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21.
E. C. Jorgenson 《Journal of nematology》1984,16(2):154-158
Granular and liquid commercial humates, with micronutrients, and a microbial fermentation product were compared in several combinations with nematicides for their effects on cotton lint yield and root-knot nematode suppression. Fumigant nematicides effectively reduced cotton root galling caused by root-knot nematodes, and cotton lint yields increased. Organophosphates and carbamates were not effective. Occasionally, cotton lint yields were increased or maintained with combination treatments o f humates, micronutrients, and a microbial fermentation product, but galling o f cotton roots by root-knot nematodes was usually not reduced by these treatments. 相似文献
22.
23.
M. V. Gusev T. G. Korzhenevskaya L. V. Pyvovarova O. I. Baulina R. G. Butenko 《Planta》1986,167(1):1-8
Tobacco (Nicotiana tabacum L.) shoots associated with the nitrogen-fixing cyanobacterium Anabaena variabilis Kütz. (ATCC 29413) were regenerated in mixed cultures of tobacco callus and the cyanobacterium. The cyanobacteria were localized inside the tissues as well as on the surface of regenerated shoots, formed heterocysts, and were capable of acetylene reduction. 相似文献
24.
Specific protein inhibitors of microbial serine proteinases were isolated from wheat (Triticum aestivum L.), rye (Secale cereale L.) and triticale using affinity chromatography on subtilisin-Sepharose 4B. The wheat inhibitor had an isoelectric point (pI) at pH 7.2, while the rye inhibitor consisted of two forms with pI values of 6.8 and 7.1. In triticale, two components were present with pIs 7.2 and 6.8. All the inhibitors had M
r values of approx. 20 000. The isolated proteins were effective inhibitors of subtilisins Carlsberg and BPN, and of fungal proteinases (EC 3.4.21.14) from the genus Aspergillus, but they were completely inactive against trypsin (EC 3.4.21.4) chymotrypsin (EC 3.4.21.1) and pancreatic elastase (EC 3.4.21.36). The inhibitors formed complexes with subtilisin in a molar ratio of 1:1. The results of chemical modifications seem to indicate that the isolated inhibitors have methionine residues in their reactive sites.Abbreviation pI
isoelectric point 相似文献
25.
26.
Three post-emergence herbicides (2,4-D, picloram and glyphosate) were applied to samples of an Alberta agricultural soil at
concentrations of 0, 2, 20, and 200 μg g−1. The effects of these chemicals on certain microbial variables was monitored over 27 days. All herbicides caused enhancement
of basal respiration but only for 9 days following application, and only for concentrations of 200 μg g−1. Substrate-induced respiration was temporarily depressed by 200 μg g−1 picloram and 2,4-D, and briefly enhanced by 200 μg g−1 glyphosate. It is concluded that because changes in microbial variables only occurred at herbicide concentrations of much
higher than that which occurs following field application, the side-effects of these chemicals is probably of little ecological
significance. 相似文献
27.
Soliman A. Haroun 《Genetica》1996,98(1):103-106
Cytological studies were carried out on two wild species (L. hirsutum and L. pennellii) and the cultivated species (L. esculentum) of tomato and their F1 hybrids. Both parents and hybrids show a diploid chromosome number of 2n=24. The meiotic behaviour of the cultivated species showed a high degree of chromosome homology resulting in a high level of chiasmata frequency per bivalent. In contrast, the two wild species showed a slight increase in uniyalent frequency and a decrease in bivalent formation and chiasmata frequency. The meiotic behaviour of the hybrids showed a high level of univalents and low levels of bivalents as well as trivalents. Highly significant decreases in chiasmata frequency and increases in meiotic abnormalities, especially in the L. esculentum X L. pennellii hybrid, also were detected. The high meiotic irregularity and low chiasmata frequency recorded in the second hybrid indicated the disharmony and difference between its parental genomes and also served to predict its sterility. With regard to degree of pairing recorded in the hybrids, there is a possibility that sterility in such cases may refer to genetic factors in addition to the previously mentioned reasons. Pollen fertility showed no great difference between L. esculentum and L. hirsutum and their F1 hybrid, but a significant decrease was recorded in the L. esculentum X L. pennellii hybrid, which was clearly associated with high meiotic irregularity, low chiasmata frequency and chromosome association. 相似文献
28.
Comparative study of two meromictic basins of Lake Banyoles (Spain) with sulphur phototrophic bacteria 总被引:1,自引:1,他引:0
The annual limnological dynamics of two meromictic basins of Lake Banyoles (C-III and C-IV) have been studied and compared
on the basis of their physical, chemical and biological characters. Stability values calculated for both basins gave 865 g
cm cm−2 and 495 g cm cm−2 for C-III and C-IV respectively. These values are in agreement with the fact that C-IV was almost completely mixed during
winter. In this basin, during stratification, the monimolimnion increased in thickness as the stability increased. Isolation
of the respective monimolimnia resulted in the development of anoxic conditions and the accumulation of sulphide in both C-III
and C-IV, which favoured the development of dense populations of sulfur phototrophic bacteria. The purple sulphur bacterium
Chromatium minus and the green sulphur bacterium Chlorobium phaeobacteroides were identified as the main components of these photosynthetic populations. The different depths at which the O2/H2S boundary was situated in both basins (and consequently the different light intensity reaching this zone) determined the
growth of these bacteria. Light intensities at the chemocline of C-IV reached values up to 5% of surface incident light. In
contrast, in C-III this variable was sensibly lower, with values depending on season and seldom reaching 1%. Phototrophic
bacteria were consequently found earlier in C-IV than in C-III, where no significant concentrations were found until August.
Finally stability is discussed as an important factor controlling chemical and biological dynamics in meromictic lakes. 相似文献
29.
Leaf decomposition of the exotic evergreen Eucalyptus globulus (eucalyptus), and three native deciduous tree species, Alnus glutinosa (alder), Castanea sativa (chestnut) and Quercus faginea (oak), was compared in a second order stream in Central Portugal. Changes in dry weight, nitrogen and polyphenolic compounds and microbial colonization were periodically assessed for three months.Negative exponential curves fit the leaf weight loss with time for all leaf species. Mass loss rate was in the order alder (K = 0.0161) > chestnut (K = 0.0079) > eucalyptus (K = 0.0068) > oak (K = 0.0037). Microbial colonization followed the same pattern as breakdown rates. Evidence of fungal colonization was observed in alder after 3 days in the stream, whereas it took 21 days in oak leaves to have fungal colonization. Fungal diversity was leaf species-dependent and increased with time. In all cases, percent nitrogen per unit leaf weight increased, at least, at the initial stages of decay while soluble polyphenolics (expressed as percentage per unit leaf weight) decreased rapidly in the first month of leaves immersion.Intrinsic factors such as nitrogen and polyphenolic content may explain differences in leaf decomposition. The possible incorporation of eucalyptus litter into secondary production in a reasonable time span is suggested, although community balance and structure might be affected by differences in allochthonous patterns determined by eucalyptus monocultures. 相似文献
30.
Summary We studied interspecific alarm communication between two species of social wasps in a nesting association in northwestern Costa Rica by testing the alarm responses ofPolybia occidentalis andMischocyttarus immarginatus to venom of both species. This is the first investigation of alarm pheromone in the genusMischocyttarus. M. immarginatus did not respond with alarm behavior to the venom of either species.P. occidentalis, which responds to its own venom with alarm behavior (Jeanne, 1981), also responded with alarm behavior to the venom ofM. immarginatus, but with much less intensity. Since heterospecific venoms did not release species-typical levels of alarm behavior, we conclude that interspecific alarm signalling plays no role in the nesting association. 相似文献