Resistance to Alternaria Blight in Brassica juncea (var. RLM619) Induced by Combination of Elicitors and Inoculation with Alternaria brassicae under Controlled Environment
2014
Sharma, Sanjula | Sohal, BS
The present experiment was conducted under controlled environmental conditions. Indian mustard (Brassica juncea var. RLM619) was grown in pots in an incubator at 25±2ºC temperature under 16/8 h light/dark period, RH 60–70%) for one week and watered with combinations of Benzothiadiazole (BTH) and Salicylic acid (SA) elicitor's viz. T1 (3.3ppm BTH + 33.3ppm SA) and T2 (6.6ppm BTH + 16.6ppm SA). The experiment revealed changes in activities of defense enzymes viz, Peroxidase (PO), Superoxide dismutase (SOD) and Phenylalanine ammonia lyase (PAL); phenolics; chlorophyll and carotenoid content on application with both the combinations of elicitors as compared to control. Out of the two combinations tried, spray with T1 was observed to be more effective. Significant elicitation in activity of defense enzymes, phenolics, total chlorophyll and carotenoid content was observed by inoculation with spores of Alternaria brassicae in the cotyledonary leaves of one week old seedlings sprayed with both the treatments on all days of observation (3ʳᵈ, 5ᵗʰ and 7ᵗʰ days after inoculation). Effect of combinations of elicitors (T1 and T2) on the SOD activity in the cotyledonary leaves did not show a regular trend in the activity. Both combinations of elicitors have demonstrated a beneficial effect in eliciting the defense response by increasing chlorophyll and carotenoid contents. The improvement of plant growth and development produced by these elicitor's treatments suggests crop tolerance in response to these chemicals, although effective formulations that are safe to humans must be developed before this technology can be used commercially. These results suggest that pretreatment with biological or chemical defense activators can induce local and systemic resistance to Alternaria blight.
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