Search Results
Abstract
Effects of NAA and BA in media on plantlet vigor and suitable methods of acclimatization to field conditions for garlic (Allium sativum L. ‘Katei’), obtained from shoot apices in vitro, were studied. After 60 days of culture, plantlet growth was normal and vigorous when produced on Murashige and Skoog (MS) medium containing both NAA and BA at 0.01 mg·liter-1. Bulb formation was observed in plantlets after 60 days by transferring to the medium containing both NAA and BA at 0.01 mg·liter-1 or NAA at 0.1 mg·liter-1 and BA at 0.01 mg·liter-1. For acclimatization, aseptic bulb-lets were transferred to subculture medium containing both NAA and BA at 0.1 mg liter-1; plants were obtained after 50 days of acclimatization on rockwool, vermiculite, or soil. All of the plants survived under acclimatization conditions of 20C with a 16-hr day-length of 20 μmol·s-1m-2. Rockwool was found to be the best medium for acclimatization, followed by soil and vermiculite. Chemical names used: 2-(l-naphthyl)acetic acid (NAA); N-phenylmethyl)-1H-purin-6-amine (BA).
Several experiments were conducted to evaluate the influence of explant type, sucrose level, and callus development time on sweetpotato [Ipomoea batatas (L.) Lam] in vitro culture. Shoot tip, petiole, and leaf of Selection 75-96-1 was used as explants in Murashige and Skoog (MS) media with different plant growth regulators. Calli derived from shoot tip and petiole produced 42.1% and 10.3% somatic embryos, respectively, but the leaf failed to produce somatic embryos. The effect of sucrose level was determined using shoot tip as explants. Compared with 3% sucrose in the same plant growth regulators level medium during callus initiation and callus proliferation periods, 5% sucrose level suppressed root growth and improved shoot regeneration. The callus development time was measured by using shoot tips on callus initiation medium containing 1.5 mg/L alpha-Naphthaleneacetic acid (NAA) and 0.25 mg/L Kinetin (KIN) plus 5% sucrose. When explants were cultured for less than 6 weeks during callus initiation, then transferred onto plant regeneration medium, plant regeneration via organogenesis occurred; whereas, maintaining cultures for more than 12 weeks on the same callus initiation/proliferation medium, plant regeneration was favored via embryogenesis. Explant type and other factors affecting plant regeneration noted here could be applied to protoplast culture, somatic hybridization, and transformation in sweetpotato.
The red raspberry industry of the Pacific Northwest depends upon chemical primocane suppression to temporarily reduce competing vegetation during fruit development. This practice increases yield and harvest efficiency, but can reduce cane vigor, number and diameter over time. Few chemicals are available for this purpose and thus the potential of nonchemical alternatives is being explored. The purpose of this project was to evaluate the potential of blown air as a thigmic stress to temporarily suppress primocane growth.
Blown air treatments were applied once (12 PM) or twice (12\4pm) per day, five days per week using a portable leaf blower generating winds of 273 km per hr. Treatments also included several rates of three experimental herbicides and an untreated control. All treatments were applied when primocanes were 10-15 cm in length and blown air treatments continued through fruit development. Primocane development was monitored over the course of the season.
Blown air reduced primocane length by 15-30% prior to harvest giving control equivalent to current chemical methods. Blown air increased cane diameter but reduced yield by reducing fruit numbers. Reductions in fruit numbers are likely due to flowering\fruiting points removed by blown air.
The objective was to determine optimum conditions for embryogenic callus, embryo, organogenesis, and embryogenesis developed from leaf, petiole, stem, and tip tissues of the sweetpotato `Jewel' cultivar and from subcultured callus. Embryogenic callus was developed from stem and tip tissues on MS medium containing combinations of BA and NAA only under light conditions. Plant regeneration via organogenesis was developed from stem and tip tissues on medium including 1, 3 and 4 mg/L BA under dark and light conditions, while no plant regeneration via organogenesis was developed from leaf and petiole tissues. Frequencies for plant regeneration via organogenesis from the tissues were very low. No plant regeneration via embryogenesis was developed from the four tissues on medium having any combinations of BA+NAA and of kinetin+NAA. Embryogenic callus was observed in the subculture of callus developed from petiole and tip tissues on medium containing 0.2 and 2 mg/L 2,4-D only under dark conditions. Embryo was found in the subculture of callus from the tissues on medium containing 0.2 mg/L 2,4-D only under both conditions. Plant regeneration via embryogenesis was obtained in the subculture of callus from the tissues. Plant hormones and other factors affecting plant regeneration from the four tissues of the `Jewel' cultivar and other elite cultivars are currently being investigated at our lab for its application in transformation.
Proponents of global climate models predict a doubling of world CO2 concentration from 350 to 600 ppm by the year 2030, concurrent with a 2-5°C temperature increase. Consequences of this “greenhouse effect” on Oryza sativa L. were determined using four rice lines selected for their widespread use in cultivation and research. A 2×2 factorial design was used with CO2 at 350 and 600 ppm and day/night temperature regimes of 31/27°C and 37/33°C. Combined effects of CO2/temperature were determined during 5 harvests from seeding to reproductive maturity. Elevated CO2 enhanced dry weight and photosynthetic capacity over both temperature regimes relative to plants grown at ambient CO2. The 37/33°C day/night temperature regime increased sterility in rice by decreasing pollen shed.
Abstract
Leaf resistance (r1) in fully exposed leaves of bud-failure (BF) sensitive subclones of 2 almond (Prunus amygdalus Batsch) cultivars was much greater than in leaves of non-BF-sensitive (normal) subclones of these cultivars. The differences in resistance were evident at ambient temperatures between 26° and 38°C, and temperatures of fully exposed leaves on BF-sensitive plants exceeded ambient temperature and averaged 5° higher than leaf temperature of normal plants. The difference between BF-sensitive and normal subclones was not apparent below 25° or above 39°. Increase in resistance preceded the development of abnormal growth patterns characteristic of the BF syndrome, and these differences may serve to identify BF sensitivity at incipient stages of the syndrome. Stress is accentuated in BF-sensitive clones between 26° and 38° because transpirational cooling is suppressed; however, the physio-chemical basis of BF sensitivity remains obscure.
Abstract
An alley cropping trial with various vegetable crops and Leucaena leucocephala (Lam.) de Wit was carried out on an Oxic Paleustalf soil in southern Nigeria. With application of N, P, and K fertilizer, there were no yield differences between crops grown with alley cropping compared to control plots. With no fertilizer application, alley-cropped paitsai (Brassica chinensis L.) enhanced yield and plant mineral concentration. Alley cropping gave higher plant stand of direct-seeded paitsai, mainly due to reduced soil erosion.
This study was carried out to optimize conditions for plant regeneration of sweetpotato [Ipomoea batatas (L.) Lam] using shoot tips, petioles, and leaves of Selection 75-96-1 as explants in Murashige and Skoog (MS) with several growth regulators at different levels. Callus initiation and callus proliferation media were 9.0 μm 2,4-dichlorophenoxyacetic acid (2,4-D) and 9.0 μm 2,4-D + 1.1 μm N 6-benzyladenine (6-BA) in protocol I; 8.1 μm α-naphthaleneacetic acid (NAA) + 1.2 μm kinetin (KIN) and 5.4 μm NAA + 4.6 μm KIN in protocol II; 0.9 μm 2,4-D, and 0.9 μm 2,4-D + 1.2 μm N-isopenylamino purine (2iP) in protocol III; NAA (8.1 μm) + KIN (1.2 μm) and 2,4-D (0.9 μm) + 2ip (1.2 μm) in protocol IV, respectively. In protocol I and II, shoot tip, petiole, and leaf were used, but only petiole and leaf in protocol III and IV. In the protocol I and II, somatic embryos were obtained only from shoot tip explants; in protocol III and IV, only from petioles. The frequencies of somatic embryo development were 33.3% in protocol I, 42.1% in protocol II, 21.2% in protocol III, and 10.3% in protocol IV, respectively. The leaf explants failed to produce somatic embryos in all the experiments. In protocol I, somatic embryogenesis occurred through the well-known sequence of globular-, heart-shaped-, torpedo-, and cotyledon-type embryos. However, in protocol II, the structures resembling plumule and radicle were observed before the emergence of torpedo/cotyledon type embryo clusters. The somatic embryogenesis in protocol III and IV was similar to that in protocol I. Growth regulators influenced somatic embryo development. Further, this study showed that explant resource and growth regulators affected the frequency of plant regeneration in sweetpotato.
Several characteristics of amylases involved in starch degradation were studied in extracts from immature (30 days before harvest) `d'Anjou' pears (Pyrus communis L.). Enzyme activity was not detected until after at least 60 minutes of incubation in frozen or lyophilized tissues. Activity increased significantly after 90 minutes and increased linearly after 2 to 12 hours of incubation. Activity was greater, however, in frozen than in lyophilized tissues. Three buffers (acetate, tris-HCl, and imidazole-HCl) were used at a range of pH levels (4.6-8.2) to ascertain the optimum assay system. Highest specific activity was recorded with acetate buffer at pH 5.6. The Km value in this system was 1.43 × 10-3g·ml-1. Specific activity increased as Ca concentration in the reaction mixture increased from 1 to 15 mm CaCl2 but did not change as Ca concentration increased from 15 to 25 mm CaCl2. The `d'Anjou' pear amylases were purified 5.7-fold using ammonium sulfate fractionation.
A chimeric construct, containing the synthetic cryIIIA (Btt) gene, the NPTII selectable marker and the uidA reporter gene, was incorporated via Agrobacterium tumefaciens into eggplant, variety Hibush. The synthetic cryIIIA gene, altered at the nucleotide level without changing the amino acids of the toxic protein by J. Kemp of New Mexico State Univ., Las Cruces, is adapted for high expression in plant cells. To verify the transgenic status, GUS assays were performed on over 300 plants, from which 185 were confirmed to be transgenic. Physical incorporation of the chimeric construct was further confirmed by Southern analysis of about 30 transgenic plants; both single and multiple site incorporation of the Btt gene were found. Resistance to Colorado potato beetle (CPB) was assessed by: a) placing egg masses of CPB on leaves of plants grown in the growth chamber; b) placing first-instar larvae on detached leaves; c) observing 173 transgenic plants under field conditions. About 60% of the transgenic plants displayed a very high level of resistance to CPB. No larvae survived on the resistant plants longer than 50–60 hours after hatching. Upon selfing, the transgenic plants with a single construct segregate in the S1 generation in a Mendelian fashion.