摘要:

AbstractGametophytes ofOnoclea sensibiliswere grown under continuous white light of 90 lux. Filaments were produced having 4–6 cells before the initiation of 2‐dimensional growth. There was a close correlation between the average cell number of a population of plants and the proportion of 2‐dimensional forms. 8‐Azaguanine produced a general inhibition of growth, and it was shown that the reduced proportion of 2‐dimensional plants caused by 8‐azaguanine was a secondary consequence of the general growth inhibition. IAA however gave a true specific inhibition of 2‐dimensional growth.Based on these experiments the proper criteria for establishing a specific inhibition of 2‐dimcnsional growth arc discussed. These criteria are applied in a critical review of previous papers on the inhibition of 2‐dimensional growth. It is concluded that no firm evidence is available that inhibition of protein synthesis specifically blocks 2

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07294.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractCyclic fluctuations in stomatal aperture, transpiration rate and leaf water potential under constant environmental conditions have been investigated in intact plants of cotton, pepper, and sunflower. Stomatal aperture and transpiration rate were least when leaf water potential was high and were greatest when leaf water potential was low.Lowest leaf water potential values lagged behind the occurrence of highest transpiration rates, and high overall resistance to water flow occurred in cycling plants. Both of these are considered essential for the occurrence of persistent cyclic behaviour. Hydropassive opening of stomates as the leaves wilted facilitated cycling in cotton and pepper, but not in sunflower, where hydropassive opening did not occur.The roots were identified as the site of the major resistance to water flow in the plant and further experiments directly showed the importance of this root resistance in initiating cycling by causing water stress in the leaves as the stomates opened.Root resistance varied diurnally, becoming increasingly important at night. Root resistance naturally rose to high levels in cotton. High levels were induced in pepper or sunflower by having the roots in deionized water for several days or by anoxia.Quantitative measurements of overall plant resistance were made from leaf water potential and transpiration rate data.The results are discussed and it suggested that plant resistance mayindirectlybe of importance in the movement of water from the plant to the air.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07295.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe growth of crown‐gall tumors on primary pinto bean leaves (Phaseolus vulgarisL. cv. “Pinto”) between day 3 and day 6 after inoculation was found to be proportional to the number of tumors on the leaves. Similar differences observed in the growth of tumors induced by adenine, methionine and asparagine requiring mutants ofAgrobacterium tumefaciens(Smith and Town.) Conn appear to be due to the same phenomenon. Tumors induced by these auxotrophs thus show no obvious growth differences from those induced by the prototrophic strain despite the lower specific infectivity and the existence of a mutational lesion in these bacteria. A diffusible growth factor(s) produced by the tumor tissue is proposed to account for the relation between tumor number and early tumor g

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07296.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractA tumor growth factor was extracted from primary pinto bean leaves{Phaseolus vulgarisL. cv. “Pinto”) having crown‐gall tumors. Application of these extracts to primary pinto bean leaves at day 3 after inoculation withAgrobacterium tumefaciens(Smith and Town.) Conn resulted in an increase in the diameter of tumors on these leaves after 24 hours that was 25–60 percent greater than that of the controls. No growth promoting activity was detected in comparable extracts from control leaves or from cultures of the bacterium. The tumor growth factor did not affect tumor number when applied in this fashion. The active extracts were fractionated on Sephadex (1–15 columns and an active component obtained which eluted in a volume suggesting a molecular weight in the range of 100–200. A spectrum of the material in this fraction is shown and some of the characteristics of this material are described. Reasons are presented for considering this growth factor to be identical with at least one of the growth factors previously hypothesized to account for the greater tumor growth observed as tumor number is increased in

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07297.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractA method is described whereby diffusible native growth substances are forcibly extracted by centrifugation. Centrifugates are relatively pure, highly active when tested for auxins and gibberellins, and contain far less inhibitors than solvent extracts.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07298.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractReduction in the amount of light supphed during the mid‐rest period caused a hetter leaf bud opening in the peach as compared with natural winter daylight; this includes darkness, short photoperiod and reduced light intensity. The quantitative nature of this light effect was shown. The role of light as a factor regulating dormancy is discusse

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07299.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractDevelopment of amylopectin‐1, 6‐glucosidase (amylopectin 6‐ glucanohydrolase) activity in germinating peas occurs under conditions in which protein synthesis is inhibited and α‐ and β‐amylase fail to increase in activity. An increase in activity of amylopectin 6‐glucanohydrolase can be obtained in cell free homogenates of imbibed pea seeds under autolytic conditions. Activation is shown to occur in a particulate fraction and to be due to the action of a proteolytic enzyme in the homogcnates. A system could be constituted consisting of a particulate fraction and trypsin which lead to a rapid activation of the amylopectin 6‐glucanohvdrolase. This is regarded as proof that enzymes in germinating seeds can be formed by liberation or activation of precursor forms. The implications of thi

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07300.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractWhile both the total sugar content and cold hardiness greatly increased during artificial cold acclimation, no direct parallelism was demonstrated. In fact, plants hardened in the dark exhibited an increase in hardiness during the period when the total sugar content declined, furthermore, while there was evidence for an accumulation of sugars (especially sucrose) incorporation of14C indicated that all of the isolated fractions were in a dynamic state.Dehardening, paralleled by a large increase in the starch content, was more rapid in the light than in the dark. Furthermore, in stems the sugar content increased after 3 days of dehardening but declined after 7 days. This increase may represent the release of sugars from a previously unextractable form such as a glycoprotein complex.Starvation experiments indicate that photosynthates produced during the cold acclimation period are preferentially used during cold acclimation rather than reserve carbohydrates. This was also indicated by the smaller amount of starch hydrolysis in plants hardened in the light. Thus, while there appears to be a role for carbohydrates in the cold acclimation process, the lack of parallelism between sugar content and hardiness may be interpreted as indicating 1) cold acclimation is not merely an accumulation of sugars or an osmotic effectper se, and 2) under normal conditions, the level of carbohydrates is not limiting the rate or degree of cold acclimation.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07301.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractComparative Effects of 6‐Furfurylaminopurine and 6‐(γ, γ‐Dimethylallylamino) purine on Growth, Peroxidase, Chlorophyll and Carotenoid Content. —6‐Furfurylaminopurine (FAP) and 6‐(γ, γ‐dimethylallylamino) purine (IPA) both inhibit root growth and cause an increase in peroxidase activity. When used at 10−8and 10−8M, IPA stimulates elongation of the coleoptile test, at 10−4Mboth FAP and IPA provoke an inhibition. FAP and IPA maintain a high level in chlorophylls and carotenoids in floating leaves discs. In all these experiments, IPA has thus a

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07302.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractAeration of root culture medium with air containing 5 % or 10 % CO2enhances growth, particularly lateral initiation and growth, compared with aeration wilh air or CO2‐free air. This beneficial effect of enhanced CO2pressure on the growth of cultured roots of Atson Elite 56 wheat ean also be demonstrated in presence of a high (40 %) and inhibiting level of oxygen.14C labelling from a carbonate–bicarbonate solution of pH 7.0 by cultured wheat roots is enhanced by light and this labelling is not inhibited by the presence of 1 % ethyl ureth

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07303.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY