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Abstract
A sugary-1 breeding population of maize (Zea mays L.), AS11, has hypersensitive resistance (Rp 1 d gene) to common leaf rust (CLR) (Puccinia sorghi Schw.) and is resistant to maize dwarf mosaic virus (MDMV) strains A and B. It is released for its potential value in sweet corn improvement.
Abstract
‘Andover’ parsnip (Pastinaca sativa L.) is being released for commercial fresh-market and home garden production as a cultivar with desirable root type and resistance to field and storage attack by Itersonilia perplexans Derx. (1-4), which causes a foliar leaf spot, and, in storage, a root canker followed by root deterioration. The disease is commonly known as parsnip canker. A need for resistance to deterioration in storage gave rise to the breeding program. It was found that canker was a major reason for this deterioration, although other organisms are known to be involved.
In 1997 and 1998, we determined the effects of defoliation on return bloom and fruit set following a light cropping year. In one study, `Braeburn' trees were hand-thinned to a crop density (CD) of 3 fruit/cm 2 trunk cross sectional area (TCSA) in late May 1997, and then either completely defoliated or half of the tree defoliated by hand on one of five dates between June and Sept. 1997. Compared to a nondefoliated control, both whole and half-tree defoliation on all dates reduced fruit count and yield efficiency (kilograms per square centimeter of TCSA) and affected fruit weight, starch, firmness, and soluble solids in 1997. In 1998, return bloom and fruit set were reduced by most 1997 defoliation treatments. Compared to other dates, defoliation on 3 July caused the greatest reduction in return bloom in both whole and half-defoliated trees. In another study, `Braeburn' trees were hand-thinned to a CD of 5 in late May 1998; complete defoliation by hand on 1, 15, or 29 July reduced return bloom and fruit set in 1999; the 1 July treatment resulted in zero return bloom. `Golden Delicious' and `York' trees were thinned to a CD of 3 in late May 1998 and were hand-defoliated on 21 July or 12 August by removing every other leaf or removing three of every four leaves over the entire tree. In 1999, return bloom and spur and lateral fruit set were reduced by all defoliation treatments. Fruit set was most reduced by the 12 Aug. treatment. Fruit set for `York' was lower than for `Golden Delicious' in all cases.
Surveys were sent to 53 North American universities offering horticulture curricula to characterize the types of degrees offered, student demographics, participation in distance education, remuneration and assistance available for graduate students, and faculty rank and salary distributions. Twenty-five institutions responded. This represented 10 PhD, 14 MS, and 12 M. Agr. or MS non-thesis professional degree programs in horticulture and 13 PhD, 13 MS, 12 M. Agr. or M. non-thesis degree programs in plant sciences or a closely related area. On average, graduate students were predominantly Caucasian (70.7%), followed by Asian (16.1%), Black (3.2%), Hispanic (2.6%), and Native American (0.2%). Most were supported by research assistantships (56.3%), with the second largest group being self-supported (13.8%). Teaching assistantships were a small source of support (4.6%). Stipends (12-month equivalent) where variable among fellowships ($2000 to $30,000), teaching ($6600 to $25,000), research ($2000 to $25,239), extension ($12,000 to $17,000), or combination assistantships ($900 to $26,000). Most assistantships included a stipend plus in-state and out-of-state tuition waivers: about half included medical insurance. Mean full-time in-state tuition and fees was $6,535, while out-of-state was $13,876. Participation in distance courses was greatest for non-degree students (18.3%), and low for all others (9.2% to 6.4%). The average academic unit had 15.1 professors, 8.9 associate professors, 6.8 assistant professors, 0.3 senior lecturers, and 1.6 lecturers with mean reported average salaries of $85,142; $70,132; $58,918; $55,608; and $37,887, respectively.
Abstract
About 2000 pollinations of Pbaseolus coccineus × P. acutifolius, P. coccineus × P. vulgaris, P. vulgaris × P. acutifolius, and F2 (P. vulgaris × P. coccineus) × P. acutifolius produced more than 1500 excisable embryos, about half of which elongated and produced leaves and roots when embryo cultured on a relatively simple medium in the dark. Damaging cotyledonary buds on small embryos or removing cotyledons from larger embryos before culture enhanced germination. Transplanting germinated embryos into pots resulted in greater than 50% mortality. Hybrids tended to be intermediate to parental species in vegetative and floral characteristics but percent stainable pollen was lower. Anthers did not dehisce and percent stainable pollen was lowest in P. vulgaris × P. acutifolius and F2 (P. vulgaris × P. coccineus) × P. acutifolius hybrids. Since P. coccineus × P. acutifolius and P, coccineus × P. vulgaris hybrids were sufficiently fertile to produce advanced generations, P. coccineus may be useful as a bridge between P. vulgaris and P. acutifolius.
Abstract
Four tall fescue (Festuca arundincea Schreb.) cultivars: ‘Alta’, ‘Falcon’, ‘Rebel’ and ‘Houndog’ were examined for turf performance under a tree shade. ‘Alta’ showed a more inferior turf performance than the rest of the 3 cultivars. No difference between cultivars in turf quality was detected among ‘Falcon’, ‘Rebel’ and ‘Houndog’ under the tree shade. Shade resulted in a greater reduction in plant size than in plant density. All cultivars produced a reasonable turf stand under 70% tree shade. No shade related disease problem was found in the tall fescue cultivars tested.
European corn borer (ECB), Ostrinia nubilalis Hübner, can severely affect sweet corn quality. Selection techniques in field experiments have improved ear feeding resistance associated with morphological features and/or allelochemicals. A laboratory bioassay was used to detect chemical resistance factors in silk and kernel tissues of 10 variously resistant sweet corn genotypes. When added to a nutritively complete diet, kernel tissue from W182E, MN275, and MN272 decreased (P ≤ 0.05) 10-day larval weight (66.3, 61.7, and 54.5 mg, respectively) while kernel tissue from MG15, MN270, and MN3053 increased (P ≤ 0.05) 10-day larval weight (88.3, 81.5, and 80.8 mg, respectively) compared to a cellulose control (71.0 mg). These weight differences, however, were not significant developmentally as 10-day larval maturation (fourth to fifth instar) and pupation time (13.9 to 16.3 days) were similar to the cellulose control (fifth instar and 14.8 days). Silk tissue additions to the diet decreased (P ≤ 0.05) 10-day larval weight compared to the cellulose control (71.0 mg). Larvae exposed to diet containing silk tissue from MN3053, W182E, and `Apache' were lightest (9.1, 8.3, and 7.8 mg, respectively). The heaviest larvae exposed to silk tissue were from diet including `Jubilee' tissue (54.1 mg). Contrary to the instar levels found on the cellulose control, larvae feeding for 10 days on a diet containing silk tissue mainly were at third or early fourth instar excluding larvae exposed to `Jubilee' silk (fourth to fifth instar). For all genotypes, silk additions to diet increased the pupation time compared to kernel additions. Kernel, and especially silk tissue, may contain chemical resistance factors which decrease larval weight and increase developmental time. Identifying sweet corn genotypes with chemical resistance factors may enhance ECB resistance breeding efficiency.
A 2-year trial was established in Oct. 2016 in western Oregon to evaluate the effects of various in-row mulch treatments on establishment of northern highbush blueberry (Vaccinium corymbosum L. ‘Duke’). The treatments included douglas fir [Pseudotsuga menziesii (Mirb.) Franco] sawdust, black weed mat (woven polypropylene groundcover), green weed mat, and sawdust covered with black or green weed mat. For the most part, plant nutrient concentration and content were unaffected by the color of the weed mat. In both years, mulching with weed mat over sawdust reduced soil NO3-N compared with weed mat alone. The only other soil nutrient affected by mulch was K, which was highest with sawdust mulch and intermediate with black weed mat alone in year 2. There were inconsistent effects of mulch on leaf nutrient concentration during the study. In 2018, leaf N concentration was lowest with black weed mat over sawdust. There were few mulch effects on nutrient concentrations in senescent leaves in both years and in harvested fruit in year 2. Mulch had greater effect on nutrient concentration in dormant plant parts after the second growing season than after the first, with the addition of sawdust under weed mat leading to significant differences for many nutrients in various plant parts compared with weed mat alone. Total uptake of N ranged from 12 kg·ha−1 (black weed mat) to 17 kg·ha−1 (black weed mat over sawdust) in year 1 and averaged 33 kg·ha−1 in year 2, with no effect of mulch. Fertilizer use efficiency for N was 8% to 12% in year 1 and 42% in year 2. Uptake of other nutrients was unaffected by mulch and, depending on the year, ranged from 1.3 to 4.3 kg·ha−1 P, 4.0 to 8.0 kg·ha−1 K, 2.1 to 4.9 kg·ha−1 Ca, and 1.0 to 1.5 kg·ha−1 Mg. Each of these other nutrients was derived from the soil or decomposing roots.
Abstract
Interlocular Cavitation (IC) in snap bean pods was studied in 8 commercial cultivars under several irrigation regimes on a sandy soil. In susceptible cultivars, IC was consistently associated with heavy irrigation during pod growth. Little or no IC was found when no more than 1.27 cm of water was applied per week. Irrigation also influenced pod yield, plant weight, ratio of pod weight to plant weight, pod composition, and seed number. Cultivars susceptible to IC showed rapid increase in pod weight when irrigated after 2-3 weeks of moisture stress conditions. However, this rapid increase in pod weight did not induce IC under the conditions tested. Proportion of pod P and K in relation to Ca and Mg increased as irrigation levels were increased. Seed number was related to irrigation and the severity of IC, depending upon cultivar.
Osmoconditioning was examined as a presowing seed treatment for its influence on germination, rate of germination, and initial seedling root growth in seeds of A morpha fruticosa L. (imbibed for 48 hrs) and Hippophae rhamnoides L. (imbibed for 18 hrs) at 25C. Based on preliminary studies, seeds were imbibed in one of five osmotic solutions (0, -0.2, -0.7, -1.5, or -3.0 MPa) prepared with polyethylene glycol-8000. Seeds were then sown in test tubes containing plugs of Oasis growing medium saturated with osmotic solutions of no drought (0 MPa) or drought (-1.0 MPa) conditions at 15-35C. Root growth was measured with an image analysis system. Total root growth per seedling was less for both species in drought conditions regardless of temperature. Presowing treatments did not produce large differences in germination or rate of germination in either species.