摘要:

The growth of two provenances ofPinus sylvestrisL. were compared with two provenances ofPicea abies(L.) Karst. and withPinus contortaDougl. when grown in solution cultures with low nutrient concentrations. Nitrogen was added at different exponentially increasing rates, and the other nutrients were added at a rate high enough to ensure free access of them to the seedlings.During an initial period of the culture (a lag phase), when the internal nutrient status was changing from optimum to the level of the treatment, deficiency symptoms appeared. The needles yellowed and the root/shoot ratio increased. The initial phase was followed by a period of exponential growth and steady‐state nutrition. The needles turned green again, and the root/shoot ratio stabilized at a level characteristic of the treatment. These patterns were the same as previously reported for other tree species.The relative growth rate during exponential growth was numerically closely equal to the relative nitrogen addition rate. The maximum relative growth rates were about 6 to 7.5% dry weight increase day‐1. This is a much lower maximum than for broad‐leaved species (about 20 to 30% day‐1) under similar growth conditions.The internal nitrogen concentrations of the seedlings and the relative growth rates were stable during the exponential period. Close linear relationships were found between these parameters and the relative addition rate up to maximum growth.During steady state the relative growth rates of the different plant parts were equal. However, there were large differences between genotypes in absolute root growth rate at the same seedling size because of differences in root/shoot ratio. Lodgepole pine had the highest root growth rate, whereas that of Norway spruce, especially the southern provenance, was remarkably low. Yet, Norway spruce had a high ability to utilize available nutrients. In treatments with free nutrient access, growth allocation to the shoot had a high priority in all genotypes, but there was still a marked tendency for luxury uptake of nutrients. Nitrogen productivity (growth rate per unit of nitrogen) was lower than in broadleaved species and highest in lodgepole pine. The relevance of the dynamic factors, i.e. maximum relative growth rate, nutrient uptake rate, nitrogen productivity, growth allocation and root growth rate, are discussed with regard to conifer characteristics and selectio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02368.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Shoots of cold‐acclimated seedlings ofPinus sylvestrisL. were exposed to a temperature of –7°C for 4 h, in darkness or at a photon flux density of 1 300 μmol m‐2s‐1. Before and after freezing, fluorescence kinetics of intact needles and isolated chloroplast membranes were measured at both room temperature and 77 K. Maximum and variable fluorescence yield of photosystem II both at room temperature and 77 K decreased strongly after freezing in light, whereas the initial fluorescence yield was little affected. Quenching of maximum and variable fluorescence of photosystem I at 77 K also occurred. The results show that freezing in light damages photosystem II, thereby increasing the radiationless decay at the reaction centres of photosystem II. This is a typical symptom of photoinhibition of photosynthesis. Freezing in darkness did not significantly reduce fluorescence yield of photosystem II or photosystem I. Moreover, electron transport capacity was not significantly affected. We therefore suggest that the inhibition of the CO2assimilation in pine seedlings by freezing alone does not involve thylakoid ina

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02369.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The differential response of white clover (Trifolium repensL. cv. Regal Ladino) and berseem clover (Trifolium alexandrinumL. cv. Mississippi ecotype) was investigated by treating greenhouse cultured plants with 4‐(2,4‐dichlorophenoxy)butyric acid (2,4‐DB). Berseem clover plants were significantly injured by a treatment concentration of 0.6 kg ha‐1of 2,4‐DB, whereas white clover plants were not injured by treatment levels below 2.4 kg ha‐1. The metabolism of 2,4‐DB in cell suspension cultures of white clover and berseem clover was investigated using [ring‐14C]‐2,4‐DB and non‐labeled 2,4‐DB. White clover cell cultures metabolized ca 4‐fold more 2,4‐DB than berseem cultures over a 44‐h treatment period. The decrease in berseem cell population was 4‐fold greater than the decrease in white clover cell population in response to the 8 μM2,4‐DB treatment. The herbicide and its [ring‐14C]‐labeled metabolites were isolated from treated cells and medium after 44 h by partition and thin‐layer chromatography. White clover cells metabolized 90% of the [14C]‐2,4‐DB and berseem clover cells metabolized 22% of the herbicide. The major portion of the radiolabel was in the glycoside fractions from extracts of both species. The differential response ofTrifoliumspecies to 2,4‐DB is implied to be due to the differential rate of 2,4‐D

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02370.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The spectrophotometrically‐determined activity of NAD+‐malate dehydrogenase (MDH, EC 1.1.1.37) from white spruce [Picea glauca(Moench) Voss] needles was assayed with NADH and oxaloacetate. Activity was very low when extracted with only acetate buffer (pH 5.4), phosphate buffer (pH 6.8), or Tris‐HCl buffer (pH 8.0). However, activity increased from 1 to over 200 μmol (g dry weight)‐1min‐1with the addition of polymers such as polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) and the detergents, Tween 80, Tergitol 15‐S‐9 and Triton X‐100. Best activity was observed when extracted in a buffer at pH 6.8 and with 1% (v/v) for the three detergents and PEG, and 6% (w/v) for PVP.MDH activity decreased with age of the needles on the tree. Six‐year‐old needles contained only about one‐fifth of the activity of current year, fully‐expanded needles. The main decrease in enzyme activity was observed in one‐year‐old needles. Protein content obtained from needles extracted with just phosphate buffer (pH 6.8) was very low, but increased greatly when the above chemicals were added to the buffer. In contrast with needles, extracts of vegetative buds contained much higher levels of MDH and protein when extracted with only phosphate buffer (pH 6.8). Although MDH activity in needle extracts declined with storage of the extracts at 4°C in the dark for 6 days, the decrease was least for buffers containing a combination o

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02371.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The relative growth rate of pot‐grown plants ofPoa pratensisL. cv. Holt, origin 69s°N, was increased by 20–40% by photoperiod extension with low intensity incandescent light from 8 to 24 h at 9–21°C. The main increase occurred over the 14 to 18 h photoperiod range. The true photoperiodic nature of the response was demonstrated by the effectiveness of night interruption in stimulating growth. Fortnightly sprayings with gibberellic acid (GA3) (3 × 10‐6to 3 × 10‐5M) mimicked all the effects of long days, whereas (2‐chloroethyl)‐trimethylammonium chloride (CCC) counteracted the effects of long days. Both growth substances exhibited pronounced interactions with photoperiod, GA3being most effective in short days and CCC in long days. The growth stimulation, whether caused by long days or GA3, was exerted mainly through increases in individual and total leaf area. This was associated with a reduction in CO2, exchange rate and a parallel fall in specific leaf weight. Proportionally, however, the increase in leaf area was greater than the fall in CO2exchange rate, resulting in a 38 to 118% increase in photosynthesis per leaf. No evidence was found of any direct and promotive effect of transition to long days on the CO2exchange rate of alread

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02372.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The apical bud and the axillary buds of Witloof chicory (Cichorium intybusL. cv. Tardive d'Anvers) remain in the vegetative state if they are left on the root and maintained at 18°C. Flowering occurs in long days of 16 h after a pretreatment of either 8 weeks at 3°C, 3 days in complete anoxia at 15°C, or 4 days in the presence of ethylene (1000 ppm) at 15°C. In contrast, the adventitious buds which spread out on the root after ablation of the collar flower in a photoperiod of 16 h without particular pretreatment. The grafting of apical buds onto roots after different treatments shows that cold and ethylene act on the root, whereas anoxia acts directly at the level of the bud. It seems that the inhibition of the flowering of preformed buds (apical and axillary) stems from the collar. A hypothesis is proposed to explain this inhibition and why it is broken by cold, anoxia and ethyl

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02373.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The inhibitory effects of aminooxyacetic acid (AOA) and cobalt chloride (CoCl2) on brassinosteroid (BR)‐induced epinasty in tomato plants (Lycopersicon esculentumMill. cv. Heinz 1350) are evaluated. CoCl2dramatically decreases petiole bending and ethylene production as the concentration increases from 50 to 200 μM.The content of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) in the petiole, instead of accumulating, is reduced and does not change over the concentration range tested. Inhibition of BR‐induced epinasty by AOA results from inhibition of ACC synthesis. There are dramatic reductions in petiole bending, ethylene and ACC production as the concentration of AOA is increased from 50 to 200 μM.Maximum inhibition occurs when the plants are pretreated with the inhibitors. The degree of inhibition increases as the length of pretreatment increases from 1 to 4 h. The response of BR‐treated plants to AOA and CoCl2is similar to the effect of auxin, indicating the integral relationship between

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02374.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

No changes in metabolism of adenosine phosphates as a function of short day induction were detected in cotyledons ofPharbitis nilChois strain Violet. A gradual increase in ATP level was detected throughout the dark period in plumules. A rapid decline of ATP pool size was observed in induced plumules shortly after floral induction. The decline occurred close to the 14th hour of the dark period, 1 to 1.5 h after the dark period length required for a 90% flowering response, which is thought to be the minimum time required for transport of the floral stimulus (and assimilates) from the induced cotyledons to the plumule. Transport of the major adenylates from the cotyledons was verified using [14C]‐adenine. Estimates of the amount, and rate, of adenylate transport suggest that the cotyledons could be an important source of adenylates to re‐establish the ATP pool size in evoked plumu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02375.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The evolution of endogenous ethylene, the conversion of 1‐aminocylopropane‐1‐car‐boxylic acid (ACC) to ethylene and the amounts of ACC (free and conjugated) have been followed during the senescence of oat (Avena sativaL. cv. Victory) leaf segments. During the first three days of incubation of leaf segments in darkness, endogenous ethylene evolution and ACC‐dependent ethylene production displayed a close relationship, both showing an increase followed by a decrease to the basal rate. However, unlike ethylene production, the level of ACC increased during the five days of incubation in the dark without any decline. It is concluded that ACC synthesis does not limit ethylene production, at least in the last stages of leaf senescence when ethylene production markedly decreased. The level of conjugated ACC increased and reached a plateau already at the first day of incubation. Yet, at the progressive stages of senescence, when the level af ACC gradually increased, no further conjugation of ACC could be detected. Thus, conjugation of ACC cannot account for ethylene drop at the last stages of oat leaf s

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02376.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Full activity of hydrogenase is induced in autotrophic or heterotrophicScenedesmus obliquus[strain D3 (Gaffron)] cells after 2 h under anaerobic adaptation. Semi‐aerobic conditions allow only an induction of 20% activity. Hydrogenase is completely inactivated by oxygen in cell free preparations. Semi‐aerobic adaptation of hydrogenase is enhanced by glucose and inhibited by sodium azide. It is concluded that respiration enhances hydrogenase activation by creating an oxygen free microclimate and by providing energy in the form of

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02377.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY