Vol. 5 No. 1
Biochemical factors for TLCV tolerance in tomato genotypes.
Abstract: An experiment was conducted during 2000 – 05 to evaluate 25 tomato (Lycopersicon esculentum Mill.) genotypes for resistance to tomato leaf curl virus. The percent disease incidence and coefficient of infection in the genotypes was highest in early autumn (planting in last week of August) followed by spring-summer (planting in first week of February) and autumn-winter (planting in second week of October) seasons suggesting significant influence of environment on symptom expression apart from white fly population. The three moderately resistant lines emerged from the study viz., ‘H-24’, ‘Agata’ and ‘EC-321425’ showing very low coefficient of infection (2-6), were crossed with 5 highly susceptible testers with very high coefficient of infection ( above 21), namely ‘Punjab Chhuhara’, ‘Pusa Ruby’, ‘Ratan’, ‘Hisar Arun’ and ‘Patharkutchi’ in line x tester mating design. The hybrids recorded a range of intermediate disease reaction and it varied widely in 2 seasons suggesting polygenic nature of disease resistance. Higher total phenol content in the leaves estimated at 80 days growth stage appeared to have determined the resistance actively in the host. Exploitable level of disease resistance could be achieved in very few hybrids involving moderately resistant x susceptible cross.
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