HARIPRASAD REDDY, KPARAMESH, M2019-05-072019-05-072018http://krishikosh.egranth.ac.in/handle/1/5810102172D5720The present investigation was carried out with 55 single cross hybrids derived by crossing 11 inbreds in half diallel and their 11 parents under normal (Experiment I) and rice fallow situation (Experiment II) for identification of favourable alleles in inbreds and to get information on combining ability and heterosis for yield and yield components, at Sri Venkateswara Agricultural College, Tirupati. Further generation mean analysis (Experiment III) was carried out to assess the gene action for yield and yield components in five selected cross combinations. In experiment I, based on per se performance the parents viz., BML 2, BML 14, CM 119 and BML 51and hybrids viz., BML 7 × BML 15, BML 6 × BML 7, BML 2 × BML 7, BML 7 × CM 119 and BML 7 × BML 14 were identified as the best parents and hybrids, respectively. The studies on identification of favourable alleles (μG') revealed that for first target hybrid DHM 117 (BML 6 × BML 7), the donors BML 15 and BML 2 and for second target hybrid DHM 113 (BML 2 × BML 7), the donors BML 15 and BML 6 showed highest frequency of favourable alleles (μG') to further improve their yield performance. Similarly, for first superior cross BML 7 × BML 15, the donors BML 14 and CM 119; for second superior cross BML 7 × BML 14, the donors BML 15 and BML 2 were showed highest frequency of favourable alleles (μG'). Hence, utilization of the identified donor inbreds with favourable alleles in the recycling or pedigree breeding programmes may improve the performance of the parents of the target hybrids and thereby utilized in enhancement of the hybrid performance. Combining ability analysis results revealed that yield and yield components displayed non-additive gene action in their inheritance and it could be suggested xx that heterosis breeding can profitably be used for exploitation of hybrid vigour in maize on commercial scale. The parents viz., BML 7, BML 51, CM 119 and BML 2 were identified as best general combiners and the hybrids BML 5 × CML 124, BML 51 × BML 5, BML 6 × BML 7 and BML 7 × BML 14 were identified as best specific cross combinations for yield and yield components. Based on the per se performance, combining ability and heterosis the hybrids viz., BML 7 × BML 15, BML 6 × BML 7, BML 2 × BML 7, BML 7 × CM 119 and BML 7 × BML 14 were identified as the best hybrids. Hence, these crosses could be suggested for use in hybrid breeding programmes or further forwarded to advanced generations in order to isolate desirable transgressive segregants. In experiment II, under rice fallow situation, based on per se performance the parents viz., BML 2, BML 14 and BML 6 and the hybrids viz., BML 7 × BML 15, BML 2 × BML 7, BML 7 × BML 14, BML 6 × BML 7 and BML 7 × CM 118 were identified as the best parents and hybrids, respectively. The results on identification of favourable alleles (μG') under rice fallow situation revealed that for first target hybrid DHM 117, the donor inbreds BML 15 and BML 2 and for second target hybrid DHM 113, the donor inbreds BML 15 and BML 14 showed highest frequency of favourable alleles (μG') to further improve their yield performance. Similarly, for first superior cross BML 7 × BML 15, the donors BML 2 and BML 6; for second superior cross BML 7 × BML 14, the donors BML 15 and BML 2 showed highest frequency of favourable alleles (μG'). Based on mean and gca effects, the inbreds BML 2 and BML 15 were identified as the best parents and based on mean and sca effects the hybrids viz., BML 7 × BML 15, BML 2 × BML 7, BML 7 × BML 14 and BML 7 × CM 118 were identified as promising hybrids for yield and yield components. Heterosis studies revealed that the hybrids viz., BML 7 × BML 15 and BML 2 × BML 7 were identified as best hybrids as they exhibited significant standard heterosis. Hence, these hybrids could be exploited in heterosis breeding programme to improve kernel yield in maize under rice fallow situation. Based on the per se performance, combining ability and heterosis the hybrids viz., BML 7 × BML 15, BML 2 × BML 7, BML 7 × BML 14, BML 6 × BML 7 and BML 7 × CM 118 were identified as the best hybrids under rice fallow situation and suggested for best utilization in rice fallow system. For both normal and rice fallow situations the inbreds viz., BML 7, BML 2 and BML 51 were identified as the best parents. The hybrids viz., BML 7 × BML 15, BML 2 × BML 7, BML 7 × BML 14 and BML 6 × BML 7 exhibited good per se performance, combining ability and heterosis estimates for yield and yield components both in normal and rice fallow situations. Hence, these hybrids could be suggested for effective utilization in both normal and rice fallow situations. xxi In experiment III, generation mean analysis for yield and yield components in five crosses viz., BML 7 × BML 15, BML 6 × BML 7, BML 2 × BML 7, BML 7 × CM 119 and BML 7 × BML 14 deciphered the importance of epistatic effects besides the major components viz., additive and dominance gene effects for all the traits in majority of the crosses. Though both additive and non-additive gene actions were significant, non-additive gene actions played predominant role in the inheritance of the traits. Majority of the traits are under the influence of duplicate epistasis besides non-additive type of gene effects for which bi-parental mating or reciprocal recurrent selection may be adopted followed by pedigree method of selection to modify the genetic architecture of maize for attaining higher yield.en-USnullThesis