Agriculture Reference
In-Depth Information
7.7 Efficient Management of Manure
Since CH
4
is produced under anaerobic conditions, so by improving organic matter
management or incorporating organic matter into soil during off-season drained
period, CH
4
emissions can be reduced significantly (Kalra et al.
1996
). Debnath
et al. (
1996
) showed that by application of fermented manure like biogas slurry,
CH
4
emissions from rice fields can be reduced without hampering the productivity.
8 Crop Improvement for Reducing GHG Emissions
Perhaps one of the most challenging means of mitigation of GHG emissions is the
crop improvement. Scientists are pursuing this field of research quite vigorously.
Though not much success has been achieved, yet a strong database has certainly
been created through worldwide researches on this topic. Many scientists and in-
stitutions are working on this aspect for the mitigation of GHG emissions. Like
many parts of the world, efforts are on in India also to develop crops with certain
characteristics so that the plants emit less GHGs without causing any reduction in
the yield.
8.1 Plant Physiology and Molecular Biological Approach
The aerenchyma tissues in the leaf, roots and clum of rice plants act as an efficient
channel for gaseous exchange between soil and atmosphere (Raskin and Kende
1985
). Satpathy et al. (
1998
) also reported a negative correlation between oxi-
dase activity of the root tip and CH
4
flux. Higher oxidase activity in the vicinity
of the rice plant roots inhibits methanogenesis and increases CH
4
oxidation (Ota
1970
). Lueders and Friedrich (
2002
) reported that addition of electron acceptors
stimulates microbial population that is competitive to methanogens by suppress-
ing methanogenic metabolic pathways, thereby reducing methane emission from
rice fields. Application of mycorrhiza and methanotrophs can effectively reduce
methane emission from rice fields by suppressing methanogen population in rice
soil (Lakshmanan et al.
2009
).
Rice Cluster I (RC-I) refers to the orders
Methanosarcinales
and
Methanomi-
crobiales
that carry the
mcr-A
gene coding for methyl coenzyme M reductase (
mcr
A
; Grosskopf et al.
1998a
). This group of bacteria, abundant in soil in all parts
of the world, is responsible for CH
4
emissions through the process of acetoclastic
methanogenesis (conversion of acetate to CH
4
) or hydrogenotrophic methanogen-
esis (conversion of H
2
O plus CO
2
into CH
4
;Conrad et al.
1993
). Grosskopf et al.
(
1998b
) and Kudo et al. (
1997
) studied the
16S rRNA
sequence of Rice Cluster I.
