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Distribution of Allomyces in Nigerian soils
600
Transactions British Mycological Society
I am grateful to Dr M. B. Ellis for his advice, and to Mr S. L. Everist for permission to examine the collections of A. aulacocarpa in herb. BRI. REFERENCES
DEIGHTON, F. C. (1972). Synonymy of Hansfordia pulvinata (Berk. & Curt.) Hughes. Transactions of the British Mycological Society 59, 531-536. ELLIS, M. B. (1971). Dematiaceous Hyphomvcetes. Commonwealth Mycological Institute, Kew. SYDOW, H. (1927). Fungi in itinere costaricensi collecti. Pars tertia. Annales Mycologici 25,1-160. EXPLANATION OF PLATE
91
Spilodochium acacioe (All x 600 approx.) Fig. I. Sporodochia in surface view. Fig. 2. Sporodochia in section. Fig. 3. Simple and compound conidia.
DISTRIBUTION OF ALLOMTCES IN NIGERIAN SOILS R. O. ALABI
Adeyemi College, University
ofIfe, Nigeria
Allomyces arbuscula and A. moniliformis were first described in India by Butler (1911) and in North Carolina, U.S.A., by Coker and Braxton in 1926 (Emerson, 1941). Subsequent reports show they are widespread in tropical and warm temperate countries occurring mostly in moist soils (Emerson, 1941; Wolf, 1941). Soil samples sent to Emerson (1941) from the Congo, Uganda and Rhodesia yielded both species. The two species were recorded in Nigeria by Alabi (1967) but they were obtained from Crotalaria seeds used as baits for Saprolegniaceae in surface water. In this study, an attempt was made to establish the distribution of Allomyces in different habitats and to ascertain whether they are soil or aquatic fungi. A study was made of the occurrence of Allomyces in various soils, from the seashore to the savannah region. Random soil samples were taken from both dry and wet places (river beds, bottom of ponds, margins of streams and ponds, gardens and forests) from Lagos to Dorin at different seasons of the year. Water samples were also taken from as many of these places as possible. Where the ponds and streams dried up during the dry season, water samples were taken during the rains and soil samples during the dry seasons. The procedure for isolating Allomyces is similar to that reported by Alabi (1967). The viability of resistant sporangia was tested by storing stock cultures of Allomyces in (21) wide-mouthed bottles from which aliquots of water were taken and baited at monthly intervals from January 1970 to July 1972. Trans. Br. mycol. Soc. 63 (3), (1974). Printed in Great Britain
Trans. Br. mycol. Soc.
Vol. 63. Plate 91
(Facing p. 600)
Notes and Brief Articles Table
I.
Occurrence
601
ofAllomyces in different habitats %
River bed soils Clayey margin of stream Mangrove swamp River banks Open forest River side in Savanna Garden soils Forest soil Bottom deposit of stream Savanna Soil Sandy margin of stream Lagoon Surface water Sandy Soil Sea Shore
7°
68 66
64 5°
4° 40
40 3°
10
4 2 2
o
°
Table 2. Effect of temperature on the viability
ofAllomyces
Weeks Temperature (0C)
,
2
8
16
32
64
+ + + +
+ + +
+ + +
+ + +
+ + +
IO
20 25 3° 35 40
The method used in the study of the effect of storage on the propagules of Allomyces in soil was to blend soils from Allomyces rich areas and store them in plastic buckets. At monthly intervals, 20 g of the soil was treated as described above. Temperature effect was investigated by keeping some of the soil samples in incubators maintained at 15, 20, 30, 35, 40 and 45°C and testing them for Allomyces at z-week intervals. Allomyces arbuscula and A. moniliformis occurred frequently in the soil samples. A comparison of the resistant sporangia of the two species showed that the Nigerian isolates are larger than those from Cuba and Mexico (Wolf, 1941) but fit the dimensions of those from other tropical countries (Emerson, 1941) - A. arbuscula, 31-40 x 47-70 /lm and A. moniliformis 36-48 x 68-7 2 /l m . Allomyces occurred mostly in soils and very sparingly in surface water. All except sandy soils yielded the fungus. It is also interesting that soils from predominantly grassland areas gave a poor yield whereas in the same vegetation zone riverside soils showed a considerable amount of Allomyces (Table I). In the Allomyces-rich swamp near Lagos where a more detailed study was carried out, results indicated that the mid-rainy season was a most favourable period for the collection of this fungus. Trans. Br. mycol. Soc. 63 (3), (1974). Printed in Great Britain
602
Transactions British Mycological Society
Stock cultures maintained in water remained viable after 30 months. Soil samples kept at temperatures up to 30°C yielded Allomyces for 64 weeks. At 35°C the temperature effect was noticeable after 2 weeks. At higher temperatures no positive results were obtained even after I week (Table 2). Emerson (1941) felt that Allomyces was a truly aquatic fungus. Willoughby (196 I) found that it occurred in marginal situations. Jeffery & Willoughby (1964) working on the distribution of the fungus in Australia considered Allomyces to be a soil fungus since evidence showed it as occurring in a variety of soils. Alabi (1967) contended that its occasional presence in water may be due to leaching of soils from margins of streams. Results from this study tend to lend more weight to the contention that Allomyces is a soil fungus and not truly aquatic. Only sandy soil samples did not yield Allomyces. From the nature of the sandy soils sampled it appeared that lack of moisture, and a relatively higher soil temperature may have been responsible for the absence of this fungus, a contention that needs to be investigated further. The distribution of Allomyces is country-wide especially where the soil is moist. Samples sent from the far north, areas that can be styled semidesert, did not yield Allomyces. This leads one to conclude that in Nigeria, factors such as soil temperature and low moisture are primary factors that determine the occurrence of this fungus. This hypothesis is further strengthened by the result of the survey in the swamp whereby there was a noticeable decrease in the frequency of occurrence during the mid-dry season. REFERENCES
ALABI, R. O. (1967). Studies of some tropical aquatic phytomycetesfound around Ibadan. M.Sc. Thesis University of Ibadan. BUTLER, E.J. (I9II). On Allomyces-a new aquatic fungus. Annals of Botany 25, I023I034· EMERSON, R. (1941). An experimental study of the life cycles and taxonomy of Allomyces. Lloydia 4, 77- I 44· JEFFREY, J. M. & WILLOUGHBY, L. G. (1964). A note on the distribution of Allomyces in Australia. Nova Hedwigia I, 507-515. SPARROW, F. K. (1960). Aquaticphycomycetes. Ann Arbor: University of Michigan Press. WILLOUGHBY, L. G. (1961). The ecology of some lower fungi in Esthwaite Water. Transactions of British Mycological Society 44, 305-352. WOLF, F. T. (1941). A contribution to the life history and geographical distribution of genus Allomyces. Mycologia 33, 158-173.
Trans. Br. mycol. Soc. 63 (3), (1974-). Printed in Great Britain
Transactions British Mycological Society
I am grateful to Dr M. B. Ellis for his advice, and to Mr S. L. Everist for permission to examine the collections of A. aulacocarpa in herb. BRI. REFERENCES
DEIGHTON, F. C. (1972). Synonymy of Hansfordia pulvinata (Berk. & Curt.) Hughes. Transactions of the British Mycological Society 59, 531-536. ELLIS, M. B. (1971). Dematiaceous Hyphomvcetes. Commonwealth Mycological Institute, Kew. SYDOW, H. (1927). Fungi in itinere costaricensi collecti. Pars tertia. Annales Mycologici 25,1-160. EXPLANATION OF PLATE
91
Spilodochium acacioe (All x 600 approx.) Fig. I. Sporodochia in surface view. Fig. 2. Sporodochia in section. Fig. 3. Simple and compound conidia.
DISTRIBUTION OF ALLOMTCES IN NIGERIAN SOILS R. O. ALABI
Adeyemi College, University
ofIfe, Nigeria
Allomyces arbuscula and A. moniliformis were first described in India by Butler (1911) and in North Carolina, U.S.A., by Coker and Braxton in 1926 (Emerson, 1941). Subsequent reports show they are widespread in tropical and warm temperate countries occurring mostly in moist soils (Emerson, 1941; Wolf, 1941). Soil samples sent to Emerson (1941) from the Congo, Uganda and Rhodesia yielded both species. The two species were recorded in Nigeria by Alabi (1967) but they were obtained from Crotalaria seeds used as baits for Saprolegniaceae in surface water. In this study, an attempt was made to establish the distribution of Allomyces in different habitats and to ascertain whether they are soil or aquatic fungi. A study was made of the occurrence of Allomyces in various soils, from the seashore to the savannah region. Random soil samples were taken from both dry and wet places (river beds, bottom of ponds, margins of streams and ponds, gardens and forests) from Lagos to Dorin at different seasons of the year. Water samples were also taken from as many of these places as possible. Where the ponds and streams dried up during the dry season, water samples were taken during the rains and soil samples during the dry seasons. The procedure for isolating Allomyces is similar to that reported by Alabi (1967). The viability of resistant sporangia was tested by storing stock cultures of Allomyces in (21) wide-mouthed bottles from which aliquots of water were taken and baited at monthly intervals from January 1970 to July 1972. Trans. Br. mycol. Soc. 63 (3), (1974). Printed in Great Britain
Trans. Br. mycol. Soc.
Vol. 63. Plate 91
(Facing p. 600)
Notes and Brief Articles Table
I.
Occurrence
601
ofAllomyces in different habitats %
River bed soils Clayey margin of stream Mangrove swamp River banks Open forest River side in Savanna Garden soils Forest soil Bottom deposit of stream Savanna Soil Sandy margin of stream Lagoon Surface water Sandy Soil Sea Shore
7°
68 66
64 5°
4° 40
40 3°
10
4 2 2
o
°
Table 2. Effect of temperature on the viability
ofAllomyces
Weeks Temperature (0C)
,
2
8
16
32
64
+ + + +
+ + +
+ + +
+ + +
+ + +
IO
20 25 3° 35 40
The method used in the study of the effect of storage on the propagules of Allomyces in soil was to blend soils from Allomyces rich areas and store them in plastic buckets. At monthly intervals, 20 g of the soil was treated as described above. Temperature effect was investigated by keeping some of the soil samples in incubators maintained at 15, 20, 30, 35, 40 and 45°C and testing them for Allomyces at z-week intervals. Allomyces arbuscula and A. moniliformis occurred frequently in the soil samples. A comparison of the resistant sporangia of the two species showed that the Nigerian isolates are larger than those from Cuba and Mexico (Wolf, 1941) but fit the dimensions of those from other tropical countries (Emerson, 1941) - A. arbuscula, 31-40 x 47-70 /lm and A. moniliformis 36-48 x 68-7 2 /l m . Allomyces occurred mostly in soils and very sparingly in surface water. All except sandy soils yielded the fungus. It is also interesting that soils from predominantly grassland areas gave a poor yield whereas in the same vegetation zone riverside soils showed a considerable amount of Allomyces (Table I). In the Allomyces-rich swamp near Lagos where a more detailed study was carried out, results indicated that the mid-rainy season was a most favourable period for the collection of this fungus. Trans. Br. mycol. Soc. 63 (3), (1974). Printed in Great Britain
602
Transactions British Mycological Society
Stock cultures maintained in water remained viable after 30 months. Soil samples kept at temperatures up to 30°C yielded Allomyces for 64 weeks. At 35°C the temperature effect was noticeable after 2 weeks. At higher temperatures no positive results were obtained even after I week (Table 2). Emerson (1941) felt that Allomyces was a truly aquatic fungus. Willoughby (196 I) found that it occurred in marginal situations. Jeffery & Willoughby (1964) working on the distribution of the fungus in Australia considered Allomyces to be a soil fungus since evidence showed it as occurring in a variety of soils. Alabi (1967) contended that its occasional presence in water may be due to leaching of soils from margins of streams. Results from this study tend to lend more weight to the contention that Allomyces is a soil fungus and not truly aquatic. Only sandy soil samples did not yield Allomyces. From the nature of the sandy soils sampled it appeared that lack of moisture, and a relatively higher soil temperature may have been responsible for the absence of this fungus, a contention that needs to be investigated further. The distribution of Allomyces is country-wide especially where the soil is moist. Samples sent from the far north, areas that can be styled semidesert, did not yield Allomyces. This leads one to conclude that in Nigeria, factors such as soil temperature and low moisture are primary factors that determine the occurrence of this fungus. This hypothesis is further strengthened by the result of the survey in the swamp whereby there was a noticeable decrease in the frequency of occurrence during the mid-dry season. REFERENCES
ALABI, R. O. (1967). Studies of some tropical aquatic phytomycetesfound around Ibadan. M.Sc. Thesis University of Ibadan. BUTLER, E.J. (I9II). On Allomyces-a new aquatic fungus. Annals of Botany 25, I023I034· EMERSON, R. (1941). An experimental study of the life cycles and taxonomy of Allomyces. Lloydia 4, 77- I 44· JEFFREY, J. M. & WILLOUGHBY, L. G. (1964). A note on the distribution of Allomyces in Australia. Nova Hedwigia I, 507-515. SPARROW, F. K. (1960). Aquaticphycomycetes. Ann Arbor: University of Michigan Press. WILLOUGHBY, L. G. (1961). The ecology of some lower fungi in Esthwaite Water. Transactions of British Mycological Society 44, 305-352. WOLF, F. T. (1941). A contribution to the life history and geographical distribution of genus Allomyces. Mycologia 33, 158-173.
Trans. Br. mycol. Soc. 63 (3), (1974-). Printed in Great Britain