Classification of forage crops based on pollination
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Procedures in breeding forage crops are based upon the same genetic principles
utilised in the breeding of other crops. Yet, forage breeding presents certain difficulties
which must be recognised and understood by the breeder. The difficulties arise from the
diversity in pollination of the different species, irregularities in fertilization and seed
setting, the perennial nature of most forage species, and differences in the evaluation and
maintenance of new strains. Examples are :
(a) Most important forage species are cross pollinated. The heterozygosity in cross-
pollinated species makes it difficult to propagate and maintain the identity of lines.
(b) Self incompatibility is common in many forage species, limiting the extent to which
they may be inbred.
(c) Many forage species have small floral parts, making artificial hybridization tedious.
(d) Some grasses reproduce largely by apomixis (seed setting without union of sperm and
egg) presenting problems in crossing and obtaining gene recombination.
(e) Many forages are poor seed producers, or produce seed of low viability
(f) Many forages produce weak seedlings and stands are not easily established.
(g) Isolation and clean land on which new strains may be increased without
contamination are not always available.
(h) The initial evaluation of selected plants or lines in the breeding nursery is generally
based on the performance of spaced plants or rows, which may not accurately
represent the performance of the strain in a thickly seeded stand as grown by the
farmer.
(i) Forage species are often seeded in mixtures with other species which complicates the
evaluation of individual strains.
(j) Strains may perform differently with different systems of grazing management
(k) Most forages are long-lived perennials and many years are required to evaluate
persistence and productiveness of new strains.
(l) Many forage species are polyploids, which increases their genetic complexit
utilised in the breeding of other crops. Yet, forage breeding presents certain difficulties
which must be recognised and understood by the breeder. The difficulties arise from the
diversity in pollination of the different species, irregularities in fertilization and seed
setting, the perennial nature of most forage species, and differences in the evaluation and
maintenance of new strains. Examples are :
(a) Most important forage species are cross pollinated. The heterozygosity in cross-
pollinated species makes it difficult to propagate and maintain the identity of lines.
(b) Self incompatibility is common in many forage species, limiting the extent to which
they may be inbred.
(c) Many forage species have small floral parts, making artificial hybridization tedious.
(d) Some grasses reproduce largely by apomixis (seed setting without union of sperm and
egg) presenting problems in crossing and obtaining gene recombination.
(e) Many forages are poor seed producers, or produce seed of low viability
(f) Many forages produce weak seedlings and stands are not easily established.
(g) Isolation and clean land on which new strains may be increased without
contamination are not always available.
(h) The initial evaluation of selected plants or lines in the breeding nursery is generally
based on the performance of spaced plants or rows, which may not accurately
represent the performance of the strain in a thickly seeded stand as grown by the
farmer.
(i) Forage species are often seeded in mixtures with other species which complicates the
evaluation of individual strains.
(j) Strains may perform differently with different systems of grazing management
(k) Most forages are long-lived perennials and many years are required to evaluate
persistence and productiveness of new strains.
(l) Many forage species are polyploids, which increases their genetic complexit
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