bluuebunny/crossref_metadata_2025 huggingface dataset:
Inheritance of Resistance to Neck-rot Disease Incited by Botrytis allii in Bulb Onions
Authors: Lin Mau-Wei , Watson James F. , Baggett James R.
Published: January 2019

The inheritance of resistance to neck rot, incited by Botrytis allii Munn, was studied in four crosses between resistant and susceptible bulb onion (Allium cepa L.) lines, one cross between two resistant lines, and one cross between two susceptible lines. Using tests of excised scale pieces inoculated with a spore suspension and incubated in plastic boxes at 20C for 6 days, parents, F1, F2, and backcrosses were assigned disease indices (DI) derived from infection severity scores of individual bulbs. Generation means and frequency distribution of DI indicated that inheritance was quantitative and mostly additive with a small amount of dominance for susceptibility. Estimates of gene effects using a three-parameter model also indicated that additive effects predominated, with some dominance and no epistasis. Broad-sense heritability estimates ranged from 42% to 63% in the resistant x susceptible crosses.
Genetic Relationships among Cultivars and Landraces of Lima Bean (Phaseolus lunatus L.) as Measured by RAPD Markers
Authors: Nienhuis James , Tivang Jan , Skroch Paul , dos Santos Joao B.
Published: January 2019

Knowledge of relative genetic distance among genotypes is useful in a breeding program because it permits organization of germplasm resources. Genetic distance (GD) was estimated among 65 Phaselous lunatus L.. accessions, which included 4 large-seeded and 7 small-seeded cultivars and 54 germplasm accessions (landrace's) from the Caribbean and North, Central, and South America. Based on 125 polymorphic random amplification polymorphic DNA (RAPD) bands, two major clusters, which generally correspond in seed size and geographic region to [be Mesoamerican and Andean gene pools, were observed among the landraces (GD = 0.726 ± 0.041). Four Fordhook cultivars and a landrace from the United States formed a separate cluster that is more distantly related to the small- (GD) = 0.561 ± 0.039) than to the large-seeded cluster (GD = 0.303 ± 0.022). The mean GD between the Andean and Mesoamerican (0.726), Mesoamerican and Fordhook (0.561), and Andean and Fordhook (0.303) clusters were all significant. The significant GD between the Andean and Mesoamerican groups supports the hypothesized existence of two major gene pools in lima bean. The RAPD marker diversity of the Mesoamerican group was the largest (0.1 10), followed by the Andean (0.097) and Ford hook (0.062) groups. The plot of the relationship between the coefficient of variation (cv) and sample size (number of bands) indicates that cvs as low as 10% for estimating CD between Andean and Mesoamerican lima bean accessions can be achieved by sampling as few as 100 bands.
Yield and Fruit Size Stability Differs among Bell Pepper Cultivars
Authors: Stoffella Peter J. , Locascio Salvador J. , Howe Teresa K. , Olson Steve M. , Shuler Kenneth D. , Vavrina Charles S.
Published: January 2019

Bell pepper (Capsicum annuum L.) cultivars were grown in nine Florida environments to evaluate phenotypic stability of marketable fruit yield (t-ha-') and mean fruit size (g/fruit). A stable cultivar excelled for a particular trait when grown in either favorable or unfavorable environments. A stable cultivar for a given trait was defined as one with an individual mean greater than the grand mean (mean of all cultivars) (x > X), a regression coefficient (b1) ≤ 1 (individual genotypic mean regressed against environmental means), nonsignificant deviation mean squares from regression (S2d), coefficient of linear determination (R2) > 0.50, and coefficient of variation (cv) < the pooled cv. `Ssupersweet 860', `Whopper Improved', and `Ranger' were stable for mean marketable fruit weights and fruit size, and `Ssupersweet 860' and `Whopper Improved' were stable for mean fruit size. Bell pepper cultivars were differentiated for phenotypic stability of yield and fruit size or adaptability to diverse environments. Therefore, through stability analyses, bell pepper plant breeders can identify cultivars or select advanced breeding lines that express adaptability for fruit yields or size to diverse environmental conditions or cultural practices.
Delay of Disease Development in Transgenic Petunia Plants Expressing Cucumber Mosaic Virus I17N-Satellite RNA
Authors: Kim Shin Je , Paek Kyung-Hee , Kim Byung-Dong
Published: January 2019

A cDNA clone of cucumber mosaic virus (CMV) 117 N-satellite RNA driven by the cauliflower mosaic virus (CaMV) 35S transcript promoter, was stably integrated into the genome of Petunia hybrida `Bluepicoti' tissues by Agrobacterium tumefaciens Ti plasmid-mediated transformation. Transgenic plants producing CMV satellite RNA showed delayed disease development when inoculated with CMV-Y, a helper virus for the I17N-satellite RNA. Furthermore, transgenic petunia plants showed delayed disease development against tobacco mosaic virus (TMV), a tobamovirus not related to CMV. Northern blot analysis revealed that large amounts of unit length satellite RNA (335 bp) were produced in CMV-infected transgenic petunia plants; whereas, mainly transcripts driven by the CaMV 35S promoter (approximately 1 kb) were produced in TMV-infected transgenic plants. SDS-PAGE and Western blotting showed that symptom reduction was correlated with a reduction in the amount of viral coat protein in transgenic plants.
The Effect of Temperature on Uptake of NAA by Redchief `Delicious' Apple Leaves
Authors: Black Brent L. , Petracek Peter D. , Bukovac Martin J.
Published: January 2019

The effect of temperature on uptake of C-labeled NAA was determined using detached apple leaves. Uptake by both adaxial and abaxial surfaces was measured at 15 and 35C over a 24-hotm period. Foliar absorption of NAA by the abaxial surface was greater than that by the adaxial surface. Absorption by the abaxial surface increased linearly (P < 0.001) with temperature over the range of 15 to 35C. These results are discussed in relation to fruit thinning. Chemical name used: 2-(1-naphthyl)acetic acid (NAA).
Regulation of Fermentative Metabolism in Avocado Fruit under Oxygen and Carbon Dioxide Stresses
Authors: Ke Dangyang , Yahia Elhadi , Hess Betty , Zhou Lili , Kader Adel A.
Published: January 2019

`Hass' avocado (Persea americana Mill.) fruit were kept in air, 0.25% O2 (balance N2), 20 % O2 + 80% CO2, or 0.25% O2 + 80% CO2 (balance N2) at 20C for up to 3 days to study the regulation of fermentative metabolism. The 0.25% 02 and 0.25% 02 + 80% CO2 treatments caused accumulations of acetaldehyde and ethanol and increased NADH concentration, but decreased NAD level. The 20% O2 + 80% CO2 treatment slightly increased acetaldehyde and ethanol concentrations without significant effects on NADH and NAD levels. Lactate accumulated in avocadoes kept in 0.25 % 02. The 80% CO, (added to 0.25% O2) did not increase lactate concentration and negated the 0.25% O2-induced lactate accumulation. Activities of PDC and LDH were slightly enhanced and a new isozyme of ADH was induced by 0.25% O2, 20% O2 + 80% CO2, or 0.25 % O2 + 80% CO2; these treatments partly reduced the overall activity of the PDH complex. Fermentative metabolism can be regulated by changes in levels of PDC, ADH, LDH, and PDH enzymes and/or by metabolic control of the functions of these enzymes through changes in pH, ATP, pyruvate, acetaldehyde, NADH, or NAD. Chemical names used: alcohol dehydrogenase (ADH), adenosine triphosphate (ATP), lactate dehydrogenase (LDH), nicotinamide adenine dinucleotide (NAD), reduced NAD (NADH), pyruvate decarboxylase (PDC), pyruvate dehydrogenase (PDH).
Sucrose Ester-based Coatings Formulated with Food-compatible Antioxidants in the Prevention of Superficial Scald in Stored Apples
Authors: Bauchot A.D. , John P. , Soria Y. , Recasens I.
Published: January 2019

Treatments were applied in Italy, United Kingdom, and Spain to test their effectiveness in controlling superficial scald in apples (Malus domestica Borkh.) after cold storage. In Italy where mature `Red Chief' and `Golden Delicious' were stored at 3-4C for 4 months, scald incidence was reduced by postharvest dipping in a sucrose-ester based coating, Semperfresh, formulated with the antioxidants, ascorbyl palmitate, and n-propyl gallate. In the United Kingdom and Spain, early harvested `Granny Smith' were stored at 0C for 4 and 6 months. In the United Kingdom, ascorbyl palmitate applied with Semperfresh significantly reduced scald upon withdrawal from 4 months of storage near 0C, but not after 10 days at room temperature. Bringing the apples to ambient temperature for 20 hours 1 month into cold storage reduced scald almost as much as diphenylamine application, but the beneficial effects seen after 4 months of cold storage did not persist after 6 months of storage. In Spain, controlled atmosphere storage (3% O2 + 3% CO2) was as effective as diphenylamine treatment, even after 6 months of storage; CaCl2 was slightly effective after 4 months of storage, but none of the coating treatments significantly reduced scald. Treatments applied after 6 weeks were ineffective.
Mitochondrial Self-restoration as an Index to the Capacity of Avocado Fruit to Sustain Atmospheric Stress at Two Climacteric States
Authors: Moriguchi Takaya , Romani Roger J.
Published: January 2019

A strong association is implicit between mitochondrial function and the energy demands of cells responding to stress. Yet, the dynamics of this organelle-cellular dependency have been difficult to resolve. This study examines a new diagnostic parameter namely, mitochondrial maintenance and self-restoration as exhibited by the course of respiratory functions (states 3 and 4 respiratory rates, respiratory control) of mitochoudria extracted during and after exposure of intact `Hass' avocado (Persea americana) fruit to different stress atmospheres: anoxia (100% N2) or high (25% and 75%) CO2 for varying durations. Comparisons are made with direct exposure of the mitochondria themselves to similar atmospheres. In general, exposure of the fruit to CO2 rich atmospheres enhanced the capacity of their mitochondria to restore energy-linked functions whereas anoxia caused irreparable damage. The physiological (climacteric) state of the fruit also affected the stress capacity of the mitochondria contained therein, anaerobiosis being more harmful to mitochondria in riper fruit. In contrast to their effects in vivo, in vitro anoxia appeared to sustain mitochondrial energy-linked functions, whereas high CO2 was clearly harmful. These and other observations are discussed in the context of mitochondrial self-restoration or homeostasis and its relevance to postharvest stress-atmosphere storage for purposes such as pathogen suppression or insect control.
Heritable Pleiotropic Effects of the Nectarine Mutant from Peach
Authors: Wen I-C , Sherman W.B. , Koch K.E.
Published: January 2019

Peach-to-nectarine mutations are associated with broad pleiotropic effects. The present study addresses the heritability of nectarine-specific effects in three hybrid families. A comparison of peach and nectarine siblings showed that nectarine fruit were smaller (less fresh weight), rounder, darker, redder, and had higher levels of sugars and organic acids. These heritable characteristics are similar to effects of spontaneous peach-to-nectarine mutations described previously.
Characterizing and Quantifying Anthocyanins in Red Pears and the Effect of Light Quality on Fruit Color
Authors: Dussi Maria Claudia , Sugar David , Wrolstad Ronald E.
Published: January 2019

The anthocyanin in `Sensation Red Bartlett' pear skin was characterized and quantified, and the effect of light quality on fruit color development was evaluated. Anthocyanin concentration was related to fruit chromaticity values. Pigments were analyzed using high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). One of two spots detected in the TLC chromatogram did not change color with molybdate sprays, indicating the possible presence of peonidin. HPLC analysis confirmed the presence of a major and a minor pigment, which co-eluted with cyanidin 3-galactoside and peonidin 3-galactoside. Monomeric anthocyanins in the pear skin extract were 6.83 mg/100 g of fruit peel. To study light quality, gelatin filters allowing passage of different wavelengths of-light were attached over the exposed side of `Sensation Red Bartlett' pears 1 month before harvest. Chromaticity was recorded before the filters were attached and after their removal at harvest using the Commission Internationale del'Eclairage (L*, a*, and b*) color space coordinates. Following color measurements, anthocyanin was extracted from individual skin disks. Skin beneath all filters yielded less hue than the control. Wavelengths that transmit above 600 nm had the largest effect on chroma, a*, and b* values. Fruit wrapped in aluminum foil to obscure all light had the highest luminosity. Wavelengths from 400 to 500 nm gave darker, less chromatic, and redder pear fruit. All treatments yielded higher anthocyanin content than the control. There was a tendency toward increased anthocyanin content with longer wavelengths. The simple linear regression of the log anthocyanin content on L* value and (a*/b*) provided an R2 = 0.41.
Injury and Yield of Leafhopper-infested Dry Beans
Authors: Lindgren Dale T. , Coyne Dermot P.
Published: January 2019

Differences in potato leafhopper (Empoasca fubae Harris) injury symptoms were noted in 22 cultivars or lines of dry beans (Phaseolus vulgaris L.) in a 1991 field trial at North Platte, Neb. Seed yield, biomass, and plant injury symptoms were recorded. The same 22 dry bean cultivars or lines were planted in a split-plot design, with main plots protected (sprayed with insecticide) vs. unprotected (not sprayed) and cultivars or lines as subplots in 1992 and 1993. Significant differences were observed between cultivars/lines for leafhopper injury and yield in all 3 years. `Tacaragua' (black-seeded) and pinto `Sierra' were highly resistant to leafhoppers, with no visual leafhopper injury symptoms in all 3 years. Significant negative correlation coefficients between leafhopper injury symptoms and yield were recorded in the protected (4.50) and unprotected (-0.33) plots in 1993 but only in the unprotected (-0.46) plots in 1992. A cultivar x spray interaction response to leafhoppers occurred in 1992 but not in 1993. The degree of leafhopper injury symptoms varied between years.
Evaluating Analytical Procedures for Quantifying Ammonium in Leaf Tissue
Authors: Ali Anwar G. , Lovatt Carol J.
Published: January 2019

The effects of different methods of sample preparation, extraction, and storage on the recovery of the combined pool of ammonia plus ammonium (NH3 + NH4+) from `Washington' navel orange leaves previously incubated in solutions of increasing NH4 Cl concentrations were assessed. Procedures and instruments for quantifying NH3 + NH4+ were tested for their sensitivity, reproducibility, and freedom from interference by amino acids. Reliable recoveries of NH3 + NH4+ free from amino acid interference, were obtained with oven-dried (60C) leaves ground to pass through a 40-mesh screen, extracted by homogenization in 10% TCA or by shaking in 2% acetic acid, and then filtered and analyzed on the basis of differences in electrical conductance between the sample and the reference cell. Methods measuring NH3 + NH4+ in KCl extracts by reaction with salicylate-nitroprusside in the presence of hypochlorite were compromised by significant color formation due to amino acids. Using fresh or freeze-dried leaf samples resulted in lower recoveries than use of oven-dried samples. Storage at -20C of fresh or oven-dried leaf samples in 10% TCA before or after homogenization and filtration did not alter NH3 + NH4+ levels, whereas storage of these samples at 4C increased NH3 + NH4+ levels.
Variation in the Quercetin Content in Different Colored Onions (Allium cepa L.)
Authors: Patil Bhimanagouda S. , Pike Leonard M. , Yoo Kil Sun
Published: January 2019

The aglycone, or free quercetin, and total quercetin content of 75 cultivars and selections was analyzed by reverse-phase high-performance liquid chromatography. Quercetin glycosides were hydrolyzed into aglycones. Total quercetin content in yellow, pink, and red onions varied from 54 to 286 mg·kg-1 fresh weight in different onion entries grown during 1992. White onions contained trace amounts of total quercetin. Free quercetin content in all the onions was low (< 0.4 mg·kg-1) except in `20272-G' (12.5 mg·kg-1 fresh weight). Bulbs stored at 5, 24, and 30C and controlled atmosphere (CA) for 0,1,2,3,4, and 5 months showed a most marked change in total quercetin content at 24C compared to other treatments, with a rise in mid-storage followed by a drop. Storage at 5 and 30C also demonstrated a similar change. However, total quercetin content did not vary significantly in bulbs stored at CA for 5 months. We conclude that genetic and storage factors affect quercetin content on onions.
The Effect of Irradiance, Defoliation, and Bulb Size on Flowering of Nerine bowdenii W. Watson (Amaryllidaceae)
Authors: Theron K.I. , Jacobs G.
Published: January 2019

Large Nerine bowdenii bulbs (>14 cm in circumference) were exposed to low ligbt intensities for different periods during two successive growing seasons. The flowering percentage and number of florets in the current season's inflorescence were recorded at anthesis. Small and large bulbs were subjected to continual defoliation starting at different times during the growing season. Bulbs were dissected at planting (26 Sept. 1992) and on 12 Jan. 1993 (nondefoliated control bulbs) to determine growth and developmental stage. At anthesis, inflorescences were harvested and the florets per inflorescence were counted. After anthesis in the fall, all bulbs were dissected and the following variables recorded: 1) percentage flowering, quiescence, or abortion of the current season's inflorescence; 2) developmental stage of quiescent inflorescences; 3) number of florets in the outermost inflorescence; 4) developmental stage of the innermost inflorescence; 5) number of leaves or leaf bases in each growth unit; 6) number of daughter bulbs; and 7) dry weight of new leaf bases. There were three reasons for nonflowering of the bulbs, viz., failure to initiate an inflorescence, inflorescences remaining quiescent, and inflorescence abortion. Individual florets that had not reached stage “Late G” (gynoecium elongated, carpels fused) at the start of rapid inflorescence elongation aborted. The more florets that aborted, the greater the probability that the entire inflorescence aborted. The inflorescence was more vulnerable to stress during the first half of the growing season due to its relatively weak position in the hierarchy of sinks within the bulb.
Optimum O2 or CO2 Atmosphere for Storing Broccoli Florets at Various Temperatures
Authors: Izumi Hidemi , Watada Alley E. , Douglas Willard
Published: January 2019

`Marathon' broccoli (Brassica oleracea L. var. italica) florets were stored in air, low O2(0.25%, 0.5%, and 1 %) or high CO2(3%,6%, and 10%) at 0, 5, and 10C. Oxygen consumption and CO2 production were reduced under low O2 or high CO2atmosphere, the reduction being greater at lower O2 and higher CO2 levels. No differences were found in ethylene production among the different atmospheres. Low O2 and high CO2 retained color of broccoli florets to about the same extent at 10C but had no effect at 0 and 5C. Development of soft rot and browning was suppressed by low O2 or high CO2, but offensive off-odor occurred in 0.25%02 at all temperatures and 0.5% O2 at 10C. These results indicate that the best O2 and CO2 levels seem to be 0.5% O2 and 10% CO2 at 0 and 5C, and 1% O2 and 10% CO2 at 10C.
Avocado Fruit Skin Fluorescence following Hot Water Treatments and Pretreatments
Authors: Woolf Allan B. , Laing William A.
Published: January 2019

Longitudinal halves of freshly harvested avocado fruit (Persea americana Mill. `Hass') were pretreated at 38C for 1 hour in a water bath, while the other half remained at 20C in air. Then the entire fruit was either treated from 1 to 10 minute at 50C, or held at 20C (controls). Fruit quality (daily evaluation of browning and internal quality when ripe), and pulse amplitude modulated (PAM) fluorescence measurements, were made on the skin of each fruit half 1 hour after hot water treatment (HWT), 3 hours later, and each subsequent day until ripening. The pretreated half of the fruit showed almost no development of external browning during the ripening period, while the nonpretreated halves were severely damaged by HWTs. External browning increased with longer HWT duration. Heat damage was also evident as hardening of the skin when fruit ripened, and such damage was reduced by pretreatment and increased with longer HWT duration. HWT had a rapid and marked effect on chlorophyll fluorescence (Fv/FM ratio) of avocado skin. Whereas fluorescence of control fruit remained constant over the first 5 days, in both pretreated and nonpretreated fruit, within 1 hour of HWT, the Fv/FM ratio had dropped to near minimal levels, with little further change. The value of Fv/FM 3 to 6 hours after the HWT was directly related to the duration of the HWT (P <0.0001). Although pretreatment almost eliminated browning, little effect of pretreatment could be detected in the Fv/FM ratio. There was a strong negative correlation (r = 0.93, P < 0.0001) between external browning and Fv/FM for nonpretreated fruit, but this correlation was not significant for pretreated fruit. We conclude that chlorophyll fluorescence clearly reflects effects of heat on the photosynthetic systems in avocado fruit, but does not detect the alleviation of heat damage by pretreatments.
Influence of Variation in Plant Characteristics Caused by Bulb Weight on Inflorescence and Individual Flower Longevity of Asiatic Hybrid Lilies after Harvest
Authors: van der Meulen-Muisers José J.M. , van Oeveren Joop C.
Published: January 2019

Nongenetic variation in cut flower longevity due to plant characteristics was investigated in whole inflorescences and individual flowers of Asiatic hybrid lilies (Lilium L.). To distinguish this variation from genetic variation, plant characteristics of five cultivars were varied by using bulbs of three significantly different weight classes per cultivar. Inflorescence longevity depended on total number of floral buds, number of buds opening and variation in bud length. Variation in individual flower longevity per cultivar appeared to be small, despite a larger number of buds per stem with increasing bulb weight. Plant characteristics caused only small nongenetic variation in individual flower longevity when compared to inflorescence longevity. Therefore, individual flower longevity appears to be the best criterion to discriminate among longevity levels for a lily breeding program.
Clone × Environment Interactions for Yellow-flesh Intensity in Tetraploid Potatoes
Authors: Haynes Kathleen G. , Sieczka Joseph B. , Henninger Melvin R. , Fleck Diane L.
Published: January 2019

For the yellow-flesh fresh market, potato (Solanum tuberosum L.) cultivars with intense yellow-flesh are desired. The effects of clone, environment and clone × environment interactions on the intensity of the yellow-flesh trait in tetraploid potatoes were investigated. Twenty-four yellow-flesh clones, including 23 USDA selections and the check cultivar Yukon Gold, were evaluated for tuber yellow-flesh color as measured by a reflectance colorimeter in replicated field trials in Presque Isle, Maine in 1991 and 1992, and in Riverhead, N.Y., and Bridgeton, N.J., in 1992 and 1993. There were significant differences among environments and among clones for yellow-flesh intensity. The clone × environment interaction was also significant. Broad-sense heritability of yellow-flesh intensity was estimated as 0.93 with a 95% confidence interval of 0.92-0.97. The instabilities noted in some of these clones, although statistically significant, are of limited practical concern. The intensity of yellow-flesh will be an important trait for breeders to select in developing new yellow-flesh cultivars. However, in testing yellow-flesh clones for future cultivar release, the role of environment and clone environment interactions on other agronomic traits will probably be more important than the environment and clone environment interactions on the intensity of yellow-flesh.
Senescence in Parental and F1 Plants of a shrunken2 Sweet Corn
Authors: Russo V.M.
Published: January 2019

Senescence occurs at the cellular and tissue levels. It is under genetic and environmental control and factors affecting initiation and speed of development of senescence can be passed from parental to F1 plants. This study was conducted in the greenhouse and field to determine how senescence patterns in F1 plants of a shrunken2 sweet corn (Zea mays L.) hybrid compared to those of parental inbreds. Greenhouse grown plants were left intact and field grown hybrids and parental inbreds had one or both reproductive organs removed or were left intact. Senescence patterns in stalk internodes were similar in greenhouse and field grown F1 and inbred plants. Senescence patterns in shank internodes in greenhouse grown plants were different from those of field grown plants. Senescence ratings in stalks increased as developmental stage advanced. Expression of stalk senescence in internodes below the node bearing ears appears to be suppressed by hybrid vigor. In field tests, destruction of the tassel before expansion (decapitation) appears to suppress senescence in internodes above I7, with this effect somewhat dependent on plant developmental stage.
Characterizing the Novel Fruit Surface Morphology of `Marina' Peach Using Scanning Electron Microscopy
Authors: Creller Michael A. , Werner Dennis J.
Published: January 2019

Scanning electron microscopy (SEM) was used to compare the novel surface morphology of `Marina' peach [plant introduction (PI) 133984] to a normal peach (`Contender') and a nectarine (`Sunglo'). Samples were collected before, during, and after anthesis. Compared to `Contender', `Marina' showed different trichome structure, lower trichome density, and delayed initiation of trichomes on the gynoecium. No pubescence was observed on `Sunglo' nectarine at any sampling date. Trichomes were present on the flower bud scales of all three cultivars. Arrangement and structure of trichomes on flower bud scales of `Marina' differed from those on `Contender' and `Sunglo'.
Postharvest Longevity of Cut-flower Gerbera. I. Response to Selection for Vase Life Components
Authors: Wernett Heidi C. , Sheehan Thomas J. , Wilfret Gary J. , Marousky Francis J. , Lyrene Paul M. , Knauft David A.
Published: January 2019

A broad source of Gerbera × hybrida Hort. germplasm was evaluated for vase life. Senescence mode, i.e., bending or folding of stems or wilting of ligulae was also recorded for flowers evaluated. Intensive selection was practiced to improve vase life. About 10% of the plants from a sample population were selected for having flowers with high vase life. Progeny means for vase life resulting from a topcross between these plants and `Appleblossom' were used to select five plants (about 1.5% of the sample population) whose flowers had high vase life. A diallel cross using these five plants as parents resulted in a progeny population with an increase in mean vase life of 3.4 days compared to mean vase life for the initial sample population. Increases in vase life means for days to bending, folding, and wilting were 0.3, 3.5, and 1.2 days, respectively. Plants with flowers which senesced due to wilting had the longest mean vase life before and after breeding. Changes in proportion of senescence modes were observed; bending decreased, folding and wilting increased. Frequencies of bending, folding, and wilting were compared to vase life means for 10 progenies. Proportion of bending generally decreased as vase life increased.
Cold Hardiness of Evergreen Azaleas Is Increased by Water Stress Imposed at Three Dates
Authors: Anisko Tomasz , Lindstrom Orville M.
Published: January 2019

The effect of water stress imposed at three dates in late summer and early fall on cold hardiness was examined in Rhododendron L. `Coral Bell', `Hinodegiri', and `Red Ruffle'. The persistence of the water stress-induced cold hardiness was also examined following plant recovery from the stress. Container-grown plants were exposed to three weeks of reduced water supply starting 8 Aug., 29 Aug., or 19 Sept., while control plants were well watered. Cold hardiness of leaves, lower, middle, and upper stems was evaluated with laboratory freeze tests. Reduced water supply independent of time initiated increased cold hardiness by 1 to 4C in the majority of the tested plant parts in the three cultivars. Cold hardiness of all plant parts tested strongly depended on the current water status of the plants as indicated by the stem water potential. In most cases, 3 weeks after rewatering, the cold hardiness of previously water stressed plants did not differ from that of nonstressed plants.
Low-oxygen Atmosphere Increases Fructose 2,6-bisphosphate in Fresh-cut Carrots
Authors: Kato-Noguchi Hisashi , Watada Alley E.
Published: January 2019

This study was undertaken to determine the effect of low-O2 atmosphere on the concentration of fructose 2,6-bisphosphate (Fru-2,6-P2), which can activate the enzyme pyrophosphate-dependent:phosphofructokinase (PPi-PFK) to catalyze the reaction from fructose 6-phosphate to fructose 1,6-bisphosphate (Fru-1,6-P2). Fru-2,6-P2 remained unchanged in carrot (Daucus carota L.) root shreds stored under air, but it increased 3.0- and 5.3-fold at 2% and 0.5% O2 atmosphere, respectively, at 5C, and the increases were almost twice as great at 15C. The concentration of PPi ranged from 17 to 33 nmol·g-1 fresh weight, which is more than sufficient for the PPi-PFK to proceed. Thus, low-O2 atmosphere appeared to hasten glycolysis of carrot shreds by increasing Fru-2,6-P2, which activated PPi-PFK toward glycolysis.
Bloom Thinning `Loadel' Cling Peach with a Surfactant
Authors: Southwick Stephen M. , Weis Kitren G. , Yeager James T.
Published: January 2019

Hand thinning fruit is required every season to ensure large fruit size of `Loadel' cling peach [Prunus persica (L.) Batsch] in California. Chemical thinning may lower costs of hand thinning. A surfactant, Armothin {[N,N-bis 2-(omega-hydroxypolyoxyethylene/polyoxypropylene) ethyl alkylamine]; AKZO-Nobel, Chicago; AR}, was sprayed at 80% of full bloom (FB), FB, and FB + 3 days. The spray volume was 935 liters/ha. Concentrations of AR were 1%, 3%, and 5% (v/v). An early hand thinning in late April, a normal hand thinning at 13 days before standard reference date (early May), and a nonthinned control were compared to bloom-thinned trees for set, yield, and fruit quality. AR resulted in no damage to fruit; however, slight leaf yellowing and burn and small shoot dieback were seen at the 5% concentration. Fruit set, and therefore, the number of fruit that had to be hand thinned, were reduced with 3% AR applied at 80% FB and 5% AR applied at all bloom phenophases (stages of bloom development). Thinning time was reduced by 37% (5% AR applied at 80% FB), 28% (5% applied at FB), and by 20% (3% applied at 80% of FB), compared to the normally hand-thinned control. Although AR resulted in early size (cross suture diameter and weight) advantages, at harvest there were no significant differences in fruit size among all AR treatments and the normally hand-thinned control. Total and salable yields of AR treatments and the normally hand-thinned control were equal. Armothin shows promise for chemical thinning of peach when used as a bloom thinner.
Long-term Effects of Propagation by Tissue Culture or Softwood Single-node Cuttings on Growth Habit, Yield, and Berry Weight of `Northblue' Blueberry
Authors: El-Shiekh Ahmed , Wildung David K. , Luby James J. , Sargent Kay L. , Read Paul E.
Published: January 2019

Plants of `Northblue' blueberry, propagated in tissue culture (TC) or from softwood, single-node cuttings (ST), were evaluated in field plantings established in 1984 at Becker and Grand Rapids, in central and northern Minnesota, respectively. Plantings were observed from 1987 through 1994 to determine the persistence of such effects as increased vigor, more spreading growth habit, and higher yield observed for TC plants during the initial 3 years after planting. TC plants had significantly higher yields at Grand Rapids in 1989 and 1994. At Grand Rapids, the consistently greater plant spread (bearing area) of TC plants resulted in higher yields of TC plants over all years combined. At Becker, TC and ST plants did not differ for plant height or spread after 10 years and, in 2 of 5 years, ST plants had heavier average berry weights. At Grand Rapids, TC plants did not differ consistently in height, or subjective ratings of the amount of bloom or crop. The effects of propagation method on yield and growth habit of `Northblue' are limited to early years in warmer locations, but can be of longer-term significance in colder areas with shorter growing seasons and lower winter temperatures, where plant spread is a more important factor than plant height in determining yield.
Randomly Amplified Polymorphic DNA Loci from a Walnut Backcross [(Juglans hindsii × J. regia) × J. regia]
Authors: Woeste Keith , McGranahan Gale H. , Bernatzky Robert
Published: January 2019

Twenty-five random decamer primers were used to evaluate the level of polymorphism between Persian walnut and the Northern California black walnut. Sixty-six randomly amplified polymorphic DNA (RAPD) markers were identified using an interspecific walnut backcross population [(Juglans hindsii × J. regia) × J. regia]. Segregation data from these polymorphisms were joined to a previously published set of restriction fragment-length polymorphism (RFLP) marker data to expand the genetic map of walnut to 107 markers in 15 linkage groups.
Percent Drupelet Set Varies among Blackberry Genotypes
Authors: Strik Bernadine , Mann Juliet , Finn Chad
Published: January 2019

Twenty-one genotypes of blackberry (Rubus L. subgenus Rubus Watson) were evaluated for percent drupelet set in 1993 and eleven genotypes were evaluated in 1994. Commercial cultivars were chosen to represent types (trailing, erect, and semi-erect) of blackberries grown in the United States. Secondary fruit were picked when green but developing a red blush during the early- and late-ripening season. Drupelets and pistils per fruit were counted to calculate percent set. In 1994, ripe fruit ranging in size were harvested for `Boysen', `Marion', `Thornless Evergreen', and `Chester Thornless' and drupelet per fruit were counted. Drupelet set among genotypes ranged from 40% to 86% in 1993 and 39% to 78% in 1994. Most genotypes had a higher percent set on early flowers compared to later ones. Drupelet set and number were not correlated with fruit weight among genotypes. In `Boysen', `Marion', `Thornless Evergreen', and `Chester Thornless', drupelet number was correlated with fruit weight, although the relationship in `Chester Thornless' was not as strong as the others. It is unclear what factors limit drupelet set in the genotypes studied.
Physical Characteristics of Mature Green and Ripe Tomato Fruit Tissue of Normal and Firm Genotypes
Authors: Wann E.V.
Published: January 2019

Tissue firmness of ripe tomatoes is controlled by cell wall integrity of the fruit tissue and by the enzymatic softening that normally occurs during ripening. This study was conducted to determine the physical characteristics of cells and tissues of mature green (MG) and ripe fruit that might account for differences in firmness between `Rutgers' (normal), `Flora-Dade' (Firm), and two mutant lines called high-pigment (T4065 hp) and dark-green (T4099 dg), both of which possess extra firm fruit. Fruit samples were tested for resistance to a force applied to whole fruit and to sections of the pericarp tissue and by stress-relaxation analysis. Determinations were also made of cell density and cell wall content within the pericarp tissue. Fruit of mutant lines had firmer tissue than either `Rutgers' or `Flora-Dade' at MG or ripe. Whole fruit compression measurements showed that T4099 dg was firmer than T4065 hp or `Rutgers' at MG and firmer than `Flora-Dade' and `Rutgers' when ripe. Whole fruit of `Flora-Dade' were significantly firmer than `Rutgers' at MG and ripe. Firmness measured by compressive strength also showed that mutant lines had firmer pericarp tissue than the wild types at both MG and ripe stages. Stress-relaxation analysis showed that MG fruit of T4099 dg had greater tissue elasticity than `Rutgers' or `Flora-Dade'. Ripe fruit of both mutant lines had more tissue elasticity than wild types. There were no apparent differences among the genotypes due to tissue relaxation. From these analyses, tissue elasticity appears to be a significant parameter in determining tissue firmness in the tomato genotypes used in this study. Firmness and textural quality of ripe tomatoes appeared to be dependent on elasticity of the pericarp tissue and on the level of enzymatic softening during ripening.
Field Testing Bacterial Wilt-resistant Tomato Somaclones
Authors: Bobisud Carol A. , Martin Susan P. , Sekioka Terry T.
Published: January 2019

`Healani' tomato (Lycopersicon esculentum Mill.) somaclones were tested in a bacterial wilt (Pseudomonas solanacearum E.F. Smith) infected field. Survival percentages of selected somaclonal lines were from 40% to 100%, while the original `Healani' had a survival rate of 0% and resistant `Kewalo' had 30%. Eighteen bacterial wilt resistant somaclonal lines were selected and tested for retention of horticultural characters in a noninfected field. `Healani' significantly outyielded all tested somaclonal lines in total fruit weight and total number of fruit per plant. `Healani' had greater fruit diameter than seven of the lines, greater width of the outer wall of the fruit pericarp than seventeen of the lines, and fewer locules in the fruit than seven of the lines.
Using a Porous-tube System to Study Potato Responses to Constant Water Tension in a Rooting Matrix
Authors: Cao Weixing , Tibbitts Theodore W.
Published: January 2019

A system maintaining continuous water tension on a nutrient solution has been developed to control root zone moisture levels for plants in microgravity conditions. This study was conducted in a growth chamber to characterize potato (Solanum tuberosum L.) responses to constant water tension compared to plants grown with no tension using a free-water technique. In three separate experiments, plants were grown in trays filled with a 4-cm layer of 1-mm-diameter isolite (porous ceramic) particles. Ten porous stainless-steel tubes, 4 cm apart, were buried in the medium, and nutrient solution was drawn through the porous tubes under a constant water tension of -0.5 kPa maintained with a siphon system. For the free-water treatment, trays were slanted, and solution was supplied along the upper end of trays, passed under the medium, and then collected at the lower end and recirculated. The same nutrient solution was recirculated through both treatments at a flow rate of 150 ml·min-1 through each tray and maintained at a pH of 5.6. Uniform micropropagated `Norland' potato plantlets were transplanted into replicate trays and maintained at 18C, 70% relative humidity, and a continuous photosynthetic photon flux (PPF) of 450 μmol·m-2·s-1. Water tension reduced total plant dry weight, leaf area, leaf number, and stolon number by >75%, but specific leaf weight increased compared to free water. However, tubers enlarged more rapidly with water tension, and plants consistently partitioned a greater fraction of biomass into tubers (than into shoots). Tuber weight was greater with water tension than in the free-water culture in Expt. 1 harvested 37 days after transplanting, however it was less in Expt. 2 when plants were grown to a larger size for 52 days before harvest. Leaf CO2 assimilation rate, stomatal conductance, and transpiration were reduced with water tension, although the relative water content of leaves was not significantly affected. Also, with water tension, concentrations of N, P, Zn, and Cu in leaf tissues decreased, whereas tissue Fe increased compared to plants grown with free water. The results in this study demonstrate that constant water tension significantly affects potato plant growth and shifts biomass partitioning toward tubers.
Iron Deficiency Stress Influences Physiology of Iron Acquisition in Marigold (Tagetes erecta L.)
Authors: Albano Joseph P. , Miller William B.
Published: January 2019

Excised roots of `First Lady' marigold (Tagetes erecta L.) grown in an aerated 0 Fe nutrient solution had Fe(III)-DTPA reductase activity 14-fold greater, and an enhanced ability to acidify the rhizosphere than plants grown in a solution containing 0.018 mm (1 ppm) Fe-DTPA. Reductase activity and rhizosphere acidification of plants grown in 0.018 and 0.09 mm Fe-DTPA were similar. Manganese concentration in leaves of plants grown in the 0 Fe treatment was 2-fold greater than in leaves of plants grown in the 0.018 mm Fe-DTPA treatment. These results indicated that `First Lady' marigold is an Fe-efficient plant that possesses both an inducible or adaptive reductase system and the ability to acidify the rhizosphere, and that these Fe-efficiency reactions do not occur when Fe is sufficient. Chemical name used: ferric diethylenetriaminepentaacetic acid, monosodium salt (Fe-DTPA).
Sugar Accumulation Enhanced by Osmoregulation in Satsuma Mandarin Fruit
Authors: Yakushiji Hiroshi , Nonami Hiroshi , Fukuyama Toshio , Ono Sukeyuki , Takagi Nobuo , Hashimoto Yasushi
Published: January 2019

The effect of water stress induced to enhance sugar accumulation in Satsuma mandarin (Citrus unshiu Marc.) fruit was investigated. Satsuma mandarin trees were subjected to water stress using mulch cultivation from late August to early December. In mulch treatment, soil was covered with double-layered plastic sheets that prevented rainfall from permeating the soil, but allowed water from soil to evaporate. The water status of soil, fine roots, pericarps, and juice vesicles was determined using the isopiestic psychrometer. As the severity of water stress increased, both water potential and osmotic potential of fine roots and pericarps significantly decreased in plants grown under mulch cultivation compared to well-watered trees. Although water potential and osmotic potential decreased, turgor of both roots and pericarps of the water stressed trees did not decrease under water stress conditions. Because turgor was maintained, osmoregulation occurred in Satsuma mandarin trees in response to water stress. The osmotic potential of juice vesicles in water-stressed fruit gradually decreased, and sugars accumulated in vesicle cells. Concentrations of sucrose, fructose, and glucose increased in fruit sap under water stress, and the acidity in the fruit juice increased. Furthermore, the total sugar content per fruit of water stressed trees was significantly higher than in fruit of well-watered trees. These results suggest that sugar accumulation in Satsuma mandarin fruit was not caused by dehydration under water stress but rather that sugars were accumulated by active osmoregulation in response to water stress. When sugar components in osmoregulated fruit were analyzed, it was found that monosaccharides, i.e., glucose and fructose, were largely responsible for active osmoregulation in fruit under water stress conditions.
Photosynthetic Photon Flux, Photoperiod, and Temperature Effects on Emissions of (Z)-3-hexenal, (Z)-3-hexenol, and (Z)-3-hexenyl Acetate from Lettuce
Authors: Charron Craig S. , Cantliffe Daniel J. , Wheeler Raymond M. , Manukian Ara , Heath Robert R.
Published: January 2019

To investigate the effects of environment on plant volatile emissions, `Waldmann's Green' leaf lettuce was cultivated under different levels of photosynthetic photon flux (PPF), photoperiod, and temperature. A modified growth chamber was used to sample plant volatile emissions nondestructively, over time, and under controlled conditions. Total volatile emission rates were significantly higher from lettuce cultivated under PPF of 360 or 200 μmol·m-2·s-1 compared to 105 μmol·m-2·s-1, and significantly higher under a 16-h photoperiod than an 8-h photoperiod. No differences were detected among emission rates from different temperature treatments. In controlled environments, emissions could be regulated by adjusting environmental conditions accordingly.
The Influence of Foliar-applied Urea Nitrogen and Saline Solutions on Net Gas Exchange of Citrus Leaves
Authors: Romero-Aranda R. , Syvertsen J.P.
Published: January 2019

We compared net gas exchange rates of CO2 and H2O vapor of greenhouse-grown `Duncan' grapefruit (Citrus paradisi Macf.) and `Valencia' orange [C. sinensis (L.) Osbeck] leaves after multiple foliar sprays of urea N with and without NaCl: CaCl2 solutions. Highly saline solutions (3.8 dSm-1) caused necrotic burn symptoms after leaf chloride levels reached 7 mmol·m-2. Grapefruit leaves had higher leaf Cl and more burn symptoms than orange leaves. The remaining green areas of all salt-stressed leaves, however, had similar rates of net CO2 assimilation (ACO2) and stomatal conductance (gs) as water-sprayed control leaves. Total leaf N and chlorophyll increased with repeated foliar applications of urea solutions regardless of salinity levels in the spray solution. Thus, salts in solution did not interfere with foliar absorption of N. High urea N solutions (33.6 g·liter-1) without salts caused foliar burn and leaf abscission after one application. Three sprays of urea-N solution (11.2 g·liter-1) increased N concentration of N-deficient leaves about 60% and increased ACO2 rate about 50%. ACO2 did not increase when nitrogen concentration in leaves exceeded a threshold value of about 200 mmol·m-2 so photosynthetic nitrogen use efficiency (PNUE = ACO2/N) decreased with increasing leaf N concentration. Net gas exchange and PNUE was higher for grapefruit than for orange leaves. Leaf Cl levels from foliar-applied salts may not be as detrimental to leaf gas exchange as Cl from salts in soil-applied irrigation water.
In vitro Tomato Fruit Cultures Demonstrate a Role for Indole-3-acetic Acid in Regulating Fruit Ripening
Authors: Cohen Jerry D.
Published: January 2019

An in vitro system was used for the production of tomato (Lycopersicon esculentum) fruit in culture starting from immature flowers. This system produced small parthenocarpic (seedless) fruit in response to 10-4m indole-3-acetic acid (IAA) supplied in the medium. Other auxins, auxin conjugates and antiauxins tested were not effective or produced markedly fewer fruit. Additional IAA supplied to the fruit culture media before breaker stage resulted in an increase in the time period between breaker and red-ripe stages from 7 days without additional IAA to 12 days when 10-5m IAA was added. These results suggest that significant changes in the ripening period could be obtained by alteration of auxin relationships in tomato fruit.