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Subject: Plant Pathology × Author: Harleen Kaur × End date: 2018 × Start date: 2010 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Pathogenic and genetic variability in isolates of Fusarium moniliformeSheld. causing stalk rot of maize (Zea maysL.) and its managemen
    (PAU, 2012) Harleen Kaur; Chander Mohan
    Disease surveys revealed that Fusarium stalk rot was present in all the maize growing areas of Punjab and disease incidence and severity were comparatively high on private company hybrids (31-Y-45 and Double) as compared to public sector hybrids (PMH 1and PMH 2).Maximum disease incidence and severity were found in the district of Hoshiarpur closely followed by Nawanshahar during both Kharif and spring seasons. Frequency of occurrence of Fusarium moniliformeon stalk rot infected plants was highest followed by Macrophomina phaseolina and Cephalosporium maydis.In all, 56 isolates of F. oniliforme were obtained. They were grouped into seven major clusters based on their cultural and morphological characteristics. Pathological behavior of all isolates of F. moniliforme differed on a set of five inbred lines (LM-13, CM-140, CM-143, CML-25 and CM-600) and four maize hybrids (PMH 1, JH 3459, NK 6240 and 31-Y-45). On the basis of multivariate cluster analysis of pathogenicity data, seven clusters were formed and each cluster represented a specific disease reaction to a particular hybrid/inbred tested. The isolate Fm 10 was found most pathogenic with average disease index (ADI) of 66.6 per cent hereas,the isolate Fm 45 was found least pathogenic with ADI of 42.5 per cent. Cross infectivity studies revealed that the maize isolate of F. moniliforme was pathogenic to wheat and basmati rice and non-pathogenic to peas, non-basmati rice and sugarcane. Likewise, sugarcane isolate of F. moniliforme was found most virulent; wheat and rice isolates moderately virulent and basmati rice and pea isolates were comparatively less virulent on maize. Out of twenty RAPD markers used to study the molecular variability of all 56 isolates of F. moniliforme, 18 showed amplification with a total of 220 amplified fragments. The PIC value was found lowest in primer OPT-9 and highest in primer OPT-12. Dendrogram based on molecular data generated by 18 RAPD primers showed six complete clusters and one independent lineage. When the clusters obtained by morphological, pathological and molecular data werecompared, no association could be obtained among cultural characteristics, virulence pattern and RAPD pattern. Studies of antagonistic potential of native biocontrol agents against F.moniliforme revealed that richoderma harzianumisolate, Th1 showed strong mycoparasitism by completely covering the mycelium of pathogen within 4 days of incubation under in vitroconditions. Two methods of application viz. seed treatment with Th1 @ 20 g/kg seed and amending the soil with FYM supplemented with talc based formulation of T. harzianum found promising in pot house studies, were further tested under field conditions. The maximum disease control and seed germination were obtained when soil was broadcasted with FYM supplemented with T. harzianum@ 2 kg talc/q FYM and amendment of soil with FYM supplemented with T. harzianum@ 100g/hill, respectively. Maximum increase in grain yield was obtained in FYM supplemented with T. arzianum@ 100g/hill