Combine Effects of Simulated Acid Rain and Meloidogyne incognita infestation on Plant Vigor and Antioxidative Defense Mechanisms in Chickpea

The present study investigated the combined effects of simulated acid rain (SAR) and root-knot nematode (Meloidogyne incognita) on growth, yield, physiological parameters, biochemical responses and disease development in chickpea. Plants were exposed to 6.0 to 3.0 SAR acidity levels (pH) in combination with M. incognita inoculation to evaluate the combined stress effects. Results revealed that increasing acidity levels of SAR significantly reduced plant growth and yield parameters, including plant growth, yield, nodulation, leaflet area, and relative water content, compared to untreated uninoculated control (UUC) and untreated inoculated control (UIC). The maximum reduction in growth and yield parameters was observed under the pH 3.0 + M. incognita treatment, showing severe synergistic stress effects. Photosynthetic pigments, leghaemoglobin content, protein content and nitrate reductase (NR) activity also declined progressively with increasing acidity levels under nematode infestation. The highest proline accumulation and antioxidant enzyme activities (SOD, CAT and POX) were observed in plants exposed to pH 3.0 plus M. incognita. The galling and egg mass production of M. incognita declined gradually with increasing acidity and showed near complete suppression under highly acidic treatments (pH 3.5 + M. incognita and pH 3.0 + M. incognita).