Agriculture Reference
In-Depth Information
metabolites, which are necessary molecules for the establishment of symbiosis
between N-fixing bacteria or rhizobium (Long, 2001) and arbuscular
mycorrhizal fungi, and their host plant, respectively (Akiyama et al., 2005).
In addition to the affects of plant growth on soil properties, it can also
control erosion, influence atmospheric climate and affect the activities of other
organisms. The effects of plant growth on the atmospheric climate are through
affecting CO 2 cycling and sequestration in soil as well as production of O 2 by
photosynthesis and the process of evapo-transpiration. Therefore, plant growth
can affect both the quality of atmospheric climate as well as the important
process of global warming.
T OPSOIL AND C HEMICALS
There are different chemicals used to inhibit the negative effects of weeds
and pathogens in soil on plant growth and crop production. Although such
chemicals can control weeds and pathogens, they may also have adverse
effects on the environment and soil microbes. The effects of different
chemicals on soil microbes depend on plant and microbial species and kind
and amounts of chemical used to treat weeds and pathogens (Schreiner and
Bethlenfalvay, 1997; Samarbakhsh et al., 2009). In their research work
Samarbakhsh et al. (2009) tested the single and combined effects of different
species of AM fungi including Glomus mosseae , G. etunicatum and G.
intraradices and different fungicides including benomyl, vitavax and captan
on corn growth and yield under field conditions. Different species of AM
fungi affected corn growth and yield differently when subjected to fungicides.
The symbiosis between G. mosseae and corn was the most established one
under fungicide treatment. The least unfavorable effects of fungicides on corn
root colonization by AM fungi were related to Benomyl.
Accordingly, it is suggested that biological methods be used to inhibit the
adverse effects of weeds and pathogens on crop production. Use of organic
farming is recommendable as a friendly method to the environment. However,
it must be performed in way, which controls weeds and pathogens, while
producing acceptable amounts of yield. Organic farming has become very
common in different parts of the world (Willer and Yussefi, 2005) to alleviate
the followings: 1) enhanced production of greenhouse gases, 2) global
warming, 3) excess use of chemical fertilization, 4) increased resistance of
pathogens to chemicals, 5) reduced quality of agricultural crops, 6) increasing
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