Hybrid Vigour
This is the genetic phenomenon where the characteristics shown by the offspring are
more marked than the average of the two parents of a species. This is a strong argument
in favour of using hybrid seed, which can often produce plants that are hardier and grow
more strongly than either parent.
Hybrid Seed
This is produced by specialist seed producers, mainly for sale to technically advanced
farmers. Although it can produce much higher yields and the plants may be stronger and
more uniform, hybrid seed, especially of cereals, should be regarded with suspicion by
subsistence farmers, for the following reasons:
- it is more expensive than non-hybrid seed;
- it should only be once-grown. If the seed produced from hybrid seed is grown the
following season (twice-grown) the resulting crop is likely to be very mixed in
appearance, growth period etc. and will generally perform less well than a
comparable non-hybrid crop. This means that the farmer has to find the money to
buy seed every year instead of growing it for himself, free of charge; - it requires a high level of crop management for several years before the full
economic potential of hybrid seed is reached, and - many hybrid varieties have a lower content of edible protein than open pollinated
varieties.
In the UK the current performance of hybrid wheats and oilseed rape has not been
significantly more cost effective than non-hybrid equivalents—the seed is still rather
overpriced.
Availability of Hybrid Seed
Despite the problems noted above, the potential for the increase in global food
production through the use of hybrid seed is enormous. Hybrid seed is a powerful force
in modern agriculture and it is likely to become increasingly so in the future and plant
breeders are working hard to improve the agronomic characters of hybrids, to
complement their higher yields.
The most commonly grown hybrid seed is maize, and some wheat and rice hybrids
are also available. Other commonly used hybrids include sunflower, sugar beet and a
wide range of vegetables including tomato, cucumber and many of the Brassica family.
Legume hybrids such as pigeon pea and chickpea are also available.
A composite variety of maize or any other crop is not strictly speaking a variety (or
cultivar) but is a population of plants containing genes from many previous parental
generations.
By selection of plants over many years composites reach a state of equilibrium with
the environment in which they are grown. As a result they are often a fairly mixed