bluuebunny/crossref_metadata_2025 huggingface dataset:
Superficial Scald, Carbon Dioxide Injury, and Changes of Fermentation Products and Organic Acids in `Cortland' and `Law Rome' Apples after High Carbon Dioxide Stress Treatment
Authors: Fernández-Trujillo J. Pablo , Nock Jacqueline F. , Watkins Christopher B.
Published: January 2019

`Cortland' and `Law Rome' apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] were either nontreated or treated with the inhibitor of superficial scald development, DPA, and exposed to air or CO2 (40 or 45 kPa) in air at 2 °C for up to 12 days. Fruit exposed to air or 45 kPa CO2 were sampled during treatment, and peel and flesh samples taken for fermentation product and organic acid analyses. After treatment, fruit were air stored for up to 6 months at 0.5 °C for evaluation of disorder incidence. `Cortland' apples were most susceptible to external CO2 injury and `Law Rome' to internal CO2 injury. DPA treatment markedly reduced incidence of both external and internal injury. Fermentation products increased in peel and flesh of both cultivars with increasing exposure to CO2, but the extent of the increase was cultivar dependant. Acetaldehyde concentrations were about 10 times higher in peel and flesh of `Law Rome' than that of `Cortland' apples. Ethanol concentrations in the flesh were similar in both cultivars, but were about twice as high in `Cortland' than in `Law Rome' peels. Neither acetaldehyde nor ethanol concentrations were affected consistently by DPA treatment. Succinate concentrations, often regarded as the compound responsible for CO2 injury, increased with CO2 treatment, but were not affected by DPA application. Citramalate concentrations were reduced by CO2 treatment in `Law Rome' peel, but other acids were not consistently affected by CO2. Results indicate that acetaldehyde, ethanol or succinic acid accumulation are not directly responsible for CO2 injury in apples. Chemical name used: diphenylamine (DPA).
Springtime 15Nitrogen Uptake, Partitioning, and Leaching Losses from Young Bearing Citrus Trees of Differing Nitrogen Status
Authors: Lea-Cox John D. , Syvertsen James P. , Graetz Donald A.
Published: January 2019

15Nitrogen uptake, allocation, and leaching losses from soil were quantified during spring, for 4-year-old bearing `Redblush' grapefruit (Citrus × paradisi Macf.) trees on rootstocks that impart contrasting growth rates. Nine trees on either the fast-growing `Volkamer' lemon (VL) (C. volkameriana Ten & Pasq.) or nine on the slower-growing sour orange (SO) (C. aurantium L.) rootstocks were established in drainage lysimeters filled with Candler fine sand and fertilized with 30 split applications of N, totaling 76, 140, or 336 g·year-1 per tree. A single application of double-labeled ammonium nitrate (15NH 154NO3, 20% enriched) was applied at each rate to replicate trees, in late April. Leaves, fibrous roots, soil, and leachates were intensively sampled from each treatment over the next 29 days, to determine the fate of the 15NH 154NO3 application. Newly developing spring leaves and fruit formed dominant competitive sinks for 15N, accounting for between 40% and 70% of the total 15N taken up by the various treatments. Large fruit loads intercepted up to 20% of this 15N, at the expense of spring flush development, to the detriment of overall tree N status in low-N trees. Nitrogen supply at less than the currently recommended yearly rate of 380 g/tree exceeded the requirements of 4-year-old grapefruit trees on SO rootstock; however, larger trees on VL rootstock took up the majority of 15N from this rate over the 29-day period. Nitrogen-use efficiency declined with increasing N rate, irrespective of rootstock. The residual amounts of 15N remaining in the soil profile under SO trees after this time represented a significant N leaching potential from these sandy soils. Therefore, under these conditions, present N recommendations appear adequate for rootstocks that impart relatively fast growth rates to Citrus trees, but seem excessive for trees on slower-growing rootstock species.
Specific Functions of Red, Far Red, and Blue Light in Flowering and Stem Extension of Long-day Plants
Authors: Runkle Erik S. , Heins Royal D.
Published: January 2019

For many long-day plants (LDP), adding far red light (FR, 700 to 800 nm) to red light (R, 600 to 700 nm) to extend the day or interrupt the night promotes extension growth and flowering. Blue light (B, 400 to 500 nm) independently inhibits extension growth, but its effect on flowering is not well described. Here, we determined how R-, FR-, or B-deficient (Rd, FRd, or Bd, respectively) photoperiods influenced stem extension and flowering in five LDP species: Campanula carpatica Jacq., Coreopsi ×grandiflora Hogg ex Sweet, Lobelia ×speciosa Sweet, Pisum sativum L., and Viola ×wittrockiana Gams. Plants were exposed to Rd, FRd, Bd, or normal (control) 16-hour photoperiods, each of which had a similar photosynthetic (400 to 700 nm) photon flux. Compared with that of the control, the Rd environment promoted extension growth in C. carpatica (by 65%), C. ×grandiflora (by 26%), P. sativum (by 23%), and V. ×wittrockiana (by 31%). The FRd environment suppressed extension growth in C. ×grandiflora (by 21%), P. sativum (by 17%), and V. ×wittrockiana (by 14%). Independent of the R: FR ratio, the Bd environment promoted stem extension (by 10% to 100%) in all species, but there was little or no effect on flowering percentage and time to flower. Extension growth was generally linearly related to the incident wide band (100 nm) R: FR ratio or estimated phytochrome photoequilibrium except when B light was specifically reduced. A high R: FR ratio (i.e., under the FRd filter) delayed flower initiation (but not development) in C. carpatica and C.×grandiflora and inhibited flower development (but not initiation) in V.×wittrockiana. Therefore, B light and the R: FR ratio independently regulate extension growth by varying magnitudes in LDP, and in some species, an FRd environment can suppress flower initiation or development.
Genetic Variances and Selection Potential for Selenium Accumulation in a Rapid-cycling Brassica oleracea Population
Authors: Kopsell Dean A. , Randle William M.
Published: January 2019

Beneficial effects of selenium (Se) can be delivered to humans through enriched plant foods. Plants in the Brassicaceae are good sources of sulfur (S) and can be enriched with Se. Breeding plants to be more efficient at Se accumulation may complement enrichment efforts. Because Se and S are chemically similar and can compete in plant metabolic pathways, S levels must be considered when attempting to manipulate Se, and vice versa. The objectives of this study were to establish genetic variances for S and Se accumulation, and to determine if simple recurrent selection could be used to manipulate Se accumulation in a rapid-cycling (Brassica oleracea L.) population. Progeny from a North Carolina Design II mating scheme were grown in two seleniferous environments and expressed variability for Se and S accumulation. Narrow sense heritability estimates for Se and S accumulation were moderate (0.55 to 0.75), which suggested progress was possible. However, standard errors were large and may influence expected progress during improvement efforts. Plants of a rapid-cycling B. oleracea were also subjected to two cycles of divergent selection for Se accumulation in leaf tissues. Realized heritabilities were high during selection for both high and low Se accumulation. Simultaneous evaluation of all populations revealed actual gains from selection to be 4.8% and 4.0% per selection cycle for high and low Se accumulation, respectively. Predicted gains for Se accumulation in the plants were 6.8%. Selection for Se accumulation was successful and indicates population improvements for such traits are possible within the B. oleracea analyzed. Breeding plants that are more efficient at accumulating Se could be a useful tool towards Se enrichment.
Molecular Analysis of Hybrids among the Ornamental Eucalypts Eucalyptus macrocarpa, E. pyriformis, and E. youngiana
Authors: Neaylon Kirsty , Delaporte Kate L. , Sedgley Margaret , Collins Graham G. , Conran John G.
Published: January 2019

The potential for hybridization among three species of Eucalyptus L'Hér in the Series Macrocarpae, E. macrocarpa Hook (Mottlecah), E. pyriformis Turcz. (pear-fruited mallee), and E. youngiana F. Muell. (large-fruited mallee), was investigated using molecular data generated by randomly amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR) analysis. Samples of DNA from seedlings derived from controlled pollinations, and from different individuals from each species, were amplified with six different 10-mer primers. The presence or absence of RAPD fragments was used to generate a dendrogram based on genetic similarity, an ordination derived by multidimensional scaling (MDS), and a minimum spanning tree (MST) to show the relative links and dissimilarities between the individuals tested. Two clusters were identified on the unweighted pair-group method arithmetric average dendrogram. The first included all of the E. macrocarpa genotypes and all but one of the E. macrocarpa hybrids. The second included all of the E. youngiana and E. pyriformis genotypes and their hybrids. The MDS ordinations placed the hybrid seedlings between the parent species. From the 30 progeny investigated, 28 were assessed from the molecular data to be hybrids from controlled pollinations. The remaining two seedlings appeared to be derived from self-pollination. The parentage of two mature trees, thought to be natural hybrids involving the three species, was also investigated. One was confirmed as a cross between E. youngiana and E. pyriformis, but the second was less certain because of its low genetic similarity to all other individuals, and may be a hybrid involving species not included in this study.
Differences in Fruit Development among Large- and Small-fruited Cultivars of Saskatoon (Amelanchier alnifolia)
Authors: McGarry Roisin , Ozga Jocelyn A. , Reinecke Dennis M.
Published: January 2019

Fruit growth in saskatoons (Amelanchier alnifolia Nutt.), an emerging horticultural crop across the Canadian prairies, results from development of the mesocarp and the endocarp-locular-ovular structure which includes the developing seeds. Contribution of these tissues to fruit size was assessed using transverse sections of ovaries sampled at six developmental stages among large- and small-fruited cultivars. Mesocarp development was similar among the larger-fruited cultivars (Thiessen, Northline, and Smoky); the number of cells increased rapidly through Stage I [162 to 293 growing degree days (GDDs)] of fruit growth, and cell number increase was minimal during Stages II (293 to 577 GDDs) and III (577 to 747 GDDs). In `Regent' fruit (a small-fruited cultivar), the maximal rate of cell division was delayed until Stage II and the mesocarp contained fewer cells than the larger-fruited cultivars at harvest maturity. Mesocarp cell enlargement was similar among all of the cultivars studied where cell expansion was maximal during Stage I and continued at a slower rate during Stages II and III. The area of the endocarp-locular-ovular structure was greatest for `Thiessen' and `Northline', midrange for `Smoky', and smallest for `Regent'. Data suggest that a minimum number of mesocarp cells early in fruit development is required to attain maximal mesocarp size, and that differences in cultivar fruit size are a function of both the mesocarp and the endocarp-locular-ovular structure.
Developmental Consequences of Cold Temperature Stress at Transplanting on Seedling and Field Growth and Yield. I. Watermelon
Authors: Korkmaz Ahmet , Dufault Robert J.
Published: January 2019

Watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) seedlings transplanted before the last frost date may be exposed to temperatures alternating between freezing and optimal until field temperatures finally stabilize. Cold stress may ultimately reduce growth and yield. To simulate such temperature alternations that occur naturally after field transplanting, diploid `Carnival' watermelon seedlings were exposed immediately before field planting to cyclic cold temperature stress at 2 ± 1 °C then transferred to a greenhouse at 29 ± 5 °C. In 1997, transplants were exposed to 2 °C from 3 to 81 hours and in 1998, exposure ranged from 9 to 81 hours. Cold-stressed seedlings were field planted after all potential risk of cold stress in the field had passed. In 1997, cold stress decreased seedling shoot and root fresh and dry weights, leaf area, chlorophyll and carbohydrate contents but not seedling height. In 1998, all seedling growth variables decreased in response to longer durations of cold stress. Plants cold stressed for up to 81 hours transpired more for 1 week after transplanting than those exposed to shorter periods of cold stress. In both years, vining (date first runner touched the ground), flowering, and fruit set were delayed significantly as cold stress hours increased. Although early yields were unaffected, total yields decreased linearly in both years with increasing hours of cold, with 38 to 40 hours of cold stress reducing yield 10% in both years. Data indicate that `Carnival' watermelon transplants exposed to cold stress soon after transplanting may suffer yield reductions.
Selection Influences Heritability Estimates and Variance Components for Anthracnose Resistance in Populations Derived from an Intraspecific Cross of Tomato
Authors: Stommel John R.
Published: January 2019

Genetic characterization of anthracnose resistance in tomato (Lycopersicon esculentum Mill.) caused by Colletotrichum coccodes (Wallr.) Hughes was accomplished using populations developed from crosses between the anthracnose susceptible cultivar US28 and three resistant breeding lines (115-4, 625-3, and 88B147) that varied in their degree of anthracnose resistance and relative stage of adaptation for commercial use. These lines were of common parental lineage with resistance derived from the small-fruited L. esculentum USDA PI 272636. Anthracnose lesion diameters and fruit weight were measured in puncture inoculated fruit of parental, F1, F2, and backcross generations within each cross. Correlation coefficients between fruit size and lesion diameter were low and generally nonsignificant. Estimates of broad and narrow sense heritabilities for resistance were moderate and declined as relative anthracnose susceptibility of the resistant parent increased coincident with increasing horticultural adaptation. A simple additive dominance model, m[d][h], was adequate to explain the genetic variance for anthracnose resistance in all crosses. Genetic variance for anthracnose resistance was primarily additive. The minimum number of effective factors or loci conditioning anthracnose resistance declined during attempts to transfer high levels of resistance from PI 272636 into adapted breeding lines.
Identification of Pecan Cultivars and Their Genetic Relatedness as Determined by Randomly Amplified Polymorphic DNA Analysis
Authors: Conner Patrick J. , Wood Bruce W.
Published: January 2019

Genetic variation among pecan [Carya illinoinensis (Wangenh.) C. Koch] cultivars was studied using randomly amplified polymorphic DNA (RAPD) markers. Using a combination of primers, a unique fingerprint is presented for each of the pecan genotypes studied. The genetic relatedness between 43 cultivars was estimated using 100 RAPD markers. Genetic distances, based on the similarity coefficient of Nei & Li, varied from 0.91 to 0.46, with an average value of 0.66 among all cultivars. The phenetic dendrogram developed from cluster analysis showed relatively weak grouping association. However, cultivars with known pedigrees usually grouped with at least one of the parents and genetic similarity estimates appear to agree with known genetic relationships.
Characterization of Heat Shock Protein Expression in Apple Peel under Field and Laboratory Conditions
Authors: Ritenour Mark A. , Kochhar Sunita , Schrader Larry E. , Hsu Tsui-Ping , Ku Maurice S.B.
Published: January 2019

Western immunoblot analyses showed that small heat shock proteins (smHSPs) are low or undetectable in the peel of `Fuji', `Jonagold', `Criterion', `Gala', and `Delicious' apples [(Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] growing shaded within the tree canopy (shade apples), but are high in apples growing exposed to direct sunlight (sun apples). `Fuji', `Jonagold', and `Gala' sun apples sampled biweekly between 1 July and 21 Oct. 1997 were highest in content of smHSPs on 31 July, 13 Aug., and 10 Sept., corresponding to some of the warmest periods of the sampling period. The smHSPs started to disappear first in `Gala', the earliest maturing cultivar, and last in `Fuji', the latest maturing cultivar indicating that maturity might play a role in regulating smHSP accumulation. In sun apple fruit left on trees for 60 to 120 days beyond commercial maturity and exposed to field temperatures as low as -4 °C, a 71.7 ku (u = unified atomic mass unit) polypeptide was detected with a polyclonal antiwheat (Triticum aestivum L.) HSP70 in the peel and cortex of all five cultivars. While no smHSPs were detected in these apples, three smHSPs, as detected by antibodies against pea (Pisum sativum L.) cytosolic HSP18.1, could be induced in the same fruit 24 hours after heating to 45 °C for 4 hours. In `Fuji' shade apples heated at 40 °C, smHSP accumulation was detected after the second hour of a 4-hour heat treatment and continued to increase over the next 48 hours at 22 °C. Levels of HSP70 did not change in `Fuji' shade apples heated at 45 °C for 2, 4, or 6 hours, but smHSPs became detectable immediately after each of these heat treatments and further increased over the next 24 hours at 22 °C. Accumulation of smHSPs was maximal in the 4-hour heat treatment. After a 4-hour heat treatment at 45 °C, smHSPs increased during the next 48 hours at 22 °C and then declined by 72 hours. Using two-dimensional electrophoretic analysis, as many as 17 proteins ranging from 15 to 29 ku were found to accumulate in the peel 48 hours after a 4-hour heat treatment. Thus, apples can respond rapidly to high temperature stress, even at advanced stages of maturity, by synthesizing smHSPs, which likely play an important role in protecting cellular biochemical processes during these periods of stress.
Genetic and Morphological Analysis of the Origin and Identity of Perennial Lavatera (Malvaceae) Cultivars
Authors: Grant Mike L. , Miller Diana M. , Culham Alastair
Published: January 2019

Knowledge of the origin of Lavatera L. (tree mallows) cultivars helps to predict their cultural requirements. Eighteen accessions representing 15 cultivars, 14 accessions of 7 species, and 5 accessions of an F1 hybrid between the putative parents of the cultivars were sampled for morphological variation and for randomly amplified polymorphic DNA (RAPD) fingerprint variation. Species-specific molecular markers were identified from the RAPD profiles. Chimeral elements were not distinguishable by RAPD analysis. Principal component analysis identified the majority of the cultivars to be selections of hybrid origin, probably from a narrow genetic base. Two cultivars were derived directly from individual species. The resolving power of RAPD markers and morphology was similar although RAPD data offered greater ability to ascribe parentage while morphology offered optimal discrimination of cultivar selections.
Whole-plant Carbon Dioxide Exchange Responses of Angelonia angustifolia to Temperature and Irradiance
Authors: Miller Amanda M. , van Iersel Marc W. , Armitage Allan M.
Published: January 2019

Light and temperature responses of whole-plant CO2 exchange were determined for two cultivars of Angelonia angustifolia Benth., `AngelMist Purple Stripe' and `AngelMist Deep Plum'. Whole crop net photosynthesis (Pnet) of `AngelMist Purple Stripe' and `AngelMist Deep Plum' were measured at eight temperatures, ranging from 17 to 42 °C. Pnet for both cultivars increased from 17 to ≈20 °C, and then decreased as temperature increased further. Optimal temperatures for Pnet of `AngelMist Purple Stripe' and `AngelMist Deep Plum' were 20.8 and 19.8 °C, respectively. There was no significant difference between the two cultivars, irrespective of temperature. The Q10 (the relative increase with a 10 °C increase in temperature) for Pnet of both cultivars decreased over the entire temperature range. Dark respiration (Rdark) of both cultivars showed a similar linear increase as temperature increased. As photosynthetic photon flux (PPF) increased from 0 to 600 μmol·m-2·s-1, Pnet of both cultivars increased. Light saturation was not yet reached at 600 μmol·m-2·s-1. The light compensation point occurred at 69 μmol·m-2·s-1 for `AngelMist Purple Stripe' and at 89 μmol·m-2·s-1 for `AngelMist Deep Plum'. The lower light saturation point of `AngelMist Purple Stripe' was the result of a higher quantum yield (0.037 mol·mol-1 for `AngelMist Purple Stripe' and 0.026 mol·mol-1 for `AngelMist Deep Plum'). The difference in quantum yield between the two cultivars may explain the faster growth habit of `AngelMist Purple Stripe'.
Antioxidant Responses in Harvested Leaves of Two Cultivars of Spinach Differing in Senescence Rates
Authors: Hodges D. Mark , Forney Charles F. , Wismer Wendy V.
Published: January 2019

The objective of this study was to assess responses of certain antioxidants in harvested leaves of selected cultivars of spinach (Spinacia oleracea L.) differing in postharvest senescence rates in order to explore the significance of these antioxidants in postharvest senescence regulation and dynamics. Ten cultivars were grown in both field plots and laboratory growth chambers, harvested at maturity, and their leaves detached and stored at 10 °C in the dark. Following postharvest analysis, two cultivars were identified consistently as having relatively high (`Spokane F1') and low (`BJ 412 Sponsor') postharvest senescence rates. These two cultivars were then grown in a growth chamber for 45 days and their leaves detached and stored as above. At the point of harvest (day 0) and on days 4, 8, 12, 16, and 20, samples were analyzed for activities of ascorbate peroxidase (ASPX; EC 1.11.1.11), catalase (CAT; EC 1.11.1.6), and superoxide dismutase (SOD; EC 1.15.1.1), and (ii) concentrations of malondialdehyde (MDA, an indicator of lipid peroxidation), total ascorbate, reduced ascorbate (AsA), oxidized ascorbate (DAsA), total glutathione, reduced glutathione (GSH), and oxidized glutathione (GSSG). Although MDA accumulated in leaves of both cultivars concomitant with time after detachment, levels became significantly higher in `Spokane F1'. It is argued that declining activities of ASPX and levels of ascorbate and increasing activities of SOD manifested in accumulation of hydrogen peroxide in `Spokane F1', leading to a greater potential for lipid peroxidation in this cultivar than for `BJ 412 Sponsor'. SOD activities and glutathione levels may have increased as a result of elevated oxidative stress in `Spokane F1'. Increased hydrogen peroxide accumulation in `Spokane F1' relative to `BJ 412 Sponsor' may have contributed to an increased rate of senescence in the harvested leaves of this cultivar.
Cultivar Identification in Olive Based on RAPD Markers
Authors: Besnard Guillaume , Breton Catherine , Baradat Philippe , Khadari Bouchaib , Bervillé André
Published: January 2019

One hundred and thirteen olive (Olea europaea L.) accessions were characterized using randomly amplified polymorphic DNA (RAPD) markers. Forty-five polymorphic RAPD markers were obtained enabling us to distinguish 102 different RAPD profiles. The approximate estimation of the probability of obtaining the same RAPD profile for two different trees was between 6.75 × 10-5 and 4.82 × 10-14. A dendrogram was constructed using Ward's minimum variance algorithm based on chi-square distances. This led to a more clear-cut classification of profiles than the classical approach of unweighted pair group method with arithmetic average. Twenty-four clusters of RAPD profiles were shown in Ward's dendrogram. Reliability of the dendrogram structure was checked using variance analysis. RAPD data exhibited an acceptable resolving power for cultivar identification. A combination of three primers was proposed for rapid molecular identification of cultivars in collections and in nurseries.
A Genetic Linkage Map for Watermelon Based on Randomly Amplified Polymorphic DNA Markers
Authors: Levi Amnon , Thomas Claude E. , Zhang Xingping , Joobeur Tarek , Dean Ralph A. , Wehner Todd C. , Carle Bruce R.
Published: January 2019

A genetic linkage [randomly amplified polymorphic DNA (RAPD)-based] map was constructed for watermelon [Citrullus lanatus (Thunb.) Matsum and Nakai] using a BC1 population [PI 296341-fusarium wilt resistant × New Hampshire Midget (fusarium susceptible)] × `New Hampshire Midget'. The map contains 155 RAPD markers, and a 700-base pair sequenced characterized amplified region (SCAR) marker that corresponds to a fragment produced by the RAPD primer GTAGCACTCC. This marker was reported previously as linked (1.6 cM) to race 1 fusarium wilt resistance in watermelon. The markers segregated to 17 linkage groups. Of these, 10 groups included nine to 19 markers, and seven groups included two to four markers. The map covers a genetic linkage distance of 1295 cM. Nine of the 10 large linkage groups contained segments with low (or no) level of recombination (0 to 2.6 cM) among markers, indicating that the watermelon genome may contain large chromosomal regions that are deficient in recombination events. The map should be useful for identification of markers linked closely to genes that control fruit quality and fusarium wilt (races 1 and 2) resistance in watermelon.
Inheritance of Male Sterility in Lesquerella fendleri
Authors: Dierig David A. , Tomasi Pernell M. , Ray Dennis T.
Published: January 2019

Lesquerella fendleri (Gray) Wats. (lesquerella, Brassicaceae), native to the southwestern United States, is a potentially useful industrial oilseed crop. The seed oil contains hydroxy fatty acids, similar to castor (Ricinus communis L.) seed oil. The unique properties of the oil, along with coproducts, allow additional applications that would not compete with castor oil. Plants with vestigial anthers (male-sterile) were discovered in a greenhouse-grown, nonselected population in 1993. The inheritance of the trait was investigated through four crop seasons. Crosses were made among male-sterile and male-fertile plants from an open pollinated population, thus, they were heterozygous for many traits. Statistical analysis indicated that male sterility is expressed as a result of two nonlinked nuclear genes with epistatic relations and different cytoplasms, which cause partial or total fertility restoration. These ratios fit a 13:3 epistatic ratio, indicating that male sterility is controlled by homozygous recessive alleles at one locus in combination with at least one dominant allele at the second locus, i.e., ms1ms1 Ms2_. Some cross results were skewed in favor of fertile phenotypes presumably due to cytoplasmic effects causing partial fertility restoration. Male-sterile lines could be used for hybrid development and this information will be helpful in implementing a strategy for hybrid development. Hybrid plants and higher yields will enhance the potential for commercialization of this new alternative crop.
Root and Shoot Characteristics of Peach Trees with Different Growth Habits
Authors: Tworkoski Thomas , Scorza Ralph
Published: January 2019

Shoot and root characteristics of four peach tree [Prunus persica (L.) Batsch (Peach Group)] growth habits (compact, dwarf, pillar, and standard) were studied. In compact trees, leaf number (1350/tree) was twice, but leaf area (6 cm2/leaf) was half that of pillar and standard trees. The number of lateral branches in compact trees (34) was nearly three times more than in pillar and standard trees. Leaf area index (total one-side leaf area per tree divided by the canopy cross-sectional area of the tree) of pillar trees was greater than compact, dwarf, and standard trees (13 compared with 4, 4, and 3, respectively) due to a narrower crown diameter. Dwarf trees were distinct with few leaves (134/tree) and less than half the roots of the other growth habits. Compact trees produced more higher order lateral (HOL) roots than pillar and standard trees. More second order lateral (SOL) roots were produced by compact than standard trees (1.2 vs. 0.8 SOL roots per centimeter first order lateral root). Pillar trees had higher shoot: root dry weight (DW) ratios (2.4) than compact and standard trees (1.7 for both) due to lower root DWs. Root topology was similar among compact, pillar, and standard peach trees but root axes between branch junctions (links) were significantly longer in compact trees. Compact trees had more and longer HOL roots in roots originating near the root collar (stem-root junction) (i.e., more fibrous roots) and this appeared to correlate with more lateral branches in the canopy. These results indicate significant differences in root as well as shoot architecture among growth habits that can affect their use as scion or rootstock cultivars.
Shell Seal Breakdown in Almond is Associated with the Site of Secondary Ovule Abortion
Authors: Gradziel T.M. , Martínez-Gómez P.
Published: January 2019

California almonds [Prunus dulcis, syn. P. amygdalus, P. communis] possess a moderately lignified `paper' shell rather than the stony, peach-pit type shells common to European and Asian cultivars. At nut maturity, more than 70% of shells of the principal California cultivar Nonpareil can be split. Use of a mechanical shaker to harvest nuts increased the proportion of nuts with split shells by 40% when compared to hand harvest. All shell splitting occurred at the ventral suture with ∼ 80% of the splits occurring at the site of the degenerating funiculus leading to the aborted or secondary ovule. Remaining splits occurred near the site of the funiculus feeding the viable ovule, and only rarely at the suture line. Abortion of one of the two ovules in the almond ovary is often initiated at or shortly after bloom, and so the final site of shell splitting appears to be predetermined early in fruit development. Measurements of the strength of the inner endocarp wall at 50 days after flowering showed distinct weaknesses in the areas of the developing funiculi. Similarly, damage to the developing kernel at 60 days after flowering by the leaffooted bug (Leptoglossus clypealis Heiderman) occurred along the ventral suture, with 80% of the damage located at the point of attachment of the secondary funiculus.
Genotypic and Environmental Variation in Antioxidant Activity, Total Phenolic Content, and Anthocyanin Content among Blueberry Cultivars
Authors: Connor Ann Marie , Luby James J. , Tong Cindy B.S. , Finn Chad E. , Hancock James F.
Published: January 2019

Dietary antioxidants may have a role in preventing some of the chronic diseases in humans resulting from free radical oxidation of lipids and other cellular components. Blueberries (Vaccinium L. sp.) are considered one of the best fresh fruit sources of antioxidants, and there is the potential to increase the antioxidant activity further through breeding. Thus, the variability of fruit antioxidant activity (AA) was examined among a set of 16 highbush and interspecific hybrid cultivars grown at locations in Minnesota (MN), Michigan (MI), and Oregon (OR) over 2 years (1998 and 1999) to determine effects of genotype, year, and location. Nine cultivars were common to all three locations in both years. Antioxidant activity, total phenolic content (TPH), and total anthocyanin content (ACY), were determined in triplicate samples from each genotype. Cultivars differed significantly (P ≤ 0.05) in AA, TPH, and ACY both within and over locations. The single location mean AA for all cultivars changed significantly between the 2 years in OR and in MI, while the single location mean for TPH differed between the 2 years in MN and MI. Changes in cultivar rank were significant for AA, TPH, and ACY between years within each location. Significant changes in rank for TPH and ACY were also noted between pairs of locations as well. Pearson's correlation for AA (based on cultivar means) appeared highest between MN and OR (r = 0.90) and MN and MI (r = 0.69) in 1998; correlations between locations for the combined years were 0.74 for MN and OR, 0.55 for MN and MI and 0.45 for MI and OR. For the group of nine cultivars, AA correlated well with TPH within each location, with r ranging from 0.67 to 0.95 for data from individual and combined years. Correlation of AA with ACY at each location was lower than that for AA with TPH, in both individual and combined years. This study demonstrates significant genotype× environment interaction for AA in blueberry.
Physiological and Anatomical Characterization of a Late-storage Root-forming Mutant of Sweetpotato
Authors: Nakatani Makoto , Tanaka Masaru , Yoshinaga Masaru
Published: January 2019

A late-storage root-forming mutant (`KM95-A68') of sweetpotato [Ipomoea batatas (L.) Poir.] was characterized to clarify the genetic and physiological mechanisms of storage root formation. This mutant originated from a somaclonal mutation of `Kokei No. 14'. Storage roots of `KM95-A68' are rare and, when formed, develop 2 or 3 weeks later than those of `Kokei No. 14' from which it originated. Morphological characteristics of the canopy and leaf photosynthetic rates of `KM95-A68' were similar to those of `Kokei No. 14'. No apparent differences were observed in the anatomy of root cross sections of `KM95-A68' and `Kokei No. 14'. An apparent increase in the root zeatin riboside (ZR) levels were observed in `Kokei No. 14' at storage root formation. Root ZR levels differed between `Kokei No. 14' and `KM95-A68'. The onset of increase in root ZR levels was delayed by 2 or 3 weeks in `KM95-A68' in comparison to `Kokei No. 14'. Maximum root ZR levels in `Kokei No. 14' were 2.2 times higher in comparison to `KM95-A68'. This appeared to be a factor in delayed storage root formation of `KM95-A68'. Results of reciprocal grafts of `KM95-A68' and `Kokei No. 14' indicated that the late storage root-forming characteristic of `KM95-A68' is a characteristic that arises from the root itself.
Iron Deficiency Induced Changes in Iron Reductase Activity in Papaya Roots
Authors: Marler Thomas E. , Cruz Ruben dela , Blas Andrea L.
Published: January 2019

Four papaya (Carica papaya L.) cultivars were cultured aeroponically or in perlite to determine the magnitude, timing, and root locality of Fe reductase induced by Fe deficiency. Five soybean [Glycine max (L.) Merrill] lines with a known range of Fe-deficiency chlorosis scores were cultured in perlite for comparison. Speed of inducement of Fe reductase activity was determined in plants cultured without Fe for 0 to 17 days. Location of Fe reductase activity was determined by sectioning roots from the tip to 60 to 70 mm proximal to the root tip from plants cultured without Fe for 16 to 19 days. The Fe reductase system was induced in all papaya cultivars after 7 to 11 days without Fe, and activity increased through 17 days. Iron reductase activity in all papaya cultivars was comparable to the most tolerant soybean line. The zone of highest activity was the apical 10 mm of roots. These results indicate that papaya roots are highly efficient in induced Fe reductase activity. The highest activity in root tips underscores the importance of maintaining a healthy, continually growing root system with numerous growing points when culturing papaya in alkaline substrates.
A Reflective, Processed-Kaolin Particle Film Affects Fruit Temperature, Radiation Reflection, and Solar Injury in Apple
Authors: Glenn D. Michael , Prado Ernesto , Erez Amnon , McFerson James , Puterka Gary J.
Published: January 2019

Particle film technology is a new tool for tree fruit production systems. Trials were performed in Santiago, Chile, and Washington and West Virginia to evaluate the effect of particle film treatments on apple [Malus sylvestris (L.) Mill var domestica (Borkh.) Mansf.] fruit temperature and the incidence of solar injury. Fruit surface temperature was reduced by the application of reflective particles and the amount of temperature reduction was proportional to the amount of particle residue on the fruit surface. Effective solar injury suppression was achieved with spray applications of 45 to 56 kg·ha-1 of a reflective, processed-kaolin particle film material in concentrations ranging from 3% to 12% in some of the locations. The timing of application to suppress solar injury was not clearly defined. The processed-kaolin particle film material was highly reflective to the ultraviolet wavelengths and this characteristic may be important in reducing solar injury to both fruit and leaves.
Pistachio Rootstocks Influence Scion Growth and Ion Relations under Salinity and Boron Stress
Authors: Ferguson L. , Poss J.A. , Grattan S.R. , Grieve C.M. , Wang D. , Wilson C. , Donovan T.J. , Chao C.-T.
Published: January 2019

Performance of `Kerman' pistachio (Pistacia vera L.) trees on three rootstocks (P. atlantica Desf., P. integerrima Stewart and `UCB-1', a P. atlantica × P. integerrima hybrid) was evaluated with 2-year-old trees grown in sand-tank lysimeters under combined SO42- and Cl- salinity and boron (B) stress for 6 months. Four salinity treatments were imposed by irrigating the plants with water at electrical conductivity (ECiw) of 3.5, 8.7,12, or 16 dS·m-1 each containing B at 10 mg·L-1. Growth of `Kerman' was evaluated based on increase in total leaf area, increase in trunk diameter, and total above-ground biomass production. All growth parameters decreased as salinity increased, but were not significant until ECiw exceeded 12 dS·m-1. However, growth of `Kerman' on P. atlantica and `UCB-1' was considerably better than on P. integerrima at 16 dS·m-1. The onset and severity of foliar injury differed among scions and treatments and was attributed primarily to B toxicity, rather than the effects of salinity. Concentrations of B in injured leaf tissue ranged from 1000 to 2500 mg·kg-1. Leaf injury decreased with increasing salinity, although leaf B was not significantly reduced suggesting an internal synergistic interaction between B and other mineral nutrients. However for P. vera on P. integerrima, the highest level of salinity produced the greatest injury, possibly as a combination of B plus Cl- and/or Na+ toxicity. Leaf transpiration, stomatal conductance, and chlorophyll concentration of P. vera, determined by steady-state porometry, were also reduced to a greater degree by combined salinity and B when budded on P. integerrima than on the other two rootstocks.
Yield Reduction Caused by Twospotted Spider Mite Feeding in an Advanced-cycle Strawberry Breeding Population
Authors: Walsh Douglas B. , Zalom Frank G. , Shaw Douglas V. , Larson Kirk D.
Published: January 2019

Forty-eight strawberry (Fragaria ×ananassa Duchesne) or (Fragaria L. sp.) genotypes from the University of California advanced-cycle breeding population were evaluated over 7 years for susceptibility to and tolerance of infestation by two-spotted spider mite (Tetranychus urticae Koch). In pairwise tests, 23 photoperiodically short-day genotypes were compared with the short-day cultivar Chandler, and 23 day-neutral genotypes to the day-neutral cultivar Selva. Feeding by T. urticae resulted in substantial yield reductions regardless of genotype. Yield reduction from feeding by T. urticae averaged 29.9% for short-day and 23% for day-neutral genotypes. Calculation of variance components for day-neutral genotypes determined that none of the variation in yield was explained by the interaction of genotype and T. urticae infestation, whereas 24.4% of the variation in yield for short-day genotypes was explained by the interaction of genotype and T. urticae infestation. Under current strawberry production practices in California there appears to be little potential for breeding direct resistance to T. urticae for day-neutral genotypes. However, some gains in breeding direct T. urticae resistance may be achieved within short-day genotypes. Phenotypic path-coefficient analysis for direct and indirect effects, and simple correlation coefficients of T. urticae feeding determined there were substantial differences between short-day and day-neutral genotypes in their yield responses to T. urticae feeding. For short-day genotypes, the greatest direct effect on yield resulted from T. urticae feeding in June. For day-neutral genotypes, the greatest direct effects resulted from T. urticae feeding in April and May and were probably due to the day-neutral genotype's more complex flowering responses. Several high-yielding cultivars have been developed and released over the 7 years of this study. It appears the new cultivars that were bred for current cultural practices exhibited a consistent plant response for greater yield both in the presence and absence of T. urticae feeding.
Genetic Diversity of a Capsicum Germplasm Collection from Nepal as Determined by Randomly Amplified Polymorphic DNA Markers
Authors: Baral J. , Bosland P.W.
Published: January 2019

Domesticated chile (Capsicum annuum L. var. annuum) is a widely cultivated spice and vegetable crop. It originated in the Western Hemisphere, but spread rapidly throughout the globe after the voyage of Columbus. However, very little is known about the genetic diversity of chile in Asia and especially in Nepal. Thus, research was conducted to document morphological as well as molecular characterization of C. annuum var. annuum landraces collected from Nepal. Genetic diversity in C. annuum var. annuum landraces from Nepal was investigated using randomly amplified polymorphic DNA (RAPD) markers and compared with that of C. annuum var. annuum landraces from the center of diversity, Mexico. RAPD marker based cluster analysis of C. annuum var. annuum clearly separated each accession. All accessions of C. annuum var. annuum from Nepal grouped into a single cluster at a similarity index value of 0.80, whereas, accessions from Mexico grouped into eight different clusters at the same similarity level indicating greater genetic diversity in Mexican accessions. RAPD analysis indicated that the Nepalese chile population went through an additional evolutionary bottleneck or founder effect probably due to intercontinental migrations. Some Nepalese accessions had unique RAPD markers suggesting that additional sources of genetic variation are available in Nepalese germplasm.
Use of a Hydrophobic Particle Film as a Barrier to Extrinsic Ice Nucleation in Tomato Plants
Authors: Wisniewski Michael , Glenn D. Michael , Fuller Michael P.
Published: January 2019

Extrinsic ice nucleating agents (such as ice-nucleation-active bacteria, dew, etc.) significantly limit the ability of herbaceous plants to supercool. It is believed that with an absence of these extrinsic nucleating agents, a plant could supercool to less than -4 °C. Other evidence, however, indicates that intrinsic nucleating agents may limit the extent of supercooling. Infrared video thermography was used to study freezing in young, `Rutgers' tomato (Lycopersicon esculentum L.) plants and to determine if a hydrophobic barrier on the plant surface could prevent extrinsic nucleating agents such as Ice+ bacterial strain (Cit7) of Pseudomonas syringae Van Hall from initiating freezing within a plant. Freezing tests were conducted in a programmable freezing chamber, a radiative frost chamber, and outdoors. Freezing was visualized and recorded on videotape using an infrared radiometer. Freezing of the plants was induced extrinsically by application of droplets (5 to 7 μL) of water containing Cit7. To provide a barrier to the action of extrinsic ice nucleating agents, an emulsion of hydrophobic kaolin (aluminum silicate mineral) was applied to the plant surface before application of an extrinsic nucleating agent. Results indicate that dry, young tomato plants can supercool to as low as -6 °C whereas plants having a single droplet of Cit7 would freeze at -1.5 to -2.5 °C. Application of the hydrophobic barrier blocked the effect of Cit7 and allowed whole plants to also supercool to -6 °C, despite the presence of frozen droplets on the leaf surface. When whole plants were sprayed with water and Cit7 using an aerosol sprayer and exposed to -3 °C, plants coated with the hydrophobic particle film exhibited significantly less foliar injury then nontreated plants. Similar results were obtained using the radiative frost chamber. Experiments conducted under natural frost conditions also resulted in less injury to the coated plants. The hydrophobic kaolin particle film performed better at preventing plants from freezing due to extrinsic ice nucleation than nonaltered, hydrophyllic kaolin alone or an antitranspirant with putative frost protection properties.
Molecular Diversity Analysis of Cultivated Carrot (Daucus carota L.) and Wild Daucus Populations Reveals a Genetically Nonstructured Composition
Authors: Bradeen James M. , Bach Inga C. , Briard Mathilde , le Clerc Valérie , Grzebelus Dariusz , Senalik Douglas A. , Simon Philipp W.
Published: January 2019

A sample of 124 Daucus carota L. accessions, including cultivated carrot [D. carota ssp. sativus (Hoffm.) Arcangeli] and related wild subspecies, using a variety of molecular markers was examined. Represented within the samples were wild accessions from 18 countries, 14 of 16 major root types of European origin, and examples of major North American and Asian cultivated carrot types. Amplified fragment length polymorphism (AFLP) and inter-simple sequence repeat (ISSR) markers revealed extensive variation within D. carota. Although cultivated carrot and wild D. carota subspecies can cross freely, cultivated and wild carrots clustered separately, supporting the possibility that human selection for desirable horticultural traits has artificially reduced gene flow between cultivated and wild forms. Our analyses support the likelihood that North American D. carota populations arose due to introduction of weedy materials rather than escape of cultivated forms. With the exception of wild vs. cultivated types, no genetic alliances were evident in dendrogram topology. Furthermore, between and even within nonmapped marker classes, dendrogram topology predictions were not consistent. Generally poor correlations among root types, geographic origin, mitochondrial, plastid, and specific nuclear diversity and AFLP/ISSR data were also observed. We concluded that genetic diversity in carrot is extensive and relatively nonstructured in nature.
Polyploidy-induced Changes in the Breeding Behavior of Hatiora ×graeseri (Cactaceae)
Authors: Karle Renate , Parks Constance A. , O'Leary Maureen C. , Boyle Thomas H.
Published: January 2019

Spontaneous chromosome doubling occurred in shoot apices of two diploid (2n = 22) Hatiora ×graeseri Barthlott ex D. Hunt (Easter cactus) clones and yielded stable periclinal cytochimeras with a diploid epidermis and tetraploid subepidermis. The cytochimeras produced disomic gametes (n = 22) and displayed tetrasomic inheritance at polymorphic isozyme loci. Diploid clones were highly self-incompatible (SI) but both cytochimeras were self-compatible (SC). Analysis of pollen tube growth in selfed or outcrossed styles revealed that polyploidy altered the incompatibility phenotype of pollen without affecting the incompatibility phenotype of the pistil. Morphological data (guard cell length, stomatal density, and pollen diameter), segregation ratios at isozyme loci, and fruit/seed yields indicate that S1 progeny are SC, nonchimeral, and tetraploid. Breakdown of the SI system in the cytochimeras was attributed to formation of compatible heteroallelic pollen. These results provide a rational explanation for the correlation between ploidy level and breeding behavior in cacti. Production of SC autotetraploid clones from SI diploids by chromosome doubling may be useful in development of cacti as fruit crops.