Objectives and approaches in the breeding of perennial legumes for use in temporary pasturelands

Abstract

Legumes are the major element of grassland ecosystem, on which the forage quality depends. Breeding of pasture varieties in perennial legumes firstly aims at achieving tolerance and persistence of the legume component in the pasture. In species having low natural grazing tolerance (lucerne and red clover) it is necessary to conduct breeding for biological, morphological and physiological characteristics, directly related to grazing tolerance. In the species having high grazing tolerance (white clover, birds foot trefoil, sainfoin), the pasture persistence is considered as a function of particular morphological characteristics, adaptive potential and stress tolerance. The indirect breeding for pasture persistence includes also breeding for competitive ability and co-adaptivity with grass pasture species adapted to the region and practices of cultivation, as well as breeding for improved nodulation and nitrogen fixation as an important element of the adaptive ability. The breeding for grazing tolerance and persistence is concentrated also on the mechanisms of self-maintenance of the legumes in the pasture - vegetative reproduction, spread and self-seeding. Many breeding programmes are concentrated also on morphology providing better intake by the animals, on main and specific quality characteristics, on anti-nutrient factors, on adaptation to systems and practices of pasture establishment and use. The breeding strategy using germplasm consolidated through the mechanisms of specific adaptation to unfavourable or specific agro-ecological conditions and influences - i.e. breeding through ecotypic selection is considered to be the most efficient for grazing purposes. The interactions in the system: pasture species - companion species in the pasture herbaceous community - grazing animals (kind, category, grazing style and behaviourial reactions) and the applied regime of use of the pasture are direct and strong. These interactions are of essential importance in genotypic differentiation of the pasture ecotypes. The adaptive variability of the pasture ecotypes is used directly, as well as in recombination breeding.Leguminoze su glavni element ekosistema travnjaka od cega zavisi kvalitet krmnih biljaka. Oplemenjivanje pasnjackih sorti visegodisnjih leguminoza prvo ima za cilj postizanje tolerancije i upornosti komponente leguminoze u u pasnjaku. Kod vrsta koje imaju nisku prirodnu toleranciju ispase (lucerka i crvena detelina), neophodno je sprovesti uzgoj za bioloske, morfoloske i fizioloske karakteristike, u direktnoj vezi sa tolerancijom ispase. U vrstama koje imaju visoku toleranciju ispase (bela detelina, zuti zvezdan, esparzeta), perzistencija se smatra funkcijom pojedinih morfoloskih karakteristika, adaptivni potencijalom i tolerancijom na stres. Indirektno gajenje na perzistenciju pasnjaka ukljucuje i oplemenjivanje na konkurentsku sposobnost i koadaptivnost vrsta trave sa pasnjacima prilagodjeno regionu i praksi kultivacije, kao i uzgoja na poboljsanju nodulaciju i fiksaciju azota kao vazan element adaptivne sposobnosti. Oplemenjivanje na toleranciju ispase i istrajnost je takodje koncentrisano na mehanizmima samostalnog odrzavanja mahunarki na pasnjacima - vegetativnog razmnozavanja, siri i samo-setve. Mnogi programi za uzgoj su takodje usmerena na morfologiju kojom se obezbedjuje bolji unos od strane zivotinja, na magistralne i specificne karakteristike kvaliteta, na faktor anti-nutrijenata, na prilagodjavanje sistemu i praksi osnivanja i koriscenja pasnjaka. Strategije oplemenjivanja koriscenjem germplazme konsolidovana kroz specificne mehanizme adaptacije na nepovoljne ili odredjene agroekoloske uslove i uticaje - tj kultivacije kroz ekotipicnu selekcije se smatra da je najefikasnija za svrhu ispase. Interakcije u sistemu: pasnjacke vrste - pratece vrste u pasnjackoj zajednici zeljastih biljaka - ispasa zivotinja (vrsta, kategorija, stil ispase i bihaviurlne reakcije) i primenjeni rezim koriscenja pasnjaka je direktan i jak. Ove interakcije su od sustinskog znacaja u genotipskim diferencijacijama ekotipova pasnjaka. Adaptivna varijabilnost ekotipova pasnjaka se direktno koristi, kao i u rekombinantnom oplemenjivanju.