THE INTERACTION OF HIGHER PLANTS AND SOIL MICRO-ORGANISMS: II. STUDY OF THE MICROBIAL POPULATION OF THE RHIZOSPHERE IN RELATION TO RESISTANCE OF PLANTS TO SOIL-BORNE DISEASES

1940 ◽  
Vol 18c (9) ◽  
pp. 444-455 ◽  
Author(s):  
M. I. Timonin
Keyword(s):  
Small Proportion ◽  
Comparative Studies ◽  
Root Rot ◽  
Microbial Population ◽  
Higher Plants ◽  
General Trend ◽  
Fertilizer Treatment ◽  
Plating Method ◽  
Rhizosphere Population ◽  
Micro Organisms

Comparative studies of flax varieties resistant and susceptible respectively to wilt, and of tobacco varieties resistant and susceptible to black root rot, showed higher numbers of micro-organisms in the rhizosphere of the susceptible than of corresponding resistant plants. Though plants of the same variety showed considerable variation in rhizosphere population under field and greenhouse conditions, the general trend remained the same. The abundance of micro-organisms in the rhizosphere of plants of the same variety grown in plots receiving different fertilizer treatment showed relatively little difference, even though the soils varied greatly in productivity.Numbers of micro-organisms in the rhizosphere of flax were greater when the water content of the soil was maintained at 30%, than when held at 60%, of total moisture-holding capacity. However, the microbial population in the soil distant from the roots was lower in the drier soil.Differential counts of fungi and actinomycetes indicated that the number of colonies developing from spores or conidia comprised a small proportion of the total count. Sporulation of fungi was more profuse in soil distant from the plant than in the rhizosphere.The contact slide method indicated a greater number of micro-organisms in the rhizosphere than in soil distant from the roots and showed differences between the rhizosphere of resistant and susceptible varieties which agreed with results from the plating method.

THE INTERACTION OF HIGHER PLANTS AND SOIL MICRO-ORGANISMS: I. MICROBIAL POPULATION OF RHIZOSPHERE OF SEEDLINGS OF CERTAIN CULTIVATED PLANTS

1940 ◽  
Vol 18c (7) ◽  
pp. 307-317 ◽  
Author(s):  
M. I. Timonin
Keyword(s):  
New Species ◽  
Relative Abundance ◽  
Microbial Population ◽  
Higher Plants ◽  
Cultivated Plants ◽  
Plating Method ◽  
Different Types ◽  
Micro Organisms ◽  
A New Species

The microbial population in the rhizosphere of wheat, oats, alfalfa, and peas was studied and the relative abundance of different types of micro-organisms recorded. By means of the plating method it was found that bacteria and actinomycetes were 7 to 71 times greater in the rhizosphere than in the soil distant from the roots, whereas fungi were but 0.75 to 3.1 times more numerous.Different varieties of plants affected the activity of the various groups of soil micro-organisms differently. Thus fungi were more numerous in the rhizosphere of oats, and bacteria in the rhizosphere of alfalfa. Seventeen genera of fungi were represented in isolates from the rhizosphere of seedlings and the soil distant from the roots. However, no marked difference was observed in the types isolated from the rhizosphere of different varieties of seedlings. A fungus isolated from the rhizosphere of alfalfa proved to be a new species and the genus Spicularia Persoon was amended to include it.

The growth of Easter lily (Lilium longiflorum) as influenced by vesicular–arbuscular mycorrhizal fungi, Fusarium oxysporum, and fertility level

1978 ◽  
Vol 56 (21) ◽  
pp. 2773-2780 ◽  
Author(s):  
R. N. Ames ◽  
R. G. Linderman
Keyword(s):  
Fusarium Oxysporum ◽  
Root Rot ◽  
Mycorrhizal Fungi ◽  
Control Plant ◽  
Fertilizer Treatment ◽  
Fertility Level ◽  
High Inoculum ◽  
Easter Lily ◽  
Vesicular Arbuscular ◽  
Pot Culture

Easter lily bulbs were inoculated in the greenhouse with pot-culture inoculum containing a mixture of four vesicular–arbuscular (VA) mycorrhizal fungi as well as other fungi and bacteria, including pathogens. These organisms had multiplied in association with roots of lily, onion, and clover in pot cultures inoculated with sievings from lily field soils. Growth, as measured by bulb weight gain, root volume, and total leaf area, was determined on lily bulb plants inoculated at two inoculum levels and grown under three fertilizer regimes. Growth of plants inoculated with pot-culture inoculum was less than that of controls, especially in plants given the high inoculum (which included pot-culture plant roots) and the high rate of fertilization. The growth reduction apparently was due to the combined effect of greater incidence of Fusarium oxysporum root rot infections, damage to roots from fertilizer, and lower incidence of VA mycorrhizal infections. More mycorrhizal infections occurred in the low-fertilizer treatment than in the high- or no-fertilizer treatments at both high and low inoculum levels, but more F. oxysporum root rot occurred in the high-inoculum, high-fertilizer treatment.In a second experiment, lily seedlings that lacked bulb nutrient reserves were grown at a low fertilizer level and inoculated with Acaulospora trappei without any pathogens. Mycorrhizal plants were significantly larger than nonmycorrhizal control plants, and their tissues contained more N, P, K, Ca, and Mg than control plant tissues.

Comparative studies on the photosynthesis of higher plants

1973 ◽  
Vol 19 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Hideo Imai ◽  
Masataka Fukuyama ◽  
Yoshio Yamada ◽  
Togoro Harada
Keyword(s):  
Comparative Studies ◽  
Higher Plants

Comparative Studies of Herbicide Resistant Mutants of Synechocystis 6714 and of Higher Plants

1990 ◽  
pp. 543-546 ◽  
Author(s):  
A.-L. Etienne ◽  
C. Astier ◽  
G. Ajlani ◽  
D. Kirilovsky ◽  
J.-M. Ducruet ◽  
...  
Keyword(s):  
Comparative Studies ◽  
Higher Plants ◽  
Herbicide Resistant ◽  
Resistant Mutants

STUDIES ON FOOT AND ROOT ROT OF WHEAT: II. CULTURAL RELATIONSHIPS ON SOLID MEDIA OF CERTAIN MICRO-ORGANISMS IN ASSOCIATION WITH Ophiobolus graminis SACC.

1933 ◽  
Vol 8 (6) ◽  
pp. 545-552 ◽  
Author(s):  
W. C. Broadfoot
Keyword(s):  
Root Rot ◽  
Potato Dextrose Agar ◽  
Wheat Seedlings ◽  
Reliable Indication ◽  
Solid Media ◽  
Metabolic Products ◽  
Growth Reaction ◽  
Bacteria And Fungi ◽  
Micro Organisms ◽  
Pot Culture

The antagonistic and compatible growth relationships of 66 cultures of bacteria and fungi, most of which were from the soil, towards O. graminis on potato dextrose agar and Molisch's salt peptone agar, were compared with the effect of each on the virulence of this pathogene on wheat seedlings in open soil culture.Of the 21 cultures which controlled the virulence of O. graminis in the soil, only 15 of these were antagonistic on potato dextrose agar, while of the 45 cultures which gave intermediate or no control, 17 were compatible and 28 were decidedly antagonistic. From data secured indirectly, the antagonism or compatibility of the micro-organisms toward O. graminis, observed on potato dextrose agar, did not seem to depend on active alkali or acid more than on other metabolic products. The study apparently demonstrates that the growth reaction of various micro-organisms and O. graminis, associated on the two solid media used, is not a reliable indication that the same micro-organism will or will not suppress the virulence of this pathogene on wheat in soil in open pot culture.

scholarly journals Digestion of grass lipids and pigments in the sheep rumen

1974 ◽  
Vol 32 (2) ◽  
pp. 327-340 ◽  
Author(s):  
R. M. C. Dawson ◽  
Norma Hemington
Keyword(s):  
Small Proportion ◽  
Polar Compounds ◽  
The Other ◽  
Chlorophyll Pigments ◽  
Rapid Decomposition ◽  
Other Hand ◽  
Sheep Rumen ◽  
Micro Organisms

1. Digestion of grass lipids and pigments in the rumen of the sheep has been studied during starvation and following the administration of 14C-labelled grass.2. Both galactolipids contained in chloroplasts are rapidly degraded, although mono-galactosyldiglycerides disappear faster than digalactosyldiglycerides. It was concluded that rumen micro-organisms are mainly responsible for this degradation, although grass itself also contains enzymes which can degrade galactolipids.3. Rumen contents can degrade added 14C-labelled mono- and digalactosyldiglycerides in vitro at a rate sufficient to account for the disappearance of galactolipids in the intact rumen. The initial enzyme attack is probably a successive deacylation to give monogalactosylglycerol and digalactosylglycerol.4. Most of the chlorophyll pigments are rapidly converted into phaeophytins by loss of magnesium. A small proportion of chlorophyll a and more of chlorophyll b remains intact even after 24 h starvation. On the other hand, about half the phaeophytin undergoes further rapid decomposition to yield phylloerythrin.5. Although the grass phospholipids are extensively degraded, β-carotenes and many non-polar compounds, e.g. steroids, appear to undergo little change in the rumen.

THE ACCURACY OF THE PLATING METHOD FOR ESTIMATING THE NUMBERS OF SOIL BACTERIA, ACTINOMYCES, AND FUNGI IN THE DILUTION PLATED

1939 ◽  
Vol 17c (3) ◽  
pp. 72-86 ◽  
Author(s):  
Norman James ◽  
Marjorie L. Sutherland
Keyword(s):  
Bacterial Population ◽  
Accurate Estimate ◽  
Poisson Series ◽  
Plating Method ◽  
Successive Period ◽  
The Mean ◽  
Data Yield ◽  
Micro Organisms ◽  
Abnormal Variation ◽  
Number Of Bacteria

During the crop seasons of 1936, 1937, and 1938, 1465 samples of field soil, held in the laboratory one day after crushing, were plated by the recognized technique in four replicates of one dilution for counts of fungi, and of a higher dilution for counts of bacteria and of actinomyces. A χ2 value was calculated for each set or counts. These values for each group of micro-organisms were distributed into classes, and the number in each class was compared with the theoretical for the Poisson series. The data for each year indicate that the fungal counts conform to expectancy on the basis of random sampling, and show that the method provides a reasonably accurate estimate of the population in the dilution plated capable of developing under the conditions of growth. Too many sets of counts of bacteria in each year yield high χ2 values. The counts of actinomyces conform to expectancy.In an attempt to determine the cause of this abnormality for sets of counts of bacteria, samples were plated on the afternoon of the day they were taken from the field. Three hundred and four samples plated in six replicates of one dilution, and another 100 samples plated in four replicates, yield χ2 values whose distributions conform to expectancy. Accordingly, the plate method provides a satisfactory estimate of the bacterial population of soil in the dilution plated if the procedure is carried out within six hours after sampling. Data on 88 samples plated on the day of sampling, on 88 samples held one day, on 88 samples held two to five days, and on 88 samples held eight to thirteen days show that the discrepancy between the actual and theoretical distributions of χ2 values becomes progressively greater at each successive period of holding the samples. Further, the data indicate that the area sampled, the season, the medium used and the technique of plating bear no relation to the abnormal variation in counts of bacteria on replicate plates.A record was kept of the presence of abnormal types of bacterial colonies and various genera of fungi on all plates from 468 samples plated one day after sampling and crushing during 1938. The data show that sets having pin-point colonies or spreading colonies of the Mucorales on one or more plates usually have high χ2 values. Counts on such plates should be excluded from the estimate of the mean number of bacteria in the sample. Likewise, the number of actinomyces colonies on each plate from these samples was recorded. The χ2 values for these counts were found to conform to expectancy, indicating that the factor or factors associated with a large number of high χ2 values for counts of bacteria does not affect the count of actinomyces in the same way.Percentage moisture and P values corresponding to χ2 values for the counts of bacteria obtained each year were correlated. The data yield coefficients that are not significant in each case.

Biological and ecological aspects of nitrogen fixation by free-living micro-organisms

1969 ◽  
Vol 172 (1029) ◽  
pp. 367-388 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Soil Fertility ◽  
Biological Nitrogen Fixation ◽  
Higher Plants ◽  
Symbiotic Association ◽  
Free Living ◽  
Blue Green Algae ◽  
Ecological Aspects ◽  
Micro Organisms ◽  
Biological Nitrogen

Biological nitrogen fixation is a characteristic of certain micro-organisms, which may be free-living or occur in symbiotic association with higher plants. The purpose of this paper is to summarize some of the biological and ecological aspects of nitrogen-fixation by free-living forms. Biochemical aspects have been reviewed in other contributions to this discussion by Drs Wilson, Burris, and Cox & Fay. Nitrogen fixation by heterotrophic micro-organisms has been considered by Jensen (1965); nitrogen fixation by blue-green algae by Fogg & Stewart (1965), and by Stewart (1966, 1969), while Moore (1966) has evaluated the contribution of nitrogen-fixing micro-organisms to soil fertility.

Axenic culture of the foreign grain beetle, Ahasverus advena (Waltl) (Coleoptera, Silvanidae), and the rôle of fungi in its nutrition

1965 ◽  
Vol 55 (4) ◽  
pp. 681-690 ◽  
Author(s):  
S. T. Hill
Keyword(s):  
Relative Humidity ◽  
Propylene Oxide ◽  
Small Proportion ◽  
Wheat Germ ◽  
Development Time ◽  
Simple Technique ◽  
Axenic Culture ◽  
Complete Development ◽  
Micro Organisms

The extent of the dependence of the foreign grain beetle, Ahasverus advena (Waltl), upon moulds in its diet was investigated.Using a simple technique, the insect was cultured axenically at controlled temperature and relative humidity on an autoclaved mixture of rolled oats, wheatfeed and dried yeast. After the mixture was sterilised by exposure to propylene oxide vapour, virtually no larvae completed development on it in the absence of living micro-organisms, and this effect was unchanged by the addition of a mixture of B-vitamins followed by autoclaving. However, when fungi were grown on the food previously sterilised with propylene oxide, it again permitted the complete development of the insect.Autoelaved wheat germ was not a suitable diet for A. advena unless a small proportion of dried yeast was added before autoclaving. It is concluded that living fungi are not essential in the diet of the insect, but that they may supplement an otherwise inadequate diet.The minimum development time from egg to adult on a complete food at 80 per cent. E.H. and 30°C. varied from 18 to 25 days.

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