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GP 643 CONCEPTS IN HETEROSIS BREEDING                                                                 (2L+1P) II

Theory

UNIT I
Heterosis: Introduction, Nomenclature and definitions of heterosis - Heterosis in natural and bred population; Evolutionary aspects - Genetic consequences of selfing and crossing in self-and cross-pollinated and asexually propagated crops crops;

UNIT II
Pre Mendelian and Post Mendelian ideas - Genetic theories of  heterosis – Physiological, Biochemical and molecular factors underlining heterosis; theories and their estimation; - Evolutionary concepts of heterosis

UNIT III
Prediction of heterosis from various crosses - Inbreeding depression, frequency of inbreeding and residual heterosis in F2 and segregating populations, importance of inbreeding in exploitation of heterosis – case studies. - Relationship between genetic distance and expression of heterosis – case studies; Divergence and Genetic Distance analyses-morphological and molecular genetic distance in predicting heterosis, Development of heterotic pools in germplasm/genetic stocks and inbreds, their improvement for increasing heterosis

UNIT IV
Types of male sterility and use in heterosis breeding, Maintenance, and transfer of different types of male sterility.Fertility restoration- Genetics,Allelic relationship and breeding of new restorer lines. Hybrid seed production methods involving 3-lines, 2-lines and 1-line system, Development of inbreds and parental lines- A, B and R lines Use of self-incompatibility in development of hybrids

UNIT V
Fixation of heterosis in self, cross and often cross pollinated crops, asexually / clonally propagated crops, Apomixis in fixing heterosis-concept of single line hybrid.

UNIT VI
Molecular basis of heterosis, molecular basis of male sterility and fertility restoration, genetic basis of inbreeding depression. Heterosis breeding in wheat, rice, cotton, maize, pearl millet, sorghum and oilseed crops

Practicals
Selection indices and selection differential – calculations and interpretations - Male sterile line characterization in millets; using morphological descriptors; restorer line identification and diversification of male sterile sources - Male sterile line creation in dicots comprising oilseeds, pulses and cotton; problems in creation of CGMS system; ways of overcoming them - Male sterile line creation, diversification and restoration in forage crops; understanding the difficulties in breeding apomicts; Estimation of heterotic parameters in self, cross and asexually propagated crops - Estimation from the various models for heterosis parameters -Hybrid seed production in field crops – an account on the released hybrids; their potential; problems and ways of overcoming it; hybrid breeding at National and International level; opportunities ahead.

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