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61.
Jürgen M. Schmitt Christine Michalowski Hans J. Bohnert 《Photosynthesis research》1988,17(1-2):159-171
Mesembryanthemum crystallinum responds to high salinity in the soil by shifting the mode of carbon assimilation from the C3 mode to Crassulacean acid metabolism (CAM). Several enzymes of carbon metabolism have increased apparent activities in the CAM mode, including phosphoenolpyruvate carboxylase (PEPcase) and pyruvate orthophosphate dikinase (PPDK). We have identified cDNA clones for PEPcase and PPDK by immunological screening of a cDNA library constructed in the protein expression vector lambda gt11. The clones were characterized by immunoblotting and RNA blotting techniques. RNA blotting showed that during CAM induction the steady-state level of mRNAs for both PEP case and PPDK increased.Abbreviations IPTG
isopropyl thiogalactoside
- PEP
phosphoenolpyruvate
- PEPcase
phosphoenolpyruvate carboxylase
- PPDK
pyruvate orthophosphate dikinase
- Xgal-5
bromo-4-chloro-3-indolyl-beta-D-galactopyranoside 相似文献
62.
Results are presented of an investigation on electric and magnetic fields leaking from inductive (magnetic) heaters that are used for thermal processing of high-power electron tubes and lasers in an industrial plant. Measurements of electric and magnetic fields were done using both commercially available and laboratory-developed instrumentation. Isotropic H-field sensors were developed to allow quantitative evaluation of high-intensity magnetic fields. Ten induction heaters with nominal A.C. power ranging from 2.5 kW to 15 kW and operating at frequencies between 300 kHz and 790 kHz were surveyed. Electric field strengths up to 8 kV/m and magnetic field strengths up to 20 A/m were measured. 相似文献
63.
The influence of soil texture on Soybean yield in the presence of Heterodera glycines was investigated by comparing yields of susceptible cultivars with a resistant cultivar for 2 years. Soybean yield was negatively correlated with increasing sand content (P = 0.05). Yields of susceptible cultivars were suppressed with increasing sand content. Final nematode population densities were lowest in plots with greatest sand content. Soybean infection by SCN, as determined by the number of cysts 30 days after planting, was not consistently related to soil texture over 2 years. Initial nematode population density was positively related to soybean yield the first year and negatively related to soybean yield the second, probably a result of greater yield suppression by H. glycines in plots with greater sand content. 相似文献
64.
The effects of soil acidity on the growth and N2-fixing activity of white clover in seven acid topsoils and subsoils of New Zealand were investigated using a glasshouse experiment.The application of phosphate (Ca(H2PO4)2) to the soils resulted in very large increases in white clover growth on all soils. The application of phosphate, as well as increasing P supply, also decreased 0.02M CaCl2-extractable Al levels, but had little effect on exchangeable Al levels.Where adequate phosphate was applied, increasing rates of lime (CaCO3) resulted in increased plant growth on most soils. N2[C2H2]-fixing activity was increased by the first level of lime for one soil, but generally remained approximately constant or declined slightly at higher rates of lime. Up to the point of maximum yield, white clover top weight was more highly correlated with 0.02M CaCl2-extractable soil Al than with exchangeable Al or pH. At pH values greater than 5.5, plant yield declined on some soils, apparently because of Zn deficiency. The data suggest that white clover is unlikely to be affected by Al toxicity at 0.02M CaCl2-extractable Al levels of less than about 3.3 g g–1. However, there were differences between soils in apparent plant tolerance to 0.02M CaCl2-extractable Al, which appeared to be caused by differing C levels in the 0.02M CaCl2 extracts. 相似文献
65.
Water culture, growth chamber, greenhouse and field experiments were conducted to compare the effect of NH4−N and NO3−N on yield and N uptake of rapeseed (Brassica campestris L.). In water culture, the yields of 28-day old rapeseed plants grown at 14 μg N ml−1 were double with NO3 compared to NH4, but N uptake was little affected. There was no such effect when concentration was reduced to 3.5 or 7 μg N ml−1. The yield and N uptake of 26-day old rapeseed grown on six soils (pH 4.6 to 6.5) in pots in a growth chamber were much greater
with NO3 than with NH4, although N concentration was more in the NH4- than the NO3-grown plants. In a greenhouse experiment with rapeseed grown on 12 potted soils, the N uptake of applied N was greater with
NO3 than with NH4 on all soils. Averages were 63% with NH4 and 78% with NO3. However, NH4-fixation capacities of the soils were only weakly correlated with yield from the two sources of N (r=0.48) and the relation
was similar with N uptake. In contrast to the behavior of water culture, growth chamber and greenhouse experiments, the 33
field experiments did not show consistent difference in seed yield with NH4 and NO3 applied at time of seeding. In nine field experiments where band application was used for Ca(NO3)2, (NH4)2 SO4, NH4 NO3, yield tended to be greatest for (NH4)2SO4. However, in 19 experiments on acid soils with and without lime, yields in most cases were similar with (NH4)2SO4 and NH4 NO3. Nitrification inhibitors were added to spring banded NH4-based fertilizers in five experiments, but the yields were not influenced.
Scientific Paper No. 558, Lacombe Research Station, Agriculture Canada. 相似文献
66.
The effect of soil salinity and soil moisture on the growth and yield of maxipak wheat (Triticum aestivum L.) was studied in a lath-house experiment in whih, chloride-sulphate salt mixtures were used to artificially salinize a sandy loam soil from Al-Jadyriah Baghdad. Five soil salinity levels of ECe's equal to 1.7 (Control) 4.2, 5.8, 8.1, 9.4 and 11.0dSm–1 were prepared and used at 3 levels of available soil moisture depletion, namely, 25, 50, and 75% as determined by weight. Both growth (vegetative) and yield components were studied throughout the growing season.Results showed that increasing the soil salinity from 1.7 to 11.0 dSm–1, and decreasing the available soil water from 75 to 25% resulted in independent and significant decreases in Mazipak wheat growth and yield components at different stages of plant development. Root growth showed more sensitivity to both available soil water and soil salinity level than other components. It has been concluded that at soil salinity levels of more than 8.0 dSm–1, available soil water became a limiting factor on wheat growth and the maintenance of 75% of available soil water during the growth period is recommended to obtain satisfactory grain yield. 相似文献
67.
Ola Palm W. Lionel Weerakoon M. Ananda P. de Silva Thomas Rosswall 《Plant and Soil》1988,108(2):201-209
Sesbania sesban was evaluated as green manure crop for lowland rice in the Dry Zone of Sri Lanka. The legume was grown during a fallow period
before lowland rice (Oryza sativa) and ploughed under just before transplanting. Weight loss and nitrogen content in litterbags containing leaves, stems and
roots of the legume were monitored. Comparisons were made between rice yields from 20 m2 plots after green manuring in combination with different nitrogen fertilizer levels (0, 2.4, 4.8 and 7.2 gm−2) and nitrogen fertilizer (9.6 gm−2) alone. Above-ground biomass ofS. sesban was 440 gm−2 (dry wt) when ploughed under after 84 days growth. N-content in leaves, stems and roots was 3.76%, 0.41% and 0.73%, respectively.
This gave a N-input fromS. sesban of 9.2 gm−2 (8.3 g from above-ground parts and 0.9 g from roots). The corresponding K and P inputs were 7.3 and 0.6 gm−2 respectively. The nitrogen rich leaves, which contained 88% of the nitrogen in the above-ground parts, decomposed and released
its nitrogen much more rapidly than the stems and roots. After only four days the leaves had released 5.3 g Nm−2 and after 14 days they had released 6.4 g Nm−2. The highest rice yield (505 gm−2) was obtained usingS. sesban and 4.8 gm−2 of N-fertilizer. The yields with only N-fertilizer or onlyS. sesban were 442 gm−2 and 396 gm−2, respectively. Due to the rapid decomposition of the nitrogen rich leaves,S. sesban did not behave as a slow release fertilizer. Thus, it is not necessary to apply nitrogen fertilizers as a basal dose. 相似文献
68.
Victor Chude 《Plant and Soil》1988,112(2):293-295
The profile distribution of total and extractable B was determined in 16 Nigerian cacao-growing soil profiles formed from
different parent materials. Total B for all soils ranged from 8 to 54μgg−1 with a mean of 24μgg−1. The soils formed from sandstones in the rainforest zone contained higher amounts of total B than soils derived from basement
complex. Boron extractable in hot water, in 0.1% CaCl2, and in 1N NH4OAc varied from 0.13 to 1.38, 0.44 to 1.20 0.03 to 0.56μgg−1 respectively. The corresponding means were 0.66, 0.75 and 0.27μgg−1 B. Soils on metamorphic rocks gave the highest values. All extractable B values were related to organic matter while only
CaCl2-extractable B correlated with total B. Generally total and extractable B values were higher in the top soils than in the
subsoils. 相似文献
69.
Abstract.
- 1 For the understanding of the influence of natural selection on the persistence of host selection behaviour in populations of Drosophila parasitoids it is important to know whether parasitoids will become time- or egg-limited. We investigated whether the Drosophila parasitoid Leptopilina clavipes (Hartig) meets egg- or time-limited conditions in the field.
- 2 To this end the following aspects of the parasitoid's life were studied: egg load at emergence, travelling velocity between patches, patch residence times, oviposition rates and life expectancy. Together with the results from earlier studies on host and patch distributions, this formed the input of a ‘Monte Carlo’ simulation model, in which the life history of an individual parasitoid can be traced.
- 3 The simulations revealed that under the conditions found in the field 12.9% of the parasitoid population is egg-limited. The model was also run for a number of scenarios which reflect ‘good’ or ‘bad’ circumstances. In most cases a significant proportion of the parasitoid population proved to be egg-limited.
- 4 For the measurement of travelling velocities and patch residence times a marking method, especially applicable to small-sized parasitoids such as L.clavipes, is described. Marking did not affect survival, host habitat location or host detection rate. Parasitoids were found to be attracted to the odour of fruit-bodies of Phallus impudicus, the most important breeding substrate of their hosts.
70.
Detection of native-like models for amino acid sequences of unknown three-dimensional structure in a data base of known protein conformations. 总被引:13,自引:0,他引:13
We present an approach which can be used to identify native-like folds in a data base of protein conformations in the absence of any sequence homology to proteins in the data base. The method is based on a knowledge-based force field derived from a set of known protein conformations. A given sequence is mounted on all conformations in the data base and the associated energies are calculated. Using several conformations and sequences from the globin family we show that the native conformation is identified correctly. In fact the resolution of the force field is high enough to discriminate between a native fold and several closely related conformations. We then apply the procedure to several globins of known sequence but unknown three dimensional structure. The homology of these sequences to globins of known structures in the data base ranges from 49 to 17%. With one exception we find that for all globin sequences one of the known globin folds is identified as the most favorable conformation. These results are obtained using a force field derived from a data base devoid of globins of known structure. We briefly discuss useful applications in protein structural research and future development of our approach. 相似文献