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The resistance of `Carolina Cayenne' (Capsicum annuum L.) to root-knot nematode Meloidogyne incognita (Kofoid & White) Chitwood races 1, 2, 3, and 4 was measured. Egg counts from roots were used to determine the plant's resistance to M. incognita. Few eggs were observed on `Carolina Cayenne' roots, whereas all races of M. incognita produced numerous eggs on the susceptible `NuMex R Naky' roots. The results indicated `Carolina Cayenne' is a source of resistance to all known races of M. incognita.
Abstract
Reports concerning the success of no-till (NT) production of vegetable crops are mixed, with results influenced by soil type, precipitation, mulching, and weed control. Similar yields have been obtained with no-tillage (NT) and conventional tillage (CT) of sweet corn (4), tomatoes (3), potatoes (2), and cabbage (1). Conversely, yield suppression in NT has been reported for cucumbers (3), cabbage (5), and tomatoes and bell peppers (4). Beste (3) reported that lima bean yields were similar in both tillage systems. Snap beans have been grown successfully in NT systems, and yields have been equivalent to or greater than CT snap beans (6-8).
The chinch bug, Blissus occiduus Barber, has been documented as a serious pest of buffalograss, Buchloë dactyloides (Nutall) Engelmann, and zoysiagrass, Zoysia japonica Steudel, turf grown in the Midwest. In addition to these two warm-season turfgrasses, several other warm-season grasses, including bermudagrass, Cynodon dactylon (L.) Pers., may also be at risk of B. occiduus infestations. This research evaluated selected bermudagrass and zoysiagrass cultivars for resistance to B. occiduus. Eleven zoysiagrass and four bermudagrass cultivars were evaluated for resistance to B. occiduus using no-choice studies under greenhouse conditions. Based on turfgrass damage ratings, the zoysiagrasses ‘Diamond’, ‘Zoro’, and ‘Emerald’, and bermudagrass ‘Mini Verde’ were identified as moderately resistant to B. occiduus. The zoysiagrasses ‘Zenith’, ‘Meyer’, and ‘Crowne’, and bermudagrasses ‘Tifway 419’ and ‘Tifsport” were characterized as highly to moderately susceptible to B. occiduus. These results provide the first report of resistance to B. occiduus in zoysiagrass and bermudagrass germplasm.
Traditionally, American ginseng (Panax quinquefolium L.) seeds are stratified for 18 to 22 months, before seeding, in a sandbox buried outdoors in late August or early September. Uncontrolled fluctuating temperature and moisture levels and the presence of pathogenic organisms in the seed box can cause seeds to sprout prematurely, rot, dry out and die. A study was initiated to shorten the lengthy stratification period, and to increase seed viability and percentage of germination by stratifying seeds indoors under a controlled environment. Seeds were subjected to various periods of warm [15 or 20 °C (59 or 68 °F)] and cold [2 °C (35.6 °F)] temperature stratification regimes in growth chambers. Embryo growth and viability, and seed moisture content were tested periodically during stratification. The best warm regime for embryo development, seed viability and germination after subsequent cold treatment was 15 °C (59 °F). The first “split” seeds, indicating incipient germination, were observed after 3 months of warm [15 °C (59 °F)] and 4 months of cold [2 °C (35.6 °F)] treatment, when average embryo length reached 6 mm (0.24 inch). Greenhouse germination of stratified seeds was as high as 80%. The results from this study indicate that good germination is possible when ginseng seeds are stratified indoors under a controlled environment and seeds can be made to germinate at any time of the year.
Rudbeckia L. are valuable nursery crops that offer broad adaptability and exceptional ornamental merit. However, there is little information on interspecific and interploid crossability and ploidy levels of specific cultivars. The objectives of this study were to determine the ploidy levels and relative DNA contents (genome sizes) of selected species and cultivars, to evaluate self-compatibility and crossability among species and ploidy levels, and to explore reproductive pathways in triploid R. hirta L. with the goal of facilitating future breeding endeavors and development of new hybrids. Reciprocal interspecific crosses were performed between R. hirta cultivars and R. fulgida Ait., R. missouriensis Engelm. ex C.L. Boynton & Beadle, and R. subtomentosa Pursh. as well as reciprocal interploid crosses among four R. hirta cultivars. A combination of relative DNA content analysis and chromosome counts was used to test for hybridity and to determine ploidy levels for selected species, cultivars, and interploid R. hirta F1 hybrids. Of the specific clones tested, R. subtomentosa and R. missouriensis were diploid, R. fuligida varieties were tetraploid, and R. hirta include both diploid and tetraploid cultivars. Mean 1Cx DNA content varied over 320% among species. The interploid R. hirta crosses produced triploids as well as pentaploids and hexaploids. Seedlings from open-pollinated triploid R. hirta appeared, based on diverse phenotypes and DNA contents, to be aneuploids resulting from sexual fertilization, not apomixis. Of the 844 seedlings from interspecific F1 crosses, only one individual, R. subtomentosa ×R. hirta, had a DNA content intermediate between its parents and was confirmed as the only interspecific hybrid. Although most taxa had low self-fertility, seedlings (with genomic sizes similar to their maternal parent) resulted after interspecific crosspollination, indicating that pseudogamy is one reproductive pathway in Rudbeckia species.
This study was conducted to determine if there is a difference between the career advancement of alumni of ornamental horticulture associate (terminal) degree and nondegree programs. A survey of the alumni of three associate degree and three nondegree training programs was administered, using guidelines from career advancement validation research conducted at Alverno College, Milwaukee. Wis. (Ben-Ur and Rogers, 1994). Six programs were selected from North Carolina, Maine, Ohio, and southeastern Canada, including parts of Ontario and Quebec and all of New Brunswick and Nova Scotia. The programs were selected because of their perceived high reputations, as based on a survey sent to eight selected Longwood Gardens staff (Kennett Square, Pa.) and six professors in the Plant and Soils Science Department at the University of Delaware (Newark). Survey respondents were initially chosen based on their knowledge of the field of horticulture and of ornamental horticulture educational programs. The statistical analysis of the data did not support the presupposition that there would be a significant difference between the career advancement in favor of graduates from horticultural associate degree programs.
The genus Deutzia, in the Hydrangeaceae family, includes ≈60 species that range in ploidy from diploid (2x) to tetradecaploid (14x). There have been extensive breeding efforts for Deutzia, but this has been limited to a few parental species. Although there have been numerous studies of the cytogenetics of some species of Deutzia, the ploidy level of many species remains unknown, and there are few cytogenetic data available for Deutzia hybrids and cultivars. The purpose of this study was to validate the identification and determine the genome sizes and ploidy of a diverse collection of Deutzia species and hybrids using cytology and flow cytometry. Accessions were identified using the most current taxonomic key and voucher specimens were deposited for each at the North Carolina State University herbarium. Corrected and updated species names are provided for all cultivars and accessions studied. Traditional cytology was performed for roots of representative taxa to calibrate the genome size with the ploidy level. The genome size and estimated ploidy were determined for 43 accessions using flow cytometry. Ploidy levels were reported for the first time for three species of Deutzia including D. calycosa (2n = 4x = 52), D. paniculata (2n = 4x = 52), and D. glauca (2n = 12x = 156). The base and monoploid genome size (1Cx) were somewhat variable and ranged from 1.20 to 2.05 pg. No anisoploid hybrids were documented, suggesting the presence of an interploid block. The information produced from this study are beneficial to future curation, research, development, and improvement of this genus with corrected nomenclature and clone-specific data regarding cytogenetics.
Expression of lactoferrin (LF) gene, a cationic iron-binding glycoprotein, was investigated in transgenic tomato plants (Lycopersicon esculentum Mill.). Resistance of the transgenic tomato plants to the pathogen (Ralstonia solanacearum Smith) causing bacterial wilt was also determined. Tomato line F7926-96, susceptible to bacterial wilt, was transformed with Agrobacterium strain C58C1 containing a plasmid construction carrying a modified LF cDNA. The introgression of LF cDNA into the susceptible tomato line was confirmed by Southern blot and the expression of full-length lactoferrin transcript and protein was also detected by northern and western blots, respectively. Based on resistance to kanamycin, a Mendelian segregation for a single locus insertion was observed in the T1 and T2 generations and all T1 and T2 plants resistant to kanamycin showed the single corresponding band of LF cDNA in Southern blot analysis. Two transgenic tomato lines inoculated with 1 × 107 and 1 × 108 colony-forming units (CFU)/mL with Rs isolate NC251 (K60, race 1) exhibited early resistance and subsequent susceptibility, while 44% to 55% of plants survived until maturity (fruit ripening) when inoculated with 1 × 105 CFU/mL in comparison with the fully susceptible tomato line. The latter resistance to bacterial wilt in transgenic tomatoes with the stable Mendelian segregation patterns for the LF gene suggests a potential new approach to consider for control of bacterial wilt of tomato. The possible value of this gene along with other plant genes to control bacterial pathogens is discussed.