摘要:

AbstractIn long‐term experiments comparing the results of single and repeated treatment of dwarf peas with gibberellic acid, both once‐treated and weekly‐treated plants formed more internodes than control plants. The initial high rate of internode formation in the once‐treated peas dropped rapidly reaching that of control plants three weeks after treatment. Weekly‐treated plants maintained a higher rate of internode formation.The ratio of internode lengths of once‐treated plants to control plants was high (over 3) for the internodes which were elongating during or shortly after the single treatment but dropped rapidly and approached unity in later‐developed internodes. The ratio of internode lengths of weekly‐treated plants to control plants continued to be high throughout

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb05016.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractSoybean (Glycine maxL. ev. Columbus) seedlings grown in culture solution were treated with cadmium as CdSO4. Final concentrations of cadmium (Cd2+) in the solution were 0, 0.45, 0.90, and 1.35 μM.Soybean leaves, analyzed 10 days after Cd2+was added to the culture solution, showed increased respiration rate and activities of malate dehydrogenase, acid phosphatase, ribonuclease, deoxyribonuclease, and peroxidase but decreased activity of carbonic anhydrase. Increased activity of hydrolytic enzymes and peroxidase reflects a general senescence response while the carbonic anhydrase decrease is consistent with an antagonism between cadmium and endogenous zinc. Chlorosis, epinasty, abscission of leaves, and decreased growth rate occurred in seedlings treated with 1.35 μMCd2

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb05017.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractHypocotyl explants ofBeta vulgarisL. were grown on defined agar media with different combinations of IAA and kinetin at varying concentrations of nitrogen or sucrose. The cultures were kept in light (18 h a day) at 27°C for 5 weeks. Root initiation and callus growth were recorded and the callus tissue was analysed for N and K.Root formation was found to increase with increasing nitrogen concentration (from 5 mMto 23.3 mM) in the medium at 10.0 mg/1 of IAA, whereas no stimulation was found at 0.1 mg/1 of IAA. When raising the sucrose level from 20 g/1 to 100 mg/1 at 10.0 mg/1 of IAA and 1.0 mg/1 of kinetin, root initiation was also stimulated. At a lower kinetin and auxin level, however, no increase was recorded.Callus growth was affected by changes in the nitrogen or sucrose concentration of the culture media. The nitrogen content of the callus tissue increased with rising nitrogen concentration of the media. When raising the sucrose level instead of the nitrogen level, the nitrogen content of the tissue decreased

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb05018.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractDifferent methods (physiological, electrophysiological and biochemical) were used in order to show, during a 24 h period, a change in sensitivity ofBidens pilosusseedlings to the pricking of one of the cotyledons. The sensitivity is maximum in the morning and in the evening; it decreases during the light period (day) and the dark period (night). The minimum of the sensitivity occurs in the middle of the day and 3 to 4 h after the beginning of the night.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb05019.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractIndole‐3‐acetic acid (IAA) contents in plant extracts were determined spectrofluorometrically after conversion of the compound into indolo‐α‐pyrone. The method is sensitive and accurate and showed good reproducibility. The values obtained by this method corresponded well with those obtained with the Avena coleoptile straight‐growth assay.Impurities in extracts often cause various difficulties. Colored compounds influence the readings and may even make indole‐3‐acetic acid determination impossible by strong quenching of the fluorescence light. Insoluble compounds can be formed in the reaction and cause increased opalescence and light scattering which interferes with the fluorescence measurements. The necessities for the method to be reliable are that the insoluble compounds are removed or brought into solution and that the exciting light is sufficiently monochromatic.Indolo‐α‐pyrone is fairly stable in the dark but is rapidly broken down by UV radiation. This decay may be used as a check to see if the measured light represents fluorescence

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb05020.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractMultiphasic kinetics were indicated for uptake of ammonium and potassium by intact cirtrus seedlings as measured by a continuous flow technique. Uptake at low concentration, below 10−3M, was biphasis. The patterns for ammonium uptake by 60‐day‐old and 180‐day‐old seedlings were similar, but the rates of uptake per g dry weight of root were greater for the young

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb05021.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractGrowth of stem, leaf, and inflorescence explants from mature coconut (Cocos nuciferaL.) palms on a new mineral formulation (Y3) was superior to that on the minerals of White, Heller, or Murashige and Skoog. Cell division in the upper part of cultured explants gave rise to a layer of white callus within a month.The effects of omitting entirely or altering the concentration of individual elements in the Y3 formulation were investigated. It was concluded that growth on White's and Heller's minerals was seriously limited by deficiencies in macro‐elements,i.e.nitrogen (particularly ammonium), potassium and phosphorus, as well as micro‐elements,i.e.iron, iodine and molybdenum. The Murashige and Skoog formulation, on the other hand, was deficient only in certain micro‐elements (particularly io

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb05022.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractMaximum rates of net photosynthesis forCitrus sinensis(L.) Osbeck andCitrus paradisiMacf. cultivars were observed at the lowest temperature (22°C) under which these subtropical species were examined. Net photosynthesis decreased with higher temperatures or greater vapor pressure differences between leaf and air. The reduction in net photosynthesis due to higher temperatures was associated with reductions in mesophyll conductance to CO2; whereas, the effects of greater vapor pressure differences on net photosynthesis were associated with changes in total leaf conductance to water vapor. Actual water‐use efficiency was reduced at higher temperatures and greater vapor pressure differences, but intrinsic water‐use efficiency, calculated for a constant vapor pressure difference, increased with increases in vapor pressure difference indicating a possible adaptive mechanism for conditions of high evaporative demand. Day‐today increases in net photosynthesis, total leaf conductance to water vapor and mesophyll conductance were observed as plants were subjected to the same temperature and humidity treatments on progressive days. Growing plants under higher irradiances increased their photosynthetic rates and mesophyll conductance to CO2but leaf conductance to water vapor was unaffected by irradiance pretreatment. Consequently, acclimation to radiation can only account for a small part of the day‐to‐day changes in gas exchange. Other possible explanations for these day‐to‐day changes were discussed. Significant differences were not observed among trees of ‘Campbell Valencia’ orange, ‘Parent Navel’ orange and ‘Frost Marsh’ grapefruit in responses of net photosynthesis and leaf conductance t

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb05023.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractComparisqns were made between ‘Campbell Valencia’ orange (Citrus sinensis(L.) Osbeck), and ‘Gabon Cherry‐orange’ (Citropsis gabunensis(Engl.) Swing.), ‘Frost Lisbon’ lemon (Citrus limon(L.) Burm. f.) and ‘Eremolemon’ (Eremocitrus glauca(Lindl.) Swing. ×Citrus limon(L.) Burm. f.) and between diploid and autotetraploid ‘Lisbon’ lemons with respect to the influences of temperature and humidity on net photosynthesis and transpiration.Net photosynthesis, leaf conductance to water vapor and water‐use‐efficiency ofCitropsis gabunensiswere lower than withCitrus sinensis.‘Eremolemon’ had higher net photosynthesis and higher water‐use‐efficiency than ‘Lisbon’ lemon, but only small differences were observed between the two species in leaf conductance to water vapor. Small, nonsignificant, differences were observed between diploid and tetraploid ‘Lisbon’ lemons in responses of net photosynthesis and leaf conductance to temperature and humidity. Temperatures above 30°C and increases in vapor pressure difference caused declines in net photosynthesis and increases in vapor pressure difference resulted in decreases in leaf conductance to water vapor

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb05024.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractExperiments with Grand Rapids lettuce seeds (Lactuca sativaL.) maintained in darkness or irradiated with red light have shown that the inhibition of germination induced by low concentrations of ABA (2, 4, 6 μM) could be overcome by gibberellins (GA3or GA4). The same results were obtained, although to a lesser extent, under the influence of two out of the four cytokinins tested (K and BAP) for seeds maintained in darkness.To suppress the block induced by higher concentrations of ABA (for example 8 μM), it was necessary to apply a cytokinin (K, BAP, Z or 2iP) and a gibberellin (GA4or GA3) simultaneously, or a cytokinin following a red light treatment.Experiments conducted in darkness in which ABA (8 μM) was applied together with a cytokinin (BAP) and a gibberellin (GA4) showed that the gibberellin and the cytokinin played similar roles towards each other and towards A

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1976.tb05025.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY