pistachio (Pistacia vera L.) pollen was examined for capacity to germinate in vitro 2 days after anthesis and at intervals of time after storage at ambient laboratory conditions or at − 20°C. In 1986, fresh pollen of each of four clones examined had high germination percentages on a range of sucrose and agar concentrations. After 1 week at room temperature, germination percentages were < 6%. However, when the same week-old pollen was treated to effect gradual hydration at high humidity prior to being placed on the germination medium, germination increased to > 80% for ‘Peters’ pollen and 10.4% to 63.8% for the three other clones. In 1987, similar results were obtained for ‘Peters’ pollen, where pollen hydrated at high humidity had germination rates at least 50% that of fresh pollen when stored up to 18 days at ambient laboratory temperature and humidity. Pollen stored at −20° showed more exacting in vitro germination requirements than fresh pollen, particularly as time in storage increased. ‘Peters’ pollen retained germination levels comparable to fresh pollen after 4 months at −20°, but, by 12 months, germination percentages had fallen sharply.
Rooting Cofactors in Five Acer Species
Authors: Kling Gary J. , Meyer Martin M. , Seigler David
Published: August 2022

Methanolic extracts from leaves, young stems, and old stems of five Acer (maple) spp. were tested for their effects on adventitious root initiation in mung bean (Vigna radiata Wilcox’) cuttings. An extract from the leaves of A. ginnala strongly stimulated root initiation, and the active compounds in this fraction were not synergistic with IAA. This extract was more stimulatory than IAA on mung bean cuttings and stimulated root initiation in softwood cuttings of A. saccharinum and A. griseum. Preliminary characterization of this extract indicates that it is a phenolic compound and/or a weak acid. Chemical name used: 1H-indoIe-3-acetic acid (IAA).
Effects of Simulated Acid Rain on Cadmium Mobilization in Soils and Subsequent Uptake and Accumulation in Poplar and Sunflower
Authors: Gingas V.M. , Sydnor T.D. , Weidensaul T. Craig
Published: August 2022

Sunflower (Helianthus annuus L. ‘Mammoth’) and poplar (Populus × ‘Androscoggin’ H.) plants were grown in a medium containing one of five Cd concentrations, ranging from 0.13 to 13.20 μg·g−1 and watered with one of five simulated rain treatments (pH 3.2-5.2) to determine the effects of precipitation acidity on Cd mobilization and resulting effects on plant growth. Treatment rain acidity was insufficient to lower the medium solution pH to levels conducive to high Cd desorption. Plants accumulated < 1% of the total Cd applied (as CdCl2) for all Cd treatments. Root and foliar Cd concentrations increased with Cd treatment levels. Poplar accumulated proportionally more Cd in foliage than in roots for all treatments. Sunflower accumulated proportionally more Cd in leaves than in roots for the 0.29, 0.62, and 3.20 μg·g−1 Cd treatments and in roots for the 0.13 and 13.20 μg·g−1 Cd treatments. Cadmium treatments and Cd concentrations in the medium, roots, and foliage were not related to changes in plant dry weights, heights, or essential element concentrations in media, roots, or foliage of either species.