摘要:

Phenolics from dried leaf tissue of 47 species ofMedicagowere examined using two-dimensional chromatography on polyamide plates. A few samples from the closely related generaMelilotusandTrigonellawere also studied. Compounds tentatively identified as cyanidin, quercetin, kaempferol, luteolin, apigenin, chrysoeriol, tricin, and coumestrol were found. Proanthocyanidins were not detected in the leaf tissue of any of the species. Apigenin was found in all species ofMedicagoexceptM. cretaceabut not in the one species ofMelilotusor the two ofTrigonellastudied. Two additional compounds as yet unidentified were also restricted toMedicago. All of the phenolics were detected as aglycones with the possible exceptions of glucuronides andC-glycosides which are strongly resistant to hydrolysis. Data for the phenolic compounds were subjected to numerical taxonomic analysis. The single species ofMelilotusand the two species ofTrigonellawere dramatically different fromMedicagoin their phenolic composition. A number of controversial species placed inMedicagoby some taxonomists, and inTrigonellaby others, proved to have phenolic profiles much likeMedicagoand quite unlike the species ofTrigonellaexamined. The annual species comprising subgenusSpirocarpos, which are morphologically distinct from the remaining species ofMedicago, were not clearly distinguishable from the other species collectively on the basis of phenolic chemistry. However, within subgenusSpirocarposthe most sharply distinguished subgroup on morphological criteria, sectionPachyspirae, tended to be different chemically from the remaining species of the subgenus. When the species ofMedicagoexcept for subgenusSpirocarposwere analysed separately, it was found that the two major phylads of these tended to be distinguishable chemically. These included a group of perennials (subgenusMedicagosectionFalcago) and a group of peculiar species (subgenusOrbicularia) tending morphologically towards the genusTrigonella). Appreciable intraspecific diversity was found for phenolic chemistry but significantly less than interspecific variation. In a few cases species which are quite similar morphologically diverged chemically, most notably the two species of subgenusLupularia.

ISSN:0008-4026    

DOI:10.1139/b82-301

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The ultrastructure of thePolymyxa graminisLedingham zoospore is described with emphasis on the flagellar apparatus. The unique characteristics of this zoospore are the two kinds of rootlets which extend from the proximal ends of each kinetosome to the plasmalemma. One rootlet consists of a microtubule pair with electron-opaque backing along part of its length which ends abruptly at the plasmalemma. The other rootlet consists of three microtubules which, on reaching the plasmalemma, curve around sharply and extend ribbonlike along the side of the zoospore adjacent to the plasmalemma. This arrangement of rootlets is replicated on the second kinetosome. The kinetosome and transition zone are structurally similar to those in certain protozoa and unlike those found in other groupings of zoosporic fungi or algae.

ISSN:0008-4026    

DOI:10.1139/b82-302

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The extent of incongruence between vegetative, floral, fruit, pollen, and chemical characters inMedicagowas assessed numerically. Moderate incongruence was found among the sets of characters, except for pollen traits which were highly incongruent with the remaining characters. Employing 99 vegetative, floral, and fruiting characters, and Lefkovitch's consensus coordinates as a suitable compromise between the sets, cluster analysis was carried out on the 55 species ofMedicago.

ISSN:0008-4026    

DOI:10.1139/b82-303

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The redistribution of nutrients after fire was examined by igniting samples of spruce needles, birch leaves, and lichen and leaching the ash through a soil column, under laboratory conditions. Nitrogen was lost from the tissue samples at temperatures above 200 °C. Up to 40 kg/ha can be lost from the woodlands during a fire. Leaching of the plant tissue ignited at 500 °C for 2 min removed about a third of the cations, as well as 10% of the phosphorus, but very little ammonium or nitrate. The cations were adsorbed by the organic and subsoil horizons, so that losses from the soil column were small (10–15 kg/ha). Ninety percent of the phosphorus removed from the ash and the organic horizons was absorbed by the subsoil horizons. The leachates of the lichen ash were acid and low in nutrients, promoting nutrient removal from, or redistribution within, the soil column. The nutrient flush from subarctic woodland fires is small compared with the flush from other ecosystems.

ISSN:0008-4026    

DOI:10.1139/b82-304

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Two different sites in central Iowa were planted with hybrid poplars and subsequently sampled over a growing season for spores of endogonaceous fungi. At one of the sites, the effects of plowing and herbicide treatment on spore numbers also were examined. Ten species of fungi in the generaAcaulospora, Gigaspora, andGlomuswere recorded at the first site. The second location yielded 12 species from the same genera. In both sites, the distribution of spores was highly variable. The poplars rarely became endomycorrhizal and had no effect on spore populations during the experimental period. Changes in spore populations were correlated with soil-moisture level. Evidence was found for some depression of spore production caused by plowing and herbicide treatment. The conclusion was drawn that small samples with but few replicates may not adequately represent populations of endogonaceous spores.

ISSN:0008-4026    

DOI:10.1139/b82-305

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Patterns of dry matter distribution to male and female organs and to ancillary floral organs were examined in five angiosperm species with hermaphrodite flowers (Lilium superbum, Hibiscus trionum, Podophyllum peltatum, Trillium grandiflorum, andErythronium albidum). Facultatively self-fertilizing species had higher ratios of female:male allocation while the obligate outbreederL. superbumhad higher male:female patterns. About half the floral dry matter (44–66%) was found in perianth parts as opposed to sporophylls in all species. These preliminary results and others drawn from the literature support the hypothesis that outbreeding species show relatively greater expenditure on male function than self-fertilizing species.

ISSN:0008-4026    

DOI:10.1139/b82-306

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Mycelial growth and conidial germination ofCryphonectria cubensis(Bruner) Hodges were inhibited by phenolic compounds ofEucalyptusspp. Inhibitory activity of caffeic,p-coumaric, ferulic, gallic, protocatechuic, gentistic, and benzoic acids varied with the concentration, presence, and numbers of -OH and -OCH3substituents attached to the aromatic ring of these substances. The possible role of these compounds in the resistance of eucalypts againstC. cubensisis discussed.

ISSN:0008-4026    

DOI:10.1139/b82-307

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Contemporaneousin situacetylene-reduction,15N2-fixation, and3H2-exchange assays reveal parallel patterns of N2fixation and H2utilization in natural populations of the blue-green algaeAnabaenaandAphanizomenon. As spring and summer blooms progress, increasing ratios of acetylene reduction versus15N2fixation closely follow elevated rates of cellular H2utilization. Both acetylene-reduction and H2-utilization rates were largely attributable to blue-green algae as opposed to associated bacteria and other phytoplankton. It is concluded that elevated H2utilization reflects increased H2production via nitrogenase. This can be substantiated by monitoring rising acetylene-reduction versus15N2-fixation ratios during bloom development. Simultaneous deployment of the above techniques provides evidence for (a)in situH2production and (b) seasonal trends in rates of H2production among natural blue-green algal populations.

ISSN:0008-4026    

DOI:10.1139/b82-308

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

A new medium for growingCypripedium reginaeWalt. axenically from seed was designed. Liquid culture proved unsuitable, hence a 1% agar medium supplemented with 5% potato extract was used to investigate optimal mineral element, vitamin, amino acid, sugar, and growth regulator supplements for germination, and subsequent growth. A modified Pfeffer solution with 1400 mg/L NH4NO3 + 19 mg/L ammonium citrate + 2% dextrose + 10 mg/L niacin + 5 mg/L calcium pantothenate + 5 mg/L thiamine HCl + 1 mg/L kinetin + 0.1 mg/L α-naphthaleneacetic acid gave best germination and growth to 2 years with little or no phenolic production. Gamborg's B5 medium and Murashige–Skoog (MS) medium were less than optimal when tested against the above medium. Growth regulators were more active when sterilized by membrane filtration instead of autoclaving. Of the three aminopurines tested, kinetin, benzylaminopurine (BAP), and 6(γ,γ-dimethylallylamino) purine (γγ), the order of activity was initially γγ → BAP → kinetin, but kinetin produced better greening of protocorms and plantlets, and eventually greater survival. Hence, it was chosen for further study. The auxins indole-3-acetic acid (IAA), naphthalene acetic acid (NAA), indole-3-butyric acid (IBA), and 2,4-dichlorophenoxyacetic acid (2,4-D) were also tested alone and in combination with the aminopurines. They did not stimulate germination, but improved growth and survival when combined with aminopurines. The most active of the auxins were NAA → IAA → IBA → 2,4-D. A kinetin:NAA ratio of 10:1 was very satisfactory.

ISSN:0008-4026    

DOI:10.1139/b82-309

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Morphological mutants of the marine red algaGracilaria tikvahiaehave been isolated in an initial attempt to develop improved strains for mariculture by selection of plants with altered growth habits. Both spontaneous and ethylmethanesulphonate-induced mutants were collected for this study. The phenotypes of the mutants range from plants with extremely fine, highly branched fronds to plants with thick puffy fronds. Among 10 mutants selected for more detailed study, 9 have distinctly different phenotypes. Genetic results identify nine mutant cistrons corresponding to the nine phenotypes. All the phenotypes are transmitted as single, mostly recessive, Mendelian mutations, with possible linkage appearing in two combinations of mutants. Growth trials in culture indicate that at least some of the mutants grow better than a genetically related wild type. In general, plants with increased branching showed the greatest promise.

ISSN:0008-4026    

DOI:10.1139/b82-310

出版商:NRC Research Press    

年代:1982

数据来源: NRC