**5. Problems associated with breeding of tropical forage legumes**

and mutation resulted in the development of >15 varieties for different berseem growing regions of India. Inter-specific hybridization have been used to improve resistance to biotic and abiotic stresses and extended length of the vegetative period because genes for wide scale adaptability are widely distributed in several wild species of *Trifolium* (**Table 3**). Interspecific hybrids of berseem with *Trifolium apertum* [31], *T. constantinopolitanum* [32], *T. resupinatum* [33] and *T. vesiculosum* [34] were successfully developed and progenies of interspecific hybrids showed introgression of various desirable traits, including late flowering and resistance to

Tropical Forage Legumes in India: Status and Scope for Sustaining Livestock Production

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A major breakthrough in berseem breeding in India was achieved through induction of polyploidy. The work on polyploidization of berseem genome was started with the aim to induce greater leaf and stem size [35, 36]. Autotetraploid induced by using colchicine treatment, and selection at tetraploid level resulted in the development of first polyploid variety 'Pusa Giant' with more fodder production and good regeneration capacity, uniform and higher yield throughout the season than diploid varieties released for general cultivation in India [37]. Another big achievement in polyploidy breeding was achieved at IGFRI, Jhansi by developing an autotetraploid variety namely 'Bundel Berseem-3' through colchiploidy followed by recurrent single plant selection followed with mass selection [28]. Major success in Berseem breeding was achieved by induction of longer duration mutant in Mescavi variety through gamma ray treatment which resulted in 'BL-22' a variety released

**Desirable characters References**

[31]

[78]

[31, 79]

[33, 80]

[32]

crude protein, high digestibility and palatability, basal branching

flowering, resistance against root rot and

stem rot, high protein content

alkalinity tolerance

root rot and stem rot

root rot and stem rot diseases.

**Species Chromosome** 

**number (2n)**

*T. alexandrinum* ecotype Mescavi 2n = 16 Annual, multicut, highly productive,

*T. alexandrinum* ecotype Fahli 2n = 16 Annual, single cut, self-compatible, stem

*T. apertum* 2n = 16 Annual, profuse basal branching, late

*T. resupinatum* 2n = 16 Root rot and stem rot resistance, soil

**Table 3.** Desirable characters in berseem ecotypes and wild *Trifolium* species.

*T. constantinopolitanum* 2n = 16 Profuse basal branching, resistance against

*T. alexandrinum* ecotype Saidi 2n = 16 Annual, 2–3 cut, stem and basal branching [78] *T. berytheum* 2n = 16 Biotic resistance [79] *T. salmoneum* 2n = 16 Biotic resistance [79]

*T. meironense* 2n = 16 Biotic resistance [31]

*T. vesiculosum* 2n = 16 Lateness, disease resistance [25]

branching

Tropical forage legumes breeding programmes are associated with certain unique problems. Most of the tropical pasture legumes still possess traits of wild plants that include seed shattering, small seed size, seed dormancy, relatively slow germination rates, etc. In most of the cases we have very little knowledge about the basic biology of the species. Some of the problems include overlapping of vegetative and reproductive growth phases, uneven pod setting, nonsynchronous maturity and seed shattering in forage legumes [24]. Inherent heterozygosity as most forage species are cross pollinated. Self-incompatibility limits the extent to which they may be inbred; small floral parts make artificial hybridization tedious; poor seed producers; or produce seed with low viability as well as inherently low seedling vigor and competitive ability. Many forage species produce weak seedlings and stands are not easily established. Strains may perform differently with different systems of grazing management. Persistence of perennial tropical forage legumes is not as a single trait, but rather as a complex of traits dependent on various factors, such as diseases, insects, abiotic stresses, or management stress. Fertility barriers of one sort or another are very common in tropical forage legume breeding *viz*., berseem [25], owing to the wild nature of the species and inadequate knowledge of interor intra-specific variation.
