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  • Author or Editor: M.C. Scott x
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Physiological disorders of apples, such as cork spot and bitter pit, are a result of low soil calcium, low or excessive soil moisture, large fruit size, and environmental conditions. We report on the effect of microirrigation treatments on apple fruit when irrigation is applied as water alone or water plus a calcium (Ca)/boron (B) solution with applications applied over the tree canopy or under the tree canopy. Apples were harvested from trees in their 4th to 7th leaf and the number of fruit and size of fruit varied from year to year. In most years, there were no significant differences among treatments for fruit Ca. Fruit B was significantly higher in treatments where B was applied through the irrigation. Fruit N/Ca levels were lower when the fruit size was smaller, which was due to a higher number of fruit per tree. Year to year variations in fruit Ca levels also were likely to temperature, humidity, rainfall, fruit size, and shoot growth.

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Saline agricultural drainage water may be used as a resource to grow high value horticultural crops and reduce the volume of drainage for eventual disposal. To explore reuse options the effects of salinity and timing of application were tested on selected leafy vegetables grown in 24 sand culture plots in Riverside, Calif. The leafy winter vegetables included `Ruby Red Chard' Swiss chard [Beta vulgaris L. var. flavescens (Lam.) Lam.], `Space' spinach (Spinacia oleracea L.), `Vitamin Green' salad greens [Brassica rapa L. (Narinosa Group)], `Red Giant' mustard greens [Brassica juncea L. (Czerniak)], pac choi [Brassica rapa L. (Chinensis Group)], `Winterbor' kale [Brassica oleracea L. (Acephala Group)], tatsoi [Brassica rapa L. (Narinosa Group)], `Salad King' curly endive (Cichorium endivia L.), and `Red Preco No. 1' radicchio (Cichorium intybus L.). All vegetables were planted at the same time and irrigated initially with tap water and nutrients. At 3 and 7 weeks after seeding (application times), six salinity treatments were initiated by adding salts to the irrigation water to represent the chemical compositions of drainage waters found typically in the San Joaquin Valley, Calif. The six salinity treatments had electrical conductivities of 3 (control), 7, 11, 15, 19, or 23 dS·m-1. A randomized complete block design was used with (6 salinities × 2 application times × 2 replications). Within each plot a 1.5-m row of each of the nine vegetables was grown as split plots. Salinity reduced fresh weight (FW) yields of all species. Salt stress applied at 3 weeks after seeding reduced FWs for seven of the nine vegetables compared to salination at 7 weeks. Analyses of salt tolerance curves, maximum yields, and the point of 50% yield reduction (C50) were conducted. Greens produced the highest biomass at 874 g/plant, but was the most affected by application time. Swiss chard and radicchio were not significantly affected by timing of salinity application, and Swiss chard was the most salt tolerant overall. Greens, kale, pac choi, and to a lesser extent, tatsoi, have potential as winter-grown, leafy vegetables in drainage water reuse systems.

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Four chrysanthemum (Dendranthema grandiflora) spontaneous and radiation-induced sports from the cultivar `Charm' and phenotypically differing only in flower color were individually characterized using arbitrary signatures from amplification profiles (ASAP). ASAP analysis is based on a two-step arbitrary primer amplification procedure that produces “fi ngerprints of fingerprints.” In the first step, `Charm', `Dark Charm', `Dark Bronze Charm', `Salmon Charm', and `Coral Charm' were fingerprinted by DNA amplification fingerprinting (DAF) with standard octamer arbitrary primers. Diluted products from three monomorphic fingerprints for each cultivar were subsequently reamplified using four minihairpin decamer primers. Each of the 12 ASAP profiles revealed polymorphic loci that were used to uniquely identify cultivars and estimate genetic relationships. The ASAP technique permits identification of previously genetically indistinguishable plant material and should facilitate marker assisted breeding and protection of ownership rights.

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Four chrysanthemum (Dendranthema grandiflora) spontaneous and radiation-induced sports from the cultivar `Charm' and phenotypically differing only in flower color were individually characterized using arbitrary signatures from amplification profiles (ASAP). ASAP analysis is based on a two-step arbitrary primer amplification procedure that produces “fingerprints of fingerprints.” In the first step, `Charm', `Dark Charm', `Dark Bronze Charm', `Salmon Charm', and `Coral Charm' were fingerprinted by DNA amplification fingerprinting (DAF) with standard octamer arbitrary primers. Diluted products from three monomorphic fingerprints for each cultivar were subsequently reamplified using four minihairpin decamer primers. Each of the 12 ASAP profiles revealed about 30% polymorphic loci and some were used to uniquely identify cultivars and estimate genetic relationships. The ASAP technique permits identification of previously genetically indistinguishable plant material and should facilitate marker assisted breeding and protection of ownership rights.

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The genetic distance of closely related cultivars of Dendranthema grandiflora (chrysanthemum) was assessed using DAF. Thirteen cultivars of chrysanthemum included in the study were members of the following series: Charm (five), Davis (four), and Pomona (four). The genetic variability within and between series were evaluated using 11 arbitrary octamer primers. A few polymorphic loci were evident that uniquely identified closely related cultivars within a series. In contrast, there were many polymorphisms between members of different series. Genetic distances between cultivars within and between series were calculated using marker comparison and UPGMA (cluster analysis). The average distance between series was 10-fold greater than between cultivars within a series. DNA from all cultivars belonging to a series also were bulked to generate DNA profiles containing unique amplified products for each series. Polymorphic loci that were generated by the DAF technique possibly could be used for patent protection and phylogenetic studies and may be useful in breeding for chrysanthemums.

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Three methods to inoculate Lycopersicon esculentum 'VF Pink' seedlings with tomato spotted wilt virus (TSWV) were compared. Treatments were 1) two inoculations by hand (rubbing leaves with a sterile cotton swab), 2) a single inoculation using a paint sprayer at 3.56 × 105 N· m-2, and 3) two spray inoculations. All three methods were effective (>95% infection) under moderate temperatures in the spring, but hand inoculation was not effective under hot conditions in the summer. In another experiment, spray inoculation was used to compare effects of light intensity and the leaf inoculated on susceptibility of L.. hirsutum PI 127826, L. pimpinellifoliom LA 1580 and `VF Pink' to TSWV isolate 85-9. All three genotypes were susceptible under full sun and 60% shade cloth in the greenhouse. Inoculation of youngest leaves produced the highest virus titer. Background optical density for noninoculated plants differed between lower and upper leaves in the ELISA assay.

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Seedlings of eight accessions of L. hirsutum and susceptible L. esculentum `VF Pink' controls were spray inoculated twice in the greenhouse with tomato spotted wilt virus (TSWV) Arkansas 85-9. Plants lacking symptoms were reinoculated, then evaluated for TSWV by enzyme-linked immunosorbent assay (ELISA). Controls were consistently infected; sixty noninfected L. hirsutum were propagated by cuttings and inoculated with TSWV isolates T2 (lettuce), G-87 (gloxinia), 87-34 (tomato) and a mixture of the four isolates. All selections became infected in at least one test, but systemic infection was often delayed. Additional wild Lycopersicon species and numbers of accessions evaluated for resistance to TSWV include L. cheesmanii (9), L. chmielewskii (17), L. hirsutum (24), L. hirsutum f. glabratum (17), L. parviflorum (4) and L. pennellii (44). No new sources of strong resistance have been identified yet. Evaluation of additional species and accessions is continuing.

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DNA amplification fingerprinting (DAF) was used to study genetic relationships between closely related chrysanthemum cultivars (Dendranthema grandiflora Tzvelev.). Twenty-one cultivars were examined that belonged to the Anne, Blush, Boaldi, Charm, Davis, and Pomona series (families). The genetic variability of cultivars within and between series was evaluated using eleven arbitrary octamer primers. A few polymorphic characters uniquely identified closely related cultivars within each of the series. In contrast, many DNA polymorphisms were observed between members of the different series. Phenetic patterns were established by unweighted pair group cluster analysis using arithmetic means (UPGMA) and principal coordinate analysis (PCO). The average distance between series was 10-fold greater than between cultivars within a series. DNA from all cultivars belonging to a series were also bulked to generate profiles containing unique amplified products for each series. Cluster analysis and PCO of bulked DNA clearly grouped Charm and Pomona together. However, series grouping did not correspond to morphology of inflorescence types. The results demonstrate the utility of the DAF technique in distinguishing clonal materials and its potential use for patent protection, phylogenetic studies, and for identifying useful markers in breeding applications.

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The chrysanthemum (Dendranthema grandiflora Tzvelev.) cultivars `Dark Charm', `Salmon Charm', `Coral Charm' and `Dark Bronze Charm' are either radiation-induced mutants or spontaneous sports of `Charm' and constitute a family or series of plants that primarily differ in flower color. These cultivars, which were difficult to differentiate genetically by DNA amplification fingerprinting (DAF), were easily identified by using arbitrary signatures from amplification profiles (ASAP). Genomic DNA was first amplified with three standard octamer arbitrary primers, all of which produced monomorphic profiles. Products from each of these DNA fingerprints were subsequently reamplified using four minihairpin decamer primers. The 12 primer combinations produced signatures containing ≈37% polymorphic character loci, which were used to estimate genetic relationships between cultivars. Forty-six (32%) unique amplification products were associated with individual cultivars. The number of ASAP polymorphisms detected provided an estimate of the mutation rate in the mutant cultivars, ranging from 0.03% to 1.6% of nucleotide changes within an average of 18 kb of arbitrary amplified DAF sequence. The ASAP technique permits the clear genetic identification of somatic mutants and radiation-induced sports that are genetically highly homogeneous and should facilitate marker assisted breeding and protection of plant breeders rights of varieties or cultivars.

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Abstract

Phorone reduced bitter pit of apples during 4 seasons. The degree of control varied between cultivars and seasons. The study was carried out in 3 Australian states and New Zealand and involved ‘Cox's Orange Pippin’, ‘Golden Delicious’, ‘Granny Smith’, and ‘Twenty Ounce’. The apples were held in sealed or unsealed polyethylene bags, and the chemical was placed in small containers among the fruit or was injected into the core. Phorone was as effective in reducing bitter pit as a postharvest dip in 4% (w/w) calcium chloride, but it sometimes induced an off flavor. Chemical names used: 2,6-dimethyl-2-5-heptadien-4-one (phorone).

Open Access