General Procedure for Hybrid Production or Hybridization
- Hybrid production or involves following main steps (i.e. steps in crossing).
- Choice of parents
- Evaluation or testing of parents
- Protection of male parent
- Emasculation
- Bagging
- Tagging
- Pollination and bagging, tagging
- Aftercare
- Harvesting
Production of F1 hybrids
In plants
- Crossing two genetically different plants produces a hybrid seed (plant) by means of controlled pollination.
- To produce consistent F1 hybrids, the original cross must be repeated each season.
- As in the original cross, in plants this is usually done through controlled hand-pollination, and explains why F1 seeds can often be expensive.
- F1 hybrids can also occur naturally, a prime example being peppermint, which is not a species evolved by cladogenesisor gradual change from a single ancestor, but a sterile stereotyped hybrid of watermint and spearmint.
- Unable to produce seeds, it propagates through the vining spread of its own root system.
- In agronomy, the term “F1 hybrid” is usually reserved for agricultural cultivars derived from two different parent cultivars, each of which are inbred for a number of generations to the extent that they are almost homozygous.
- The divergence between the parent lines promotes improved growth and yield characteristics through the phenomenon of heterosis ("hybrid vigour"), whilst the homozygosity of the parent lines ensures a phenotypically uniform F1 generation.
- Each year, for example, specific tomato "hybrids" are specifically recreated by crossing the two cultivars over again.
- Two populations of breeding stock with desired characteristics are subject to inbreeding until the homozygosity of the population exceeds a certain level, usually 90% or more. Typically this requires more than ten generations.
- After this happens, both populations must be crossed while avoiding self-fertilization.
- Normally this happens in plants by deactivating or removing male flowers from one population, taking advantage of time differences between male and female flowering or hand-pollinating.
- In 1960, 99 percent of all corn planted in the United States, 95 percent of sugar beet, 80 percent of spinach, 80 percent of sunflowers, 62 percent of broccoli, and 60 percent of onions were hybrid.
- Such figures are probably higher today. Beans and peas are not commercially hybridized because they are automatic pollinators, and hand-pollination is prohibitively expensive.
Hybrids
- Hybrid plants are the result of the deliberate cross-pollination of two selected lines of plants.
- Hybrids are commonly produced to make seed that combines the best characteristics of the parents--productivity, uniformity, vigour, pest resistance.
- Seeds collected from hybrids usually do not grow true to their hybrid parents; rather they often revert and display characteristics from more distant progenitors.
F1 hybrid seed
- Many selectively bred vegetable varieties are F1 hybrids (Filial 1, the frist filial generation).
- F1 hybrids are made by crossing two distinctively different parent lines or parent cultivars to produce an offspring that is different from the parental types but with specific desirable characteristics from either or both parents.
- F1 hybrids are created for exceptional vigour and improved growth, quality, uniformity, and yield.
- Seed from F1 hybrids will not breed true-to-type. F1 hybrids must be remade by controlled pollination every time seed is needed.
- (That is why F1 hybrids are expensive.)
- This is a time consuming and exacting breeding process not usually undertaken by home vegetable gardeners.
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