摘要:

The nuclear condition of vegetative mycelia of several races ofPuccinia reconditaf. sp.tritici,P. graminisf. sp.tritici,P. coronataf. sp.avenae, andGymnosporangium asiaticumwas determined by propidium iodide staining. Cultures originating from the uredinial stage ofP. reconditaf. sp.tritici, from the uredinial stage ofP. coronataf. sp.avenae, and from the spermogonial stage ofGymnosporangium asiaticumwere all predominantly monokaryotic. The dikaryotic condition was observed in two cultures from the uredinial stage ofP. graminisf. sp.triticiandP. reconditaf. sp.tritici, in one culture from the aecial stage ofGy. asiaticum, and in germ tubes from uredospores ofPucciniaspp. Measurements of the DNA content indicated monokaryotic diploid cultures and dikaryotic haploid cultures in thePucciniaspecies. InGy. asiaticum, all nuclei were haploid, but the nuclei had twice as much DNA as haploid nuclei in thePucciniaspp.

ISSN:0008-4026    

DOI:10.1139/b84-032

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The authors follow, from full bloom to ripening, the development of the fruit ofPrunus serotina, which lasts 13 weeks. Microscopic observations of serial sections, taken from different stages of development, reveal three distinct phases of growth. After fertilization an increase in the number and size of the cells of the mesocarp contributes to rapid growth of the dimensions of the fruit. Toward the end of this first phase, the endocarp starts to differentiate and thickens considerably. Two distinct layers become apparent: an interior one composed of horizontal elongated fibers and another, exterior, composed of isodiametric sclereids. The second stage is characterized by a decrease in the rate of growth of the fruit. The most important anatomical changes are observed in the seed, in which the embryo grows to invade most of the space delimited by the seed coat. At the end of their maturation, the cherries show another growth period, resulting in yet another increase in the size of the cells of the mesocarp. The vascular system comprises one dorsal, two lateral, two ventral, and two ovular bundles. The development of the fruit ofPrunus serotinais compared with that of other species ofPrunus.

ISSN:0008-4026    

DOI:10.1139/b84-033

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Cobalt treatment of iron-stressed sugar beet plants resulted in leaf cobalt concentrations nearly three times as high as in cobalt-treated control plants. When iron-stressed plants were treated with cobalt and iron together, cobalt was transported into leaves in preference to iron. The transport system in iron-stressed sugar beet appears to be relatively specific for iron and cobalt because iron-stressed plants supplied with manganese, zinc, and copper did not transport these elements in similarly enhanced amounts. Measurements of metal contents of chloroplasts isolated nonaqueously showed that both cobalt and iron were readily transported into chloroplasts (and therefore the leaf symplast) within 48 h. The implications of these results on the mechanism of iron transport across the root plasmalemma are discussed.

ISSN:0008-4026    

DOI:10.1139/b84-034

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Molliardiomyces, a new genus of the Hyphomycetes, is described for anamorphic states of some species of the Sarcoscyphaceae (Pezizales, Sarcoscyphineae):Sarcoscypha coccinea,S. occidentalis,Phillipsia domingensis,P.guatemalensis,P.lutea,Pithya cupressina, andNanoscypha tetraspora. Conidiophores are erect to repent or submerged, monenematous, smooth, hyaline, and irregularly branched or unbranched. Conidia are produced blastically from sympodially proliferating conidiogenous cells. The conidia are smooth, one celled, hyaline or pale yellow, subglobose, ellipsoidal or obovate, with granular contents or containing small oil drops, with bases truncate or rounded, and with or without a frill. Nutritional requirements for production of conidia varied markedly from species to species. Germination of the conidia has not been observed.

ISSN:0008-4026    

DOI:10.1139/b84-035

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Forty-onePohliataxa coded for their expression of 36 qualitative morphological characters are analyzed using cladistic and phenetic methods. Phenetic approaches include similarity graph clustering and divisive methods utilizing information theoretic criteria. The Wagner Tree parsimony method and character compatibility analysis provide estimates of cladistic relationships. Four major lineages within the genus differ primarily in sporophyte characters, with specific differences based largely on gametophytic features. Peristome simplification may have occurred several times withinPohlia. An infrageneric classification is proposed with diagnostic descriptions and nomenclature provided.

ISSN:0008-4026    

DOI:10.1139/b84-036

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The relative contributions of various plant parts to the integrated productivity ofMacrocystis integrifoliaBory were determined by extrapolating the net photosynthetic capacity of each part, as observedin vitro, to its proportional contribution to the biomass of aM.integrifoliakelp bed. The nongrowing plant parts (primarily mature and senescing blades) which represented 66% of the total plant biomass were responsible for 58% of the plant's net productivity. This productivity was assumed, in part, to support growing portions of the plant and, in part, to be stored as reserves for the initiation of late-winter growth. Within the three classes of blades studied (growing, mature, and senescing), which constituted 79% of the total plant biomass, there were no significant differences in photosynthetic pigment concentrations or in net photosynthetic rates. Dark respiration rates were significantly different between these three classes of blades: the older the blade, the lower the respiratory rate.Macrocystis integrifoliaoptimized its productivity by reducing the respiratory demands of the fully grown tissue, and by having all blades contribute to the net photosynthate pool. These adaptations vary from those of the deeper-waterMacrocystis pyrifera(L.) C. Ag., which has been shown by others not to have differential respiratory rates and to have net productivity generally restricted to the shallow-water canopy.

ISSN:0008-4026    

DOI:10.1139/b84-037

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The primary leaves of bush bean plants pretreated daily with very low levels of ozone (0.02 or 0.05 ppm) pass through stages of varying susceptibility to a subsequent acute dose. This variation in response can only partly be accounted for by stomatal behaviour. Present studies indicate that the levels of the oxyradical scavenger, superoxide dismutase (SOD), assayed in leaf homogenates, appear to play no role in the phenomenon. No observed changes in the levels of extracted SOD following various low ozone pretreatment regimes could be related to changes in susceptibility to acute injury, in comparisons with control plants maintained in charcoal-filtered air prior to acute fumigation. The only significant increases in SOD levels which appeared to be directly related to ozone exposure occurred simultaneously with the appearance of visible symptoms of injury from either the cumulative chronic or acute ozone exposures.

ISSN:0008-4026    

DOI:10.1139/b84-038

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Flowering inLathyrus macrorhizustakes place the whole year round, irrespective of photoperiod. Minimum flower production often occurs at the end of a spell of continuously decreasing air temperatures and is always preceded by a heavy rain period; the length of time following the end of this period is inversely proportional to air temperature. Maximum flower production often occurs at the end of a spell of continuously increasing air temperatures and is always preceded by a period of drought. It is suggested that flowering cycles correspond with cycles of metabolic activity in tubers, depending on respiratory gas exchanges and on temperatures. [Journal translation]

ISSN:0008-4026    

DOI:10.1139/b84-039

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Erica×darleyensisgrownin vitroand under proper conditions has a rhythmic growth. The length of limbs and internodes of 145 branches was measured. After analysis, the results have led to a model. An attempt to interpret the architecture of a single branchin vitrois proposed.

ISSN:0008-4026    

DOI:10.1139/b84-040

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

A culture system designed to study root growth and mycorrhizal formation is described. This technique allows shoots of seedlings to grow in the air while roots of the seedlings are growing in an aseptic condition where their growth and differentiation, fungal colonization, mantle formation, and mycorrhizal association can be observed. Packing vermiculite and ground peat moss into the tubes stabilized the pH. This technique has been successful with two pine species and three mycorrhizal fungi.

ISSN:0008-4026    

DOI:10.1139/b84-041

出版商:NRC Research Press    

年代:1984

数据来源: NRC