摘要:

Collections of acorns were made in southern Wisconsin from trees identified on leaf and bark characters asQuercus macrocarpaMichx.,Q. bicolorWilld., and their hybrid×Q. schuetteiTrel. Measurements were made of peduncle length, cup fringe length, acorn width, and acorn length. Cup fringe length and acorn length and width decreased and peduncle length increased fromQ. macrocarpathrough the hybrid toQ. bicolor. The hybrid was clearly separated fromQ. macrocarpaon peduncle length. A possible introgression between ×Q. schuetteiandQ. bicolorwas noted.

ISSN:0008-4026    

DOI:10.1139/b60-061

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

The existence in peas of both physical and physiological resistance to attack byAscochyta pisiwas indicated. Infection was possible at constant temperatures ranging from 45 to 80° F. The temperature subsequent to incubation had a marked effect on infection: the appearance of the symptoms was delayed and the number and size of lesions were increased at the lower temperatures.A. pisican utilize nitrate, ammonium, amide, and amino nitrogen. Growth is dependent upon both pH and the nitrogen source. A wide variety of carbon sources can be utilized byA. pisibut the isolates differ with regard to their abilities to utilize the different carbon sources. The pH of the medium is of importance at the initiation of pycnidial production. Exhaustion of the carbon supply is apparently a factor in the initiation of sporulation.

ISSN:0008-4026    

DOI:10.1139/b60-062

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

The life history of wild rice is traced from the appearance of the first submersed leaves in the spring until the seed of this annual plant is buried at the bottom of a lake in the fall. The characteristics of the three types of leaves are discussed. The change from the simple vegetative apex to the many-tipped, young inflorescence occurs early. Thus the potential yield in rice grains is determined as the tips of the upright leaves reach the surface of the water and before the stem elongates. The inflorescence develops acropetally as does each spikelet. Only at the later stages can the pistillate and staminate spikelets be distinguished. The development of the microspores and the nuclear changes in the embryo sac have been elucidated. InZizaniathe embryo development has been found to be a variant of that found inPoawhile the endosperm develops chiefly from the outside. A well-differentiated abscission layer develops at the base of each spikelet.

ISSN:0008-4026    

DOI:10.1139/b60-063

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

The influence of maternal tissues on loose smut (Ustilago nuda(Jens.) Rostr.) infection of hybrid tissues was investigated through histological studies of artificially inoculated kernels of susceptible and resistant varieties of barley and their reciprocalF1hybrids. Depending on the stage of development of the kernel scanty to abundant mycelium was observed in the crease region, integument, aleurone, endosperm, and embryo of the susceptible kernels. In kernels of the resistant varieties, mycelium was not observed in the aleurone, endosperm, or embryo although present in the chalazal region and the parenchyma associated with the vascular bundle. After floret inoculation, the maternal tissues ofF1hybrid kernels of reciprocal crosses between the susceptible and resistant varieties had a mycelial development similar to that in the female parental varieties. Hybrid tissues of Odessa (susceptible) × Anoidium possessed a scanty mycelial development, whereas those of the reciprocal appeared to be free. Hybrid tissues of the reciprocal crosses between Odessa and Trebi had a scanty mycelial development. These observations indicated that maternal tissues influenced to some extent infection of the hybrid embryo. However, this influence appeared to be secondary in importance to that of the genotype of the embryo itself.

ISSN:0008-4026    

DOI:10.1139/b60-064

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

Agropyron smithiiRydb. is considered to be the correct name of the grass commonly known as western wheat grass. The pubescent varietymollehas been found to have no distinct geographical distribution within the species and is therefore reduced to the rank of form. Many of the eastern localities recorded are attributed to introduction rather than to extension of the species range. Characters of pubescence and awning show relative uniformity within the clone but a much wider variation over the entire range. Spike, spikelet, and floret pattern is compared with those of related species. Somatic chromosome counts on 62 plants from points throughout the range indicate constant octoploidy (2n = 56). Chromosomal rearrangements appear to be slight. The species does not cross with several other species tested and is apparently self-sterile.

ISSN:0008-4026    

DOI:10.1139/b60-065

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

Flax rust mycelium was grown on cotyledons of flax in a modified Knop's medium. The mycelium produced and apparently secreted a typical peroxidase-mediated indoleacetic acid 'oxidase'. Decarboxylation of radioactive indoleacetate (—C14OOH) was stimulated by Mn++(10−4and 10−3M), dichlorophenol (10−4M), and resorcinol (10−4M). Catechol (10−4M) and pyrogallol (10−4M) inhibited the reaction. Moreover, pyrogallol competitively inhibited the reaction in the presence of resorcinol. All four phenols increased oxygen uptake by the mycelium, catechol and pyrogallol being the most effective. Cu++(10−3M) inhibited the reaction by 60%; cyanide (10−3M) and diethydithiocarbamate (2 × 10−4M) were almost completely inhibitory. The results are discussed briefly in relation to host–parasite interactions and the control of indoleacetic acid oxidase activity in vivo.

ISSN:0008-4026    

DOI:10.1139/b60-066

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

The vegetation of the Hudson Bay Lowlands of Canada is known only in the most superficial terms. This contribution provides descriptions of the chief cover types of a small portion of the Lowlands near the confluence of the Hayes and Nelson rivers. The area has a continental, subarctic climate. Postglacial marine inundation has deposited thick calcareous clays; the topography is flat.On the mineral substrata of alluvial and marine deposits the chief types of vegetation are salt marsh, shrub (dominated bySalixspecies), forests ofPopulus balsamifera, and forests ofPicea glauca. They often form discrete zones in the order mentioned, and it is likely that this is a seral as well as spatial relationship. On the extensive peat substrata there are bog and fen types. In the former are distinguished two communities dominated byPicea mariana—one, termed lichen muskeg, with a ground layer ofCladoniaandLedum, and the other, moss muskeg, withPleuroziumandLedum groenlandicumas ground layer dominants. Locally, areas of lichen muskeg have been destroyed by fire and are now occupied by willow communities. In wet inland areas, moss muskeg and lichen muskeg communities are associated with palsa and string-bog features. On shallower peats, usually nearer the shores and rivers, fens predominate, withLarix laricinaandBetula glandulosaas the dominant phanerophytes.All these types have been distinguished on vertical aerial photographs, and their photographic characteristics are summarized. A detailed vegetation map illustrates their chorology.

ISSN:0008-4026    

DOI:10.1139/b60-067

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

Studies conducted in steam-sterilized soil inoculated withVerticillium alboatrumandPratylenchus penetransdemonstrated a synergistic relationship between fungus and nematode. At low and intermediate levels ofVerticilliuminoculum, the nematode increased wilt and the increase may be a function of the number of nematodes present. Except at the high inoculum levels ofVerticillium, significantly larger numbers ofP. penetransoccurred in eggplant roots in the presence than in the absence of the fungus. The nematode alone had no adverse effect on root condition or growth of eggplant.

ISSN:0008-4026    

DOI:10.1139/b60-068

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

Through the growth of the first few years, when the perimeter of the stem is fast expanding, the multiplicative pseudotransverse divisions in fusiform cambial cells occur in relatively rapid sequence, the ratio of survival of newly formed cambial cells is high, and continuous increase in mean cell length ensues. Accommodation of the cambium to circumferential expansion is thus facilitated. With increasing age and diminishing rate of perimeter growth the frequency of pseudotransverse division declines, the survival rate of new-formed cambial initials drops, and increase in cell length slackens. This gradual flattening off may continue through to the final growth, but more often fluctuations in rate of anticlinal division and cell length arise in the middle to late growth, these not always exhibiting close interrelationship. Sometimes high rates of pseudotransverse division occur in the late growth which are accompanied by only moderate reductions in cell length.

ISSN:0008-4026    

DOI:10.1139/b60-069

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

Fifteen species of aquatic Hyphomycetes are described from Canada. Further, some spore types are illustrated which do not seem to belong to known species.

ISSN:0008-4026    

DOI:10.1139/b60-070

出版商:NRC Research Press    

年代:1960

数据来源: NRC