摘要:

AbstractConsiderable variations in the content of free amino acids, elhanol‐soluble carbohydrates, starch, protein, chlorophyll, phylic acid, RNA and DNA exist in different regions of the long filaments ofCuscuta reflexa. The distinction is especially pronounced when comparison is made between the hanstoria‐bearing curls of the parasite and the apical portions of the overhanging filam

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb08876.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractWillow cuttings were used in which u narrow, longitudinal strip of bark was removed commencing from the base of the leafy shoot. Aphid colonies of different sizes were then sited on the stem either side of the strip, 10 cm below the base of the shoot. The leaves were allowed to assimilate 14CO2, and the dry weight and total activity of the honeydew from each colony was measured over a given period of time.It was found that not only did the total activity from the large colony exceed that of the small colony, but that the specific activity of the honeydew from the large colony was higher than that from the small colony. This has been taken as evidence that neighbouring pierced sieve tubes do not act independently of each other; mutual interference occurs. Increasing the distance between pierced sieve elements by dispersing the members of the large colony over a greater area of stem, did not apparently reduce interference effects.The results are explained in relation to the magnitude of the contributory length (Peel and Wealherley 1962), of individual sieve tubes pierced by the large, as opposed to the small colony.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb08877.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe reduction of nitrate in leaves establishes an ‘excess’ of cations in the tissue which is rapidly neutralized by the synthesis of malate. Malate synthesized in nitrate‐containing leaves accumulates while malate synthesized in nitrate‐depleted leaves disappears gradually. The levels of nitrate reductasc and malate synthesis change similarly during leaf growth. Good correlation was also found between the rate of protein synthesis and the rale of malate synthesis. Stoichiometric relation between the amount of nitrate reduced and malate accumulated may be observed in short‐term ex

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb08878.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractA “quasi‐diffusion resistance”, rq, is defined to accommodate the role which the thermochemical and photochemical phenomena of photosynthesis play in the control of CO2 fixation to the terminology and approach of the diffusion resistance analogue for the CO2 exchange of leaves. The relationship of rq to Rabinowitch's classical rectangular hyperbolic model of photosynthesis rate as a function of CO2 concen‐tration at the carboxylating surface is discussed. Examination of Kmapp for phos‐phopyruvate carboxylase (the predominant carboxylase in maize) suggests, as a reasonable hypothesis for light‐saturated maize leaves, that rq may be essentially independent of ambient CO2‐concentration up to at least 300 μ1/l. A corollary of the hypothesis is that an increase of diffusion resistance, rather than of rq, may account for the observed curvature of the response curves of light‐saturated maize leaf photosynthesis to ambient CO2‐concentration. An experiment carried out on fieldgrown maize plants, using a well controlled leaf chamber as a nitrous oxide diffusion porometer, gave evidence which strongly suppor

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb08879.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractPossible hormonal interactions between soybean roots and the Rhizobium initiating nodule proliferation in this genus were studied. A cytokinin has been isolated by column and paper chromatography from an effective strain of Rhizobium japonicum grown in pure culture. The substance promotes cell proliferation in a cytokinin‐requiring soybean callus tissue. The bacteria are capable of conditioning a cylokinin‐free soybean culture medium so that it is able to support the cytokinin‐requiring tissue. It is concluded that the substance is a product of the bacteria rather than an artifact of purification. This unidentified cytokinin or a substance moving to a similar Rf value on the paper chromalogram produces polyploid divisions when tested on cultured pea root segments. Some of the division figures exhibit the diploclirornosomes typical of the root nodule primordium i

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb08880.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractSeed development inPisum arvenseL. cv. New Zealand Maple has been studied in relation to changes in level of total endogenous cytokinins. Growth of both the whole seed and the embryo is diauxic, having two phases of active growth separated by a lag period. The two maxima in the growth rates of the whole seed and the embryo occur about the 23rd and 31st days after anthesis. The lag period occurs between days 26 and 28. Cell division is thought to have ceased prior to day 19 and the changes in total cytokinin content in pea seeds after this time are believed to be largely independent of cell division. The three maxima in the cylokinin content per gm. fresh weight of seed and per seed were found to be coincident with the maximum volume of endosperm per seed and the two maxima in the growth rates of the whole seed and the embryo.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb08881.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractSeedlings ofPhaseolux vulgariswere grown in media with and without iron. Growth was measured in terms of leaf length and fresh weight increase. Cyanide at&concentration of 0.05 mMwas found to inhibit severely plants growing in complete media but failed to inhibit growth to (he same extent in those plants grown in media lacking iron. It was established that this result was obtained whether the plants were grown in an unchanged medium or if the growth medium was replaced at intervals. A number of suggestions were made in an attempt to account for this anomalous behavior.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb08882.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractGA3‐treatment of dwarf maize seedlings resulted in the elongation of the leaf sheath and also an increase in α‐amylase activity. Excised leaf sheaths did not respond to GA3in leaf shealh length and α‐amylase activity. Increase in the enzyme activity is always accompanied by an increase in the length of the leaf sheath. α‐Amylase activity gradually increased as the growth of the first leaf proceeded, and a parallelism was found between the length of the leaf sheath and the enzyme activity, suggesting that the degree, of the enzyme activity depends on the length of the leaf sheath. On the other hand, IAA did not affect α‐amylase activity while it promoted leaf sheath elongation. This suggests that elongation per se is not associated with the increase in α‐amylase activity and that the enzyme‐promoting effect is specific to gibberellin. Higher α‐amylase activity and lower content of reducing sugars were detected in the older tissue of the leaf sheath, that is, in the upper half. This was the same for GAlrealed seedlings. The amount of reducing sugars was less in GA3‐trealcd seedlings. Oxygen‐uptake of the leaf sheath was higher in the upper half in both controls and GA3‐treated seedlings. It was slightly higher in the latter than in the former. From these results it was discussed 1o conclude that the processes of the GA3‐induced elongation and increase in α‐amylase activity of the leaf sheat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb08883.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe effectiveness of GA3in inducing floral‐bud initiation inImpatiens balsaminaunder non‐inductive photopcriods varies considerably at different parts of the year and appears to be determined by the prevailing temperature conditions. The period of floral‐bud initiation is shortest in October and February and increases both with decreasing temperatures in November and with increasing temperatures in August and September. Floral buds do not initiate in March and April, during which time the temperature increases considerably subsequent to the start of exper

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb08884.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractExplants of mature dormant tubers ofHelianthus tuberosuswere grown in a glucose medium. The explants were able to initiate ade novosynthesis of fructosans. Initiation of this synthesis depends on the level of sucrose and fructosylsucrose. Sucrose synthetase level in the tissue can be altered by 2, 4‐D. Fructosylsucrose synthetase seems to be induced by sucros

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb08885.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY