Investigation On The Control Of Rhizoctonia root and crown rot of rapeseed using enriched compost by antagonistic Microorganisms under In vitro and In vivo condition.

Root and crown rot of rapeseed caused by Rhizoctonia solani is one of the important disease of this crop in the country. Adoptation of biological methods, is one of the suitable method in controlling these diseases. Methodes of formulation and application of these biological compound play an important role in their success. However, in this study, impact of antagonist microorganisms along with compost in controlling Rhizoctonia root and crown rot was investigated. On first year of experiment, the antagonistic ability of 100 Pseudomonas fluorescens isolates, 100 isolates of Bacillus spp. and 100 isolates of Trichoderma spp. were tested against R. solani under in vitro and three promising isolates of each genus (P44, P55, P77, B26, B41, B96, T32, T43, T64) were selected to be tested under greenhouse conditions. Scrutiny efficacy of these isolates alone (without compost) and with compost (enriched compost) on disease and plant growth indices showed that though application of antagonist isolates alone caused significant increase in germination percentage and decrease in disease indices as compared to infested control check plants, but application of them along with compost not only increasing germination rate of seeds up to control check treatment, but caused significant reduction in disease indices and increase in dry root and shoot weight as compard to control check plants. According to the results obtaind, three promising antagonist organisms (P44, B96, T32) along with compost, alone or in combination, were selected for field trail in Kermanshah, west Azarbayjan and Mazandaran provinces. Experiment comprised 10 treatments which were replicated 4 times and arranged in completely randomized block design. Result of field experiments showed that all treatment containing antagonists caused significant increase in number of seedlings in unit area at six leaf and rosette stages as compared to infested control check treatment, also in all treatments root and crown infestation were significantly less than control check treatment before 50 harvest and the yield was significantly higher than control check treatment in all provinces. It was revealed that treatments 4(P44), 6(B96+T32), 9(B96+P44) and 10(Carboxin Tiram) at six leaf stage and 3(B96), 5(T32), 6(B96+T32), 9(B96+P44) and 10(Carboxin Tiram) at rosette stage were at par with control uninfested check treatment in all provinces. As far as root and crown infestation before harvest stage is concerned, though 4(P44), 8(B96+P44+T32) uninfested control check treatments were statistically at same level but the yield in 3(B96), 4(P44), 6(B96+T32), 7(P44+T32), 8(B96+P44+T32) and 10(Carboxin Tiram) and uninfested control check treatments at all three provinces were at par or their yield were higher than uninfested control check treatment.