Antioxidant enzyme responses and metabolite functioning of Pisum sativum L. to sewage sludge in arid and semi-arid environments

The productivity of plants is a direct variant of the countless biotic and abiotic stresses to which a plant is exposed in an environment. This study aimed to investigate the capabilities of leguminous plant garden pea (Pisum sativum L.) to resist water deficit conditions in arid and semi-arid areas when applied with varied doses of sludge for growth response. The effect of sludge doses was evaluated on crop yield, antioxidant enzymes, viz., ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), superoxide dismutase (SOD), and glutathione reductase (GR), and metabolites (ascorbic acid, glutathione, and total protein content). The effective sludge concentrations with respect to seed weight and crop yield were found to be in the following trend: D-2 (6.25%)>D-3 (12.5%)>D-1 (2.5%)>D-0 (control) under organic amendment (OA). Conversely, a high dose of the sludge reduced the seed weight and total crop yield. The sludge doses D-2 under arid and semi-arid conditions along with organic amendments (OA) significantly enhance the antioxidant enzyme activity, whereas sludge dose D-3 with OA ominously regulates the activity of these enzymes. Besides, seeds depicted a considerable increase in ascorbic acid, glutathione, and total protein content in arid and semi-arid conditions upon the application of sludge with OA. Sewage sludge as a source of nutrients indirectly enhances crop yield, antioxidant enzymes, and antioxidant metabolites. Thus, it improves the defense mechanism, reduces abnormal protein glycation, and depletes the susceptibility of protein to proteolysis.

Automated summary

The study found that in arid and semi-arid areas, moderate doses of sludge along with organic amendments significantly increase the antioxidant enzyme activity and antioxidant metabolites content, improving crop yield. However, excessive sludge doses may decrease crop yield.