An organo-mineral fertilizer level of 20 or 25 g kg−1 soil
significantly reduced the Na content. This, increased the ratio of
Ca:Na, thus generated more antagonistic effects to the harmful
effects of Na+ ions. The organo-mineral fertilizer may acts as a
reservoir for nutrients, ensuring slow release to the substrate
solution or directly to plant roots. It is a relatively abundant
mineral resource (Table 1).
According to our results, antioxidant enzymes activities
(Table 6) found to be identical with those reported by Lin and
Kao (1999) on rice seedling, Sulochana et al. (2002) on
groundnut, Ozturk and Demir (2003) on spinach and Jaleel
et al. (2008) on Dioscorea rotundata. The decreased POX seems
to indicate that this enzyme does not play a crucial role in defense
mechanisms against oxidative stress, or that cooperation is
activated between different antioxidant enzymes to establish a
proper H2O2 balance when POX activity is reduced by salt
toxicity (Chaparzadeh et al., 2004). Reduction of catalase (CAT)
activity under salt stress may result in H2O2 accumulation and
may be associated with its tolerance mechanism through signal
transduction (Shim et al., 2003). The organo-mineral fertilizer, in
this study, played an important role in increasing the activity of
CAT and polyphenol oxidase (PPO) (Table 6) and consequently
a weighty role in defense mechanisms against oxidative stress,
especially salinity. This may be due to the fact that this novel
fertilizer contains calcium, humic acid and rice bran which have
many properties for overcoming the salt-stress effects.