摘要:

not available

ISSN:0008-4026    

DOI:10.1139/b80-001

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The mycorrhizae and respiration of roots ofSalix nigraMarsh., were investigated for plants growing on an abandoned railroad grade in Virginia. The plants were found to be heavily colonized with vesicular–arbuscular mycorrhizae when growing on this site.Glomus fasciculatus(Thaxter) Gerd. & Trappe was the only symbiont which could be unequivocally connected with these endomycorrhizal roots.Addition of 5.0 mMKCN toS. nigraendomycorrhizae orS. rotundifoliaectomycorrhizae inhibited respiration by approximately 50%, suggesting the possible involvement of a cyanide insensitive alternate oxidase in root respiration. Addition of 2.5 mMsalicylhydroxamic acid (SHAM) to KCN inhibited roots caused an additional significant reduction of oxygen uptake in both root types. These results suggest the participation of a SHAM sensitive oxidase in the respiration of these roots. When SHAM was added alone toS. nigraendomycorrhizae a slight but insignificant reduction in oxygen uptake was observed. Conversely, SHAM caused a stimulation of oxygen uptake inS. rotundifoliaectomycorrhizae. When SHAM was followed by the addition of KCN the net result was a significant inhibition of respiration in both types of roots. These results indicate that an alternate oxidase exists in these endo- and ectomycorrhizal roots of willows which is characterized by some of the same basic features described for beech ectomycorrhizal roots.

ISSN:0008-4026    

DOI:10.1139/b80-002

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The classical difference method (based on Kjeldahl determinations) and the15N-isotope dilution method to measure dinitrogen fixation byAzospirillum brasilenseassociated with maizein vitrowere compared. Both methods resulted in an accurate measure of the amount ofAzospirilluin-fixed nitrogen found in the maize plant; 12.6% of the maize nitrogen was derived from the atmosphere. When sucrose, malate, or succinate was added as a carbon source to encourage dinitrogen fixation in the maize rhizosphere, atmosphere-derived nitrogen in the maize increased to 19.0, 28.0, and 38.0% of the total nitrogen (the remainder coming from seed nitrogen).

ISSN:0008-4026    

DOI:10.1139/b80-003

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

SAN 9789[4-chloro-5-(methylamine)-2-(α,α,α-trifluoro-m-tolyl)-3-(2H)-pyridasinone] inhibits carotenoid synthesis at the level of phytoene inPhaseolus vulgarisL. Although carotenoids are greatly reduced in the primary leaves, prolamellar bodies and thylakoid membranes are formed containing phototransformable protochlorophyll(ide). SAN 9789 also produces developmental effects similar to those of red light since seedlings treated in darkness are short, show plumular unhooking, formation of adventitious roots, expansion of primary leaves and full expansion of the first trifoliate leaf and first internode. The effect is not directly on phytochrome since far red light does not reverse the effect of SAN. If abscisic acid (ABA) is indeed formed from carotenoids, we may be observing the consequences of reduced levels of ABA leading to reduced ethylene production as occurs with red light. The first trifoliate leaf of SAN-treated plants contains practically no carotenoids (0.2%) compared with untreated 7-day-old, etiolated primary leaves yet shows normal development of etioplasts, prolamellar bodies, thylakoid membranes, and phototransformable protochlorophyll(ide). InEuglena, lack of carotenoids stops synthesis and assembly of other membrane components; in higher plants this type of regulation does not appear to operate.

ISSN:0008-4026    

DOI:10.1139/b80-004

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Root segments of loblolly pine (Pinus taedaL.) were decayed byHeterobasidion annosum(Fr.) Bref. (=Fomes annosus(Fr.) Karst.) over a broad range of wood (33–317%) and soil (36–259%) moisture contents in modified soil-block tests. Maximum weight loss occurred at 50–286% wood moisture content. Decay was inhibited at wood moisture contents over 290%. Water moved rapidly into the root segments by capillarity, and some decay occurred within 2 weeks. Water uptake was faster in inoculated segments than in noninoculated segments at a soil moisture content of 172% of the 0.2 bar (1 bar = 100 kPa) moisture content.

ISSN:0008-4026    

DOI:10.1139/b80-005

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

FivePinus banksiana(Lamb.) seedlings were fed 50 μCi of14CO2(1 Ci = 37 GBq) per seedling in August and at 2-week intervals another set of five trees was fed until December for a total of 10 feedings. Trees of each set were sampled from January to June, in their dormant frost hardy phase and in their growing phase. Sampled trees were separated into needles, bark, xylem, and roots, freeze-dried, and ground. Samples of ground tissues were extracted sequentially for saponifiable and nonsaponifiable lipids, starch, lignin, hemicelluloses, and cellulose. Some protein, amino acids, and sugars were also extracted.In the dormant trees the total amount of14C in the tissues decreased from August to December except for the needles where it increased towards December. Considerable amounts of14C occurred in the structural components of the early feedings. The14C distribution among the chemical components within the tissues was fairly similar over the entire feeding period except for an increase in root starch, xylem lipids, and sugars. No14C occurred in the amino acids. A drastic reduction in14C occurred with the onset of growth from all chemical components and little14C occurred in the new growth.The photosynthate produced during the autumn contributes substantially more to respiration than to the buildup of reserves. In conifers the important forms of food reserves are carbohydrates and lipids. There is an increase in lipid synthesis in early fall which is chiefly restricted to the xylem. All tissue components of the tree are important for storage of food reserves but they are not of equal importance simultaneously. Food reserves do not play a direct role in wood formation of the secondary meristem which is dependent on current photosynthate. Some hemicelluloses appear to be a form of food reserve in trees.

ISSN:0008-4026    

DOI:10.1139/b80-006

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The fine structure of hyphal septa in the Tremellaceae has shown a number of modifications of the characteristic dolipore–parenthesome type septum. These variations appear of phylogenetic importance and systems of classification have been proposed based upon septal pore structure of a limited number of species. This study reports the fine structure of additional tremellaceous genera,Basidiodendron, Exidiopsis, Sebacina, andTremellodendron. All species examined have dome-shaped pore caps bounded by unit membrane and with an electron-dense lamella in the pore cap lumen. Pore caps appeared nonperforate inTremellodendronandBasidiodendron, while narrow discontinuations or distinct perforations were found inExidiopsisandSebacina. Thus, their pore cap architecture is similar to that ofExidiaand other heterobasidiomycetes with the exception of species ofTremellaand members of the Filobasidiaceae. It is suggested that schemes of classification based upon the fine structure of a limited number of taxa may be premature.

ISSN:0008-4026    

DOI:10.1139/b80-007

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The development of the stalked, capitate, glandular trichomes found on the inflorescence axes ofAdenocaulon bicolorwas studied by light and scanning electron microscopy. The trichomes are not initiated until the stems have essentially ceased to grow in diameter. In early development the trichomes are biseriate, but later become several cells wide partly as the result of contributions from other epidermal cells rather than exclusively from longitudinal divisions in the developing trichome. Cell divisions occur throughout the trichome primordia and are not restricted to an acropetal or basipetal sequence. The mature trichomes are relatively large, 200–250 μm high, but are entirely of epidermal origin.

ISSN:0008-4026    

DOI:10.1139/b80-008

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Strobilurus albipilatus, S. occidentalis, andS. trullisatusare described and illustrated from Canadian material.Strobilurus lignitilis, Marasmius uliginosus, andPrunulus myceliosusare considered to be synonyms ofS. albipilatus. Strobilurus kemptonaeis considered to be a synonym ofS. trullisatus. Geographic and host ranges are expanded for all three species. Notes on extralimital species and a key to all recognizedStrobilurusspecies are presented.

ISSN:0008-4026    

DOI:10.1139/b80-009

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Variation in seed characters of 22 populations of eight largely allopatric species ofVaccinium§Cyanococcus(Blueberries) was examined in relation to latitude. Seeds collected from open-pollinated berries representing populations in eastern North America from southern Florida (27° N) to northern Newfoundland (50° N) were grown under glass at ACAD (45° N) in uniform conditions. Seeds used in the analysis were obtained from the mature plants and any variation they exhibited was presumed to be genetically rather than environmentally induced. Significant negative correlations between latitude and seed weight, seed coat thickness, time required for seed set, and time required for germination are described. Since latitude is a gross indicator of climate, these correlations may be interpreted when climatic parameters such as growing season are related to the different phenologies of northern and southern species.

ISSN:0008-4026    

DOI:10.1139/b80-010

出版商:NRC Research Press    

年代:1980

数据来源: NRC