摘要:

AbstractSucrose was supplied to stock plants ofPisum sativumL. cv. Alaska grown at different levels of irradiance. There was no significant effect on the rooting of the cuttings by sucrose supply to intact plants regardless of the irradiance. However, an increase in the number of roots per cutting was obtained at increasing concentrations of sucrose when the stock plants had been grown at 4 W m−2and their cotyledons had been removed two days before the cuttings were excised.Cotyledons were removed from stock plants at different times before the excision of cuttings with the intent to regulate the endogenous supply of carbohydrate. The number of roots per cutting was reduced by removal of the cotyledons and this reduction was correlated to the number of days the stock plants had grown without cotyledons as well as to the irradiance pre‐treatment. A greater reduction occurred in cuttings from plants grown under 4 W m−2than from those grown under 38 W m−2.The growth of the stock plants and the subsequent stem growth of the cuttings was determined by the irradiance to the stock plants and by the time of removal of the cotyledons. Exogenous supply of sucrose had no effect on the stem growth of the c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03917.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractKinetic studies on a microsomal fraction from oat roots (Arena sativa) indicate that the MgATP complex is the primary substrate for the ATPase. Free ATP was a weak competitive inhibitor. Free Mg2+appeared to be either a competitive or noncompetitive inhibitor.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03918.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractAn apparatus based on the phase‐locked loop technique has been developed in order to record automatically the resonance frequency of a mechanically vibrating plant specimen. Hereby changes in the elasticity of the plant material can be continuously recorded.In order to demonstrate the use of the apparatus, elasticity changes ofAvenacoleoptiles due to exchange of the root medium were continuously recorde

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03919.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe production of extracellular alkaline phosphatase by multicellular marine algae in axenic culture has been investigated. The algae studied were five species of Rhodophyta:Asterocytis ramosa, Goniotrichum elegans, Nemalion helminthoides, Polysiphonia urceolataandRhodosorus marinus; and one species of Phaeophyta:Ecrocarpus confervoides.The extent of enzyme activity varies from one species to another. It also varies with the phosphorus conditions under which the alga is grown. The pattern of glycerophosphate utilization suggests that this type of compound is not taken up directly by the alga but split by the external enzyme before uptake of the phosphate‐ion only. The enzyme performs its action outside the organism and appears both associated with the cells and free in the surrounding water. Assays with culture filtrate ofAsterocytisandEctocarpusshow that the enzyme is an unspecific phosphomonoesterase with optimum activity far to the alkaline side. It is activated by Zn2

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03920.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractBy means of chromatographic, mass spectrometric and enzymatic techniques the major cytokinin in butanol extracts from the milk ofCocos nuciferafruits was identified as zeatin glucoside.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03921.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractLarge changes occur in carbohydrate contents of pine (Pinus silvestrisL.) and spruce (Picea abies(L.) Karst.) seedlings cold‐hardened by photoperiod or by combined photo‐ and thermo‐period. The largest change is in sucrose content, which is almost doubled after six weeks short‐day (6/18 h) treatment; and more than doubled (spruce) or more than tripled (pine), when also temperature is lowered (10/5°C). Development of frost hardiness is strongly correlated with the change in carbohydrate contents. At dehardening, the carbohydrate content decreases rapidly, especially in pine, and the raffinose formed during the rest period disappears within 2–4 weeks. Frost hardiness decreases in parallel.The content of soluble carbohydrates may thus play a role in frost hardiness, although it is not the only factor. Bud formation at cold acclimation is not directly correlated with the changes in carbohydrate content and

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03922.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe changing levels of carbohydrates and the rates of photosynthesis in rootingPopuluscuttings are described. The cuttings were planted in a sand medium, in controlled environment conditions. There was no evidence to support the view that failure to root inP. tremulawas caused by insufficient carbohydrate reserves. In leafless hardwood cuttings, the carbohydrate levels were initially very high (14–19%) but fell rapidly (to 5–10%) as roots, callus or shoots developed. In leafy softwood cuttings, a steady accumulation of carbohydrate reserves was observed, rising from 5–10% on planting to 15–25% when roots had developed. One of the differences between the easy‐to‐rootP. × euramericanaand the hard‐to‐rootP. tremulawas the apparent downward transport of assimilates inP. × euramericana

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03923.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractKinetic studies of a dithiothreitol treated membrane ATPase fraction from sugar beet roots led to the following conclusions: 1) In the presence of MgATP, Na+and K+stimulate the ATPase activity in different ways following simple Michaelis‐Menten kinetics. Thus separate sites for Na+and K+are suggested. 2) In the absence of K+, Na+acts as an uncompetitive modifier raising the apparentKmandVmaxfor MgATP. 3) In the absence of Na+, K+activates non‐competitively with respect to MgATP. Thus K+increasesVmaxbut does not affect the apparent affinity constant. 4) K+and Na+double the rate constants. 5) In the presence of Na+or K+, Mg2+in excess acts as a weak inhibitor to Na+and/or K+activity. 6) The temperature‐activity dependence in the 5–40°C interval shows biphasic Arrhenius plots with the transition point between 15–18°C. The activation energy is lowered at temper

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03924.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractBy a combination of thin‐layer chromatography and gas liquid chromatography, a complete study of the development of the different lipid classes and of their fatty acids, during the development of the fruit ofHedera helixL., the English Ivy, has been achieved. In any part of the fruit observed, at any particular stage, the phospholipids and the neutral lipids are the most abundant lipid classes. They accumulate during the entire process of maturation, whereas significant changes occur in their relative proportions, phospholipids being largely dominant until fruit blackening.The accumulation of fatty acids during maturation is characterized by large amounts of C18:1in the neutral lipids, especially in the seed, where petroselinic acid (C18:1Δ6) reaches 86% of the total fatty acids. To a smaller extent, the phospholipids also accumulate and thus have the character of reserve molecules. However, their composition remains more stable, which relates them to the “structural lipids” such as galactolipids that maintain their characteristic fatty acid composition, despite the radical changes occurring in the fatty acid metabolism during fruit ri

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03925.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe response of cultured cotton (Gossypium hirsutumL.) ovules to the ethylene releasing growth regulator, (2‐chloroethyl) phosphonic acid (ethephon), was measured. Control ovules grown on a complete liquid medium without hormones continued the differentiation normal for cotton, although at a slower rate thanin vivo. When ethephon was added to the medium, normal organ and fiber development was inhibited but callus was induced from the micropylar end of the ovule. The callus was extremely friable and produced many free cells in the culture medium. Dry weight of the callused ovules increased over 4‐fold and total cell number increased 56% over the controls. Apparently ethylene released from the ethephon stimulated both cell division and cell expansion in forming the cal

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03926.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY