摘要:

Hordeum brachyantherumNevski (H. borealeScrib. et Sm.) was thought, hitherto, to be disjunct with its main area in Alaska, the Rockies, and adjacent parts, and of relict nature in Newfoundland and Labrador. This study, using micromorphological characters from the lodicules and epiblasts has revealed that the eastern relict population belongs to a different species, namelyH. secalinumSchreb. SinceH. brachyantherumis one of the species used as bases for Fernald's "nunatak" hypothesis, the relevance of the findings of this study are discussed with reference to the hypothesis. It is suggested thatH. secalinumarrived in Newfoundland and Labrador from its native western Europe by anthropochoric means.

ISSN:0008-4026    

DOI:10.1139/b78-011

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The influence of thermoperiodic variations on the flowering ofLilium candidumis discussed here for the first time. Our experimentation was guided by our prior knowledge of the state of the apical meristem during the biological cycle. We concluded that forcing, to be effective, must occur on growing bulbs when the meristem of the lily is in the intermediate phase.We analyzed whether a cold period was necessary. When lily plants were cultivated for 8 days at 2 °C, the meristem reached the prefloral state at the beginning of the warm period (15 °C) which followed. The inflorescence is then in full bloom during the hot period (22 °C). Flowering occurs at the end of February.However, if the cold period is eliminated (with no change in the other periods), the terminal meristem loses its activity and differentiates. It is replaced by a small cluster of meristematic cells. A bulb develops at the top of the stem replacing the inflorescence. In this case, meristematic activity now begins at the axil of the leaves and the aerial stem. The axillary buds thus produced are a result of the combined actions of suppression of apical dominance after the loss of terminal meristem activity and the application of hot temperatures (22 °C).

ISSN:0008-4026    

DOI:10.1139/b78-012

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Effects of NaCl toxicity were examined in two wheat species (Triticum durumL. cv. PEPE 2122 andTriticum aestivumL. cv. Marzotto). At NaCl concentration up to 50 mMgrowth, dry weight, succulence, and O2evolution decreased while chlorophyll and protein content increased.14CO2fixation increased at 25 mMand decreased at 50 mMNaCl; also, carboxylating and photorespiratory enzyme activities were differently affected by increased salinity. The ratio between ribulose 1, 5-diphosphate carboxylase and phosphoenolpyruvate carboxylase activities decreased, photorespiration rate was stimulated, and the O2evolving mechanism was inhibited.

ISSN:0008-4026    

DOI:10.1139/b78-013

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

An equation was derived that gives the velocity of a water drop of given size after a given distance of fall. A 4-mm drop develops nearly 11 times the momentum of a 2-mm drop such as commonly occurs in rain. A 4-mm drop reaches about 47% terminal velocity after 1 m and about 91% after 8 m. It is suggested that most splash-cup and springboard mechanisms evolved under the canopies of humid forests where large drops can exert a very great selective stimulus.

ISSN:0008-4026    

DOI:10.1139/b78-014

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

A double staining procedure using potassium permanganate and lead citrate is described. The technique, involving treatment of sections with a 1% solution of potassium permanganate followed by lead citrate staining, is shown to be more effective in producing contrast in Spurr-embedded tissue than the conventional uranyl acetate – lead citrate method.

ISSN:0008-4026    

DOI:10.1139/b78-015

出版商:NRC Research Press    

年代:1978

数据来源: NRC