摘要:

AbstractOxalate supplied toLemna gibbaL. in sterile culture was readily absorbed, stimulating growth and increasing the uptake of calcium when this element was present in the nutrient medium; in the absence of calcium, deficiency symptoms rapidly appeared. EDTA at low concentrations stimulated growth, but concentrations equivalent to those of calcium reduced the uptake of both calcium and oxalate; developing daughter fronds were chlorotic and cells from these tissues appeared to be calcium deficient.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb08574.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractSingle aqueous sprays of 2(chloroethyl)phosphonic acid (CEPA) 250, 500 and 1000 mg/1; 2,3,5‐triiodobenzoic acid (TIBA) 25, 50 and 100 mg/1; and (2‐chloroethyl) trimethyl‐ammonium chloride (CCC) 250, 500 and 1000 mg/1 were applied to squash melon (CitrullusvulgarisSchrad. var.fistu‐losusStocks.) at the 2–3 leaf stage. Though the final length of the main axis and number of lateral branches were not affected by any treatment, CEPA retarded growth of young plants by reducing the internodal length. It did not change the flowering pattern but delayed flowering and reduced the production of both pistillate and staminate flowers. However, it increased the per cent femaleness as a result of comparatively more suppression of staminate flowers. The TIBA 25 and 50 mg/1 and CCC 500 mg/1 did not affect the staminate flower production but increased the pistillate flowers, which increased the per cent femaleness. The CEPA decreased while both TIBA 25 and 50 mg/1, and CCC 500 mg/1 increased the number of fruits per plant and the yield. The mode of action of the chemicals has been

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb08575.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe soybean callus assay was used to study the effect of stratification on the cytokinin levels of the embryo dormant seed ofProtea compactaR.Br. and the seed ofLeucadendron dapbnoidesMeisn., where dormancy is coat imposed. Chilling the seed for 30 days increased germination significantly, and resulted in a simultaneous increase in the butanol soluble cytokinins of both species. It would appear as if these compounds are either synthesized or released from a bound form in embryo dormant seed. In contrast, an interconversion from water soluble to butanol soluble cytokïnins appears to account for the increase where dormancy is coat imposed. The results also indicate that for germination to take place a threshold concentration of cytokinin may be required.It is suggested that the increase in butanol soluble cytokinins may lead to the breaking of dormancy, probably by increasing radicle elongation and/or cotyledon expansion

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb08576.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractCytokinin levels in sap and vegetative buds ofPopulus×robustaSchneid have been determined during chilling and bud burst. From non‐detectable levels in December and January, parallel increases in cytokinin levels occur in sap and buds during February and March, both in material from the field and that held at 2°C in the dark. The maximum in the sap occurs two weeks prior to natural bud burst, and 3 weeks, prior to the maximum attained in the buds. Excised twigs, forced to bud burst, show a similar pattern. The role of roots as a possible source of cytokinins is discussed.Partition chromatography on Sephadex LH‐20 indicates that at least 5 cytokinins are present in buds, two of which have similar elution volumes to zeatin and zeatin riboside‐The main activity in the sap is confined to a zeatin riboside‐like

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb08577.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe effect of three herbicides—DCMU (1,1‐dimethyl‐3‐ (3,4‐dichlorophenyl) ‐urea), Simazine (2,4‐bis(ethylamino)‐ 6‐chloro‐s‐triazine), and Atrazine (2‐chloro‐4‐ethylamino‐6‐iso‐propylamino‐5‐triazine)—on the induction of nitrate reduc–tase and itsin vivoactivity was studied in detached leaves ofHordeum vulgare L. All increased both extractable nitrate reductase activity and nitrate content. The increases occurred at optimum temperatures for growth and at several concentrations of nitrate. It was also determined that the herbicides did not protect the enzyme against inactivationin vivo. Although the extractable nitrate reductase was greater, thein vivoactivity of nitrate reductase was decreased in the presence of the herbicides resulting in a higher internal concentration of nitrate. Sincein vivanitrate reduction is dependent upon photosynthesis it is reasonable that reduction is decreased by these known inhibitors of photosynthesis. Hence, the effect of the inhibitors on induction of nitrate reductase activity may be secondary. The higher concentration of nitrate resulting from a decreased rate ofin vivoreduction in the presence of the inhibitors could conceivably be responsible for

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb08578.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractHistories of radish seedlings liave been characterised by comparison with pea histones extracted and purified under the same conditions.Submitted to acrylamide gel analysis the radish histones are resolved into main protein bands comparable to those of pea or calf thymus histones. However, protein bands of lesser importance which are not to be found in electrophoretic profils of pea or calf thymus histones, appear together with the main bands of radish histones. Study of these supplementary proteins through isoelectric focusing makes it possible to distinguish two groups: contaminating acid proteins and weakly basic proteins characterised by their high amide content.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb08579.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractAbscisie acid effects on32P uptake, polysomal patterns and senescence in mimosa (Albizzia julibrissinDurazzini) hypocotyl callus tissues were compared. Incubation of hypocotyl callus tissue with, abscisic acid for 4.5 h significantly decreased tissue uptake of32P, and quantitatively, but not significantly, decreased incorporation of32P into ribosomal fractions after adjusting for uptake. Abscisic acid accelerated senescence in the callus tissues. Abscisic acid inhibition of32P uptake is presented as a possible source of misinterpretation of ribosomal32P incorporation data.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb08580.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractWhen cells ofBacillus stearothermophilus, strain NCA 1503, were grown in tryptone starch broth and subsequently transferred to tris buffer, a fraction of the cells: rapidly died in ttie buffer. This fraction increased with increasing content of calcium chloride in the growth medium. The' addition of sodium, potassium or magnesium chloride to the growth medium had no such effect. The rapid dying of the cells in tris buffer was associated with a leakage of organic material and calcium ions from the cells. The results obtained are probably caused by a damage to the osmotic barrier of the cells during their contact with the buffer. Observations: made during the present investigation and a previous one (Ljunger 1970) indicate that the heat resistance of thermophilic bacteria depends on the maintenance of a high intracellular concentration of free calcium ions.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb08581.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractCallus derived from Bel–W3 and Bel–B tobacco plants when exposed to ozone turned brown as a consequence of surface cell destruction. Ozone fumigations above a threshold concentration of 0.10 μl/1 for two hoars caused an increase in the rate of tissue carbon dioxide (CO2) evolution. The maximum increase in CO2evolution was about 65 percent for both the ozone sensitive Bel–W3 and resistant Bel–B callus. However, the ozone dosage required to attain maximum increase in CO2evolution was approximately two times greater for the resistant variety. Callus cultures that grew roots were observed to be more resistant to ozone. The addition of the antioxidant N,N'dipnenyl–p–phenylenediamine (DPPD) m the nutrient medium retarded ozone induced

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb08582.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe nitrogen–fixing blue–green algaAnabaena ambiguawas grown in a medium which contained either ammonium chloride as nitrogen source or molecular nitrogen. In the latter case the alga produced heterocysts. The material was analysed for ascorbic acid, dehydro‐ascorbic acid and diketogulonic acid. The amount of a,scorbic acid was found always to he higher in the alga grown with molecular nitrogen. When the alga grown with combined nitrogen was transferred to the medium lacking it, there was an increase in the ascorbic acid content. Conversely, when material cultured on the nitrogen–free medium was suspended in the medium containing ammonium chloride, there was a decrease in the cellular ascorbic acid. Esogenously added ascorbic acid, up to 0.5 mg per ml, increased the heterocyst frequency to nearly three times that of the control. D–isoascorbic acid, an analogue of ascorbic acid, also showed an enhancement of heterocyst production.Algal extracts were fractionated by poiyacrylamide electro–phoresis, and the presence of ascorbic acid oxidase was detected on the gels. Two bands, with Rf values 0.34 and 1.0, were found to give positive test: for the enzyme. The total enzyme activity was 16.7 % higher in cells grown with molecular nitrogen than in those grown with combined nitrogen. The exact location of the enzyme in the alga ist not known although the heterocysts were earlier shown to contain ascorbic acid. Cytochemical tests, however, indicated strong per–oxidase activity in th

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb08583.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY