Heterosis and combining ability for tomato leaf curl virus (ToLCV) and Bacterial wilt disease in tomato (Solanum lycopersicum L.)

Abstract

ToLCV (Gemini virus) and Bacterial wilt (Ralstonia solanacearum) are the important diseases affecting the tomato and cause 
more than 90 per cent yield loss especially during summer and rainy seasons. In the present experiment 63 genotypes were 
evaluated for the magnitude of resistance for ToLCV and bacterial wilt diseases. Among them, four were highly resistant and 
nine were resistant to ToLCV incidence and four were resistant and four were moderately resistant to bacterial wilt incidence. 
Only four genotypes viz., TP25, TP29, TP40 and TP43 showed combined resistance to ToLCV and bacterial wilt incidence. 
Maximum heterosis over better parent and standard parent in desirable direction were -92.03 per cent (TP24 x TP40: TP45 x 
TP25) for per cent ToLCV incidence; -92.64 per cent (TP24 x TP40: TP45 x TP25) for per cent ToLCV coefficient of infection 
and 98.15 per cent (TP1 x TP29) and 70.56 per cent (TP5 x TP29) for total yield per plant respectively. 18 crosses exhibited non 
significant (desirable) heterosis over the standard parent (TP25) in the needful direction and 15 crosses exhibited negative and 
significant heterosis over better parent for bacterial wilt incidence. The cross TP26 x TP40 for ToLCV incidence and TP24 x 
TP40 for ToLCV coefficient of infection, bacterial wilt and total yield per plant were identified as good specific combiners. The 
parents TP46, TP44 and TP27 for ToLCV incidence and ToLCV coefficient of incidence; TP24 and TP27 for bacterial wilt and 
TP5 and TP44 for total yield per plant were identified as good general combiners.