Management of Sclerotinia stem rot of rapeseed mustard using plant defense inducers
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
The stem rot caused by Sclerotinia sclerotiorum (Lib.) de Bary is one of the major diseases of rapeseed-mustard. In this study, plant defense inducers salicylic acid and sodium propionate, fungicide azoxystrobin, carbendazim and bio-control agents Trichoderma harzianum and Pseudomonas fluorescens were evaluated for the management of Sclerotinia stem rot of rapeseed-mustard. These treatments were given as seed cum foliar treatment and foliar sprays alone. In field trials conducted during 2019 and 2020, the highest per cent reduction in mean lesion length was in carbendazim @0.2 per cent as seed treatment cum foliar spray, which was 56.76 and 80.81 per cent during 2019 and 2020, respectively. It was followed by application of 100 ppm azoxystrobin as seed treatment cum foliar spray that gave 35.14 and 64.18 per cent reduction during 2019 and 2020, respectively. Under in vitro conditions carbendazim completely inhibited the growth of the pathogen at all tested concentrations followed by 150 ppm salicylic acid which inhibited growth by 49.44 per cent. The bio-control agent T. harzianum showed antagonistic activity against S. sclerotiorum and restricted growth by 45.19 per cent. The biochemical studies showed that application of 150 ppm salicylic acid as seed cum foliar spray resulted in increased activity of POD which was 217.61 units/ min/ gfw and SOD activity which was 60.09 units/ min/ gfw at 72 hours after inoculation. The PAL enzyme activity was found to be highest at 120 hours after inoculation which was 765.05 µg-t-cinnamic acid formed/ hour/ gfw. The lignin content and total phenol content was increased at 168 hours after inoculation which was 24.40 mg/g and 1.82 mg/g respectively. In quantitative expression analysis, the significant increase in activity of BjPAL and POD genes was observed at 72 hours after inoculation when compared with control. This suggests that seed treatment and foliar application of plant defense inducers are effective for induction of defense responses against S. sclerotiorum in rapeseed-mustard.
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Sudam, Shelke Saraswati (2021). Management of Sclerotinia stem rot of rapeseed mustard using plant defense inducers (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.