摘要:

In vitrotulip embryos have an active shoot-forming capacity (up to 320 neoformations per embryo, for a 20-month period) when cultured, at a temperature of 20–24 °C under a 16-h day length (4000 lx), with growth regulators: naphthalene-acetic acid (0.5 mg ∙ L−1) and benzylaminopurine (1 mg L−1) or kinetin (0.5 mg L−1) or isopentenyladenine (1 mg L−1). Repeated fragmentations improve or maintain shoot-forming ability. Nevertheless, an important genotypic effect is observed. When neoformations are subjected to a cold treatment of at least 40 days at 6 °C under short days (8 h, 2500 lx) and then transferred at 24 °C under long days (16 h, 800 lx), they produce numerous functional bulblet

ISSN:0008-4026    

DOI:10.1139/b86-243

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Light-dependent oxygen consumption (LDOC) was observed in isolated heterocysts and in intact and sonicated CO2-fixingAnabaena cylindricacells. The rate of LDOC in heterocysts was about three times that of CO2-fixing cells. Photosynthetic oxygen production byA.cylindricabecame light saturated at 0.3 to 0.5 mW cm−2. LDOC and nitrogenase activity (acetylene reduction) increased with light intensity up to 2.5 mW cm−2and incubation under air resulted in much larger relative acetylene reduction increases than incubation under N2. Carbonyl cyanide-m-chlorophenyl-hydrazone, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, and cyanide did not affect the rate of LDOC in isolated heterocysts or cell-free preparations of CO2-fixing cells. However, all three substances induced LDOC in CO2-fixing cells. Heat treatment (100 °C for 1 min) caused a doubling of LDOC. Depletion of reduced carbon reserves by dark incubation caused a similar decrease in LDOC and dark respiration. The higher rates of LDOC observed in heat-treated materials were removed by catalase, but not by superoxide dismutase. Catalase injection released half of the O2consumed through LDOC by heated preparations. LDOC increased with temperature up to 85 °C, and increased threefold with pH between pH 10 and 11.5. The possibility that LDOC may act to protect the nitrogenase of the heterocyst from oxygen inactivation is discussed.

ISSN:0008-4026    

DOI:10.1139/b86-244

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Rhabdocline parkerin. sp. (Hemiphacideaceae) is described, together with its sporodochial anamorph,Meria parkerin. sp.Rhabdocline parkerioccurs as localized endophytic infections of living Douglas-fir needles, fruiting primarily on senescent, galled, or dead needles. It is ubiquitous in western Oregon, occurring on essentially all trees sampled in an extensive survey of Douglas-fir needle endophytes, and has been recorded from Washington and northern California.

ISSN:0008-4026    

DOI:10.1139/b86-245

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

A new species ofPinusis described based on permineralized needles from the Sankebetsugawa, Haboro, and the Koyanosawa, Ikushumbetsu, Mikasa City, Hokkaido, Japan. Leaf fragments were discovered in calcium carbonate nodules with abundant ammonites dated as Santonian–Senonian (Upper Cretaceous). The leaves, borne in fascicles of three or four, are 0.9–1.1 mm in radial and 1.5–1.8 mm in tangential diameters, and fragments up to 0.5 cm long have been recovered. The vascular strand is double and bundles are separated by a large anchor-shaped band of sclerenchyma fibers. Transfusion tissue up to four cells wide and a long-base triangular endodermis with an irregular outline surround the vascular tissues. Six to eight medial and external resin canals occur within the band of small plicate mesophyll cells three or four cells wide. The uniform hypodermis from one to four cells thick lies beneath thick-walled elliptical epidermal cells. These amphistomatic leaves with deeply sunken stomata most closely resemble those ofPinus coulteriD. Don, subgenusPinus, sectionPinus, subsectionSabinianaeand have added significantly to our knowledge of permineralized Cretaceous pine needles.Pinus haboroensissp. nov. is closely compared anatomically with the other Upper Cretaceous pines from Japan and North America and primitive needle characters are discussed. Emended diagnoses forP.flabellifoliaOgura andP.bifoliataUeda and Nishida are presented, including a description of their possible affinities to sections and subsections of the genusPinus.

ISSN:0008-4026    

DOI:10.1139/b86-246

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

The effects of temperature (10, 15, 20 °C) and photoperiod (8:16, 12:12, 16:8 (hours of light: hours of dark)) on the growth and reproduction of different stages in the life history ofPorphyra columbinaMontagne were assessed. The conchocelis phase had higher growth rates at 12 h light:12 h dark, 45 μmol m−2 s−1, and 15 °C. Under all the temperatures and photoperiods tested, the conchocelis phase could propagate either by monospores or vegetative fragmentation. Conchosporangia were formed only at 10 °C and 8 h light:16 h dark or at 15 °C and either 8 h light:16 h dark or 12 h light:12 h dark. Long photoperiods inhibited conchosporangia formation at all temperatures tested with the exception of 20 °C and 16 h light:8 h dark, where sporangia was formed once. Conchospores were released when the temperature was decreased (15 to 10 °C) maintaining the photoperiod. Conchospore germination occurred under the three photoperiods and temperatures tested. Growth of juvenile fronds was maximum at 15 °C and either 12 h light:12 h dark or 16 h light:8 h dark. Fronds formed carpospores and spermatia at 15 °C and 16 h light:8 h dark only. With optimum conditions the life history was completed in 60 days. Spermatia had three chromosomes (n = 3).

ISSN:0008-4026    

DOI:10.1139/b86-247

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

The Casparian band of the exodermis of corn and onion roots matures further from the root tip than its counterpart in the endodermis. A complete suberin lamella in the exodermal cells usually develops about 10 mm proximal to the exodermal Casparian band. The distance between the exodermal Casparian band and suberin lamella in the endodermis was usually much greater than in the exodermis. Both the exodermal Casparian band and suberin lamella matured closer to the tip in onion than in corn roots. The distance from the root tip at which the exodermal Casparian band matured increased with root age during the 5-day period studied in corn grown in hydroponics and vermiculite, and onion grown in hydroponics. This difference was most pronounced in corn, in which the Casparian band matured 20 mm from the root tip when the root was 20 mm long but matured 120 mm from the tip 4 days later when the root was 170 mm long. When the growth rate of corn roots was drastically inhibited by adding polyethylene glycol to the hydroponic medium, the exodermal Casparian band and suberin lamellae were present within 10 mm of the root tip. The position in the root at which the exodermis matures is thus highly variable and can depend on the plant species, and the age and growth rate of the individual root.

ISSN:0008-4026    

DOI:10.1139/b86-248

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Seed traps positioned 1 to 100 m into a cultivated field were used to assess the seed rain from an adjacent weedy pasture. The cultivated field was in the fallow phase of a crop-fallow rotation. Two sets of traps were used: one set contained steampasteurized soil and the other contained untreated soil from the field. Traps were left in the field for 12 months and then transported to a greenhouse where they were kept for 12 additional months. Seed content was determined by field and greenhouse emergence of seedlings. The pasture was dominated by grasses, the most abundant beingPoa pratensis,Stipa comata,Bromus inermis, andAgropyron repens. Seeds of pasture species were found in decreasing numbers in the fallow field, with few found more than 7 m from the fence line in traps of both sterilized and nonsterilized soil. The fallow field was dominated by species such asSetaria viridis,Thlaspi arvense,Descurainia sophia, andSalsola kaliwhich were not found in abundance in the pasture. It was concluded that seed rain from the pasture had a significant influence on the germinable seed content of the soil of the cultivated field (at the edge only). The incursion of pasture species into cultivated land presumably has been restricted by cultural practices.

ISSN:0008-4026    

DOI:10.1139/b86-249

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

A preparation of phlein sucrase from seedling shoots of timothy (Phleum pratenseL.) is described which catalyzed the synthesis of fructan with a mean molecular size of 34 000 using sucrose as the substrate. Activity was fully sedimentable at 25 000 × g, had a pH optimum of 7.0, and aKmfor sucrose of 0.15 M. Activity was inhibited by β-mercaptoethanol and sodium diethyl dithiocarbamate. Raffinose and stachyose, but not members of the kestose series of oligofructans, could act as fructosyl donors in addition to sucrose. Formation of oligosaccharides during high molecular weight fructan synthesis was minimal, with synthesis occurring by a mechanism apparently analogous to bacterial levansucrase. These observations are discussed in relation to thein vivopatterns of fructan biosynthesis observed in different species of higher plants.

ISSN:0008-4026    

DOI:10.1139/b86-250

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

The effect of unincorporated and incorporated litter and extracts of broom-sedge, fescue, and blackberry on the mycorrhizal development and growth of black walnut seedlings was investigated in two greenhouse experiments. Seedling growth varied with method of litter application. Only fescue extract decreased growth in the extract experiment, but unincorporated and incorporated broom-sedge litter significantly (P ≤ 0.05) reduced seedling total dry weight below that of mycorrhizal control seedlings. The total dry weight of seedlings in incorporated fescue litter was reduced by 47%. The number of mycorrhizal infected root segments on seedlings grown in unincorporated litter was more than twice the number of infected roots on seedlings grown in incorporated litters. Significantly fewer mycorrhizal roots were found on seedlings grown with fescue and broom-sedge litters than on mycorrhizal control seedlings. On the average, incorporation of litter increased the percentage of leaf phosphorus, but the shoot absorption of phosphorus was considerably less for seedlings grown in incorporated fescue litter compared with unincorporated fescue litter. Seedlings grown in fescue extract had 33% less phosphorus than control seedlings. Except for possible interference with mycorrhizal development when litter was incorporated, there was no evidence to suggest that blackberry litter contains substances that are allelopathic to black walnut.

ISSN:0008-4026    

DOI:10.1139/b86-251

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Indole compounds released byHebeloma hiemaleBres. in pure culture were studied by cultivating the fungus on a nutrient solution supplemented or not with 1 mMtryptophan. Analytical thin-layer chromatography revealed numerous indole compounds in 7-week-old culture filtrates obtained in the presence of tryptophan. Such compounds were isolated by preparative thin-layer chromatography and purified by high performance liquid chromatography. The most abundant of them, i.e., indolyl-3-acetic acid, indolyl-3-carboxylic acid, and indole-3-aldehyde, were identified by mass spectrometry. Indole-3-aldehyde and indolyl-3-carboxylic acid, which were detected in filtrates throughout the culture period, might result from breakdown of indolyl-3-acetic acid by fungal exocellular enzymes.

ISSN:0008-4026    

DOI:10.1139/b86-252

出版商:NRC Research Press    

年代:1986

数据来源: NRC