Role of Nitrogen and Gibberellin (GA₃) in the Regulation of Enzyme Activities and in Osmoprotectant Accumulation in Brassica juncea L. under Salt Stress

Abstract

Salt stress alters a wide array of plant metabolic mechanisms. Different strategies of the application of nutrients and phytohormones are required to overcome the adverse effects of salt stress. The main objective of the present study was to determine if added nitrogen (N) and gibberellin (GA3) in growth medium could alleviate the adverse effects of salt stress on plant metabolism. Two‐week‐old plants were fed with: (i) 0 mm NaCl + 0 mg N kg−1 sand + 0 m GA3 (control), (ii) 100 mm NaCl + 0 mg N kg−1 sand + 0 m GA3, (iii) 0 mm NaCl + 40 mg N kg−1 sand + 0 m GA3, (iv) 0 mm NaCl + 0 mg N kg−1 sand + 10−5 m GA3, (v) 100 mm NaCl + 40 mg N kg−1 sand + 0 m GA3, (vi) 100 mm NaCl + 0 mg N kg−1 sand + 10−5 m GA3, (vii) 100 mm NaCl + 40 mg N kg−1 sand + 10−5 m GA3. Growth and physio‐biochemical attributes i.e. shoot length, leaf area, fresh weight, dry weight, net photosynthetic rate, stomatal conductance, malondialdehyde concentration, electrolyte leakage, total chlorophyll concentration, nitrate reductase and carbonic anhydrase activities, proline and glycinebetaine concentration, leaf – N, potassium (K) and sodium (Na) concentration and K/Na ratio were affected by NaCl treatment. But application of N or GA3 alone as well as in combination proved beneficial in alleviating the adverse effects of salt stress on these growth and physio‐biochemical parameters. However, N applied with GA3 proved more effective than N and GA3 applied alone. The results revealed that combined application of N and GA3 may ameliorate most of the attributes and prove to be a physiological remedy to increase the tolerance against the ill effects of salt stress in Brassica.

Calcium chloride and gibberellic acid protect linseed (Linum usitatissimum L.) from NaCl stress by inducing antioxidative defence system and osmoprotectant accumulation

“…Similar results were reported by Lutts et al (1996), Khan et al (2007) and Siddiqui et al (2008). Salt-stressed plants supplied with CaCl 2 and GA 3 alone or in combination, showed a significant decrease in electrolyte leakage compared to the plants grown with NaCl alone (Fig.…”

Morphological and physio-biochemical characterization ofBrassica junceaL. Czern. & Coss. genotypes under salt stress

“…We infer that Pro and GB accumulation in G 8 might MDA content (nmol g -1 FW) have a role in its salt tolerance. Several reports on different crops are in conformity with these results (Hanson and Burnet 1994;Dubey 1997;Mansour 2000;Ashraf and Harris 2004;Mansour et al 2005;Khan et al 2007;Siddiqui et al 2008). Data revealed that NR activity in Brassica genotypes was inhibited by salt stress (Table 1).…”

“…Moreover, maximum value for P N , Chl content and g s was observed in genotypes G 8 and G 7 and minimum genotypes G 1 and G 4 under salt stress (Table 2). Malibari et al (1993), Salama et al (1994) and Huang et al (2006) on Chl concentration and Lakshmi et al (1996), Siddiqui et al (2008) on P N and g s , also reported similar results in other plants under salt stress. Therefore, it could be possible reason to suggest that genotype G 8 is less susceptible than other genotypes, because maximum values for these parameters were recorded in genotype G 8 .…”

Salicylic acid and calcium-induced protection of wheat against salinity

“…Salinity alters many physiological and biochemical processes such as ion toxicity, mineral distribution, respiration rate, organic solutes/osmolytic synthesis, seed germination, enzymes activity and photosynthesis (Marschner 2002;Siddiqui et al 2010). Several studies reported that the high level of NaCl in a growth medium limits the plant growth and development (Gunes et al 2007;Siddiqui et al 2008Siddiqui et al , 2009aSiddiqui et al , 2009bSiddiqui et al , 2010Khan et al 2010). The complexity of salt tolerance mechanisms is varied from plant to plant and cultivar to cultivar and physiological and biochemical processes of plants (Ashraf and McNeilly 2004;Siddiqui et al 2009b).…”