Principles of Plant Breeding (2+1)

Production of Hybrid seed

1. Cytoplasm- genetic male sterility:
1. Single cross Hybrid:
A cms line is used a female parent,while the male parent is a restorer. The seed set on the female parent is hybrid seed. The resulting hybrid is male fertile since it has received the restorer gene from male parent.2:2, 2:4 proportions male to female ratiocan be used

Double crosses Hybrids:
Double cross hybrid varieties are produced by crossing two single crosses. First single cross is produced by crossing cmsline withnon restorer male fertile line. In second single cms line is crossed with a restorer line, (1:1), or two restorer line are crossed together here female line anther have been removed.

Genetic male sterility:
The male sterile msmscms is allowed to be cross pollinated with a male fertile line. (MS MS) to yield a male fertile hybrid Msms. One of the problem, the female parent 50% of plants are male fertile (Msms), the plants Must be identified and eliminated before they shed pollen.

Chemically induced male sterility:
Several chemicals induce male sterility when applied during specific developmental stages of plants – chemicals induce male sterility these chemicals are called chemical hybridizing agents which makes the pollen grain non functional it is also called chemical emasculation. Eg: Rice, Wheat. Commonly used chemical is rice in china are MG1= Zinc methyl arsenate MG2= Sodium methyl arsenate.