摘要:

Books reviewed in this article:AGRICULTURAL ECOLOGY: an analysis of world food production systemsG.W. Cox&M.D. Aitkens(1979) HardbackPLANT CELL CULTURES: RESULTS AND PERSPECTIVES. Edited by F. Sala, B. Parisi, R. Cella&O. Ciferri.INTRODUCTION TO MODERN MYCOLOGY. By J.W. Deacon. (1980)

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1980.tb00817.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11586823

出版商:Blackwell Publishing    

年代:1980

数据来源: WILEY

摘要:

AbstractMaize, barley and sunflower plants were grown in the field, well supplied with water and nutrients. During growth, net CO2exchange and transpiration of the crops at varying ambient CO2concentrations and irradiance were determined by infra‐red gas analysis. In maize the net photosynthetic rate (Pn) was linearly related to the irradiance (I) and independent of the ambient CO2concentration (Ca). The transpiration rate (ET) was also linearly related toIbut decreased strongly with increasingCa. In sunflower and barley Pnincreased andETdecreased with increasingCa. A mean stomatal conductance and intercellular CO2concentration (Ci) were calculated. In all three species the internal CO2concentration was independent of the irradiance. In maize it was also independent ofCa, but in sunflower and barleyCiwas proportional toCawith a ratio of 0.6.It is concluded that differences in stomatal behaviour are only partly species‐specific and depend mainly on growing conditions. The importance of stomatal regulation for crop growth under conditions of water shortage and CO2depletion is discus

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11586830

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractRadioisotope equilibration techniques have been used to determine the intracellular concentration of K+, Na+and Cl−, together with the unidirectional ion fluxes across the plasmalemma ofPorphyra purpurea. Influx and efflux of42K+,24Na+and36C1−are biphasic, the rapid, initial uptake and loss of tracer from individual thalli being attributable to desorption from extracellular regions. Cellular fluxes are slower and monophasic, cells discriminating in favour of K+and Cl−and against Na+. A comparison between the equilibrium potential of individual ion species and the measured membrane potential demonstrates that there is an active component of K+and Cl−influx and Na+efflux. ‘Active’ uptake and ‘passive’ loss of K+and Cl−are reduced when plants are kept in darkness, suggesting that a fraction of the transport of K+and Cl−may be due to ‘exchange diffusion’ (K+

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11586851

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractStarch levels inCommelina communisepidermis, were shown to be higher in the dark than in the light, from plants kept under an imposed photoperiodic regime. These changes were also inversely correlated with diffusive conductance (1/diffusive resistance, 1 /R) of the leaves used. Even after advancing the photoperiod by 7 h the changes in starch levels continued for at least 1 d and were still inversely correlated with 1/R.Corresponding changes in glucose levels were measured in the same tissue and were found to correlate with 1/Rat the end of the dark period and mid photoperiod, but not at the beginning of the dark period. These changes are discussed in relation to possible mechanisms of stomatal opening and closing.

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11586863

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractOxygen effects on apparent photosynthetic and dark respiratory O2exchange rates of detached leaves ofElodea canadensisMichx. (Hydrocharitaceae) were determined over a range of conditions which the submersed plant is likely to experience in shallow water. Apparent photosynthesis is inhibited by O2under all the experimental regimes of light, temperature, CO2concentration and pH. This inhibition is not caused solely by an accelerated rate of dark respiration, and the observed variations in O2inhibition are comparable to O2effects on photosynthesis and photorespiration of terrestrial C3plants. Percentage inhibition of apparent photosynthesis is enhanced by high O2and also by low CO2. These results indicate that high O2, high pH and low CO2conditions could cause major losses in photosynthetic activity under field conditions. This may account for some of the losses in biomass that are observed under still water conditions.

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11586879

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractLeaves ofAmsinckia douglasianadischarging phloem exudate after infection with the beet curly top virus (BCTV) were studied with the electron microscope. Infected tissue differed from the noninfected in having much hyperplastic phloem characterized by abnormally high proportion of sieve elements, scarcity of companion cells, degenerating parenchyma cells, and some unusually large intercellular spaces. Many spaces contained amorphous debris. Particles resembling BCTV were discernible within the debris. Such particles were encountered also in the debris trapped between stomatal guard cells. Since the phloem exudate excreted from leaves of BCTV‐infected plants contains virus particles, and since the virus is found extremely rarely in sieve elements, we suggest (1) that most of BCTV particles apparently released into intercellular spaces are derived from degenerating parenchyma cells in which the virus had multiplied; (2) that the exudate is derived from sieve elements of the hyper‐plastic phloem in which the normal functional control by companion cells is lacking; (3) that the exudate leaks from the nontransporting sieve elements through cell walls into intercellular spaces and carries the virus to the outside. Initially, stomata may serve as exits for the infectious exudate, but subsequently ruptures in the epidermis are invol

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11586898

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractRoot fatty acid composition, photosynthesis, leaf water potentials, stomatal resistances, leaf specific weights, and root: shoot ratios of soybean were measured in two temperature regimes.Groups of soybean plants were grown in controlled chambers of the Duke University Phytotron under two thermoperiods. One group of the plants was grown from seed for 3 weeks in either 29/23°C or 17/11°C thermoperiods, and another group was grown for 2 weeks in 29/23°C and then transferred to the 17/11°C thermoperiod where it remained for 8 days. Broccoli was also grown in either 29/23°C or 17/11°C thermoperiods.Soybean roots contained more unsaturated fatty acids than broccoli roots, although broccoli roots showed a larger increase in unsaturation than soybean roots with decreased temperature. The fatty acid unsaturation in the roots of soybean began to increase rapidly after the temperature regime was changed. The increase was in the new roots produced in the cold regime rather than in the pre‐existing roots.The soybean leaf water and osmotic potentials decreased about 0.4 MPa, beginning one day after the transfer from 29/23°C to 17/11°C, but recovered significantly after 8 d.Plants grown at 17/11 °C had lower rates of photosynthesis and adaxial stomatal resistances, but higher root: shoot ratios and specific leaf weights compared to plants grown at 29/23°C. Plants grown and maintained at 29/23°C showed a steady increase in photosynthetic rates over the 8‐d experimental period, whether rates were measured in 1 mol m−3or 9 mol m−3oxygen. Plants transferred to 17/11°C however maintained constant rates of photosynthesis at 1 mol m−3O2, whereas at 9 mol m−3rates declined for 2 d then were constant for the remaining 6 d of the experimental period.These results suggest that changes in membrane fatty acid unsaturation is an important aspect of plant acclimation to chilling temperatures in terms of maintaining root permeability and water uptake. However, the degree of unsaturation is not a good indicator of differences in chilling tolerance among species. The apparent acclimation of photorespiration to a constant percentage of photosynthesis suggests a role of photor

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11586908

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractThe boundary layer conductance of brass models of leaves exposed in a wind tunnel was determined from their cooling characteristics. Conductances were generally very low, as expected from large leaves. Nusselt numbers were calculated from the rates of heat loss, so that the results could be compared with established theory. There was generally good agreement between observed and calculated values. Leaves with veins displayed an apparent transition from a laminar to a turbulent boundary layer, and so did leaves inclined at an angle from the horizontal. In still air the observed rates of heat loss by natural convection were substantially higher than those calculated.

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11586917

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractMeasurements were made of the rate and pattern of14CO2fixation by the attached and detached epidermis and accompanying leaf tissue ofCommelina cyanea(C3),Zea mays(C4),Kalanchoë daigremontiana(CAM),Allium cepa(C3) andPaphiopedilum venustum(C3). Guard cell plastids of the last two species contain no starch and chlorophyll, respectively. The fine structure of guard cells of these species was also examined.The epidermis of all species when detached from the leaf fixed CO2by PEP carboxylation but at rates related to those of the underlying mesophyll. When attached to the leaf during14CO2feeding a much higher rate of accumulation of radioactivity in substances other than malate and aspartate was found. The results indicated that although concentrations of various metabolites in the two tissues varied greatly, there was fairly ready transport from mesophyll to epidermis. Of recently formed compounds, amino acids appeared to be most readily transported inCommelinaand sugars inZea and Kalanchoë. Epidermal cells appeared to be highly permeable, there being rapid and extensive loss of most labelled products from epidermis placed on CaSO4solutio

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11587001

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY