Individual and combined effects of SO2 and O3 on root knot nematode multiplication

Both (sulphur dioxide and ozone) gases have been proved harmful to all the living organisms. In the present study, root- knot nematode (Meloidogyne incognita Race 1)infected green gram (Vigna radiata cv.T-44) plants were exposed with SO2 and O3 individually or jointly in presence or absence of root-nodule bacteria (Rhizobium leguminosarum bv trifolli). Both SO2 and O3 individually reduces the fecundity, number of females and juveniles(J2&J3+J4), population(root,soil and total population) and reproduction factor (Rf) of root-knot nematode.However, O3 is proved to be more toxic to all these parameters, compared to any SO level. Although, the reductions were enhanced in SO and O joint exposures. The reductive trend in the studied parameters can be arranged as:SO2 < O3 < SO2 +O3 .The reductions were furthered by Rhizobium inoculations except fecundity. Nematode multiplication, in terms of their population andRf, was reduced gradually in gradualSO and/orO pollutant/s combinations.Thus reduction was SO2 and/or O3 concentration dependent. More reduction occurred in higher than lower SO2 and O3 joint combinations. Maximum reductions were occurred in 0.3ppm of each of SO2 and O3 mixture, particularly in presence of root- nodule bacteria.