摘要:

AbstractThe influence of UV‐B radiation from filtered or unfiltered fluorescent sunlamps on early seedling growth and translocation of65Zn from cotyledons to the shoot was examined in two cultivars of cotton, Acala and Gregg. Ten‐day‐old seedlings which had been irradiated in the greenhouse for 6 h continuously each day for 14 days with 0.81 or 1.61 W × m‐2UV‐B radiation under two unfiltered FS‐40 sunlamps, showed pronounced phytotoxic damage. This was characterized at first by bronzing and glazing of the cotyledons and later by upward curling of the leaves and abscission. Leaf expansion, dry matter accumulation, and mobilization of65Zn from the cotyledons was severely impaired in the young developing shoot under unfiltered UV‐B radiation. A significant stress response also was observed in seedlings exposed to 0.61 W × m‐2UV‐B radiation through a polystyrene filter and 0.73 W × m‐2UV‐B radiation through a cellulose‐acetate filter. This stress response was characterized by the formation of a red pigment in the petioles of the cotyledons, reduced leaf expansion, and reduced transport of65Zn. Control seedlings exposed to 0.03 W × m‐2UV‐B radiation through a mylar filter were green, had maximum leaf size and dry‐matter accumulation, and had the greatest percentage of65Zn

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03816.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe influence of UV‐B radiation (280–320 nm) from filtered and unfiltered FS‐40 fluorescent sunlamps on germination and early seedling growth was examined for a range of vegetables (tomato, radish, cucumber, lettuce, and bean) and field crops (wheat, cotton, soybean, and millet). Continuous exposure of seeds for 3 days to 26.9 × 10−2W × m−2UV‐B radiation (280–320 nm) at 25°C, had a slight effect on fresh weight of seedlings but no appreciable influence on germination percentage, or dry weight of seedlings. Extending the time of exposure to 6 days, however, resulted in abnormal seedling growth in all species but wheat. Typical responses were short, stubby roots, bronzing of the cotyledons, increased pigmentation, and abnormal curvatu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03817.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractProtein metabolism plays a major role in the development of freezing tolerance in plants. Soluble and insoluble protein concentrations were followed during induction of freezing tolerance in black locust (Robinia pseudoacaciaL.) stem tissues. Soluble proteins were fractionated using two‐dimensional polyacrylamide gel electrophoresis and examined for the presence of glycoprotein fractions. Soluble protein concentration remained relatively constant during early stages of induction of freezing tolerance but increased significantly during later stages, while insoluble protein concentration remained relatively constant throughout induction. A new soluble protein component appeared during later stages of induction and was identified as a glycoprotein. Some glycoproteins are known to have a high water‐binding capacity, which could play a role in intracellular resistance to ice formation during development of freezing tolera

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03818.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractAn acid inhibitor, probably abscisic acid (ABA) in low concentrations was found to be present in bean seeds. The evidence is based on data from paper electrophoresis, chromatography, UV absorption and growth inhibition in theLemnabioassay, sensitive down to a concentration of 10‐11MABA or 0.02–0.03 ng/flask.The inhibitor level as measured by this bioassay decreases considerably with increasing soaking time. Acid ether‐soluble inhibitors could even be detected in the soaking water from the soaked

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03819.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe level of protein synthetic activity in dark‐grown cultures ofVerticillium agaricinumwas significantly enhanced by light. As expected the enhancement of protein synthetic activity was accompanied by a transformation of cytoplasmic monoribosomes to polyribosomes. Amino acid incorporation studies utilizing the synthetic mRNA, poly (U), suggest that the transformation was preceded by an activation of pre‐existing ribosomes. The change in ribosome activity related, at least in part, to an increase in the level of peptidyl‐tRNA associated with the ribosomes. In this regard the response ofV. agaricinumribosomes was similar to ribosome activation in several higher plant systems. The initial response at the level of the ribosome remains to be eluci

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03820.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIn buds and nodes ofVitis viniferaL. cv. Riesling, the content of abscisic acid (ABA) was measured by high pressure liquid chromatography and related to bud dormancy. In the period of endogenous bud dormancy (rate of bud break is low or zero under favourable climatic conditions) the ABA content increased twelvefold. This indicates a causal relationship between endogenous bud dormancy and ABA.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03821.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractA method is described for the isolation, purification and quantitation of free cytokinin bases and ribosides using ethyl acetate at pH 7.7 for the extraction. The extraction is almost complete (97.7%) as determined by using N6‐(Δ2‐isopentenyl)adenine‐8‐14C. The subsequent fast purification by chromatography on a standardized silica gel column in chloroform‐methanol (7:3 v/v) is followed by thin layer chromatography (silica gel 60 F254) in chloroform‐acetic acid (8:2 v/v). The recovery of N6‐(Δ2‐isopentenyl)adenine‐8‐14C after this two step purification was 78–82%. The efficiency of the method was determined by applying this procedure to N6‐(Δ2‐isopentenyl)adenine and N6(Δ2‐isopentenyl)adenosine. Using gas liquid chromatography the recovery for N6‐(Δ2‐isopentenyl)adenosine was determined to be 61% and compared to 43% for N6‐(Δ2‐isopentenyl)adenosine, showing the suitability of the descr

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03822.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractTranslocation and distribution of abscisic‐(1‐14C) acid and of (5‐3H)indol‐3yl‐acetic acid in agar cylinders and in boiled and fresh petiole segments ofColeus scutellarioidesBentham have been studied by liquid scintillation counting. The hormones were simultaneously applied in donor blocks of agar. Transport and distribution data of the two compounds were compared with those of (36Cl‐)chloride in the same systems. From the data on movement in agar cylinders, diffusion coefficients of the transported compounds were approximated using a simulation model in which it was assumed that the movement was controlled by diffusion only. Movement in boiled tissue segments fitted the model if a correction factor was included in the equation for diffusion. Acropetal movement of indol‐3yl‐acetic acid in fresh petiole segments can be entirely explained in terms of passive transport and for basipetal transport it seems to be a major component. Movement of abscisic acid and of chloride in fresh petiole segments fit also a model based on diffusion. The limitations of the simulation mode

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03823.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractInFunariaspores fine structural changes occur, especially in the plastids, during prolonged incubation in darkness on an inorganic liquid medium, although under these conditions germination cannot take place. If then exposed to illumination, these spores germinate rapidly and synchronously. Chloroplasts formed in darkness have thicker grana, absorb more CO2, have a higher reducing power, and give a more intense paramagnetic resonance signal than chloroplasts formed in light.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03824.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe respiration and vitality of ungerminated bi‐ and trinucleate pollen were studied in order to determine the influence of relative humidity and temperature on metabolic activity. The gas exchange, germination capacity and staining with tetrazolium bromide were followed under standardized conditions.A constant respiration rate occurred under conditions of high relative humidity (97%). Per mg pollen, the trinucleate grains ofCompositaeandGramineaerespired 2 to 3 times as intense as 6 species of binucleate grains. Per unit of pollen protein the differences were even larger. In contrast to binucleate pollen, the longevity of trinucleate pollen was very short and the ability to germinate was lost twice as fast as the respiration capacity. This limits the use of tetrazolium bromide as an indicator of viability.At reduced relative humidities respiration was strongly restricted, but the longevity of bi‐ and trinucleate pollen considerably increased.Pollen ofGramineae, however, was very sensitive to changes in relative humidity; short exposure to low relative humidity decreased both the vitality and the capacity to resp

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03825.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY