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  • Author or Editor: J.R. King x
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Postharvest quality of `Climax' rabbiteye blueberries (Vaccinium ashei Read) was evaluated after exposure to dosages of 0, 0.75, 1.5, 2.25, or 3.0 kGy gamma irradiation (0.118 kGy·min-1) and after subsequent storage. Irradiation did not affect weight loss, but irradiated berries were softer than nontreated berries. There was also a trend toward increased decay as dose increased. Irradiation had no effect on powdery bloom or surface color; total soluble solids concentration, acidity, and pH were affected slightly. Flavor preference was highest for nonirradiated berries and generally declined as dosage increased. Irradiation at 2.25 and 3.0 kGy resulted in increased levels of xylosyl residues in cell walls, and xylosyl residues were the most abundant cell-wall neutral sugar detected in blueberries. There was no evidence of cell wall pectin loss in irradiated berries. Irradiation at 21.5 kGy lowered the quality of fresh-market `Climax' blueberries.

Free access

Abstract

‘Puget Gold’ is a partially self-fruitful apricot (Prunus armeniaca L.) that has been more prolific and reliable in bearing than other cultivars tested at Northwestern Washington Research and Extension Center, Mount Vernon. Since planting in 1979, it has produced a moderate to heavy crop every year, compared to ‘Skaha’ which did not crop at all in two seasons and set only a few fruits in most years. Because weather conditions at bloom time in early spring can inhibit pollination activity by insects, resulting in poor fruit set, the climate of the cool, moist Puget Sound region is not well suited to apricot production. Moisture-borne fungus diseases also can destroy blossoms and maturing fruit. Seven years' evaluation have shown ‘Puget Gold’ trees to be much better adapted to these adverse conditions than existing cultivars. ‘Puget Gold’ can fill a useful place in home orchards and gardens of western Washington, or other cool maritime climates.

Open Access

Abstract

Resistance in Pisum sativum to Aphanomyces euteiches was evaluated in the laboratory by the number of oospores formed in excised root tips inoculated with zoospores of the pathogen. Significantly lower mean numbers of oospores formed in root tips of 3 moderately resistant breeding lines than in those of 3 susceptible cultivars. Results were reproduceable if test procedures were adequately controlled. A sample size of 40 root tips gave 95% confidence in detecting a 40 oospore/root tip difference between means of resistant and susceptible genotypes.

Lower mean numbers of oospores formed in excised root tips of genotypes which were resistant in greenhouse tests. Inoculum concentrations of 10 to 100 zoospores/plant caused severe disease in susceptible cv. New Era, while greater amounts of inoculum were needed to cause comparable disease in 2 resistant breeding lines.

Open Access

Three 2-year field studies were conducted to evaluate 1-naphthaleneacetic acid (NAA) as a suppressant of suckers in European hazelnut (Corylus avellana L.). Treatments were basal-directed applications of NAA at 5, 10, and 20 g·L−1 a.i. applied once per season, and two sequential applications of NAA 10 g·L−1 a.i., 28 days apart, compared with 2,4-D (3.8 g·L−1 acid equivalent), and a nontreated control. Treatments were applied early in spring and repeated the following year. Both NAA and 2,4-D delayed sucker growth by 1.2- to 3.0-fold compared with the nontreated control, and response varied with experimental site and year. Sequential treatments of NAA significantly reduced sucker height and fresh weight 120 days after treatment. NAA applied in sequential treatments increased tree trunk cross-sectional area and canopy volume in two of the three experimental sites. Yield of hazelnuts increased when suckers were removed with NAA or 2,4-D compared with nontreated. Results indicate that NAA is an effective option to control suckers in hazelnuts and can help reduce herbicide and labor in sucker control.

Open Access

A genetic linkage map was constructed for watermelon based on a testcross population and an F2 population. The testcross map includes 312 markers (RAPD, ISSR, AFLP, SSR, and ASRP). This map covered a genetic distance of 1385 cM, and identified 11 large (50.7-155.2 cm), five intermediate (37.5-46.2 cm), and 16 small linkage groups (4.2-31.4 cm). Most AFLP markers are clustered in two linkage regions, while all other markers are randomly dispersed throughout the genome. Many of the markers in this study were skewed from the classical (Mendelian) segregation ratio of 1:1 in the testcross or 3:1 in the F2 population. The order of the markers within linkage groups was similar in the testcross and F2 populations. Additionally, a cDNA library was constructed using RNA isolated from watermelon flesh 1 week (rapid cell division stage), 2 weeks (cell growth and storage deposition stage), 4 weeks (maturation stage), and 5 weeks (mature fruit) after pollination. More than 1020 cDNA clones were sequenced, and analyzed using the basic local alignment search Tool (BLAST). The sequenced cDNA clones were designated as expressed sequenced tag (EST). The ESTs were searched for simple sequence repeats. About 7% of the ESTs contained SSR motifs. The ESTs containing SSRs are being used to design PCR primers and the putative markers are being tested for polymorphism among the parental lines of the mapping populations. Polymorphic markers will then be mapped using the mapping populations.

Free access

Two-year-old, field-grown golden kiwifruit (Actinidia chinensis) and fuzzy kiwifruit (Actinidia deliciosa) plants were evaluated for injury following an early freeze event of −4.1 °C on 14 Nov. 2018 in Burleson County, TX. Plant material included seven cultivars: one seed-propagated [Sungold™ (ZESY002)] and three cutting-propagated golden kiwifruit (AU Golden Dragon, AU Golden Sunshine, CK03), and one seed-propagated (Hayward) and two cutting-propagated fuzzy kiwifruit (AU Authur and AU Fitzgerald). Observations were made 5 weeks after the frost event. Base trunk diameter (BD) and maximum trunk diameter damaged (MDD) provided a reference of plant size and crude measurement of damage intensity, as evident by presence of water-soaked necrotic and/or dehydrated tissue following the removal of a thin slice of periderm, vascular cambium, phloem, and xylem. Percent of base diameter damaged (PBDD) was calculated as MDD divided by BD and provided an assessment of damage, unbiased by plant size. Percent of shoot damaged (PSD) was visually evaluated as the percentage of entire shoot system exhibiting damage. In addition, presence of basal damage (DB) and basal cracking (CB) were recorded. A strong cultivar response was observed for BD, MDD, PBDD, and PSD. Mean cultivar values for PSD ranged from 79% and 19% for AU Authur and Sungold™ seedlings, respectively, which represented extremes among cultivars. Fuzzy kiwifruit exhibited greater injury (PBDD, PSD, DB, and CB) as compared with golden kiwifruit cultivars. Basal damage and basal cracking proved unique to fuzzy kiwifruit, as DB ranged from 0% in Sungold™ seedlings to 100% in fuzzy kiwifruit ‘AU Authur’ and ‘AU Fitzgerald’. In spite of having greater vigor, golden kiwifruit plants sustained less injury. Method of propagation had no effect on injury. PBDD and PSD proved to be reliable field assays for documenting injury, based on their strong correlation value (r = 0.92). Greater relative autumn frost tolerance of golden kiwifruit over fuzzy kiwifruit cultivars is previously unreported.

Open Access