Most forage species are cross pollinated, makes it difficult to propagate and maintain the identity of lines due to heterozygous in nature.
Self incompatibility
Small floral parts. This makes difficult in hybridization.
Apomixis
Poor seed production and low viability of seeds
Difference in performance in wider and close (normal) spacing, grazing management etc.,
Polyploidy
Variation in different reproductive systems
Since most of them are perennials, require many years to evaluate the genotypes.
Many of forage produce weak seedlings and hence crop establishment is not satisfactory.
A. Forage grasses
a. Floral biology
In general, the inflorescence is pyramidal branched panicle, flowers are sessile form spikes, spikelets often with G1 G2, L1, L2 Lodicules 2, stamens 3 and gynoecium is superior one called ovary, bifid stigma. Blooming normally begins near the apex of the inflorescence and progresses more or less regularly towards the base. Blooming favoured at temperature 20 to 250C. There is wide variations in anthesis of flowers.
b. Crossing technique
Hand emasculation and pollination (as in sorghum).
Bagging inflorescence of parent clones following emasculation of the seed parent. Paper covers are used for covering the inflorescence.
Mutual pollination by bagging together the inflorescence of the parent clones without emasculation.
By hot water method: panicle is immersed in hot water with temperature around
40 to 450C for about 5 minutes.
B. Forage legumes
Floral biology
The flowers are typical legume types; Calyx 5 united; Corolla 5 – Standard 1, Wing 2, keel 2 free, stamens 10 (9+1 or 8+2, Staminodes in few), Gynoecium superior, monocarpellary. The petals partially joined and enclose the stamens and pistil. Most legumes are self pollinated and nectar is secreted at the base of the corolla tube. In red clover (Trifolium pratense) the stigma slightly protrudes above the anthers at the time anthers and stigma. In alfalfa or lucerne (Medicago sativa) pollen is dispersed by an explosive action commonly known as tripping.
Selfing and Crossing techniques
Young buds are covered with parchment paper bags in selfing. Tripping by force is done in racemes of alfalfa. Self pollination is obtained by caging individual clones with honey bees.
Development of Cumbu Nappier Hybrid -video clip (Durn:01:30 min)
Crossing technique in Lucerne-video clip (Durn:0:20 min)
