Chemistry Reference
In-Depth Information
A study on the effect of land use and organic amendments on the occurrence
and diversity of nematode-destroying fungi was conducted in Kenya.
153
From
the study, it was evident that all the sampled land uses differed in terms of
occurrence of nematode-destroying fungi, consistent with previous reports
indicating that nematode-destroying fungi were present in all habitats but at
different densities and diversities (see Table 7).
Arthrobotrys oligospora was the most abundant species of nematode-
destroying fungi in the study area, and this was attributed to the application of
inorganic and organic inputs by farmers. Jaffee
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showed that organic
amendments enhanced the build-up of resident nematode-trapping fungi in the
soil. Higher soil organic matter content protects plants against nematodes by
increasing soil water-holding capacity and enhancing the activity of naturally
occurring biological organisms that compete with nematodes in the soil.
126
Apart from the presence of organic matter, the fungi also obtain their carbon
and energy from two sources: from organic matter (saprophyte) and from
trapping nematodes (parasite), making them adaptable to a wide range of
habitats. It is possible that members of the genus were the best adapted to the
biotic and abiotic conditions prevailing in the study area. This fungus should
be recommended for further study with the aim of developing it as a biological
control agent. Such a study should be geared towards growth parameters of
the fungus, since biological, chemical and physical factors of the soil are
known to inhibit fungal growth by fungistatic compounds and is made even
more complicated by crop rotations. The ability of this fungus as a biological
control agent could be improved through genetic engineering and then
packaged for biological control purposes. Apart from introduction of
particular species from the genus, agricultural practices that stimulate build-
up of the fungi could be identified and recommended for adoption by farmers.
The study also revealed that increased land-use intensity resulted in increased
occurrence and diversity of nematode-destroying fungi. This, however, was
contrary to the expectation that beneficial microorganisms decrease with
increased intensity of land use.
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A number of explanations were used to
account for the higher frequency of occurrence of nematode-destroying fungi
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Table 7
Effect of land use on frequency of isolation, richness and diversity of
nematode-destroying fungi in Taita Taveta district, Kenya. (Source:
Wachira et al.).
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Frequency of
isolation %
Land use
Mean evenness
Mean richness
Mean Shannon
Forest
5.8
0.375
0.625
0.17
Maize/bean
27.9
1.000
3.000
1.07
Napier
20.9
1.000
2.250
0.76
Shrub
11.6
0.625
1.250
0.36
Vegetables
33.7
1.000
3.625
1.26
3.81 6 10
207
7.139 6 10
205
3.81 6 10
207
1.062 6 10
206
P-value
