摘要:

Floral buds of different stages of development were bisected and cultured in vitro. Subsequent development of floral primordia and regeneration of new apices were observed and recorded by maintaining a continuous photographic record of individual buds. In this way it was possible to correlate the time required for apical regeneration, number of subsequent primordial whorls formed on intact and cut surfaces, and the development of bisected buds as compared to control buds. It was concluded that a greater number of floral primordia are predetermined in progressively older buds and that the oldest buds are incapable of apical regeneration.

ISSN:0008-4026    

DOI:10.1139/b71-077

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Isolated sugar maple callus was grown on defined medium containing 0.2 kinetin and 2.0 ppm indoleacetic acid. Selected components of the basal medium were varied but did not result in increased tissue growth. The presence of 1, 5, or 25 ppm gibberellic acid in the culture medium did not increase the secretion of starch digesting materials by the tissue. The diameter of the starch digestion zone was not influenced by changing the acidity of the medium in the range of pH which supported tissue growth. The ability of isolated callus tissues from various species to digest extracellular starch was examined. It was found that equal amounts of various tissues do not possess an equal capacity for the in vitro secretion of extracellular materials, most probably enzymes, into the culture medium. It was found that isolated sugar maple tissue metabolized sucrose, galactose, and cellobiose while mannose and rhamnose were not used.Isolated sugar maple tissue which had been subcultured on the same medium for a long period was found to undergo nutritional changes which enabled the tissue to adapt to the medium. The starch-digestion enzyme activity of the tissue was found to increase when sugar maple tissue was placed on soluble starch medium.

ISSN:0008-4026    

DOI:10.1139/b71-078

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Formation of wound periderm appears to be a common form of resistance reaction in theArceuthobium pusillum–Larix laricinacombination, based on previous observations and an extensive examination of two witches' brooms of this host. Not only is wound periderm common in spur shoots within witches' brooms, but it also apparently restricts the development of the endophytic system in branchlets composing witches' brooms. Branchlets within witches' brooms ofPinus banksianainfected withA. pusillumandA.americanumalso produced wound periderm similar to that described in eastern larch, which may account for the relative scarcity of aerial shoots on this host and restricted development of the endophytic system.

ISSN:0008-4026    

DOI:10.1139/b71-079

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The embryological investigation ofNyssa aquaticaL.,N. bifloraWalt., andN. sylvaticaMarsh. reported here clearly delimits similarities and variations among the three species. Such evidence supports the retention of Nyssaceae as a family apart from Cornaceae. The major distinctions between the two families occur in the differentiation of the megasporocyte, development of the nucellus, degeneration of defunct megaspores, and growth pattern of the megagametophyte. Major points of similarity between the two families are the occurrence of unitegmic, pendulous, anatropous ovules, a single hypodermal archesporial cell, unequal dyad cells, hooked synergids, polar nuclei fusing before syngamy, and cellular endosperm. These same features serve also to show that Nyssaceae belongs in the order Cornales rather than Myrtales as suggested by several workers.Strong evidence is provided for the recognition ofN. bifloraas a distinct species rather than a variety ofN. sylvaticaas previously proposed by several workers. Points of distinction between the two taxa are found in the shape of the ovule, growth pattern of the nucellar apex and integument, position of the nuclei in the four-nucleate megagametophyte, and the growth pattern of the megagametophyte.Embryological features further indicate a closer relationship betweenN. aquaticaandN. biflorathan between either one andN. sylvatica. The features of greatest similarity betweenN. aquaticaandN. bifloraare the shape of the ovule and megasporocyte, growth pattern of the megagametophyte, presence of hooked synergids, and the occasional occurrence of bisporic megagametogenesis.

ISSN:0008-4026    

DOI:10.1139/b71-080

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Seed germination studies indicate thatPuccinellia nuttallianacan germinate in media with a water potential to −16 bars, with a sharp decrease in germination at −12 bars. Recovery from −42 bars is generally equal to that of control tests, indicating high salinities do not permanently inhibit germination. Seedlings are stimulated at −4 bars, but growth shows a sharp decrease between −8 bars and −16 bars. Growth and flowering are promoted by long days.P. nuttallianais not an obligate halophyte, but is tolerant of salinities which most nonhalophytes cannot endure.

ISSN:0008-4026    

DOI:10.1139/b71-081

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The influence of a range of concentrations of malonate on the rate of water absorption by the root hairs ofAvena sativais investigated. Different results are obtained when malonate is applied on root hairs of various lengths. At higher concentrations (10−6, 10−7 M) inhibitory effects are predominant, resulting in the rapid death of the root hair or heavy excretion, whereas at lower concentrations (10−8, 10−9, 10−10 M) an increase in absorption rate indicates a direct participation of malonate in respiratory metabolism.A close relationship exists between the length or age of a root hair (amount of cytoplasm present in the root hair at the region of immersion) and the inhibitory effects of malonate. The survival period is long when the root hair is young or when cytoplasm is abundant.The evidence suggests that absorption of water by root hairs ofAvena sativais perhaps not osmotic, as metabolic energy seems to be directly involved in it, at least when the plant is deprived of foliage.

ISSN:0008-4026    

DOI:10.1139/b71-082

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Comatospora suttoniiPirozynski & Shoemaker, a new Coelomycete on twigs ofPicea mariana(Mill.) BSP. in Canada is described and compared withNeottiospora caricina(Desm.) Höhn.,Tiarosporella paludosa(Sacc. & Fiori) Höhn. var.paludosa(=T. schizochlamys(Ferd. & Winge) Höhn.), and var.graminisvar. nov.,Giulia tenuis(Sacc.) Tassi ex P.A. & D. Sacc, andTiarospora perforans(Rob.) Höhn.

ISSN:0008-4026    

DOI:10.1139/b71-083

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A scanning electron microscope was used to observe variations in wax formations on leaves of cabbage (Brassica oleraceaL., var. Capitata greenback), corn (Zea maysL., hybrid var. NK KE 449), cherry laurel (Prunus laurocerasusL.), and pea (Pisum sativumL., var. Little Marvel). Results obtained by this technique compare favorably to results from a carbon replica technique. The size and shape of the wax formations on adaxial and abaxial surfaces of the same leaf differed in all genera. A study was made of surface wax development on pea leaves. Wax "crystals" on the abaxial surfaces were larger than those on the adaxial surfaces. Individual wax crystals on the first-formed leaves were two to three times larger than those on the sixth-formed leaves. Results were similar for peas, whether they were grown in growth chambers or greenhouses; this indicated that subtle changes in environment do not greatly affect the appearance of wax formations. The question of cuticular pores is discussed.

ISSN:0008-4026    

DOI:10.1139/b71-084

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A description is given of the ultrastructure of moss spores incubated in darkness and posttreated with monochromatic light. Fine structural changes occur in darkness, especially in the chloroplasts, and are also noted with inorganic medium, in spite of the lack of germination. The most conspicuous is the increase of starch grains in the chloroplasts at the beginning of the dark-incubation, and their subsequent disappearance, which coincides with an increase in the number of grana lamellae. A synthesis of chlorophyll is correlated with the decrease of the starch. The incubation of sporelings in a 0.1% solution of sucrose results in the degeneration of the chloroplasts to amyloplast-like with concentrated lamellae and the accumulation of fibrillar material in the cytoplasm. When exposed to blue and red light, the chloroplasts of both inorganic and sucrose cultures develop into normal chloroplasts. A comparison of the effects of different wavelengths of light shows that the chloroplasts of sporelings exposed to blue light remain richer in starch and have a denser stroma than red-light chloroplasts. Red light allows more effective use of reserve lipids, but there are more mitochondria after blue light. No great differences in the lamellar structures of the chloroplasts can be noted between sporelings exposed to blue and red light, unless the illumination is of very long duration.

ISSN:0008-4026    

DOI:10.1139/b71-085

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Choline content in healthy and rust-infected primary leaves of wheat was determined by microbiological assay withNeurospora crassa. Rust infection increased the content of free choline, but not the content of lipid choline in susceptible or resistant leaves.

ISSN:0008-4026    

DOI:10.1139/b71-086

出版商:NRC Research Press    

年代:1971

数据来源: NRC