摘要:

CLONING AGRICULTURAL PLANTS VIAIN VITROTECHNIQUES. Edited by B. V. CongerEFFECTS OF HEAVY METAL POLLUTION ON PLANTS. VOLUME 1. EFFECTS OF TRACE METALS ON PLANT FUNCTION (352 pp.). VOLUME 2. METALS IN THE ENVIRONMENT(257 pp.). Edited by N. W. LeppSTOMATAL PHYSIOLOGY. Edited by P. G. JarvisAND T. A. MansfieldDEVELOPMENTS IN PLANT AND SOIL SCIENCES. VOLUME 3. CARBON AND NITROGEN METABOLISM. Edited by J. D. BewleyECOLOGICAL STUDIES. VOLUME 36. PHYSIOLOGICAL PROCESSES IN PLANT ECOLOGY. TOWARD A SYNTHESIS WITH ATRIPLEX, By C. B. Osmond, O. BjörkmanandD. J. AndersonPHYSIOLOGICAL PROCESSES LIMITING PLANT PRODUCTIVITY. Edited By C. B. JohnsonMATHEMATICS AND PLANT PHYSIOLOGY. Edited by D. A. RoseandD. A. Charles‐EdwardsBIOSYNTHESIS OF ISOPRENOID COMPOUNDS, VOLUME 1. Edited by J. W. Portkr andS. L. SpurgeonSTRUCTURE AND FUNCTION OF PLANT ROOTS. Edited by R. Brouwhr, O. Gas̈paiuková, J. Kolek&B. C. LoughmanTHE CELL CYCLE(Society for Experimental Biology, Seminar Series No. 10). Edited by P. C. L.

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1982.tb00930.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.Reeve&Crozier (1980) have recently proposed a method of evaluating the accuracy of a plant growth substance analysis by using information theory to estimate whether the analysis would distinguish the growth substance from all other components of the sample. In the present article, it is argued that their method requires knowledge of the relevant analytical characteristics of all potential components of the sample, and hence is not applicable to plant extracts. Instead, the identity of a growth substance in a plant extract can only be conclusively established using techniques which yield information on its chemical structure.

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1982.tb00931.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.Re‐analysis of published data on the gecocurvature and nutation of the primary root of maize is presented. This analysis demonstrates clear evidence of nutalional oscillations occurring during georesponse. The importance of this evidence in relation to theories of nutation mechanism is discusse

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1982.tb00932.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.A system is described whereby seedling development can be analysed in terms of growth rates of specific 1 mm regions of the hypocotyl. The technique involves time‐lapse photography of marked hypocotyls in a specially designed chamber which accommodates seedlings in various orientations with respect to gravity, and under irradiation regimes differing in light quality, quantity and direction. The results of a preliminary study of the upward growth of etiolated or green cress seedlings in darkness or overhead while light are reported. Highest growth rates in etiolated seedlings were observed in zones in the upper one‐third of ihe hypocotyl. In green seedlings, growth was more prominent within the subapical zones. Light further restricted growth of the median and basal zones in both types of seedling. However, in their immediate responses to the onset of irradiation, green and etiolated seedlings differed markedly. In etiolated seedlings, recovery of growth at the apex was accompanied by the development of inhibition in the median‐basal regions; green seedlings showed a transient inhibition of growth in the apical zone together with a strong immediate inhibition in the median‐basal

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1982.tb00933.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.Growth in various regions of the hypocotyls of dark‐grown cress seedlings before and after exposure lo continuous white light has been analysed by time‐lapse photography. In the dark, growth in the hook was minimal, the upward growth of the seedling being sustained by extension of the shank, especially the uppermost zones. Following irradiation, the hook and the remainder of the hypocotyl showed dissimilar growth responses. Previously growing regions of the shank were inhibited while zones within the hook, especially the apical end of the inner (concave) side, showed marked growth stimulation. These changes in growth rates commenced within 1 h from exposure to the light stimulus and thus considerably preceded any observable changes in hook an

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1982.tb00934.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.Growth rates throughout an organ curving phototropically under continuous, unilateral while light were monitored by lime‐lapse photography of cress hypocotyls marked into 1 mm sections by two rows of ion‐exchange beads. Curvature resulted from an integrated sequence of changes in growth rate on each side of the organ, but the actual patterns of change and, therefore rales of curvature, differed within even this one species, depending upon the immediate pretreatment of the seedlings. Transference of seedlings from darkness to unilateral irradiation gave immediate growth inhibition on both sides of the organ. Curvature resulted from differential recovery of growth rate, being seen first on the shaded side, most prominently in the apical regions; only 2h after initial exposure to light did growth recover on the lit (lower) side. On the other hand, transfer of seedlings from omnilateral to unilateral irradiation of the same intensity resulted in simultaneous growth inhibition on the irradiated side and stimulated growth on the shaded side: this growth stimulation of the shaded side was greater than occurred in totally darkened control pla

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1982.tb00935.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.The leakage of electrolytes and the localization of chloride within the cells of NaCl‐imbibed seeds indicates the plasmalemma is quite permeable during the early stages of imbibition. However, lanthanum is not able to penetrate the plasmalemma, suggesting that the plasmalemma is not entirely porous. Freeze‐fracture microscopy indicates that the plasmalemma is highly convoluted but reveals a fairly normal fracture plane. These observations suggest the membrane is a bilayer and leakiness may be more related to the degree of order within the bilayered membrane than to a primary restructuring and/or reorganization of the membrane components in the dry st

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1982.tb00936.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.Modifications in plasma membrane structure and permeability were observed inChlorella sorokinianafollowing exposure to 0.2 gm−3(140 p.p.m.) O3for 30 min. Sixty‐eight per cent of the cells were plasmolysed after 15 min O3exposure with disruption of organelles similar to that previously described in higher plants. Freeze‐fracture exposed large areas of plasma membrane in 90% of the control cells and those exposed to O3for short periods. After 20 min O390% of the cells cross‐fracture, which indicates a change in molecular interactions in the membrane exposed to O3The earliest observed ultraslructural alteration is an aggregation of particles on the plasma membrane P face, statistically significant after 10 min O3Changes in86Rb influx occur during a similar time. After more extended exposure to O3the plasma membrane P face shows regions of lipid phase transition to the crystallin

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1982.tb00937.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.Rates of proton extrusion and potassium (86Rb) influx by intact roots of barley (Hordeum vulgare cvs. Fergus, Conquest and Betzes) plants were simultaneously measured in short‐term (15min) experiments. The nature and extent of apparent coupling between these ion fluxes was explored by manipulating conditions of temperature, pH and cation composition and concentration during flux determinations. In addition, the influence of salt status upon these fluxes was examined. At low K+concentrations (0.01 to 1 mol m−3), H+efflux and K+influx were strongly correlated in both low‐ and high‐K+roots, although K+: H+exchange stoichiometries were almost consistently greater than 2:1. At higher concentrations (1 to 5 mol m−3), H+efflux was either reduced or remained unchanged while K+influxes increased. In the presence of Na2SO4, rates of H+extrusion demonstrated similar cation dependence, although below 10 mol m−3Na2SO4, H+fluxes were generally 50% lower than in equivalent concentrations of K2SO4. These observations are considered in the context of current hypotheses regarding the mechanisms of k+

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1982.tb00938.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.Seedlings ofPharhitis nilshow a circadian rhythm in the capacity to flower in response to the timing of a second red light pulse given at various times after a first saturating exposure to red when this is given together with a benzyladeninc spray. There are also changes in the photon irradiance required for half maximum response to the second red pulse.The photochemical properties of phytochrome in the photoperiodically sensitive cotyledons were also shown to change rhythmically. Oscillations in both pr→ Pfrand Pfr→ Prphotoconversion characteristics persisted over at least two circadian cycles with a periodicity of about 12 h. There were, however, no significant oscillations in either Pfrpeak absorbance or in Δ(ΔA). The changes in sensitivity for the photoconversion of Pr→ Pfrdid not parallel the much larger changes in sensitivity of the flowering response to red light. The amplitude of the Pr→ Pfrrhythm was at least as great as that for Pr→ Pfr, but the flowering response to far‐red light was not rhythmic, nor was there any large change in sensitivity. The changes in photoconversion properties may reflect a basic biochemical oscillation which affects both photoreceptor properties and sensitivity to photoreceptor input.There was also a marked rhythm in the Pfr/P ratio that would be established by a saturating pulse of red light and this too may have affected the flowering response to such a pulse.Far‐red light inhibited flowering when given at any time during the inductive night. After 14 h in darkness, Pfrcould still be measured in the cotyledons and it was concluded that far‐red light inhibited flowering by removing PfrAs red light also inhibited flowering at this time, there may be two pools of phytochrome with different k

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1982.tb00939.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY