Effect of plant age and inoculum concentration on ascochyta blight development in chickpea
2006
Riaz, A. (University of Arid Agriculture, Rawalpindi (Pakistan). Dept. of Plant Pathology) | Rauf, A. (University of Arid Agriculture, Rawalpindi (Pakistan). Dept. of Plant Pathology) | Haque, M.I. | Naz, F.
The impact of plant age on Ascochyta blight of chickpea (Cicer arietinum) on two cvs. Balkasar-2000 (moderately resistant) and AUG-424 (highly susceptible) and inoculum concentration on three cvs. namely Balkasar 2000, AUG-424 and Noor-91 (susceptible) was assessed using the isolate ID-1 of Ascochyta rabiei in two separate trials in glass house. For plant age trial, both cultivars were tested at different physiological stages from 2 to 14 weeks after sowing, representing the seedling to the flowering stage. Disease was more severe on 14-week-old plants of Balkasar-2000 than it was on 2-week-old seedlings after 14 days incubation but all plants of AUG-424 were killed irrespective of any age difference. In inoculum concentration trials, a positive correlation was observed between disease severity and inoculum conc. in the range of 5x10(-4) to 8x10(-5) conidia per mL. Disease symptoms were the least severe on Balkasar-2000 with mean disease severity of 40% at the highest inoculum conc. Disease severity increased from 46 % to 100 % in Noor-91 (a susceptible cv.), when inoculum conc. increased 4 times (from 5x10(-4) to 2x10(-5) conidia per mL). Plants of AUG-424 were completely killed (100% disease severity) 14 days after inoculation at all the conc. tested. In this study, a dose of 2x10(-5) conidia per mL was considered optimal for reproducing the disease reaction. These results indicate that plant age is a significant factor towards resistance and it decreases with increase in plant age in moderately resistant cultivars. However, in susceptible cultivars, plant age has no impact on resistance.
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