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  • Author or Editor: Christine T. Stephens x
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Abstract

Thirteen seed treatments were compared to determine the optimal method to produce asparagus (Asparagus officinalis L. cv. Viking) seeds suitable for axenic culture. Treated seeds were examined for microbial contamination by culture on an agar medium and for percent germination by incubation on moistened paper. All treatments that included benomyl in acetone (2.5%, w/v) with 20% household bleach (0.1% sodium hypochlorite) were superior to the other treatments in eliminating bacterial and fungal contaminants without decreasing seed germination. Ethanol (70%) and hydrogen peroxide also decreased contamination levels, but ethanol decreased germination significantly. No evidence of internal contamination was detected when aseptic seeds were germinated and cultured on agar medium. Chemical names used: methyl(1-[(butylamino)carbonyl]-1H-benzimidazol-2-yl] carbamate (benomyl).

Open Access

Asparagus (Asparagus officinalis L.) seedlings inoculated with the sicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum (Thaxt. sensu Gerd.) Gerd. & Trappe (GF) d Fusarium oxysporum (Schlect.) Snyd. & Hans. (FO) were grown under field and greenhouse conditions. In the fi, shoot volumes of GF-inoculated plants were greater than nonGF plants from the 3rd through the 13th month of growth. By the 14th month, GF-inoculated plants grown in high-P soils had significantly lower disease ratings than nonGF plants grown in low-P soils, and rhizosphere populations of FO were lowest in high-P soils, regardless of VAM status. In greenhouse studies, FO inoculation of VAM-infected asparagus plants reduced GF root colonization levels under well-watered (0 MPa), but not under water stress, conditions (- 1.5 MPa). Well-watered plants inoculated with both FO and GF were less diseased and sustained lower rhizosphere populations of FO than plants inoculated with FO alone. The differences in FO populations and disease ratings in these studies were apparently unrelated to final plant tissue P levels.

Free access

Abstract

“Asparagus decline” decreases production and kills Asparagus officinalis L. The principal pathogens involved in the decline are considered to be Fusarium oxysporum f. sp. asparagi Cohen and Heald (FOA) and F. moniliforme (Sheld.) emend. Synder and Hans. (FM). Three- to four-month-old plants of A. officinalis and three other asparagus species were inoculated in the greenhouse and evaluated for resistance to these Fusarium spp. Of the 90 A. officinalis accessions evaluated, two all-male cultivars, Lucullus 234 and 328, received the lowest disease ratings to FOA and FM. Asparagus densiflorus ‘Sprengeri’ and ‘Myersii’ received the lowest disease ratings of the other asparagus species tested. Of the total 95 germplasm entries evaluated, 39% were more resistant than the susceptible control ‘UC 157’, 44% were rated similiar in susceptibility, and 17% were more susceptible. Accessions responded similiarly to both Fusarium spp.

Open Access

Abstract

Donor callus cells for protoplasts were initiated from mature plants of four selected crowns of asparagus (Asparagus officinalis L.) by placing spear slices on solidified Murashige and Skoog salts and vitamins medium (MS) with 3% sucrose + (in mg·liter−1): 1.0 NAA + 1.2 2,4-D + 0.9 BA or 1.0 kinetin + 2.5 2,4-D. Callus derived from these explants was further subcultured on the same medium. Optimum protoplast yields were enzymatically obtained from such calluses 10 to 20 days after subculture. Of the isolated protoplasts 65% to 75% were viable, and when plated in modified Kao and Michayluk medium at 5 × 104 or 105/ml densities, had 6.5% and 7.3% plating efficiencies, respectively. Protoplast isolations had 0.81% to 1.4% cells present that were not observed subsequently to undergo division. Only the cells of protoplasts of ‘Jersey Giant crown No. 8’ divided during 8 weeks to form microcalluses. After transfer and culture for an additional 4 to 5 weeks on solidified MS + (in mg·liter−1): 0.1 NAA + 1.0 kinetin, shoots regenerated at 28% efficiency. Shoots were rooted at 50% efficiency on solidified MS + (in mg·liter−1): 0.3 NAA + 0.7 kinetin + 2.1 ancymidol + 4% sucrose. The rooted plants were readily transferred to the greenhouse. Chemical names used: 1-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), N-(phenylmethyl)-1H-purin-6-amine (BA), N-(2-furanylmethyl)-1H-purin-6-amine (kinetin), α-cyclopropyl-α-(4-methoxy-phenyl)-5-pyrimidine methanol (ancymidol).

Open Access