Heterotic analysis and yield assessment of maize (Zea mays L.) inbred lines for developing superior hybrids under sub-tropical climatic conditions

Hybrid breeding program in maize is dependent on the availability of heterotic inbred lines for full exploitation of heterosis. Identification of heterotic patterns among inbred lines is prerequisite for obtaining high yielding superior hybrids. A total of 156 inbred lines were evaluated thoroughly, out of which, a set of 25 promising parental inbred lines, derived from different heterotic pools, semi exotic and indigenous lines, were evaluated at Ludhiana for two years. Based on their reproductive synchronization and pre-determined heterotic grouping, a total of 25 hybrids have been developed. Hybrids thus developed, were evaluated for eight yield related traits for two years at two locations (Ludhiana and Gurdaspur). Highly significant differences have been observed among the inbred lines for almost all of the traits. Likewise, high significant differences have also been observed in hybrids for both years at both locations. Yield was exhibiting significant but negative correlation with days to 50% pollen and silking for both years in inbreds. Principal component analysis also revealed that days to 50% pollen and silking, anthesis-silking interval and days to 75% brown husk were negatively correlated with yield for both years in inbreds. Both association studies and principal component analysis showed no significant association with yield in hybrids for both years at both locations. On the basis of heterotic patterns of promising inbred lines, a total of seven superior hybrids were identified having high yield constantly for both years at both locations. These promising inbred lines could be used for developing source populations for generating new inbred lines in maize and the superior hybrids could be used for further testing and promotion for adoption and commercialization in sub-tropical climate.