摘要:

Vegetative terminal long shoot buds (TLSB) and short shoot buds (SSB) were studied throughout the annual growth cycle in several trees over several years. TLSB were not totally preformed. The dormant TLSB consisted of bud scales enclosing some basal leaves and both were borne on a broad receptacle. Centripetal to the basal leaves, a series of axial leaf primordia was borne on the flanks of the apex. After dormancy a second series of axial leaves was initiated above those initiated before dormancy. Basal and both series of axial leaves elongated during shoot elongation as the terminal apex again initiated axial leaves, bud scales, and then basal leaves. After shoot elongation the first series of axial leaves was initiated before the TLSB became dormant in October. No dimorphism occurred between predormancy and postdormancy axial leaves or axial and basal leaves. Axilliary buds were initiated in the TLSB about the time of flushing. All leaves did not bear axillary buds. All axillary buds rapidly initiated a series of bud scales and then entered a slower phase of bud-scale initiation and rapid apical enlargement. Leaf primordia then were initiated at the base of the apex and borne on the broad receptacle. Apices then differentiated into axillary long shoot buds (ALSB) or SSB. ALSB developed similarly to TLSB, whereas axillary SSB initiated leaf primordia at the base of the apex and all but the last primordia to be initiated were borne on the broad receptacle. Axillary SSB were preformed but ALSB were not completely preformed and both became dormant in mid-October. The apex of a short shoot lived for up to 8 to 10 years. In each successive year it passed through phases of bud-scale initiation and leaf initiation to form a dormant preformed SSB which flushed after overwintering. Annual short shoot elongation was about 1 mm. The LSB and SSB apices varied in shape and size during the year but apical zonation was similar in all apices.Larixvegetative bud development is compared with that found in other gymnosperms.

ISSN:0008-4026    

DOI:10.1139/b79-088

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

For testing salt effects on seed andRhizobium, 10–30–10 fertilizer and KCl solutions were used; the solutions had an osmotic potential of − 2.5 MPa, equivalent to 90 kg of the fertilizer per cubic metre of water. Solution contact for 1 h slightly affected the viability ofRhizobium trifoliiDangeard but the effects were not of practical significance. Reduced viability was exhibited byFestuca arundinaceaSchreb.,F. rubraL. var.commutataGaud., andTrifolium repensL. seed which had been rinsed after 1 h of fertilizer solution contact.Agrostis albaL.,Dactylis glomerataL.,F. rubraL.,Lolium perenneL.,L. multiflorumL.,Phleum pratenseL.,T. hybridumL., andT. pratenseL. were not significantly affected. In tests of seed unrinsed after solution contact for 1 h, viability ofF. rubra, F. arundinacea, andT. repenswas significantly reduced; that ofL. multiflorumwas not.Trifolium repenswas more affected than in the test of rinsed seed.AsT. repensviability was reduced as much as 30%, seed of this species might be applied separately from hydroseeder slurries having high fertilizer concentrations. Significant effects on other species tested are too small to influence hydroseeding methods, but amount and proportion of the seed mix may be altered where high fertilizer concentrations are used.

ISSN:0008-4026    

DOI:10.1139/b79-089

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Floral apices ofChrysanthemum morifoliumcv. Dramatic form glandular trichomes on the receptacle in interfloret positions and on the corolla tube above the constriction subtended by the ovary. The glandular trichomes in both positions are initiated by the enlargement of single epidermal cells followed by a single anticlinal division and a series of periclinal divisions resulting in a 10-celled biseriate structure. Receptacular trichomes develop while florets are being initiated on the flanks of the floral apex and by the time petal primordia are initiated these trichomes are mature. Glandular trichomes on the corolla tube are initiated on peripheral florets while florets are still being initiated in a centripetal direction. Each glandular trichome has a cuticular covering beneath which secreted materials accumulate, thereby distending the cuticle. A large pore eventually forms in the cuticle and presumably allows the escape of secreted substances.

ISSN:0008-4026    

DOI:10.1139/b79-090

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Glandular trichomes on the inflorescence ofChrysanthemum morifoliumcv. Dramatic are initiated from a single epidermal cell outgrowth and develop through an anticlinal division and a series of periclinal divisions to form a biseriate multicellular structure. Cells of the young trichome contain a large nucleus with prominent nucleoli and few small cellular organelles. Prior to the secretory stage, numerous ribosomes, polyribosomes, and dictyosomes are present in a dense cytoplasm but most of the dictyosomes are lost as secretion commences. Plastids in the stalk cells senesce but in a different manner than those in the upper tiers of secretory cells. Lipoidal substances form in the degenerating plastids. Cell wall ingrowths and the deposition of a flocculent material in the primary cell wall characterize secretory hairs. In very old hairs cellular lysis takes place with mitochondria being the last cellular organelle to remain intact. The secreted material, which collects in a subcuticular space, appears to be a terpenoid. The function of this material is not known.

ISSN:0008-4026    

DOI:10.1139/b79-091

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Populations of the colonizing weedsRumex crispusL. andR. obtusifoliusL. were initiated from seed following disturbance on three occasions between May and September 1976. Three distinct cohorts were followed within each population. Cohorts which had the same order of emergence within a population but different dates of emergence had similar mortality rates. On the other hand, when cohorts of different emergence order and similar emergence dates were compared, those cohorts which emerged first had the lower mortality rates. For both species, the population arising latest in the season had the lowest percentage emergence but the greatest percentage survival of emerged plants to the time of flowering. These populations also had the best reproductive performance. The latest emerging population ofR. crispuswas the only one to produce as many seeds as had originally been sown, despite the fact that less than 10% of the emerged seedlings survived the winter and less than 1% of the seed pool gave rise to flowering plants. These results suggest that the timing of land management practices such as cultivation can have a profound effect on the success of weed populations.

ISSN:0008-4026    

DOI:10.1139/b79-092

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The levels and the developmental patterns of the two acid phosphatases inIpomoeasp. (morning glory) were influenced by the pH of the medium and whether the cultures were grown in fermentors or shake flasks. The two enzymes, which appeared in the culture medium, in the soluble fraction, and in the particulate fraction, were derepressed when suspension cultures were grown in a medium containing low concentrations of inorganic phosphate. The addition of up to 4 μmol of phosphate per millilitre to cells grown for 4 days on low phosphate did not repress the synthesis of the enzymes. However, the addition of excess phosphate resulted in a temporary cessation of phosphatase synthesis. Inorganic phosphate appeared to be only one of several factors controlling the levels of the enzymes.

ISSN:0008-4026    

DOI:10.1139/b79-093

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The patterns of nitrate reduction, nitrate accumulation, and glutamine synthetase activity as a function of leaf development were studied in glasshouse-grown sorghum (Sorghum vulgareL. var. Dourado) seedlings. Leaf nitrate reductase activity increased during early leaf development and reached a maximum at full leaf expansion which was followed by a decline with leaf maturation. Leaf nitrate content closely paralleled the pattern of nitrate reductase activity for each individual leaf along the canopy. Glutamine synthetase activity increased during early leaf development but then remained constant until senescence. Etiolated leaves from nitrate-grown plants had minimal levels of nitrate reductase activity which increased markedly upon illumination. Glutamine synthetase activity was already high in those leaves and increased only slightly during greening. Crude preparations of glutamine synthetase were insensitive to cyanide and both the biosynthetic and transferase assays were enhanced by cysteine. The relatively high activities of glutamine synthetase throughout leaf development and greening indicate that this enzyme does not limit the assimilation of nitrate into amino acids and plays a role in the assimilation of ammonia from sources other than NO3−reduction.

ISSN:0008-4026    

DOI:10.1139/b79-094

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The ATP content of lodgepole – jack pine (Pinus contorta×banksiana) hybrids in the cordillerean–boreal transition zone was monitored during sulfur dioxide fumigations. Foliage was stabilized for analysis during the course of sulfur dioxide fumigations originating from a sour gas processing plant located in west-central Alberta. Controlled sulfur dioxide fumigations of seedlings were conducted in the laboratory to measure their effect upon ATP content. Field studies demonstrated that ATP concentrations of needle cells declined as sulfur dioxide concentration increased in the ambient air. An inverse linear relationship was found between ATP content and the measured sulfur dioxide concentration. The effect could be repeated in the laboratory with growth chamber cultured seedlings only in exceptional cases. It was repeated with detached branches from the field site exposed to sulfur dioxide under laboratory conditions. The results illustrate the fundamental differences between foliage preadapted to low-level sulfur dioxide fumigations and foliage grown under optimal conditions in a growth chamber.

ISSN:0008-4026    

DOI:10.1139/b79-095

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The following new taxa in the genusGelatinosporiumPeck (Coelomycetes) are proposed:G. griseo-lanatumn.sp.,G. sinuatumn.sp., andG. stillwellin.sp.; new combinations for three species inGelatinosporium, and a new name forMicropera uncinala. Foveoslroma boyceicomb.nov. is proposed forMicropera boycei.

ISSN:0008-4026    

DOI:10.1139/b79-096

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A steady-state14C labelling system is used to simultaneously measure rates of photosynthesis and translocation before and after the onset of an osmotic shock to the base of rooted or rootlessPhaseolus vulgarisplants. In all experiments, the photosynthetic rate declines soon after the onset of a shock owing to rapid stomatal closure. The translocation rate, following a brief transient change, remains almost constant for several hours, indicating less sensitivity to osmotic shock than is shown by the photosynthetic rate. The transient changes in translocation rate are due to transient changes in the leaf relative water content. The direction of the transient depends on the nature of the osmoticum and the presence or absence of roots.

ISSN:0008-4026    

DOI:10.1139/b79-097

出版商:NRC Research Press    

年代:1979

数据来源: NRC