Screening
and genetic studies of certain maize genotype for resistance to southern corn
leaf blight in India
Omprakash1,
Rajesh Singh1, Rajeshwar Nandan1, Dan Singh Jakhar1,
KN Chourasia2
1Department of Genetics and Plant
Breeding, IAS, BHU, Varanasi-221005
2Department
of Genetics and Plant Breeding, GBPUAT Pantnagar-263145
Received: 26 August 2016 Revised
Accepted: 15 October 2016
ABSTRACT
Southern Corn Leaf Blight (SCLB) incited by Helminthosporium maydis, is a serious
disease of Maize. The 53 maize inbreds were screened for SCLB during rainy
season consequently for two year 2013 and 2014. A standard visual scale of 1 to
5 is being used by CIMMYT pathologist was considered appropriate for disease
scale. Based on disease scale Percent Disease Index (PDI) and Area under
Disease Progressive curve (AUDPC) considered as disease trait for screening of
maize germplasm as well as estimation of Genetics of SCLB. On an average over
four environments 25 resistance, 17 partial resistances, 3 susceptible lines
were identified. In general there were less diseases in E1 (Varanasi
in Northern India) than E2 (Nagenhalli in Southern India) though
equal load of inoculums were applied in both the cases. Genetics of Helminthosporium maydis were studied in
three crosses viz, CM-
212 (P1) x V- 336 (P2), CM- 212 (P1) x V- 338
(P2) and CM212 (P1) x CM145 (P2) using Scaling test, Joint Scaling Test and
Jinks and Jones (1959) six parameters model. Diseases scores of P1,
P2, F1, F2, B1 and B2
generations of the 3 crosses were used for genetics studies. All the effects (additive,
dominance, additive x additive, additive x dominance and dominance x dominance) were important for expression of SCLB in
all three crosses. Study of
generation mean analysis revealed that all three crosses exhibited duplicate
type of epistasis. Thus analysis
revealed that SCLB resistance could be population non specific, although
various types of gene effects were observed.
Key Words: Resistance, Screening, Southern corn leaf blight,
Zea mays L.