Agriculture Reference
In-Depth Information
selves produce auxins (Vandeputte et al. 2005 ; Chung et al. 2003 ; Ansari and Srid-
har 2000 ; Major et al. 2004 ) to counter this activity.
3.2   SA Application in Plant Growth and Productivity under 
Changing Regimes
The applicability of a plant hormone is testified based on an array of physiological
responses it manages under normal and stressed conditions which are expressed in
plant's optimal growth and yield. Changing climatic conditions led to identification
of several phenolic compounds that ensure the resistance of plant to withstand the
environmental inhospitable conditions. These phenolics, well known as 'salicylic
acids', are also crucial growth regulators under normal plant growth conditions,
managing leakage of reactive radicals at their suboptimal level where they can en-
able ROS signaling and protect it from oxidative damage (Castagne et al. 1999 ;
Yang et al. 2004 ). SA deficient NahG rice contains elevated level of superoxide
and H 2 O 2 , decreased level of SOD and CAT activity, thus increasing susceptibil-
ity to oxidative damage caused by the pathogen (Yang et al. 2004 ). Exogenous
applications of SA and its derivatives have shown promising prospects for future
agronomical applications, in improving growth and yield of different crop plants
such as rice, wheat, oat, maize, soybean, tomato, mustard, gram, carrot and chilli.
Furthermore, the dose-dependent exogenous application of SA under environmen-
tal or physiological stress conditions viz., high-temperature (Larkindale and Huang
2004 ; Wen et al. 2008 ), chilling, water (Hayat et al. 2008 ; Umebese et al. 2009 )
and salinity stress (Yusuf et al. 2008 ) and biotic stress (Esmailzadeh et al. 2008 ;
Chitra et al. 2006 ; Anand et al. 2008 ) is well documented, affecting cellular redox
homeostasis leading to attenuation of oxidative stress, thereby promoting photo-
synthesis (Maslenkova et al. 2009 ), nitrogen metabolism and proline content and
growth. The precise internal rise of SA has been evidenced to enable the plant to
withstand these harsh conditions expressing defense proteins, optimizing activity of
antioxidant system (Krantev et al. 2008 ; Guo et al. 2009 ; Yusuf et al. 2008 ; Hayat
et al. 2008 ), photosynthetic parameters (Fariduddin et al. 2003 ; Hayat et al. 2008 ; El
Tayeb 2005 ), enzyme activities, growth attributes and eventual yield of crop plants
(Fariduddin et al. 2003 ; Hayat et al. 2005 ; Hayat et al. 2007). Therefore, SA finds
its extensive applicability in agronomic applications and tissue culture practices
(Hayat et al. 2010 ).
3.3   SA and ROS: A Close Intracellular Interplay
The production of ROS (e.g. superoxide anions) and their secondary derivatives
(H 2 O 2 , OH , R*OH etc.) during cellular metabolic processes is a normal phenom-
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