2. Combination of parents (1) Significance Key to successful breeding: (2)Principles 1)More advantages, less disadvantages; Complementary 2)Large genetic differences 3)High combining a bility GCA: Additive gene effects SCA: Heterosis effects(non-additive) Good cultivars are not always good parents 4)Salient objective characters in one or both parents, with a high inheritability 5)Select one locally popularized cultivar as one of the parents 3) Successful Selection and combination of parents in cross breeding Tab6-1,p.90
2. Combination of Parents (1) Significance Key to successful breeding: (2) Principles 1) More advantages, less disadvantages; Complementary 2) Large genetic differences 3) High Combining ability: GCA: Additive gene effects SCA: Heterosis effects (non-additive) Good cultivars are not always good parents 4) Salient objective characters in one or both parents, with a high inheritability 5) Select one locally popularized cultivar as one of the parents (3) Successful Selection and combination of parents in cross breeding Tab. 6-1, p. 90
s3 Modes of Cross and the Techniques 杂交方式和技术 1. Modes of Cross: Number of parents Modes of combination (1) Single Cross AXB or A/b(Cytoplasm from A) BXA or b/a(Cytoplasm from B) (2) Multiple cross 1) Three way cross (A×B)×CorA/B∥C( Cytoplasm ofA,C=1/2)
§3 Modes of Cross and the Techniques 杂交方式和技术 1. Modes of Cross: Number of parents Modes of combination (1) Single Cross A×B or A/B (Cytoplasm from A) B×A or B/A (Cytoplasm from B) (2) Multiple Cross 1）Three way cross (A×B)×C or A/B//C （Cytoplasm of A,C=1/2)
2) Double Cross (A×B)×(C×D)orA/B/C/D (A×B)×(A×C)orA/B∥AC(A=12) 3) Tetra cross A/B/C/3/D(D=1/2) 4)Convergent Cross A/B/CD/3/E/F∥G/H
2）Double Cross (A×B)×(C×D) or A/B//C/D (A×B)×(A×C) or A/B//A/C (A=1/2) 3）Tetra Cross A/B//C/3/D (D=1/2) 4) Convergent Cross A/B//C/D /3/ E/F//G/H
( 3)Backcross AB//A AB/B (4) Multiple parental cross A/B+C+D+E)
(3) Backcross A/B//A A/B//B (4) Multiple Parental Cross A/(B+C+D+E)
2. Techniques of Crossing (1)Regulation/timing of flowering stages (2)Emasculation 3)Pollination (4)Post management
2. Techniques of Crossing (1) Regulation/timing of flowering stages (2) Emasculation (3) Pollination (4) Post management