摘要:

The aim of this investigation was to estimate the optimum nutrient requirements and responses to low relative nutrient addition rates of seedlings of two important broadleaf tree species in China,Populus simoniiCarr. andPaulownia tomentosa(Thunb.) Steud. In preliminary experiments the optimum nutrient proportions were estimated under high concentration conditions. The nutrients consumed were replaced by means of daily additions determined by pH and conductivity titrations without changing the nutrient solutions. A relatively high K level was needed in relation to nitrogen; higher than in birch or grey alder seedlings. To obtain a high relative growth rate, suitable proportions by weight were 100 N:70 K:14 P:7 Ca:7 Mg for thePopulusseedlings and 100 N:75 K:20 P:8 Ca:9 Mg for thePaulowniaseedlings.In studies of nutrient stress responses the relative nutrient addition rate was used as the treatment variable under low conductivity conditions. The responses and relationships were similar to those described for birch, grey alder andSalix. The relative addition rate, and there was also a strong linear regression between relative growth rate and nitrogen status. Relative growth rates were high and the maximum weight increase was about 19% day−1inPopulusand over 25% day−1inPaulownia. The nitrogen productivity ofPaulowniawas very high, 0.26 g dry weight (g N)−1h−1, and forPopulusit was 0.16 g dry weight (g

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb00358.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Cis‐abscisic acid (ABA), when applied to maize (Zea maysL. cv. LG 11) roots, decreases the rates of cell growth and cell division in the meristem. It also decreases the rate at which nuclei become labelled with [3H]‐thymidine and enter mitosis. Removing the root cap accelerates the entry of nuclei into the DNA synthetic phase of the mitotic cycle and enhances the rate of cell proliferation in the quescent centre. ABA diminishes these effects, but does not suppress them. Thus, ABA cannot wholely substitute for the presence of a cap. One of the primary effects of applied ABA is to retard cell enlargement which may in turn affect the rate of cell division; natural endogenous ABA may act similarly. ABA might in this way assist in maintaining the quiescent centre in intact roots, but cannot be the sole agent invol

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb00359.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Energy charge, [(ATP + 1/2 ADP)/(ATP + ADP + AMP)], was measured inEchinochloa crus‐galli(L.) Beauv. var.oryzicolaseeds germinated in an aerobic or anaerobic environment. Within 24 h after the seeds were imbibed, total nucleotides increased and energy charge values went from 0.6 to at least 0.8 in both air and N2. Upon transfer from air to N2, the energy charge initially decreased, but subsequently (within 24 h) increased to at least 0.8. Total nucleotides also increased after an initial decline when transferred from air to N2. Emergence of the coleoptile and radicle were also examined at oxygen levels ranging from 21% to less than 0.005%. At all O2levels, the time for 50% emergence of coleoptiles was less than for radice emergence. This was most evident when the O2concentration was 1% or less. These data indicate that one of the adaptations that allowsE. crus‐gallivar.oryzicolato germinate and grow under anaerobic conditions is its ability to maintain a high level of energy. In its natural environment, this would permit coleoptile growth and penetration of the shoot into a more aerobic z

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb00360.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The composition of lipids and fatty acids was determined at various developmental stages of gametophytes and sporophytes in the fernAdiantum capillus‐venerisL. When the lipid content was expressed per g fresh weight, triacylglycerol was a major reserve lipid in spores and remained the dominant lipid in the gametophytes up to the 15th day after germination, but it was a minor one in the pinnae of sporophytes. In contrast, triterpenoids were abundant in sporophytes but not detected in gametophytes. When the content of fatty acids was expressed in percentage of the total fatty acids, the content of arachidonic acid in phosphatidylcholine and linolenic acid in diacyglyceryltrimethylhomoserine and phosphatidylcholine was significantly higher in both pinnae and petioles of sporophtes than in gametophytes. Significant differences in fatty acid composition of phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol and triacylglycerol were also noted between gametophytes and pinnae of sporophytes. All these differences were attributed to the difference of generation rather than tissue differences or age.The content of monogalactosyldiacylglycerol, hexadecatrienoic acid in monogalactosyldiacylglycerol, and 3‐transhexadecenoic acid in phosphatidylglycerol was higher in the pinnae of sporophytes than in gametophytes or in young leaves of sporophytes. Electron microscopy of the ultrastructure of chloroplasts indicated that the high content of these components was consistent with the development of chloroplasts in pin

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb00361.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Ethanol induced germination in several partly after‐ripened dormant lines ofAvena fatuaL. The dose‐response curves for the stimulation of germination and for oxygen uptake were similar, indicating that ethanol may stimulate germination by promoting oxygen uptake. A time‐sequence study showed that ethanol stimulated oxygen uptake by as much as 70% prior to the first visible signs of germination. A similar methanol treatment failed to induce germination or significantly elevate oxygen uptake, indicating that the promotive effects of ethanol are not common to all alcohols. The stimulation of both germination and oxygen uptake by ethanol was not inhibited significantly by salicylhydroxamic acid, an inhibitor of alternative respiration. Thus, stimulation of germination and oxygen uptake by ethanol does not require the operation of the alternative pathway of respiration. Similarly, the stimulation of germination and oxygen uptake by ethanol were not inhibited by sodium azide, an inhibitor of cytochrome‐mediated respiration. However, both germination and oxygen uptake were prevented when salicylhydroxamic acid and sodium azide were administered together. Thus, stimulation of these events by ethanol requires only the operation of one or other of these pathways of respiration; a specific requirement for the operation of the alternative pathway of respiration does not exist. The function of ethanol as a promoter of respiration is discussed with reference to dormancy and involvement of the Kreb

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb00362.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The sensitivity of the circadian leaf movement ofOxalis regnelliiMig. to imipramine (a tricyclic dibenzazepine) was investigated. Imipramine, like Li+, is used as a therapeutic agent against depressive disorders in man. The therapeutic effects of the two substances might be mediated via effects on basic circadian rhythms and the cellular level. It was indeed possible to influence the circadian movement ofOxalisby imipramine; pulses (10−3M, 4h) phase shifted the rhythms and caused advances. A phase response curve is presented. No period change of the movements was caused by permanent presence of imipramine (5 ‐ 10−5or 10−5M). The nature of the imipramine‐induced phase shift is discussed and compared with Li−1effects on the same circa

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb00363.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Because the “mobilization” of nitrogen resulting from nutritional nitrogen deficiency is also prominent during leaf senescence, the characteristics of these two syndromes were compared. Oat plants (Avena sativaL. cv. Victory) were raised on a nutrient solution, complete except for nitrogen supply (i.e., with only the seed protein as nitrogen source), and the senescence of their leaves was compared with that of controls grown on a full nutrient solution. The N‐deficient plants flowered after forming only 4 leaves and each set a single seed. The nitrogen lack affected the content of chlorophyll somewhat more than the content of the amino acids or protein nitrogen. However, spraying the plants with kinetin solution was able to retain 20–30% of the chlorophyll and protein. During senescence, the chlorophyll appears to be less stable in the N‐deficient leaves than in the controls, while the protein is somewhat more stable than in the controls. Also, when the detached leaves from N‐deficient plants senesced in white light or in darkness, kinetin delayed their senescence almost as effectively as that of control leaves. Most strikingly, the stomata of N‐deficient leaves after detachment and floating on water were largely closed in light, just as in senescence, but could be partially induced to open by kinetin treatment. Since stomatal closure has earlier been shown to cause senescence, the characteristic syndrome of foliar nitrogen deficiency is concluded to be partly that

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb00364.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Effects of cold acclimation on needles of Scots pine (Pinus sylvestrisL., Provenance Södra Ydre) were studied at the membrane level. Before and after a period of cold acclimation the plasma membranes were isolated from the needles by a aqueous polymer two‐phase partition technique. Fatty acid composition of total lipids or of individual phospholipids from the plasma membrane showed that the plasma membrane fraction was different from the other microsomal fractions analyzed, especially the 18:2 levels of the individual phospholipids. Furthermore, the cold acclimation period did not result in a decreased saturation level in the plasma membranes. Different steps in cold acclimation reactions at the membrane level are discuss

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb00365.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Hyphae of light‐grownV. agaricinum(Link) Corda contain many lipid bodies. The hypae were disrupted and the membranes immediately pelleted by a 48 000gspin for 30 min. The major part (90%) of the carotenoids was found in a lipid layer on top of the supernatant. Carotenoids extracted from the lipid layer in diethyl ether had an absorption maximum at 488 nm. On the basis of spectra in different organic solvents the main component was tentatively. Thin layer chromatography of extracted and saponified carotenoids revealed the presence of one major and one minor component.The 48 000gpellet contained 80% of the NAD+‐dependent malate dehydrogenase (marker for mitrochondria), 25% of the antimycin‐resistant NADH‐cytochromecreductase (marker for mitochodria and endoplasmic reticulum) and 10% of the proteins and the carotenoids. The latter were different from the carotenoids in the lipid layer in that the absorption maximum was at 471 nm in diethyl ether.Further fractionation of the 48 000gpellet showed the presence of carotenoids in both mitochondria and endoplasmic reticulum (ER) all with an absorption maximum at 471 nm. On a thin layer plate these carotenoids migrated in one band coinciding with the minor band of the lipid layer. On a continous Percoll gradient two main areas of mitochodrial activity (1.068 and 1.063 g ml−1) were clearly separated from the ER (1.059 g ml−1). The carotenoid content was about 0.6 and 0.7–1.0 μg (mg protein)−1for mitochondria and ER, respectively, equivalent to 1–2 carotenoid molecules per 1000 lipid molecules. The possible role of these membrane‐bound carotenoid mo

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb00366.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

When young radish (Raphanus sativusL. cv, Novired RS) plants were exposed to low levels of ethylene, the fresh weight and dry weight of the tubers significantly increased. This was mainly because ethylene reduced the percentage of plants that hardly or not at all formed a tuber. Decaptated seedling cultured in vitro, were supplied with several plant growth regulators in order to determine a possible correlation between the induction of radial growth and the biosynthesis of ethylene in the hypocotyl. Indole‐3‐acetic acid, or in combination with 6‐benzylaminopurine, induced growth of the hypocotyl and markedly enhanced ethylene biosynthesis. However, the application of a precursor and an inhibitor of ethylene biosynthesis revealed that there is no direct causal relationship between radial growth and ethylene evolution. It is suggested that ethylene favoured tuber growth in intact plants by changing the partitioning of assimilates in the plant, rather than by the induction of cambial act

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb00367.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY