Effect of SO₂ on Mortality of Seed Gall Nematode, Anguina tritici and Interactive Effect of Both on Wheat

The present study was carried out to assess the interaction of biotic and abiotic pathogens on wheat crop pathosystem. Firstly, the effect of different concentrations of SO₂ (0.05, 0.1 and 0.2 ppm) were examined on mortality of seed gall nematode, Anguina tritici at different time intervals (1, 2, 3 and 4^th days). All the conc. of SO₂ were harmful to juveniles of A. tritici. The effect was directly proportional to the conc. and time periods. The interactive effect of different conc. of SO₂ with different levels (2,500, 5,000, and 10,000) of nematode were studied on plant growth (length, fresh wt., dry wt. of shoot and root, no. of tillers, leaf area) and yield parameters (length of ear, wt. of 100 grains/ear and no. of cockles/ear), photosynthetic pigments (chl a, chl b, total chl (a+b), carotenoids), seed carbohydrate (soluble and insoluble) and seed protein (soluble and insoluble) contents of wheat. All the above growth and yield as well as biochemical parameters of wheat were reduced significantly. Both the pathogens (biotic and abiotic) interacted antagonistically. Wheat plants inoculated with lower inoculum levels (2,500 and 5,000) and exposed with lower cone. of SO₂ (0.05 ppm) were found less affected in terms of all above parameters compared to higher doses of SO₂ (0.1 and 0.2 ppm) with any levels of inoculum. The lower dose of SO₂ (0.05ppm) was, however effective to kill the nematodes, consequently none of the gall was formed.