bluuebunny/crossref_metadata_2025 huggingface dataset:
Relative Performance of Strawberry Genotypes over Four Cycles of Cultivation on Fumigated and Nonfumigated Soils
Authors: Shaw Douglas V. , Larson Kirk D.
Published: January 2019

Yield and fruit size were determined for 49 strawberry (Fragari ×ananassa Duch.) genotypes during a 7 year period, in soils prepared with and without preplant soil fumigation using 2 methyl bromide: 1 chloropicrin (wt/wt). Strawberries were grown in alternate years, with the nonfumigated treatment representing the first, second, third, and fourth strawberry crop cycles initiated without soil fumigation. Highly significant (P < 0.01) effects of soil fumigation treatment were present for yield in a combined analysis over all years; fumigation increased yield by 41% over nonfumigated soils in the first nonfumigated cultivation cycle and by 68% to 74% for subsequent nonfumigated cycles. Fruit size was less affected by soil treatment but increases due to fumigation (2% to 18%) were significant (P < 0.05) in the third or fourth nonfumigated crop cycle. Genotypic variances were highly significant in the combined analysis, whereas geneti × fumigation interaction variances were significant only for fruit size and contributed <8% of the total phenotypic variance for either trait. Genetic correlations were rg = 0.77 and 0.92, respectively, for yield and fruit size treated as independent traits across soil fumigation environments. There was no evidence for genes that confer specific adaptation to nonfumigated soils, or that these genes emerge as important contributors to the phenotypic variation as the soil environment deteriorates with repeated cultivation of strawberry in nonfumigated soil. Chemical names used: trichloronitromethane (chloropicrin).
Nuclear DNA Contents of Phalaenopsis sp. and Doritis pulcherrima
Authors: Lin Sandy , Lee Hsiao-Ching , Chen Wen-Huei , Chen Chi-Chang , Kao Yen-Yu , Fu Yan-Ming , Chen Yao-Huang , Lin Tsai-Yun
Published: January 2019

Nuclear DNA contents were estimated by flow cytometry in 18 Phalaenopsis Blume species and Doritis pulcherrima Lindl. DNA amounts differed 6.07-fold, from 2.74 pg/diploid nuclear DNA content (2C) in P. sanderiana Rchb.f. to 16.61 pg/2C in P. parishii Rchb.f. Nuclear DNA contents of P. aphrodite Rchb.f. clones, W01-38 (2n = 2x = 38), W01-41 (2n = 3x = 57), and W01-22 (2n = 4x = 76), displayed a linear relationship with their chromosome numbers, indicating the accuracy of flow cytometry. Our results also suggest that the 2C-values of the Phalaenopsis sp. correlate with their chromosome sizes. The comparative analyses of DNA contents may provide information to molecular geneticists and systematists for genome analysis in Phalaenopsis. Endoreduplication was found in various tissues of P. equestris at different levels. The highest degree of endoreduplication in P. equestris was detected in leaves.
DNA Fingerprinting of Tetraploid Cherry Germplasm Using Simple Sequence Repeats
Authors: Cantini Claudio , Iezzoni Amy F. , Lamboy Warren F. , Boritzki Manuela , Struss Darush
Published: January 2019

The U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS) tetraploid cherry (Prunus L. sp.) collection at Geneva, N.Y., contains ≈75 accessions of sour cherry (P. cerasus L.), ground cherry (P. fruticosa Pall.), and their hybrids. Accurate and unambiguous identification of these accessions is essential for germplasm preservation and use. Simple sequence repeats (SSRs) are currently the markers of choice for germplasm fingerprinting because they characteristically display high levels of polymorphism. Recently SSR primer pairs from sweet cherry (P. avium L.), sour cherry, and peach [(P. persica L. Batsch (Peach Group)] have been reported. Ten SSR primer pairs were tested on 59 tetraploid cherry accessions to determine if they could differentiate among the accessions. Scorable SSR fragments were produced with all primer-accession combinations. The cherry accessions exhibited high levels of polymorphism with 4 to 16 different putative alleles amplified per primer pair. Most of the putative alleles were rare with frequencies <0.05. Heterozygosity values ranged from 0.679 to 1.00, while gene diversity values ranged from 0.655 to 0.906. The primer pairs differentiated all but two of the 59 cherry accessions. Based upon the ability of the SSR data to differentiate the cherry accessions and the high level of gene diversity, we propose that all the tetraploid cherry accessions in the USDA/ARS collection be fingerprinted to provide a mechanism to verify the identity of the individual accessions. The fingerprinting data are available on the World Wide Web (http://www.ars-grin.gov/gen/cherry.html) so that other curators and scientists working with cherry can verify identities and novel types in their collections and contribute to a global database.
Relationship Between Cold Tolerance during Seed Germination and Vegetative Growth in Tomato: Analysis of Response and Correlated Response to Selection
Authors: Foolad M.R. , Lin G.Y.
Published: January 2019

The genetic relationship between cold tolerance (CT) during seed germination and vegetative growth in tomato (Lycopersicon esculentum Mill.) was determined. An F2 population of a cross between accession PI120256 (cold tolerant during both seed germination and vegetative growth) and UCT5 (cold sensitive during both stages) was evaluated for germination under cold stress and the most cold tolerant progeny (the first 5% germinated) were selected. Selected progeny were grown to maturity and self-fertilized to produce F3 families (referred to as the selected F3 population). The selected F3 population was evaluated for CT separately during seed germination and vegetative growth and its performance was compared with that of a nonselected F3 population of the same cross. Results indicated that selection for CT during seed germination significantly improved CT of the progeny during germination; a realized heritability of 0.75 was obtained for CT during seed germination. However, selection for CT during germination did not affect plant CT during vegetative growth; there was no significant difference between the selected and nonselected F3 populations in either absolute CT [defined as shoot fresh weight (FW) under cold stress] or relative CT (defined as shoot FW under cold as a percentage of control). Results indicated that, in PI120256, CT during seed germination was genetically independent of CT during vegetative growth. Thus, to develop tomato cultivars with improved CT during different developmental stages, selection protocols that include all critical stages are necessary.
Boron Transport and Soluble Carbohydrate Concentrations in Olive
Authors: Perica Slavko , Bellaloui Nacer , Greve Carl , Hu Hening , Brown Patrick H.
Published: January 2019

Boron (B) remobilization, mannitol and glucose concentrations, and the effect of B application on changes in soluble carbohydrates were investigated in various organs of bearing `Manzanillo' olive trees (Olea europaea L. `Manzanillo'). Following foliar 10B application to leaves of various ages, there was significant 10B export out of the treated leaves, and significant 10B enrichment in nontreated adjacent organs, including inflorescences and fruit. Results demonstrated that B can be remobilized from leaves of various ages, and that foliar-applied B is phloem mobile in olive. Soluble carbohydrate analysis determined that mannitol and glucose are the predominant sugars in all organs analyzed and that the mannitol concentration in the leaves is adequate to account for all B transport. This is consistent with observations in other species, where the presence of mannitol is known to facilitate phloem B transport through formation of a mannitol-B complex. Previous reports have indicated that B application can alter carbohydrate metabolism. In the present study, foliar B application significantly suppressed glucose concentration in the leaf petioles of all ages and increased mannitol in petioles of the current-year-developed leaves.
Drought-stress Effects on Physiology, Growth and Biomass Production of Rainfed and Irrigated Bell Pepper Plants in the Mediterranean Region
Authors: Delfine Sebastiano , Loreto Francesco , Alvino Arturo
Published: January 2019

Physiological characteristics, growth, and biomass production of rainfed and irrigated bell pepper [Capsicum annuum L. var. anuum (Grossum Group) `Quadrato d'Asti'] plants were measured in the semiarid conditions of a Mediterranean summer to determine if drought stress effects are transient and do not affect plant growth and crop yield or are persistent and adversely affect plant growth and crop yield. A low midday leaf water potential indicated the occurrence of transient drought stress episodes in rainfed plants during the first 2 months of the study. Later on, predawn water potential also increased, indicating a persistent drought stress condition despite the occurrence of some rainfall. Photosynthesis was reduced when stress conditions developed, but the reduction was transient and limited to the central part of the day during the first 2 months. As plants aged, however, the impact of drought stress on photosynthesis was not relieved during the overnight recovery period. Stomatal conductance was reduced both during transient and permanent stress conditions while CO2 transfer conductance (i.e., conductance to CO2 inside the leaf) was only reduced when photosynthesis inhibition was unrecoverable. However, chloroplast CO2 concentration was higher in rainfed than in irrigated leaves indicating that CO2 availability was not limiting photosynthesis. Nonphotochemical quenching of fluorescence increased significantly in rainfed leaves exposed to permanent stress indicating the likely impairment of ATP synthesis. Transient inhibition of photosynthesis did not significantly affect leaf area index and biomass production, but growth was significantly reduced when photosynthesis was permanently inhibited. Fruit dry weight was even higher in rainfed plants compared to irrigated plants until drought stress and photosynthesis reduction became permanent. It is suggested that bell pepper growth without supplemental irrigation over the first part of the vegetative cycle does not impair plant growth and may even be useful to improve yield of early fruit.
Physiological Factors Affecting Response of Mature `Valencia' Orange Fruit to CMN-Pyrazole. II. Endogenous Concentrations of Indole-3-Acetic Acid, Abscisic Acid, and Ethylene
Authors: Yuan Rongcai , Hartmond Ulrich , Kender Walter J.
Published: January 2019

Endogenous concentrations of IAA and ABA in the peel, pulp, seed, and abscission zone of mature `Valencia' oranges [Citrus sinesis (L.) Osbeck] were determined by high-performance liquid chromatography and enzyme-linked immunosorbent assay from early November 1998 to mid-June 1999. Ethylene production of mature `Valencia' oranges during the same period was determined by gas chromatography. IAA concentrations in the pulp and seed were three to five times lower than those in the peel over the 7-month observation period. IAA concentration in the abscission zone and peel was high from late April to mid-May, the period of less responsiveness to abscission chemicals. ABA concentration in the pulp was low over the entire observation period. ABA concentration in the abscission zone and peel was low during the less responsive period. Ethylene production was always low except for a slight increase during late December and early February. The IAA to ABA ratio was high in the fruit abscission zone during the less responsive period. Fruit detachment force of CMN-pyrazole-treated fruit was positively correlated with the ratio of endogenous IAA to ABA or endogenous IAA, but negatively to endogenous ABA in the fruit abscission zone. These data suggest the balance between IAA and ABA in the fruit abscission zone may be an important factor in determining sensitivity and thereby the response of mature `Valencia' orange fruit to abscission chemicals. Chemical names used: abscisic acid (ABA); indole-3-acetic acid (IAA); 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMN-pyrazole).
Inheritance of Three Major Genes Involved in the Synthesis of Aliphatic Glucosinolates in Brassica oleracea
Authors: Li G. , Riaz A. , Goyal S. , Abel S. , Quiros C.F.
Published: January 2019

Inheritance of three major genes involved in synthesis of aliphatic glucosinolates (GSL) was followed in segregating populations of Brassica oleracea L. generated from three crosses: broccoli × cauliflower, collard × broccoli, and collard × cauliflower. Two of these genes, GSL-PRO and GSL-ELONG, regulate sidechain length. The action of the former results in three-carbon GSL, whereas action of the latter produces four-carbon GSL. We determined that these two genes act and segregate independently from each other in B. oleracea. The double recessive genotype produces only trace amounts of aliphatic GSL. The third gene, GSL-ALK controls sidechain desaturation and, as it has been observed in Arabidopsis thaliana (L.) Heynh., we found that this gene cosegregates with a fourth gene, GSL-OH, that is responsible for sidechain hydroxylation. Elucidation of the inheritance of major genes controlling biosynthesis of GSL will allow for manipulation of these genes and facilitate development of lines with specific GSL profiles. This capability will be important for improvement of Brassica breeding lines with high content of desirable GSL, like glucoraphanin, a demonstrated precursor of anticarcinogenic compounds. Additionally, this work is the first step towards cloning the major genes of the aliphatic GSL pathway, and to use these clones in transformation strategies for further crop enhancement.
Identification of Markers Linked to a Celery Mosaic Virus Resistance Gene in Celery
Authors: Ruiz Juan J. , Pico Belen , Li Genyi , D'Antonio Vincent , Falk Bryce , Quiros Carlos F.
Published: January 2019

Resistance to Celery mosaic virus (CeMV) in celery [Apium graveolens L. var. dulce (Mill.) Pers.] is recessive and determined by the single gene, cmv. We report discovery of two polymerase chain reaction-based dominant markers tightly linked to cmv in segregating F2 and BC1 populations. Marker me1em2 is associated to the dominant (susceptibility allele) and the second marker, me8em2, to the recessive (resistance allele). Simultaneous screening for both markers in segregating populations allows for identification of both homozygous and heterozygous genotypes for disease resistance. This marker system can be used for early seedling selection, which will simplify and speed development of celery cultivars resistant to CeMV.
Segregation and Linkage of Several Genes in Cucumber
Authors: Walters S. Alan , Shetty Nischit V. , Wehner Todd C.
Published: January 2019

Gene linkage was investigated in 11 families using 18 genes in cucumber (Cucumis sativus L.). The genes studied were B (black spine), B-3 (Black spine-3), B-4 (Black spine-4), bi (bitterfree cotyledons), Bt (bitter fruit), Bt-2 (bitter fruit-2), D (dull fruit skin), df (delayed flowering), de (determinate habit), F (female sex expression), gl (glabrous foliage), lh (long hypocotyl), ns (numerous spines), pm-h [powdery mildew (Sphaerotheca fuliginea Schlecht.:Fr.) resistance expressed on the hypocotyl], ss (small spines), Tu (tuberculate fruit), u (uniform immature fruit color), and w (white immature fruit color). A major objective of this study was to measure linkages of genes for fruit bitterness (Bt and Bt-2), and spine color (B-3 and B-4) relative to previously studied loci: B, bi, D, de, df, F, gl, lh, ns, pm-h, ss, Tu, u, and w. The F2 progeny of LJ 90430 × PI 173889 segregated 13 bitter fruit: 3 nonbitter fruit, indicating that different genes are controlling fruit bitterness in these lines. Bt-2 is proposed as the gene controlling bitterness of fruit in LJ 90430. It is a separate locus from Bt, that causes bitter fruit in PI 173889. Several new gene linkages were found: bi—Bt, (Bt-2)—de, D—(Bt-2), D—ns, gl—F, ss—(Bt-2), Tu—(Bt-2), and u—(Bt-2). The Bt gene appears to be linked to bi and may be located on linkage group I. Bt-2 appears to be linked with several genes that could connect linkage groups I and IV. Bt-2 was linked to u, Tu, D, and ss, that are all on linkage group IV. Bt-2 was also found to be linked loosely to de, that is on linkage group I. No linkages were found between B-3 and B-4 and the genes evaluated in this study. Weak linkages (>25 cM) between several gene combinations [(Bt-2)-de, de—ns, de—ss, de—Tu, de—u, ns—F, and ss—F] provided more evidence that linkage group I and IV may be linked. Due to the weak linkages, more information needs to be obtained using larger populations and more markers to confirm these findings.
Lovastatin Inhibition of α-Farnesene Production in Ripening Apple: Precursor Feeding Studies
Authors: Ju Zhiguo , Curry Eric A.
Published: January 2019

Effects of α-farnesene biosynthesis precursors on α-farnesene and ethylene production were studied using Lovastatin-treated or nontreated `Delicious' and `Granny Smith' apples [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.]. In nontreated fruit, α-farnesene was detected only in fruit peel (≈3 mm) and not in the more proximal cortical tissue. α-Farnesene was not detectable in preclimacteric fruit peel at harvest. Mevalonic acid lactone (MAL) or farnesyl pyrophosphate (FPP) induced α-farnesene production when fed to preclimacteric peel tissue, but hydroxymethylglutaric acid (HMG) did not. Fruit stored at 0 °C for 30 days (climacteric fruit) produced α-farnesene, and addition of HMG, MAL, or FPP further increased α-farnesene production. When treated at harvest with Lovastatin at 1.25 mmol·L-1 and stored at 0 °C for 30 days, fruit produced ethylene but did not produce α-farnesene. Whereas MAL and FPP induced α-farnesene production in peel sections from these fruit, HMG did not. Induction of α-farnesene by precursor feeding was concentration-dependent and had no effect on ethylene production. Cortical tissue sections from climacteric fruit did not produce α-farnesene unless HMG, MAL, or FPP were fed during incubation. Including Lovastatin at 0.63 mmol·L-1 in the feeding solution eliminated HMG induced α-farnesene production, but did not affect MAL or FPP-induced α-farnesene production. Neither precursor feeding nor Lovastatin treatment affected ethylene production in cortical tissues. Chemical name used: [1S-[1a (R°), 3α, 7β, 8β (2S°, 4S°), 8αβ]]-1,2,3,7,8,8α-hexahydro-3,7-dimethyl-8-[2-(tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl)ethyl]-1-naphthalnyl 2-methylbutanoate (Lovastatin).
Volatilization of 1,3-Dichloropropene in Florida Plasticulture and Effects on Fall Squash Production
Authors: Nelson S.D. , Riegel C. , Allen L.H. , Dickson D.W. , Gan J. , Locascio S.J. , Mitchell D.J.
Published: January 2019

One of the proposed alternative chemicals for methyl bromide is 1,3-D. The most common forms of 1,3-D products are cis- or trans-isomers of 1,3-D with the fungicidal agent, chloropicrin, containing such mixtures as 65% 1,3-D and 35% chloropicrin (C-35). Soil fumigants are commonly applied under a polyethylene film in Florida raised bed vegetable production. Much of the research regarding cropping system effects of alternative fumigants to methyl bromide has focused primarily on plant growth parameters, with little regard to the atmospheric fate of these chemicals. The objective of this research was to determine both the atmospheric emission of 1,3-D under different plastic film treatments and to evaluate effects of application rates of 1,3-D and C-35 on plant pests, growth, and yield of Sunex 9602 summer squash (Cucurbita pepo L.). Results showed that use of a high barrier polyethylene film (or virtually impermeable film - VIF) greatly reduced fumigant emission compared to ground cover with conventional polyethylene films or uncovered soil. Summer squash seedling survival was a severe problem in several of the 1,3-D alone treatments where no fungicidal agent was added, whereas C-35 resulted in excellent disease control at both full and one-half of the recommended application rates for this chemical. Both 1,3-D and C-35 provided good plant stands and higher yields when applied at their recommended application rates. However, all squash yields were lower than typical squash production levels due to late planting and early winter frost kill. Chemical names used: 1,3-dichloropropene (1,3-D); trichloronitropropene (chloropicrin).
Irradiance Levels Affect in vitro and Greenhouse Growth, Flowering, and Photosynthetic Behavior of A Hybrid Phalaenopsis Orchid
Authors: Konow Elise A. , Wang Yin-Tung
Published: January 2019

Presently, there are no standards for producing Phalaenopsis Blume (the moth orchids) as a flowering, potted crop. Determining optimal irradiance for in vitro and greenhouse production will help optimize growth and flowering. Four-month-old, aseptically propagated Phalaenopsis Atien Kaala seedlings with 1.0 cm leaf spread were transferred to a sterile agar medium in November 1995. They were placed under 10, 20, 40, or 80 μmol·m-2·s-1 photosynthetic photon flux (PPF) from cool-white fluorescent lamps. In June 1996, plants grown under 40 or 80 μmol·m-2·s-1 in vitro PPF had 38% greater fresh weight (FW), wider leaves, and more roots than those under the two lower PPF levels. Plants from each in vitro PPF were then transplanted and grown ex vitro in a greenhouse (GH) under high, medium, or low PPF, representing 12.0%, 5.4%, or 2.6% of full sunlight, respectively. Full sunlight at this location was 2300 and 1700 μmol·m-2·s-1 in August 1996 and January 1997, respectively. In November 1996 and June 1997, plants that had received 40 μmol·m-2·s-1 in vitro PPF and then grown under the high or medium GH PPF had the greatest FWs. Overall, plants under the high, medium, or low GH PPF had average FWs of 61, 36, or 17 g, respectively, in June 1997. By mid-September 1997, plants had increasingly larger leaves and higher concentrations of malic acid, sucrose, and starch as GH PPF increased. Leaf glucose and fructose concentrations remained constant as GH PPF increased; however, sucrose level doubled and malic acid concentration increased by nearly 50% from the low to high GH PPF. Each doubling in GH PPF more than doubled plant FW. Plants grown under the high, medium, or low GH PPF had 98%, 77%, or 2% flowering, respectively, in Spring 1998. Anthesis occurred 2 weeks earlier under the high GH PPF. Plants grown under the high GH PPF had twice as many flowers and larger flowers than those grown under the medium PPF.
Omega-3 Fatty Acid Concentration in Purslane (Portulaca oleraceae) is Altered by Photosynthetic Photon Flux
Authors: Palaniswamy Usha R. , McAvoy Richard J. , Bible Bernard B.
Published: January 2019

Purslane (Portulaca oleracea L.) is an excellent source of the essential fatty acid α-linolenic acid (LNA) but little is known of the effects of cultural conditions on LNA concentration. Purslane seedlings were grown under an instantaneous photosynthetic photon flux [PPF (400 to 700 nm)] of 299 or 455 μmol·m-2·s-1 for a daily duration of either 8, 12, 16, or 20 hours. Thus, plants were exposed to a daily PPF of 8.6, 12.9, 17.2, or 21.5 mol·m-2·d-1 in the low PPF treatment (299 μmol.m-2.s-1) and 13.1, 19.7, 26.2, or 32.8 mol·m-2·d-1 in the high PPF treatment (455 μmol·m-2·s-1). Plants in all treatments received a 20-hour photoperiod by providing ≈5 μmol·m-2·s-1 from incandescent lamps starting at the end of the photosynthetic light period. At low PPF, purslane grown under a 16 hour PPF duration produced the highest concentrations of total fatty acids (TFA) and LNA per unit leaf dry weight (DW), but at high PPF, concentrations of these compounds were highest under 8 and 12 hour PPF duration. Trend analysis indicated that maximum TFA and LNA concentrations occurred with a daily PPF of 14.1 and 17.2 mol·m-2·d-1, respectively; and in the thylakoids, protein, chlorophyll, and LNA concentrations peaked at a PPF of 21.8, 19.9, and 16.1 mol·m-2·d-1, respectively. LNA as a percentage of TFA was unaffected by treatment. Shoot DW increased with PPF up to the highest PPF exposure of 32.8 mol·m-2·d-1.
Genetic Analyses of Seed Yield in Onion
Authors: Villanueva-Mosqueda Eduardo , Havey Michael. J.
Published: January 2019

Development of two-way onion (Allium cepa L.) hybrids is difficult due to poor seed yields on inbred female parents. Seed yield of onion is affected by inbreeding depression and the seed-production environment. A standard diallel was used to estimate combining abilities for seed yield among seven inbred onion lines. Males and hybrids differed significantly (P < 0.05) for seed yields. Combinations of relatively high-by-high seed-yielding inbred parents were not always the best combinations; combinations of medium-by-medium or medium-by-high seed yielders also produced good F1 seed yielders. For the seven inbred lines, significant correlations (P < 0.05) were observed between mean seed yield per bulb and scape height. Parent-offspring regressions revealed no significant relationship between seed yields of randomly selected, open-pollinated bulbs and their S1 families. Results indicate that relative seed yields of individual bulbs after self-pollination cannot be used to predict seed yields of progeny families. However, the seed yield of inbred lines of onion may reflect the potential seed yield of F1 male-sterile lines.
Calcium-activated Root Growth and Mineral Nutrient Accumulation of Lupinus havardii: Ecophysiological and Horticultural Significance
Authors: Picchioni G.A. , Valenzuela-Vazquez M. , Armenta-Sanchez S.
Published: January 2019

Lupinus havardii Wats. (Big Bend bluebonnet) has received considerable attention as a new specialty cut flower crop. We studied the consequences of Ca fertigation on growth, water use, and mineral nutrient uptake of L. havardii (`Texas Sapphire') for 88 days in a greenhouse. Four Ca concentrations were included (as CaCl2) in the fertigation solution at concentrations of 0, 2.5, 5.0, or 10.0 mm. Calcium supply did not affect the number of racemes produced per plant or total dry matter accumulation per plant. However, root dry matter accumulation, root: shoot ratio, net root mineral nutrient accumulation (milligrams P, K, Ca, Mg, and Fe per plant; micrograms Mn, B, and Cu per plant), and the preferential allocation of mineral nutrients to roots were influenced quadratically by CaCl2 supply, increasing up to 5.0 mm CaCl2 and then decreasing at 10.0 mm CaCl2. Lack of root sink response by plants exposed to 10.0 mm CaCl2 was associated with lowest daily rate of pot evapotranspiration, probably resulting from osmotic or Cl toxicity stress. Increased root sink strength for dry matter and mineral nutrients in response to CaCl2 supply up to 5.0 mm Ca is consistent with calcicole-like behavior and the native distribution of L. havardii on xeric, calcareous soils, where root growth and expansion favoring water and mineral nutrient acquisition may be of significant adaptive value for survival. The Carelated increase in root growth was reflected in up to a 5% to 20% increase in fertilizer P and K recovery per plant. Results indicate that Ca fertilization may be an effective horticultural strategy in greenhouse production of L. havardii, particularly for matching the natural edaphic habitat of the species and thus increasing efficiency of water and mineral nutrient management.
Optimization of Transpiration and Potential Growth Rates of `Kardinal' Rose with Respect to Root-zone Physical Properties
Authors: Raviv Michael , Lieth J. Heinrich , Burger David W. , Wallach Rony
Published: January 2019

Physical characteristics of two media were studied concerning water availability to roots, as reflected in specific transpiration rate, stomatal conductance, and specific growth rate of very young leaflets of `Kardinal' rose (Rosa ×hybrida L.), grafted on Rosa canina L. `Natal Brier'. Plants were grown in UC mix [42% composted fir bark, 33% peat, and 25% sand (by volume)] or in coconut coir. Water release curves of the media were developed and hydraulic conductivities were calculated. Irrigation pulses were actuated according to predetermined media moisture tensions. Transpiration rate of plants was measured gravimetrically using load cells. Specific transpiration rate (STR) was calculated from these data and leaf area. STR and stomatal conductance were also determined using a steady-state porometer. Specific growth rate (RSG) of young leaflets was calculated from the difference between metabolic heat rate and respiration rate, which served as an indicator for growth potential. Low STR values found at tensions between 0 and 1.5 kPa in UC mix suggest this medium has insufficient free air space for proper root activity within this range. Above 2.3 kPa, unsaturated hydraulic conductivity of UC mix was lower than that of coir, possibly lowering STR values of UC mix-grown plants. As a result of these two factors, STR of plants grown in coir was 20% to 30% higher than that of plants grown in UC mix. STR of coir-grown plants started to decline only at tensions around 4.5 kPa. Yield (number of flowers produced) by coir-grown plants was 19% higher than UC mix-grown plants. This study demonstrated the crucial role of reaching sufficient air-filled porosity in the medium shortly after irrigation. It also suggests that hydraulic conductivity is a more representative measure of water availability than tension.
Identifying Differential Tissue Response in Grape (Vitis riparia) During Induction of Endodormancy Using Nuclear Magnetic Resonance Imaging
Authors: Fennell Anne , Line Michael J.
Published: January 2019

Physiological and biophysical changes were monitored during shoot maturation and bud endodormancy induction in grape (Vitis riparia Michx.) under controlled environments. Growth, dry weight (DW), periderm development, bud endodormancy, and nuclear magnetic resonance imaging (MRI) T2 relaxation times were monitored at 2, 4, or 6 weeks of long-photoperiod [long day (LD), 15 h, endodormancy inhibition] or short-photoperiod [short day (SD), 8 h, endodormancy induction] treatments at 15/9 h day/night thermoperiod of 25/20 ± 3 °C. Shoots on LD plants grew throughout the entire study period, although the rate of growth decreased slightly during the 6th week. Shoot growth slowed significantly after 2 weeks of SD, was minimal by the 4th week of SD and most of the shoot tip meristems had abscised after 6 weeks of SD. Endodormancy was induced after 4 weeks of SD. DW of the stem and buds increased with increasing duration of LD and SD. While bud DW increased more under SD than LD, stem DW increased more under LD than SD. T2 relaxation times were calculated from images of transverse sections of the grape node. There was a slight decrease in the T2 times in the node tissues with increased duration of LD treatment, whereas SD induced a significant decrease in T2 times during endodormancy induction. T2 values for the node decreased after 4 weeks of SD, coinciding with endodormancy induction. Separation of node tissues into bud, leaf gap, and the remainder of the stem and analysis of the proportion of short and long T2 times within those tissues indicated differential tissue response. A greater proportion of short T2 times were observed in the 2-week SD leaf gap tissue than in the LD and the proportion of short T2 times continued to increase with subsequent SD treatment. Bud and all other stem tissues had a greater proportion of short T2 times after 4 weeks of SD, coinciding with bud endodormancy induction. The proportion of short and long T2 times in a tissue was a better indicator of endodormancy than the averaged T2 time for the tissue. Thus, MRI allows nondestructive identification of differential tissue response to photoperiod treatments and makes it possible to separate normal vegetative maturation responses from endodormancy induction.
Almond Flower Development: Floral Initiation and Organogenesis
Authors: Lamp Bridget M. , Connell Joseph H. , Duncan Roger A. , Viveros Mario , Polito Vito S.
Published: January 2019

Scanning electron microscopy was used to examine almond [Prunus dulcis (Mill.) D.A. Webb (syn. Prunus amygdalus Batsch, Amygdalus communis L.)] flower bud development for three cultivars (Nonpareil, Carmel, and Butte) from four California locations (which span the range of almond production in California) for 2 years, and for `Nonpareil' in a single location for a third year. The objectives were to document timing of floral developmental events and to better understand the extent of variation that exists within and among cultivars, locations, and years. Results indicated that the time of floral initiation relative to hull split varied among cultivars. Median time for floral initiation in `Nonpareil' was more than 3 weeks after the onset of hull split. For `Butte' and `Carmel', median time of floral initiation preceded the onset of hull split. Extensive variation in the timing of bud development events within a cultivar was apparent. Timing of developmental events varied among locations, but no patterns emerged consistent with the north to south range which spanned 4°15' latitude and 520 km. Among years, development occurred earliest in 1997, a relatively warm year, and was delayed in 1998 and 1999, relatively cool years. Results indicate an earlier onset of floral initiation than reported in the classical literature on the subject.
Flower Production, Fruit Set, and Physiology of Bell Pepper during Elevated Temperature and Vapor Pressure Deficit
Authors: Erickson Ami N. , Markhart Albert H.
Published: January 2019

High temperature reduces fruit set in bell pepper [Capsicum annuum L. var. annuum (Grossum Group)], and reduction of pepper productivity, resulting from high temperature, may be a direct effect of temperature or an indirect effect of water stress induced by increased vapor pressure deficits (VPDs) at high temperature. We evaluated responses of plant growth, reproduction, net photosynthesis (PN), chlorophyll fluorescence, predawn respiration, leaf water potential, and stomatal conductance of `Ace' and `Bell Boy' bell pepper to elevated temperature (33 °C) with increased VPD (2.1 kPa) or elevated temperature with no increase in VPD (1.1 kPa). VPD had no effect on flower number or fruit set and did not adversely influence the physiological processes measured. Therefore, deleterious effects of high temperature on pepper fruit set does not appear to be temperature induced water stress, but is more likely a direct temperature response. Elevated temperature decreased fruit set but not flower production. Gas exchange measurements suggest failure to set fruit was not due to reduced leaf photosynthesis.
Inheritance of True Leaf Stage Downy Mildew Resistance in Broccoli
Authors: Wang Min , Farnham Mark W. , Thomas Claude E.
Published: January 2019

Downy mildew, incited by the biotrophic fungal parasite, Peronospora parasitica (Pers. Fr.) Fr., is one of the most destructive diseases of broccoli (Brassica oleracea L., Italica Group) and other related crop species throughout the world. Cultivation of resistant cultivars is the most desirable control method because it provides a practical, long-term, and environmentally benign means of limiting damage from this disease. The commercial hybrid cultivar, Everest, has been shown previously to contain a high level of downy mildew resistance. Doubled-haploid (DH) lines developed from that hybrid were also shown to exhibit a similar, high level of resistance at the three- to four-leaf stage. To determine the mode of inheritance of this true leaf resistance, the resistant DH line was crossed to a susceptible line (derived from `Marathon') to produce an F1 hybrid. Subsequently, F2 and backcross (BC) populations were developed from the hybrid. In addition, a DH population of ≈100 lines was developed from the same F1 used to create the F2 and BC. All populations were evaluated for response to artificial inoculation with P. parasitica at the three- to four-leaf stage. F1 plants were resistant like the resistant parent and F2 populations segregated approximately nine resistant to seven susceptible. Using the resistant parent as recurrent parent, BC populations contained all resistant plants, while the BC to the susceptible parent fit a 1 resistant: 3 susceptible segregation ratio. These results can be explained by a model with two complementary dominant genes. This model was confirmed by the DH population that segregated ≈1:3, resistant to susceptible. Due to the dominant nature of this resistance, controlling genes should be easily incorporated into F1 hybrids and used commercially to prevent downy mildew.
Influence of Spring and Fall Drought Stresses on Growth and Gas Exchange during Stress and Posttransplant of Container-grown Magnoli ×soulangiana `Jane'
Authors: Fernandez R. Thomas , Schutzki Robert E. , Prevete Kelly J.
Published: January 2019

Responses of Magnolia ×soulangiana (Soul.-Bod.) `Jane' (`Jane' saucer magnolia) to consecutive short term pretransplant drought stresses and recovery after transplanting were evaluated beginning October 1997 and June 1998. Plants were subjected to one (mild) or two (moderate) 3-day drought stress periods or a two 3-day and one 4-day (severe) drought stress period, each separated by two rewatering periods over 24 hours. One day after each stress period, plants were transplanted into the field and well watered to monitor recovery from stress. Plant response was determined by measuring whole-plant CO2 assimilation, leaf gas exchange (CO2 assimilation, transpiration, stomatal conductance) and canopy growth throughout stress and recovery periods. Whole-plant and leaf CO2 assimilation were lower for the stressed treatments for most of the measurements taken during stress in the fall and spring. After release from stress and transplanting, leaf CO2 assimilation returned to control levels for mild and moderate fall stresses within 2 to 3 d by the next measurement, while it was over 3 weeks until recovery from the severe stress. There was no difference in leaf gas exchange following release from stress and transplanting during the spring stress. More rapid defoliation occurred for the severe fall-stressed plants compared to the controls after release from stress in the fall. Flower number was reduced in spring for the fall-stressed plants. At termination of the experiment, the growth index was lower for severe fall-stressed plants but there were no differences for other fall stress treatments. There was no increase in growth for control or stressed plants for the spring experiment.
Inheritance of Reverse Margo Seedcoat Pattern and Allelism between the Genes J for Seedcoat Color and L for Partly Colored Seedcoat Pattern in Common Bean
Authors: Bassett Mark J. , Lee Rian , Symanietz Tim , McClean Phillip E.
Published: January 2019

Two common bean (Phaseolus vulgaris L.) genes, J (modifies seedcoat color and pattern) and L (modifies partly colored seedcoat pattern), were tested for allelism using genetic tester stocks. Those stocks have a common genetic background by backcrossing to the recurrent parent, Florida dry bean breeding line 5-593, that has black self-colored seeds and purple flowers due to the genotype T P [C r] Z J G B V Rk. Specifically, the L gene from `Thuringia' and the lers gene from `Early Wax' were tested for allelism with the j gene from various genetic tester stocks. L was found to be identical with j, but lers was a different allele at J. We propose the gene symbols J (formerly l), j (formerly L), and jers (formerly lers). The seedcoat genotype of `Thuringia' was found to be t P C z j g b vlae rkd. A new seedcoat pattern called reverse margo was found to be determined by the genotype T/t z/z j/jers in a P C G B V genetic background. A randomly amplified polymorphic DNA marker was developed for the j gene (formerly L) from `Thuringia' using bulk segregant analysis in an F2 population segregating for j vs. J in a t z genetic background, i.e., from the cross t z j × t z J in BC1 to 5-593. The linkage distance between marker OL4525 and j was determined to be 1.2 cM. In a population segregating for J and jers, the distance between the marker and jers was determined to be 4.7 cM. The utility of marker OL4525 is limited primarily to the Middle American gene pool.
Intersimple Sequence Repeat Markers for Fingerprinting and Determining Genetic Relationships of Walnut (Juglans regia) Cultivars
Authors: Potter Daniel , Gao Fangyou , Aiello Giovanna , Leslie Charles , McGranahan Gale
Published: January 2019

The utility of intersimple sequence repeat (ISSR) markers for identification of English or Persian walnut (Juglans regia L.) cultivars was explored. Four cultivars were screened with 47 ISSR primers; eight of these primers, which generated reproducible and informative data, were selected for further study. Two individuals from each of 48 cultivars, including many currently important in the California walnut industry as well as accessions from Europe and Asia, were then examined with the eight ISSR primers. Polymerase chain reaction (PCR) products were separated on agarose gels and stained with ethidium bromide. Fifty-four bands were scored as present or absent in each cultivar; of these, 31 (57%) were polymorphic among the 48 cultivars. Combined data from the eight ISSR primers provided a unique fingerprint for each of the cultivars tested. Fifteen of the cultivars could be distinguished from all others with just one primer, 31 with a minimum of two primers, and two required three primers. Pairwise genetic distances between the cultivars were calculated and a dendrogram was generated using the neighbor-joining algorithm. Some of the groupings in the dendrogram corresponded to groups which, based on known pedigrees, are genealogically closely related. Others included accessions from diverse genetic and/or geographic origins. These results can be attributed to a combination of the limitations of the ISSR method for inferring genetic relationships, on the one hand, and the complex history of walnut cultivar development involving extensive exchange and breeding of germplasm from different geographic regions, on the other.
Variation and Heritability Estimates for Antioxidant Activity, Total Phenolic Content, and Anthocyanin Content in Blueberry Progenies
Authors: Connor Ann Marie , Luby James J. , Tong Cindy B.S.
Published: January 2019

Narrow-sense heritability and among-family and within-family variance components were estimated for antioxidant activity (AA), total phenolic content (TPH), and anthocyanin content (ACY) in blueberry (Vaccinium L. sp.) fruit. AA, TPH, and ACY were determined in the parents and in 10 offspring from each of 20 random crosses for each of 2 years at Becker, Minn. Offspring-midparent regression analysis provided combined-year heritability estimates of 0.43 ± 0.09 (P ≤ 0.0001) for AA, 0.46 ± 0.11 (P ≤ 0.0001) for TPH, and 0.56 ± 0.10 (P ≤ 0.0001) for ACY. Analyses of variance delineated variation among and within families for AA, TPH, and ACY (P ≤ 0.001). Year-to-year variation in the means for all offspring genotypes was not significant for AA or TPH, but there were changes in rank between years for families and for offspring within families for these traits. Year-to-year variation in the mean for all offspring genotypes was significant for ACY, but rank changes were observed only among offspring within families, not among families. In total, 18 of 200 offspring from 7 of the 20 crosses were transgressive segregants for AA, exceeding the higher parent of the cross by at least two sds. Estimates of variance components showed that variation among families accounted for 24% to 27% of total variance for the three traits. However, variation within families was greater than that among families, accounting for 38% to 56% of total variance for the three traits. These results suggest that increasing antioxidant activity in blueberry through breeding is feasible, and that the breeding strategies utilized should exploit the large within-family variation that exists.
Genetic Relationships among Lowbush Blueberry Genotypes as Determined by Randomly Amplified Polymorphic DNA Analysis
Authors: Burgher Karen L. , Jamieson Andrew R. , Lu Xuewen
Published: January 2019

Twenty-six genotypes of lowbush blueberry (Vaccinium angustifolium Aiton) representing four geographical zones (Maine, United States; New Brunswick, northern Nova Scotia, and western Nova Scotia, Canada) were selected to obtain DNA fingerprints and to estimate genetic similarity by randomly amplified polymorphic DNA analysis. The genotypes were either native accessions or selections from crosses involving native accessions as parents or grandparents. Thirty 10-base RAPD primers were initially screened; 11 proved to be polymorphic, resulting in 73 consistent RAPD bands. All 26 genotypes could be distinguished by their unique RAPD banding patterns and three unlabeled samples were correctly identified. The RAPD band data set was analyzed with Genstat5 to calculate similarity and distance matrices. Average similarity across all genotypes was 56%. Results from average linkage cluster analysis were used to construct a dendogram which demonstrated six main clusters with an average similarity linkage of 70%. The selection `Fundy' and its parent `Augusta' clustered at 77% similarity. The corresponding principal coordinate analysis supported the clusters and identified two distinct outliers. There was a small association by geographic grouping for five genotypes from Maine. It was concluded that RAPD analysis is a useful tool for genotypic identification and estimates of genetic similarity in lowbush blueberry.
Peroxidase Isozyme Profiles in Compatible and Incompatible Pear-Quince Graft Combinations
Authors: Gulen Hatice , Arora Rajeev , Kuden Ali , Krebs Stephen L. , Postman Joseph
Published: January 2019

The similarity or differences of peroxidase isozymes in rootstocks and scions may influence their graft compatibility. This study was conducted to identify peroxidase isozymes that may be used as markers to predict compatibility between pear (Pyrus communis L.) and various quince (Cydonia oblonga Mill.) clones. `Bartlett' (BT) and `Beurre Hardy' (BH) pear cultivars are known to form incompatible and compatible grafts, respectively, with quince rootstocks. The two pear scion cultivars were budded on `quince A' (QA), `quince BA-29', and 15 selected quince clones from Turkey. Bark and cambial tissues were taken from nonbudded rootstocks and scions, and 4 cm above and below the graft union for peroxidase isozyme analysis performed by starch gel electrophoresis. Isoperoxidase analyses were also performed on samples from the graft unions collected 12 months after grafting. Many isozyme bands were observed commonly in the two scions; however, one anodal peroxidase A was detected in BH (compatible scion) but not in BT (incompatible scion) samples. This isoperoxidase was also detected in QA, Quince BA-29, and nine of the Turkish quince clones. Another isoperoxidase, band B, was detected in BH but not in BT or any of the rootstocks. However, the compatible (BH/QA) and moderately compatible (BT/BA-29) graft union tissues contained bands A and B whereas incompatible graft union tissues (BT/QA) lacked both. Graft union samples involving BT and five Turkish quince clones (705, 609-2, 702, 804, and 806) had both `A' and `B' isoperoxidases while one or both of these bands were absent in nonbudded graft partners. Field observations of 3.5 year-old grafts of BT and Turkish quince clones revealed that the vegetative growth (vigor) of BT scion was significantly greater, when grafted on these five clones, than that in graft combinations with other clones. We suggest that matching of isoperoxidase `A' in quince rootstocks and BH pear scion may be associated with a compatible graft combination. Additionally, presence of isoperoxidases `A' and `B' in the graft union tissues may be used as an indicator to predict a compatible graft between BT and quince rootstocks.