摘要:

AbstractThe transpiration response to recurrent light periods was studied'n water‐stressed wheat seedlings. Seedlings were stressed by three methods: addition of mannitol to the root medium, root cooling and drving of the roots in air. All three methods induced almost equal effects on transpiration regulation during alternating dark and light intervals. Exogenous abscisic acid supplied to the shoots of excised plants had qualitatively the same effect as water stress.Water stress and ABA increased the time lapse between light‐on and the onset of transpiration increase and lowered the amplitude of transpiration increase in light. Weak light introduced before strong light shortened the delay ti

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03996.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractCytokinin glucosides can be extracted rapidly and efficiently from plant material by means of the acid cation exchange resin Dowex 50W X8 (Baker's Analysed Reagent). In the present investigation no evidence could be found that these cytokinins are hydrolysed or retained by the Dowex resin.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03997.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe relation between the effects of auxin on growth, pH and potassium transport in hypocotyl segments ofHelianthus annuuswas studied. In a solution containing 20 mMNa2SO4auxin‐induced growth was accompanied by an auxin‐induced pH drop in the medium. (NH4)2SO4, at the same concentration, brought about an almost complete abolishment of the effect of auxin on the pH. The magnitude of auxin‐induced growth was, however, only slightly reduced. This result does not confirm the hypothesis according to which the action of auxin on growth is a result of its effect on the pH.In a solution containing 2 mMsodium phosphate buffer an inhibitory action of IAA on the release of potassium from the tissue was observed. Addition of 20 mMNa2SO4to the medium brought about a complete abolishment of this effect. The magnitude of auxin induced pH drop was, however, similar in the two treatments. It was concluded that, although under suitable experimental conditions, a close relationship may exist between the effects of auxin on pH on K+transport, the coupling between the two phenomena is not oblig

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03998.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe season dependent changes in growth response to treatment with auxin or gibberellin were studied in the aquatic macrophyteCeratophyllum demersum.Control plants show, under experimental conditions, a maximum growth in length in February. In the same period most of the lateral buds appear. Growth of the lateral buds occurs later.IAA causes a stimulation of growth in length from late November or December until February, in concentrations of 10−9Mand 10−6M. There is almost no stimulation of lateral bud formation by IAA, only a slight increase from late November until December occurs by the lowest concentrations used. The highest concentration used, 10−4M, is in most cases supraoptimal for lateral bud formation; only when plants become dormant (August), this high dose may stimulate the process.GA3, in concentrations of 10−9, 10−6or 10−4M, exhibits a dose dependent increase of the response with respect to growth in length and lateral bud formation. The response occurs earlier than that for IAA: already early in November, or December, until February.Growth of the lateral buds may show only a slight stimulation by IAA as well as GA in winter. From February until April all GA concentrations used could cause a small increase of the growth of sprouts. In the case of IAA, however, only the lowest concentration could cause a sma

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb03999.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractDiploid and autotetraploid plants of the cultivated tomatoLycopersicon esculentumcv. Lukullus (Luk) were studied under low and high salinity. Polyploids had a higher water content than diploid plants. Water content in both plant types decreased under salinity, the decrease being smaller in the polyploid plants. Dry weight of whole young plants decreased in both diploid and polyploid plants under salinity, the decrease being smaller in the latter. Transpiration of whole plants, grown in control solution, was lower in polyploid than in diploid plants and decreased more under salinity in the latter. Rate of change of water loss of detached drying leaves was similar in diploid and polyploid plants. Leaves of control diploid plants, however, lost more water per unit leaf area during the phase of stomatal closure apparently due to higher stomatal density. Polyploid plants had fewer but more open stomata per unit leaf area, under both control and saline conditions. Root pressure, determined only under control conditions, seemed to be higher in polyploid plants. No difference in Cl−concentration per unit leaf dry weight was found between diploid and polyploid plants grown in either control or NaCl solutio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb04000.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe effect of some flavonoids on the polar transport of auxins was investigated in hypocotyl sections of dark grown seedlings of cucumber,Cucumis sativusL., by means of14C labelled auxins. In experiments of 4–6 h duration quercitrin, morin, dihydroquercetin, naringin, sulfuretin and ferulic acid increased the polarity of the transport of indol‐3yl‐acetic acid (stimulation of basipetal, inhibition of acropetal transport). Naringenin, genistein and pinobanksin, on the other hand, decreased the polarity of this transport. For NAA no increase in the polarity of the transport could be observed, but all the substances tested inhibited the basipetal transport. There was no simple correlation between the effects on the polar transport and the effects on IAA ox

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb04001.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractConductimetric study of the effects of three auxins on a storage tissue.The change of conductivity of calibrated disks of potato tuber tissue was measured after a 6 h immersion in a mixed aqueous solution of 1 × 10−3Mauxin and 0.2Mmannitol, or pure auxin, or mannitol, of the same concentrations; then measured anew after a l h immersion in 0.1MKCI. The auxins used were: β‐indolyl‐acetic acid (AIA), α‐naphtyl‐acetic acid (ANA) and β‐naphtoxyacetic acid (ANOX). A final higher conductivity was observed, the effect increasing from AIA to ANA and ANOX. The physiological significance of the resul

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb04002.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractCalcicolous plants are generally more Fe‐efficient than calcifugous plants, because they respond to Fe stress by releasing H‐ions and “reductants” from their roots that causes Fe to become available. The objective of our study was to determine if differential response to Fe stress in calcicolous and calcifugous varieties affects nitrate reductase activity. T3238FER (Fe‐efficient) and T3238fer (Fe‐inefficient) tomato (Lycopersicon esculentumMill.) cultivars were grown in nutrient solutions supplied with N as NH4+‐N plus NO3−‐N, and as NO3−‐N only. The chemical reactions induced by Fe stress concomitantly increased nitrate reductase activity in roots and tops of calcicolous, but not in calcifugous tomato. This nitrate reductase activity decreased, however, when Fe was made available to the plants. When Fe stress was eliminated by adding Fe, nitrate reductase activity was comparable

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb04003.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractTime course of apical shoot growth and shoot tip abortion in northern ecotypes (lat. 69°39′N, long. 18°37′E) ofSalix pentandraand S.capreahave been investigated. In trees more than 15 years old growing under natural climatic conditions apical growth cessation and shoot tip abortion normally occurred in June‐July when the day length still was 24 h. Application of GA3, in spring to the apex effectively delayed growth cessation and shoot tip abortion. Application of kinetin was without effect. First‐year seedlings of both species grew continuously at temperatue of 9 to 24°C in 24 h photoperiod. Short days induced apical growth cessation, but two to four (S. pentandra) or three to five (S. caprea) weeks of 12 h photoperiod were required to stop the elongation growth. The results indicated that the critical photoperiod for apical growth cessation in the used ecotype ofS. pentandrawas 16 to 18 h at 18°C. Short days had a minor effect only on the formation of apical leaf primordia in small seedlings. Development of axillary buds and radial growth were stimulated by short days when compared with long days. Small seedlings of both species (3 to 8 cm high at the start) formed terminal buds in short days, but in large seedlings (more than about 15 cm high) apical growth cessation was accompanied by shoot tip abortion. Abscisic acid applied to the apex or through a leaf did not induce growth cessation inS. pentandraseedlings grown in continuous light. The growth retardants CCC, B‐9 and Phosphon D reduced growth rate under continuous light and induced shoot tip abortion in some plants. The effect of CCC was counteracted by GA3. Apical growth cessation in short days was significantly delayed by a single G

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb04004.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractBetween pH 4–10, basal ATPase activity, measured in the absence of mineral ions, was 10 to 100 times higher in the final cytoplasmic supernatant from potato tuber homogenates than in the membraneous fractions (purified plasmalemma, purified mitochondria and microsomes). The soluble ATPase was slightly inhibited, whereas the membrane‐bound ATPases were all stimulated by Mg2+ions. A further stimulation by Na+or K+ions was only observed in purified plasmalemma or mitochondria, at alkaline pH (7.5–9.5). At a fixed (Na++ K+) concentrations (80 mM), this last stimulation was much greater in purified mitochondria (350%) than in plasmalemma (33%); it also increased with (Na++ K+) concentrations up to 200 mMin mitochondria whereas, in plasmalemma, it was roughly constant for monovalent ion concentrations between 20 and 200 mM.General properties of the plasma membrane‐bound ATPase have been determined, i.e. substrate specificity, activity variations with quantity of substrate, temperature, pH,etc. Divalent cations stimulated strongly the ATPase in the following order: Mn2+>Mg2+>Ca2+. The maximum ATP hydrolysis velocity for that part of ATPase activity which is strictly dependent on Mg2+ions was 3.85 μmol × mg−1protein × h−1. This plasma membrane ATPase was not sensitive to ouabaïn o

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb04005.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY