摘要:

In vitrodevelopment of fasciation was achieved from the excised shoot apices ofCelosia cristatain a 16-h photoperiod. An 8-h photoperiod produced no development. The explants consisted of the meristematic dome with two leaf primordia. The best results were obtained with a nutrient medium composed of Murashige and Skoog salt mixture, 30 g/L sucrose, 5 g/L agar, and 1 mg/L indoleacetic acid (IAA). Isolated shoot apices developed callus at the bases of the explants and numerous leaves on one, two, or three flattened and fasciated meristems. Root initiation occurred sometimes but only after a long period of culture.

ISSN:0008-4026    

DOI:10.1139/b81-186

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Chromosome numbers and taxonomic notes are presented for 33 Alaskan vascular taxa. First counts are reported forAquilegia brevistylaHooker,Draba murrayiMulligan,Erysimum angustatumRydberg,Smelowskia calycinassp.mediaDrury & Rollins,Thlaspi arcticumPorsild,Oxytropis kobukensisWelsh,Cryptantha shackletteanaHiggins,Mertensia drummondii(Lehmann) G. Don, andErigeron muiriiGray. New ploidy levels are noted forDraba lacteaAdams,Oxytropis campestrisssp.varions(Rydberg) Barneby,Oxytropis viscidaNuttall,Oxytropis scammanianaHultén,Mertensia paniculata(Aiton) G. Don,Castilleja caudata(Pennell) Rebrecht,Artemisia senjavinensisBesser,Erigeron caespitosusNuttall, andErigeron grandiflorusHooker. Infraspecific ploidy is discussed forLuzula arcuata(Wahlenberg) Swartz,Lloydia serotina(L.) Rchb.,Rumex arcticusTrautvetter,Claytonia sibiricaL.,Papaver nudicauleL.,Oxytropis campestris(L.) DC. complex,Epilobium latifoliumL., andArtemisia tilesiiLedebour.

ISSN:0008-4026    

DOI:10.1139/b81-187

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Field-grown plants ofBrassica campestrisL. var.oleifera(summer turnip rapeseed) were harvested at various growth stages from seedling through to maturity. Cotyledons, roots, hypocotyls, leaves, stems, and flowers were sampled as available and freeze-dried prior to extraction. Chlorophyll-free, unhydrolysed alcoholic extracts were subjected to two-dimensional chromatography on polyamide thin layers to establish flavonoid patterns. Major aglycones of compounds were tentatively identified on the basis of mobility, colour reactions with a diphenylboric acid ethanolamine spray, and co-chromatography with standards. Each organ was found to have a pattern characteristic to itself which changed little with age. The greatest variety of compounds was present in leaf tissues. Only two compounds, presumably highly glycosylated derivatives of quercetin, were common to all tissues.

ISSN:0008-4026    

DOI:10.1139/b81-188

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The semiaquatic celery-leaved buttercup,Ranunculus sceleratusL. flowers under 18-h photoperiods (long days (LD)) but remains vegetative under 8-h photoperiods (short days (SD)). A minimum of 20-30 LD are required for floral bud initiation which occurs prior to the elongation of the flowering stalk. The effects of LD on flowering and the subsequent growth of the flowering stem can be mimicked with gibberellin (GA3) under SD. When plants which have been induced to flower by 28 LD are submerged, the flower stalk elongates rapidly over the next 48 h. Submergence effects can be mimicked by C2H4, but not by GA3or indole-3-acetic acid (IAA) applications.

ISSN:0008-4026    

DOI:10.1139/b81-189

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A linear displacement transducer was used to measure the leaf thickness of sun and shade leaves collected from trees growing in the mountain and eastern coalfield region of Kentucky. Leaf thickness measurements are presented for 64 southern Appalachian forest species which occupy all strata of the forest communities. Leaf thickness varied from 117.1 μm inHydrangea arborescansto 473.9 μm inIlex opaca. In all species sun leaves were thicker than shade leaves. Species considered tolerant of shade had significantly thicker sun and shade leaves than intolerant species when shrubs were included. When shrubs were excluded the sun and shade leaves of tolerant species were thinner than sun and and shade leaves of intolerant species. For all species including shrubs, sun leaf thickness for the tolerant, medium, and intolerant classes averaged 220.1, 183.5, and 213.3 μm, respectively. Although there appeared to be differences in leaf thickness between species inhabiting xeric and mesic sites, these differences were not statistically significant. Variation in sun leaf thickness within the genusQuercusranged from 130.6 μm inQuercus albato 306.5 μm inQuercus stellata. Shrub species generally had the thickest leaf blades.

ISSN:0008-4026    

DOI:10.1139/b81-190

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Phosphoenolpyruvate carboxylase (EC 4.1.1.31) and malic enzyme (EC 1.1.1.40) activities in soluble protein extracts ofAvenacoleoptiles were investigated as functions of pH. The presence of malic enzyme activity was confirmed by radiochemical assays which identified the product of the forward reaction and spectrophotometric assays which demonstrated that reduction or oxidation of NADP required all the substrates and cofactors necessary for the forward or reverse reactions. In neither assay could NADP or Mn2+be replaced by NAD or Mg2+. Activity was independent of pH (6.0 to 7.7) at malate concentrations less than 0.1 mM. At higher concentrations the pH increase raised activity by at least 100%, and substrate inhibition by malate resulted in activity at 0.97 mMmalate which was less than that at 0.5 mMmalate. The increase in malic enzyme activity with rising pH can be attributed to a decrease in substrate inhibition and a decrease inKm,app(Mn2+). pH increases between 7.0 and 7.6 increasedVmaxand phosphoenolpyruvate limited phosphoenolpyruvate carboxylase (PEPC) activity by over 200%, and decreased theKm,app(Mg2+). Inhibition of PEPC and malic enzyme by various carboxylic acids and phosphorylated sugars decreased as the assay pH rose. The results are discussed in light of contrasting suggestions concerning the role of these enzymes in cytosol pH regulation.

ISSN:0008-4026    

DOI:10.1139/b81-191

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The mitotic indices and the nuclear DNA content of the cells of the meristematic apical zone ofFucus spiraliswere investigated on young thalli 5,15, and 25 mm high. The apical cell exhibits a cell cycle with a prominent G2phase whereas the segmental derivatives, the small cells of the promeristem and, the surrounding elongating cells are characterized by a preponderant G1phase of their cycle.All the meristematic territories in the three sizes of plant studied show weak mitotic indices (0.5–1%). No significant difference is observed in the cycle features between the cells of the promeristem and the periapical zone of elongation. Hence, no change is seen in the mitotic activity of the cells which begin to differentiate. Certain similarities of structure and function among the shoot meristems of Cryptogams with a single apical cell are discussed.

ISSN:0008-4026    

DOI:10.1139/b81-192

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

An ecological survey of the vegetation of a barrier dune on the south coast of Rhode Island showedAmmophila breviligulata,Solidago sempervirens,Lathyrus japonicus, andMyrica pensylvanicato be the dominant plant species. All plants were mycorrhizal. Six species of vesicular–arbuscular (VA) fungi occurred in association with these plants, withGigaspora giganteaandAcaulospora scrobiculatathe most abundant. Also present wereGigaspora calospora,Glomus etunicatus,Glomus fasciculatus, and an undescribed species ofGigaspora. Spore densities and frequencies were measured in a transect across the dune and were compared with plant cover and physical factors (pH, soil moisture, organic matter, soil nutrients, chlorides, and sand grain size). Areas on the dune with greatest vegetation cover byAmmophilawere associated with greatest spore densities and fungal diversity in the rhizosphere. For most plant species, maximum spore density occurred in the front half of the plant's distribution range, nearest the dune crest. There was little correlation between spore populations in the soil and physical characteristics, with the exception of sand grain size. The importance of considering VA mycorrhizae in sand dune stabilization programs is discussed.

ISSN:0008-4026    

DOI:10.1139/b81-193

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Plastid and cytosolic isozymes of pyruvate kinase, hexose-phosphate isomerase, and 6-phosphogluconate dehydrogenase have been isolated and separated from seeds of the castor oil plant (Ricinus communisL.) at different stages of development. These enzymes can be detected 24 days after pollination, when the plastids contain 14% of the total cellular activities of both the pyruvate kinase and hexose-phosphate isomerase and 40% of the 6-phosphogluconate dehydrogenase activities. At this stage the seed consists mainly of nucellus, that is subsequently replaced by endosperm. The activities of the plastid isozymes increase faster than the cytosolic isozymes, until after 40 days, when endosperm fills the seed, the plastids contain 25% of the hexose-phosphate isomerase, 70% of the 6-phosphogluconate dehydrogenase, and 40% of the pyruvate kinase activities. The development of the plastid isozymes correlates with the increase in oil synthesis. This supports a central role for plastids in oil synthesis.

ISSN:0008-4026    

DOI:10.1139/b81-194

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Plants agreeing with the type specimen ofBryum oblongumLindb. were found in northern British Columbia, the Yukon Territory, and Alaska.Bryum oblongumis otherwise known from central Europe, Fennoscandia, and northern Asia. Some authors have consideredB.oblongumto be a variety or subspecies ofB.blindiiB.S.G., with which it shares a number of structural features. Shared and presumed apomorphous (derived) character-states indicate thatB.oblongumandB.blindiiare closely related, but quantitative evidence shows that the two can be distinguished by at least four structural characters. Propagula were found on about 20% of the total specimens ofB.blindiiexamined, but no propagula were observed onB.oblongum. Ecological data from collection information indicate thatB.blindiioccurs primarily on calcareous silts and clays, whileB.oblongumis more frequent on mildly acidic to neutral substrates.Bryum oblongumis considered a distinct species, and both taxa are described and illustrated.

ISSN:0008-4026    

DOI:10.1139/b81-195

出版商:NRC Research Press    

年代:1981

数据来源: NRC