Agriculture Reference
In-Depth Information
concentration of insecticides on spinach resulted in
chlorophyll reduction, which consequently damaged the
photosynthetic apparatus (Sresen
et al.,
2000). However,
in some cases positive effects of pesticides were also
observed, such as increments in the plant height, area of
leaves and the uptake of nutrients (Lagana
et al.,
2000;
Nakamura
et al.,
2000).
Lens esculentum
after treatment with the pesticide pyri-
proxyfen. The decreasing trend of nodule number was
Pisum sativum
(44),
Vigna radiata
(14),
Cicer arietinum
(5) and
Lens esculentum
(5) (Ahmed, 2014). The insecti-
cide pentachlorophenol is reported to prevent nodulation
between the legume
Medicago sativa
and the bacterium
Sinorhizobium meliloti
(Fox
et al.,
2007). In the legumes
Trifolium pratense, Medicago sativa
and
Ornithopus compres-
sus,
a significant decrease in nodule formation was
observed with the bacteria
Rhizobium
and
Bradyrhizobium
after the application of the pesticides carbendazim,
thiram and imazethapyr. The nodulation process was
greatly affected by the use of these pesticides and is sum-
marized in Table 6.1 (Niewiadomska & Klama, 2005).
The pesticides Funaben T and Pivot 100SL were
reported to have negative impacts on nodule formation
in
Medicago sativa
and
Trifolium pratense
(Niewiadomska
and Sawicka, 2002; Niewiadomska, 2004). Nodule
formation in
Pisum sativum, Phaseolus vulgaris
and
Lupinus
decreased after the application of the pesticides
Afugan, Brominal, Gramoxone and Selecron (Abd-Alla
et al.,
2000). Application of three pesticides, 2,4-D amine
salt, glyphosate (Roundup) and atrazine, to the legumi-
nous plants
Crotalaria hebecarpa, Desmodium cephalotes
and
Tephrosia strigosa
resulted in a significant decline in
the number of root nodules (Shankar
et al.,
2012).
Nodule formation in
Pisum sativum
is negatively affected
by the pesticides terbuthylazine, simazine, prometryn
and bentazone (Singh & Wright, 1999, 2002). In
Cicer
arietinum
L., the application of Pyrifos resulted in the
6.3.4 effect on nitrogen fixation
6.3.4.1 Nodule formation
Pesticide application decreases the process of nodulation
in legume plants by reducing the carbohydrate supply to
already formed nodules. This results in a decrease in
sustenance of rhizobia and lessening of biochemical sig-
nalling, which leads to inhibition of nodule development
due to decreased cell division (Anderson
et al.,
2004).
Decrease in nodule formation was observed in
Cicer ari-
etinum, Lens esculentum, Pisum sativum
and
Vigna radiata
after pesticide application (Boldt & Jacobsen, 1998). A
reduction in nitrogen fixation was observed in legume
plant roots due to the decrease in root nodule formation
and late rhizobial association (Fox
et al.,
2007). Reduced
nodule formation was observed in
Glycine max
after the
application of Afugan, Brominal, Gramoxone and
Selecron (Abd-Alla
et al.,
2000). Carbamate application
in
Pisum sativum
and
Vigna sinensis
resulted in suppres-
sion of nodule formation (Aggarwal
et al.,
1986). In
Glycine max
decline of nodule formation was noticed
after the application of imazaquin (Alonge, 2000).
Reduced nodulation was observed in
Pisum sativum
and
Table 6.1
Effect of pesticides on nodulation by symbiotic bacteria in legumes. Reproduced with permission of the
Polish Journal of
Microbiology
.
Legume
Bacterium + pesticide treatment
Average nodule
number
Colour
Trifolium pratense
Rhizobium leguminosarum
bv.
trifolii
KGL
8
Pink
Trifolium pratense
Rhizobium leguminosarum
bv.
trifolii
KGL + herbicide
3
Pink
Trifolium pratense
Rhizobium leguminosarum
bv.
trifolii
KGL + fungicide
5
Pink
Trifolium pratense
Rhizobium leguminosarum
bv.
trifolii
KGL + herbicide + fungicide
3
Pale pink
Medicago sativa
Rhizobium melilotii
Bp
15
Pink
Medicago sativa
Rhizobium melilotii
Bp + herbicide
7
Pink
Medicago sativa
Rhizobium melilotii
Bp + fungicide
8
Pink
Medicago sativa
Rhizobium melilotii
Bp + herbicide + fungicide
6
Pink
Ornithopus compressus
Bradyrhizobium
sp.
Ornithopus
B
11
Pink
Ornithopus compressus
Bradyrhizobium
sp.
Ornithopus
B + herbicide
7
Pink
Ornithopus compressus
Bradyrhizobium
sp.
Ornithopus
B + fungicide
6
Pink
Ornithopus compressus
Bradyrhizobium
sp.
Ornithopus
B + herbicide + fungicide
5
Pink
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