摘要:

Developmental stages of nodules onCaragana arborescens, a woody perennial leguminous species, were studied. Root hair invasion and early cortical infection conformed to the well-known description of herbaceous leguminous nodules having apical meristems, except that a relatively smaller number of cells was infected. In the region of maturation behind the nodule meristem the infection threads remained active throughout the growth of the nodule and served to spread the infection to newly-formed cells. In mature nodules the distribution of red pigment, leghemoglobin, corresponded exactly with the location of the active bacteroidal tissue in the apical zones. Endodermal thickening of the vascular sheath and suberization of the nodule endodermis apparently restricted nutrient diffusion and aeration within the proximal areas. Senescence commenced relatively early, presumably as a result of these factors. However, the thickening of cell walls in these areas delayed, or prevented, necrosis; and a protective periderm which supplanted the outer cortex enhanced longevity of the nodule. Nodule rootlets projecting from six- to eight-month-old nodules were observed. The development of these rootlets from lateral branches of vascular strands and from terminal extensions of the apical tips of vascular bundles within the nodule is described.

ISSN:0008-4026    

DOI:10.1139/b55-009

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

Self-compatibility (% of 'tripped' flowers setting pods) for 218 selections ofCaragana arborescensvaried continuously from 0.0 to 99.5%. The frequency distribution of the compatibility data in terms of percentage was positively skewed by an excess of low self-compatibility plants and had a mean of 36.9%. However, angular transformation of the data resulted in a distribution which approached normality. Pollen abortion, which ranged from 0 to 24%, had little if any influence upon self-compatibility. Selection for high plant vigor was accompanied by a minor reduction in compatibility. Self-incompatibility of three trees could be explained by the action of several compatibilityfactors.

ISSN:0008-4026    

DOI:10.1139/b55-010

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

The calyx tube and pedicel ofSalvia lyrataserve as a springboard mechanism from which the nutlets are thrown out violently when raindrops land on the distal part of the upper lip of the calyx. The force of the striking raindrop depresses the springy pedicel and, when this returns to its normal position, the nutlets are thrown from the calyx tube as a swimmer is projected from a diving board. The nutlets become surrounded by a coat of extruded mucilage as soon as they are wetted.Ocimum basilicumand other members of the Labiatae have similar springboard dispersal mechanisms which are operated by raindrops. The plantlets or gemmae of the succulent plantKalanchoë tubifloradevelop on narrow outgrowths from the parent leaf. These attachments serve as springboards from which the plantlets are violently discharged by raindrops. The plantlets are cup-shaped and are very effective in catching raindrops. The splashing action of raindrops may sometimes be an important agency effecting the pollination of certain cup-shaped flowers such as those ofRanunculus. About eighteen rain-operated dispersal mechanisms are now recognized. These are distributed among four of the major groups of the plant kingdom and it is probable that some examples will be found in all phyla of land plants.

ISSN:0008-4026    

DOI:10.1139/b55-011

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

With the use of a dissection squash technique an examination was made of the fusion process in fertilization in wheat. The male gamete is in the resting stage when it comes in contact with the egg cell nucleus. After penetrating into the egg cell nucleus it becomes diffuse, stains less densely, and eventually is indistinguishable from the female nuclear contents. The contents enter prophase and the chromosomes resolve on one spindle. The fusion process in the fertilization of the two polar nuclei proceeds in a similar manner but a great deal more rapidly. There is also a general discussion of the fusion process in other angiosperms and gymnosperms. The embryology of wheat is also described. Contrary to some reports the antipodals were not found to play a leading role in nursing the endosperm. The postfertilization development of the embryo and endosperm is given in Table I.

ISSN:0008-4026    

DOI:10.1139/b55-012

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

Observations at selected field locations and results of repeated inoculations have shown that Douglas fir is an aecial host ofMelampsora occidentalisJacks. A brief account of the rust's life history is given and the aecial state is described from a specimen obtained by inoculation. Arthur's diagnosis of the aeciai state ofM.albertensisArth. is replaced by a new description based on a specimen obtained by inoculation.Caeoma occidentaleArth. is shown to represent the pycnial and aecial states ofMelampsora occidentalis, notM.albertensis. The aecial states ofM.albertensisandM.occidentalis, both occurring on Douglas fir needles, are identical in gross morphology and time of appearance in nature, but can easily be distinguished from each other by spore size.

ISSN:0008-4026    

DOI:10.1139/b55-013

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

C14-Labelled glucose or glutamine was fed to wheat leaves in light or darkness, and several hours later the distribution of activity among the various plant constituents was determined following their separation by paper chromatography. From these data it was concluded that complete oxidation of glutamine to carbon dioxide proceeded at a greater rate in light than in darkness. In light glucose carbon was prevented from reaching pyruvic acid and the Krebs cycle to any great extent, but this block could be reversed by the application of ammonium nitrate to the leaves. Light or darkness had no effect on the respiration of glucose byStaphylococcus aureus.

ISSN:0008-4026    

DOI:10.1139/b55-014

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

The reactions of adult plants of 10 wheat varieties to stem rust (Puccinia graminisf. sp.triticiErikss. & Henn.) races 11, 12, 15A, 15B-1, 15B-2, 15B-3, 17A, 29, 29A, and 139 were determined at temperatures of about 60° F. and 80° F. The varieties K338 AC 2.E.2 and K117A were resistant to all races at both temperatures. Redman was resistant to all races at both temperatures except for the races 15B-1, -2, -3, which attacked it at both temperatures. This variety was somewhat more susceptible to race 12 at the low than at the high temperature. The other varieties were more susceptible at the high temperature to one or more races to which they were resistant at the low temperature. McMurachy was more susceptible at the high than at the low temperature to races 15B-1, 15B-2, and 17A; Selkirk to races 15B-1 and 15B-2; Red Egyptian to races 15B-1 and 17A;Triticum timopheevito races 15B-1, 15B-2, and 15B-3; Frontana × Thatcher II-47-37 to race 15B-1; Kentana to races 12 and 15B-2; and K58 to races 12, 15A, 17A, and 29. Since the resistance of these varieties broke down to different races, the effect of high temperature on the rust reaction of adult plants is specific for certain combinations of host variety and rust race.

ISSN:0008-4026    

DOI:10.1139/b55-015

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

The movement of moisture in large woody stems under normal conditions of uptake is described. Consideration is also given to the aberrant patterns of staining characteristic of woody stems following partial injection of lower boles of standing trees. Staining patterns resulting from very drastic disruption of the normal channels of water conduction are discussed, and the results reviewed in the light of the mechanism of moisture movement in large woody stems.

ISSN:0008-4026    

DOI:10.1139/b55-016

出版商:NRC Research Press    

年代:1955

数据来源: NRC