摘要:

The compositions of the epicuticular waxes of grassesAgropyron desertorum, Bromus inermis, Elymus cinereus, Elymus junceus, Festuca ovina, andPhleum pratensehave been determined. Hexacosanol was the principal component of wax ofA. desertorumandP. pratense, and octacosanol, of wax ofE. junceus; C40–C60esters were major components of wax ofB. inermis. Hentriacontane-14, 16-dione and the 25-hydroxy derivative were the principal components of wax ofE. cinereus, and the major constituent of wax ofF. ovinawas tritriacontane-12, 14-dione. The two β-diketone-containing grasses were glaucous.

ISSN:0008-4026    

DOI:10.1139/b77-103

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A small external force is used to produce deformation of the cells and an increase in internal hydrostatic pressure in onion epidermis cells. The subsequent change in cell layer thickness is measured as a function of time. The theory is developed to show that, for sufficiently small forces, this measurement provides enough information to determine cell membrane hydraulic conductivity and elastic modulus, and some results are given. This method should be applicable to sections containing several layers of cells from other kinds of higher plant tissue.

ISSN:0008-4026    

DOI:10.1139/b77-104

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Accumulation of phaseollin at sites of point-freezing injury on etiolated hypocotyls ofPhaseolus vulgarisoccurred in air but was prevented when seedlings were placed in air containing 15% CO2immediately after injury. The inhibitory effect was partially overcome when CO2-treated seedlings were returned to air. Phaseollin accumulation in 15% CO2did occur, however, when injured seedlings were maintained in air for 3–9 h before being transferred to CO2, indicating that the sensitivity to CO2lies at an early stage of the process leading to phaseollin production. In contrast, phaseollin accumulation at sites of infection ofP. vulgarisby an incompatible race ofColletotrichum lindemuthianumwas not inhibited by 15% CO2. These results indicate that the processes leading to the accumulation of phaseollin at incompatible infection sites and at injury sites may be regulated differently.

ISSN:0008-4026    

DOI:10.1139/b77-105

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Various carbon dioxide exchange characteristics are described for two alfalfa (Medicago sativaL.) genotypes (AT 171 and CC 120) grown at 20:15 °C and 30:25 °C day:night temperatures and 53 nE cm−2 s−1irradiance (400–700 nm). Growth at 30:25 °C as compared with 20:15 °C resulted in lower net carbon dioxide exchange rates (NCE) for both genotypes when analyzed at 20 °C, but did not cause any sizeable change for CC 120 at 30 °C. Oxygen inhibition of photosynthesis increased with irradiance to 48 nE cm−2 s−1but either declined or remained constant with further increase in irradiance. Oxygen inhibition was higher at 30 °C than at 20 °C and was not consistently influenced by growth temperature. However, the ratio of oxygen inhibition to carbon dioxide exchange rate in air containing 1% oxygen and the mesophyll resistance were greater with AT 171 grown at 30:25 °C than at 20:15 °C, particularly at high irradiances.NCEmeasured at 20 °C instead of 30 °C for plants grown at 30:25 °C was reduced to a much more marked extent with CC 120 than with AT 171; this difference was paralleled by a more marked increase in stomatal resistance length (rSL) for CC 120.rSLdecreased with an increase in irradiance, was generally higher at 20 °C than at 30 °C, and did not differ between growth temperatures when measured at an irradiance of 116 nE cm−2 s−1and a temperature equal to the day temperature of the growth regime. The results are discussed in relation to factors responsible for adaptability to different thermal environments.

ISSN:0008-4026    

DOI:10.1139/b77-106

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Nodal roots of soil-grown specimens ofAndropogon gerardiiVitman andA. scopariusMichx. were subjected to Si microassay by means of the electron-probe microanalyzer and the scanning electron microscope.Si was confined to the inner tangential wall of the tertiary-state endodermal cells in the form of nodular silica aggregates. Comparisons are made between the two species in terms of the morphology of these aggregates and the Si microassay values. The results are discussed in relation to previous studies of endodermal silicification inSorghumroots and in relation to other genera within theAndropogoneae.

ISSN:0008-4026    

DOI:10.1139/b77-107

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Pezizella chapmaniin.sp. (Helotiales) is described from apothecia found in the galleries of various bark beetles in conifers of western Canada; viz.,Dendroctonus rufipennisKirby galleries inPicea glauca(Moench) Voss;D. ponderosaeHopkins galleries inPinus contortavar.latifoliaEngelmann and inP. ponderosaLaws.;D. murrayanaeHopkins galleries inP. contortavar.latifolia; andD. pseudotsugaeHopkins galleries inPseudotsuga menziesii(Mirb.) Franco. In agar culture, a prominentMalbrancheaconidial state is produced.

ISSN:0008-4026    

DOI:10.1139/b77-108

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Harposporium rhynchosporumis described as a new species recovered from farmyard soil. The fungus was found parasitizing only one nematode species belonging to the genusPrismatolaimus. InH. rhynchosporumthe phialospores are asymmetrically heart-shaped with a spiny outgrowth to one side of their convex surface. The species is related toH. diceraeumandH. bysmatosporumand the infection cycle is probably initiated by the conidia lodging in the buccal cavity or oesophagus of the host.

ISSN:0008-4026    

DOI:10.1139/b77-109

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Nitrite production during darkness by vacuum-infiltrated strips of foliar material was investigated in 6-day-old corn, field peas, wheat, barley, and marrow and in 10-week-oldGomphrena globosa. Inclusion ofn-propanol enhanced nitrite production by 10 to 40%, at a species-specific optimum concentration of 0.5 to 1.0% v/v, in all plants exceptGomphrena. Triton X-100 (0.1% v/v) caused additional enhancement in corn only. Substantial nitrite production (59 to 94% of maximum) occurred in plants grown with moderate (5 mM) and high (20 mM) nitrate concentrations without exogenous assay nitrate; optimum exogenous nitrate concentration was 50 to 100 mM. The patterns of response towards nitrate and propanol were highly species specific. In contrast, all species responded analogously to pH of the incubating medium, yielding a maximum plateau of activity at pH 7 to 8. Nitrite production was not enhanced by substitution of nitrogen for air during vacuum infiltration and incubation. Assay conditions yielding maximum rates of nitrite production were not affected by growth conditions which yielded higher in vivo activity at high vs. low irradiance and at high vs. low nutrient nitrate. Plants grown with moderate irradiance and nitrate exhibited 1.2- to 6-fold higher in vitro than in vivo nitrate reductase (EC 1.6.6.1) activities. In plants grown at high irradiance and low nutrient nitrate, in vivo nitrite production without exogenous nitrate was severely limited byin situnitrate, indicating that nitrate reduction can be regulated by the rate of supply of substrate to foliar tissues under certain conditions.

ISSN:0008-4026    

DOI:10.1139/b77-110

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The effects of colchicine, singly and in combination with gibberellic acid (GA3), on growth of lettuce hypocotyl cells are reported. After 72 h of growth, the cells in GA3are extremely long and cylindrical, whereas those in GA3 + colchicine are very large and more or less isodiametric. The cell volume in colchicine is not significantly different from that in the water control. Kinetic data on cell growth and on dry weight of cell walls indicate a parallelism between the GA3and GA3 + colchicine treatments and between the colchicine treatment and water control. In all treatments, certain cytological changes, viz. proliferation of dictyosomes and their vesicles, increase in endoplasmic reticulum (ER) and polyribosomes, and increased connections between the ER and plasmalemma, occur at the same time as in the water conrol and proceed ahead of evident cell growth. Changes in wall fibrils and microtubules are described. It is concluded that colchicine does not inhibit the kinetics of cell growth or the deposition of wall material, but since it causes dissolution of microtubules, the deposition of new wall fibrils is random even though it shows some degree of order, and if at that time the cells are growing rapidly under the influence of GA3, they become spherical. These results are discussed with a view to understanding the mechanisms underlying cell enlargement.

ISSN:0008-4026    

DOI:10.1139/b77-111

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Tactile stimulation of Boston ivy tendrils results in the development of bilaterally symmetric discs which adhere to substrates in the vicinity of the tendrils. Our electron microscopic examination of the tendrils indicates that adhesive secretion occurs from the peripheral cells at the contact face of the discs. Cell walls in this region develop pockets which fill with adhesive and ultimately coalesce. In fully adherent discs, the adhesive occupies the region between the substrate and the cells as well as the intracellular regions between the peripheral cells. While a cuticle was present on immature discs, no cuticle-like material was observed at the contact interface of mature discs.Staining of the adhesive was enhanced by ruthenium red and potassium ferrocyanide treatments, and the adhesive bound both colloidal iron and thorium. These results indicated that the adhesive is possibly a mucopolysaccharide.

ISSN:0008-4026    

DOI:10.1139/b77-112

出版商:NRC Research Press    

年代:1977

数据来源: NRC