Studies on Groundnut Rust Caused By Puccinia Arachidis Speg.
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Date
2015-10
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University of Agricultural Science, Dharwad
Abstract
Groundnut rust caused by Puccinia arachidis Speg. is one of the most important foliar disease. Maximum disease severity of 86.42 PDI was recorded in Jambaldinni village of Raichur taluka. PaKUS isolate was found to be different from other isolates, which has recorded round shaped pustules, uredospores were oblong to ellipsoid in shape, bigger in size (585.84 µm2), showed maximum per cent germination of uredospores (90.00%) at 250C and 86.33% at pH 9. DNA amplication was observed at the region 600 bp. Variation was observed in nucleotide sequences from 77 to 99 per cent among the isolates.
At -80 and -20 0C, viability of uredospores was noticed upto 90 days. Teliospores were found in Ranebennur isolate (PaRAN) but there was no production of teliospores under modified environmental conditions and detached leaf technique. Disease intensity increased in older plants compared to young plants. Maximum germination of uredospore was observed at 2.0 per cent sucrose solution (45.33%) at 24 h after incubation.
Out of 108 genotypes screened, five genotypes viz., GPBD-4, GPBD-5, ICGV-86699, TG-72 and TG- 37A found highly resistant. Resistant genotypes had more quantity of reducing, non-reducing and total sugars as compared to susceptible genotypes.
Under in vitro condition, Azadirachta indica leaf extract was highly significant in suppressing the uredospore germination. Culture filtrate of bioagents revealed that bacterial bioagents were better than fungal bioagents in inhibiting the uredospore germination Hexaconazole under systemic and mancozeb under non systemic fungicide were found highly effective in inhibition of germination of uredospore.
In vivo studies revealed that, the treated check (Hexaconazole @ 0.1%) recorded significantly low disease (12.21 PDI) with 88.85 per cent reduction in disease severity over control and high yield (2696 kg/ha). The organic based treatment, Azadirachta indica leaf extract + Pseudomonas fluorescens recored 2511 kg/ha. Which was on par with the treated check.
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