摘要:

Abstract.The cell volume of two strains of the halophilic algaDunaliella parvawas measured by two direct methods and by electrical sizing. The results from the direct methods agreed with each other and were consistently larger than those obtained from electrical sizing. Statistical analysis showed that the cell volume populations obtained by electrical size ofD. Parvacells is due to the cell membrane having an unusually low electrical resistance relative to other cell membranes.

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11589429

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.Elongation responses of intact coleoptiles of rice (Oryza sativaL. ev. Sasanishiki) explants to various gases were examined under submerged conditions in continuously flowing gas‐saturated incubation media. Reduced O2tension (hypoxia). CO2and especially C2H4significantly stimulated coleoptile elongation; the optimal concentrations of O2, CO2and C2H4when applied singly were 0.07 m3m‐3, 0.10 m3m‐3, and 3 cm3, respectively. However, in addition to these gases other as yet unknown factors were involved in the enhanced elongation of rice coleoptiles under water.The actions of CO2and C2H4, unlike that of hypoxia, were accompanied by increases in dry weight of the coleoptiles. The effect of C2H4occurred independently of O2concentrations, whereas that of CO2occurred above 0.08 m3m‐3O2. Maximum elongation of rice coleoptiles under submerged conditions was obtained when the flowing medium was saturated with a gas mixture containing 0.10 m3m‐3O2, 0.10 m3m‐3CO2and 10 cm3m‐3C2H4, greatly surpassing elongation in static media. However, elongation in static media was greater than that in a closed atmosphere. The intercellular C2H4concentration in explants growing in static media was higher than that in a closed atmosphere. These results showed that the coleoptile elongation of rice seedlings under water may be regulated by the accumulation of CO2and C2H4in and around the seedlings under hypox

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11589438

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.Four contrasting grain legume species (Glycine max, Vigna radiata. Vigna mungoandVigna angularis) were grown as row crops with both 0.5 m and 1.0 m spacings between row centres. Light transmission profiles, at ground level, across rows of plants, were obtained for each crop on a number of occasions during growth. The proportion of the incident downward light flux density intercepted by each crop at solar noon was found to be simply and directly related to the product of the proportion of the ground area covered by the crop's leaf canopy and the proportion of the downward light flux density incident at the row centre that was intercepted by the crop. The average proportion of the incident light energy intercepted over the whole day could be related to the proportion intercepted at solar noon.

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11589442

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.Growth rates and levels of minerals, Na+, K+, Mg++, Ca++, and water were measured in dicotyledonous halophytes grown along a salinity gradient from fresh water to 720 mol m−3NaCl in a controlled environment greenhouse. Ten test species from the families Chenopodiaceae, Aizoaceae, and Batidaceae exhibited growth stimulation by 180 mol m−3NaCl and were classified as euhalophytes. Ten others from the families Chenopodiaceae, Aizoaceae, Asteraceae, Brassicaceae, Polygonaceae, Boraginaceae, Malvaceae, and Plumbaginaceae showed their best growth on fresh water and were classified miohalophytes. Salt, and particularly sodium, accumulated in all halophytes but to a significantly greater extent among euhalophytes than miohalophytes. The water content of most species increased when grown on 180 mol m−3NaCl compared to fresh water; but at higher salinities some of the species underwent dehydration. Dehydration of the succulentS. europacawas not coupled to a proportional decrease in growth. Water content and cation accumulation in euhalophytes appeared to be coordinated to produce a constant osmotic potential gradient within the shoot tissues relative to the external salinity. In contrast, miohalophytes did not appear to regulate osmotic potential as closely as euhalop

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11589448

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.It is demonstrated that after the feelling of ash coppiceCirsium palustrebecomes established from seed that was produced during the previous coppice cycle and has lain underground for several years. These seeds are light‐requiring and it is probable that their germination is triggered by exposure to light during coppicing in winter.It is assumed that the seeds become light‐requiring because phytochrome in the far‐red absorbing form high. This facilitates their incorporation in the seed bank in summer. However, the disappearance of Pfr is inhibited at low temperatures; this means that the seeds can store the light stimulus in winter and will not germinate until they experience higher temperatures in spring. The significance of the inhibition of seed germination under a leaf canopy is that it enhances the seeds chance of being incorporated in the soil seed

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11589456

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.Although daylength has a major effect on flowering and several other aspects of plant development, the actual environmental time signals for the beginning and the end of day are obscure. An intensive spectroradiometric study was carried out in three contrasting environments: namely, unshaded sites, a mature oak woodland and a sugar beet crop. Spectral photon distributions were obtained describing numerous twilight phases and intervening photoperiods throughout the year. From each, absolute photon fluence rates, photon fluence rate ratios and phytochrome photoequilibria were calculated. Although substantial changes in spectral composition occurred during twilight, they were less capable of providing reliable and accurate time signals than the absolute fluence rate; this was especially apparent beneath the canopies. Thus, spectral changes are unlikely to be valuable in photoperiodic perception. The results are discussed in relation to the possible involvement of the known plant photoreceptors in photoperiodism.

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11589464

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.Changes in crassulacean acid metabolism (CAM) in the leaves ofBryophyllum daigremontianumwere studied comparatively under closely controlled (phytotron) and semi‐natural (greenhouse) conditions utilizing measurements of natural carbon isotope composition (δ13C) of the total leaf matter. Abrupt transfer of plants from long days to short days resulted in an overall increase of CAM in mature leaves (no. 3 from the apex and older) and thus in a higher CAM level for the whole plant. Study during the course of a year in semi‐natural conditions showed that a progressive increase in length of day and day night temperature differences (February ← June) activated CAM but only a passage to short days (June ← October) produced the maximum CAM. Under the experimental conditions employed, the maximum shift from the C3‐type to the C4‐type of metabolism was observed in plants subjected to semi‐natural progressive variations in the environment, i.e. the δ13C values indicated that for plants in the greenhouse the total carbon flow entering the cells was mediated by phosphoenolpyruvate carbo

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11589470

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.Carbon dioxide is known to overcome sporophytic self‐incompatibility inBrassica.Elevated CO2(30 mmol CO2mol‐1air), supplied via a flowthrough gas system, was shown to block the formation of rejection callose in the surface stigmatic papillae ofBrassica campestrisvar. T15 following self‐pollination. Possible mechanisms by which CO2may affect callose formation are disc

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11589475

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Books reviewed in this article:NITROGEN AS AN ECOLOGICAL FACTOR.Edited by J. A. Lee, S. McNeill&I. H. RorisonBIOLOGY OF NONVASCULAR PLANTS.By H. N. Pritchard&P. T. BradtGENETIC ASPECTS OF PLANT NUTRITION(Development in Plants and Soil Sciences, Volume 8). Edited by M. R. Saric&B. C. LoughmanPHYSIOLOGICAL PLANT ECOLOGY III.Edited by O. L. Lange, P. S. Nobel, C. B. Osmond&H. Ziegler

ISSN:0140-7791    

DOI:10.1111/j.1365-3040.1984.tb01352.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0140-7791    

DOI:10.1111/1365-3040.ep11589722

出版商:Blackwell Publishing    

年代:1984

数据来源: WILEY