Sharma, Vinoy KumarKumari, Ranju2016-10-202016-10-202012http://krishikosh.egranth.ac.in/handle/1/81135An investigation was carried out to assess the extent of genetic divergence, heterosis manifestation, relation between heterosis and genetic divergence and inbreeding depression using eight inbred lines of maize. These eight parental lines including five quality protein maize (QPM) and three non-QPM inbreds were crossed in all possible combinations excluding reciprocal to generate twenty eight experimental hybrids. Twenty eight advanced generation (F2) progenies were developed by selfing. The experimental materials consisting of eight inbreds, 28 F1’s , 28 F2’s and a check were evaluated in randomized block design with three replications under timely and late sown conditions. The observations for plant height, ear length, ear girth, number of kernel rows per ear, number of kernels per row, 100 kernels weight were recorded on five random plants in each replication, whereas observations for days to 50 % tassel emergence, days to 50% silk emergence and days to 50% maturity were recorded on plot basis. An analysis of variance indicated the existence of highly significant differences among the entries in respect of all the characters studied under timely and late sown conditions and across the dates of sowing. Six isozyme systems, namely peroxidase, esterase, acid phosphatase, catalase, amylase and alcohol dehydrogenase were used for characterization of eight maize inbred lines. Isozyme pattern of peroxidase, catalase and amylase were also compared amongst the eight parental lines and fifteen single cross experimental hybrids generated from these eight inbreds. Peroxidase and catalase isozyme patterns were found to be useful in distinguishing hybrids from parental lines. An analysis of divergence using isozyme patterns based similarity coefficients and morpho-agronomical traits based average taxonomic distances reflected the existence of considerable genetic divergence among the eight inbred lines. A comparison of dendrograms obtained under timely and late sown conditions and across the date of sowing indicated a close correspondence in the clustering patterns of inbred lines. The effect due to variation in the date of sowing in the form of timely and late sown conditions did not influence the clustering pattern of maize inbreds to a considerably greater extent. Eleven experimental hybrids recorded significantly higher mean performance and significant standard heterosis for grain yield. Heterosis manifestation in most of the cases was found to be associated with simultaneous heterosis in ear length, number of kernels per row and 100 kernels weight. Keeping into consideration greater magnitude of heterosis, higher mean performance and lesser magnitude of inbreeding depression in respect of yield per plant, five crosses, namely, CM 300 x CML 142, CM 300 x CML 144, CM 300 x CML 150, CM 300 x CML 176 and CML 150 x CML 144 were identified for their further utilization in maize improvement programme for the development of superior inbred lines.enMaizeGenetic divergenceIsozyme patternHeterosisThesis