Conclusion
From the present study, the conclusion could be drawn that
Ni2+ inhibits overall growth of nitrogen fixingAnabaena cells; while SA, CaCl2 and SNP addition
significantly recovered the growth and growth regulating processes (Fig.
8). However, upon supplementation of NO (c-PTIO) or/ and
Ca2+ (EGTA) scavenger to Ni+SA+Ca, Ni+SA+NO or Ni+SA
stressed Anabaena cells, the improvement in growth caused by SA,
Ca2+ and NO was further arrested, which suggests that
Ca2+ and NO both are the part of SA induced signaling
event. But the steep decline in growth and growth regulating attributes:
EPS secretion, pigments, photosynthetic rate, nitrogen metabolism status
and antioxidants system was mainly observed under Ni+SA+Ca+c-PTIO than
that of Ni+SA+NO+EGTA treatment even in presence of SA, thereby
suggesting that SA induced positive impact on physiological and
biochemical traits of Anabaena cells are mostly regulated by
Ca2+ mediated NO signaling (Fig. 8).