Effect of Different Organic Amendments on Fusarium oxysporum f.sp ciceri Causing Chick Pea Wilt.

Chickpea (Cicer arietinum L.) is one of the most important legumes grown in Asia. Though the area under this crop is more, the average yield per hectare is low because of several biotic and abiotic factors. Among them, the wilt caused by Fusarium oxysporum f.sp. ciceri is most destructive seed and soil borne disease. (Haware et al., 1986) which threatens successful cultivation of chickpea and causes severe losses in chickpea growing areas. (Grewal et al.,1974b and Singh et al.,1977.) The organic amendments viz., saw dust, ground nut cake, FYM, soybean cake, cotton cake were used in three concentrations 0.1%, 0.2%, 0.3% . The highest per cent growth of inhibition was observed in soybean cake 0.3% (32.96%), followed by groundnut cake 0.3% (29.63%). The lowest per cent growth inhibition was observed in saw dust 0.1% (06.47%).

Efficacy of Bioagents Against Chickpea Wilt Pathogen.

Chickpea (Cicer arietinum L), wilt caused by Fusarium oxysporum f.sp. ciceri was first reported from India in 1918. ln the recent years, the biological control has received a worldwide attention and is being integrated effectively with other pesticides. The efficacy of two species of fungal bioagents such as Trichoderma viride, Trichodermo harzianum and two sps of bacterial bioagents such as Pseudomonas fluorescens and Bacillus subtilis were evaluated against Fusarium oxysporum f.sp. ciceri in vitro condition using Dual Culture Technique. The highest per cent growth of inhibition of observed Trichoderma harzianum (76.66%) followed by Bacillus subtilis (63.14%). The lowest growth inhibition was observed in Pseudomonas fluorescens (53.52%).

Efficacy of Different Inorganic Molecules on Wilt Pathogen of Chickpea.

Chickpea (Cicer arietinum L.) is one of the most important legumes grown in Asia. Though the area under this crop is more, the average yield per hectare is low because of several biotic and abiotic factors. Among them, the wilt caused by Fusarium oxysporum f.sp. ciceri is most destructive seed and soil borne disease. (Haware et al., 1986) which threatens successful cultivation of chickpea and causes severe losses in chickpea growing areas. (Grewal et al.,1974b and Singh et al.,1977.) Different insecticides and herbicides were tried under in vitro, the insecticides Emamectin benzoate 5% SG, Imidachloprid 75% WP, Quinalphos 25% EC, Entrust 80% WP were used in three different concentrations. Among these highest per cent growth of inhibition of Fusarium oxysporum f.sp. ciceri was observed in Imidacloprid 0.3g (50.92%) followed by Emamectin benzoate 0.05 mg (35.55%). The herbicides viz., Pendimethalin 30%EC, Imazathaphyr 10% SL, 2,4-D sodium salt 80%WP, Metsulfuron methyl 20% WG were used in three different concentrations, highest per cent growth of inhibition of Fusarium oxysporum f.sp. ciceri was observed in Pendimethalin 0.5ml (73.33%), followed by Pendimethalin 0.4ml (65.55%).

Effect of Iron Availability on Induction of Systemic Resistance to Fusarium Wilt of Chickpea by Pseudomonas spp

Selected isolates of Pseudomonas fluorescens (Pf4-92 and PfRsC5) and P. aeruginosa (PaRsG18 and PaRsG27) were examined for growth promotion and induced systemic resistance against Fusarium wilt of chickpea. Significant increase in plant height was observed in Pseudomonas treated plants. However, plant growth was inhibited when isolates of Pseudomonas were used in combination with Fusarium oxysporum f. sp. ciceri (FocRs1). It was also observed that the Pseudomonas spp. was colonized in root of chickpea and significantly suppressed the disease in greenhouse condition. Rock wool bioassay technique was used to study the effect of iron availability on the induction of systemic resistance to Fusarium wilt of chickpea mediated by the Pseudomonas spp. All the isolates of Pseudomonas spp. showed greater disease control in the induced systemic resistance (ISR) bioassay when iron availability in the nutrient solution was low. High performance liquid chromatography (HPLC) analysis indicated that all the bacterial isolates produced more salicylic acid (SA) at low iron (10microM EDDHA) than high iron availability (10microFe3+ EDDHA). Except PaRsG27, all the three isolates produced more pseudobactin at low iron than high iron availability.

Induction of Defense Related Enzymes and Pathogenesis Related Proteins in Pseudomonas fluorescens-Treated Chickpea in Response to Infection by Fusarium oxysporum f. sp. ciceri

Pseudomonas fluorescens 1-94 induced systemic resistance in chickpea against Fusarium wilt of chickpea caused by Fusarium oxysporum f. sp. ciceri by the synthesis and accumulation of phenolic compounds, phenylalanine ammonia lyase(PAL) and pathogenesis related(PR) proteins(chitinase, beta-1,3-glucanase and peroxidase). Time-course accumulation of these enzymes in chickpea plants inoculated with P. fluorescens was significantly(LSD, P=0.05) higher than control. Maximum activities of PR-proteins were recorded at 3 days after inoculation in all induced plants; thereafter, the activity decreased progressively. Five PR peroxidases detected in induced chickpea plants. Molecular mass of these purified peroxidases was 20, 29, 43, 66 and 97 kDa. Purified peroxidases showed antifungal activity against plant pathogenic fungi.