Alcantara, P. B.

Colombo, C. A.

Tsuhako, A. T.

Usberti, J. A., Jr.

Usberti, R.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings XXI International Grassland Congress / VIII International Rangeland Congress Search for Brachiaria brizantha Genotypes with Sexuality Levels High Enough to Allow Future Intra‐Specific Crossings J. A. Usberti Jr. Campinas Agronomic Institute, Brazil C. A. Colombo Campinas Agronomic Institute, Brazil A. T. Tsuhako Matsuda Seed and Animal Nutrition Co., Brazil R. Usberti Plant Protection Agency, Brazil P. B. Alcantara Zootecnia Institute, Brazil Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/12-2/34 The XXI International Grassland Congress / VIII International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅱ 　 瞯 ]415　 瞯Grasslands/Rangelands Production Systems——— Developing Improved PlantsSearch for Brachiaria brizantha genotypes with sexuality levels high enough to allow futureintra‐specific crossingsJ . A . Usberti J r .1 , C . A . Colombo1 , A . T . Tsuhako2 , R . Usberti3 , P . B . A lcantara41 Camp inas A gronomic Institute , E‐mail : usberti ＠ iac .sp .gov .br ; 2 Matsuda Seeds and A nimal Nutrition Co . ; 3 PlantProtection A gency ; 4 Zootechnic Institute , Sao Paulo State , Braz il .Key words : B . briz antha ,�off‐type" genotypes , sexuality levels , agronomic traits , molecular markersIntroduction B . briz antha is the most used tropical forage grass for setting cultivated pastures in Brazil , accounting for morethan ８０％ of the traded forage grass seeds . Its available cultivars have shown high forage and seed yielding potentials as well asgood field performances when in competition with several weed species . However , all of them reveal only regular forage quality( as to crude protein levels in fresh/ dry matter and forage digestibility ) , regular forage acceptability by grazing animals , highsoil fertility requirements , low tolerance to acid and/ or poorly drained soils , and so on . Being a facultative apomictic species( Alves et al . , ２００１) , most of the breeding programs are based on the selection of new cultivars in available germplasm banks .However , this methodology has not been successful in recent years , because of the remaining narrow genetic variability to beexploited . Recently , inter‐specific hybrids B . briz antha x B . ruz iz iensis have been developed , showing several desirable foragetraits but extremely poor seed yielding levels ( Lutts et al . , １９９１ ) , which prevent their uses in cultivated pastures . Therefore ,the only option seems to be the increase of the amount of genetic variation within the species , through intra‐specific crossings .To do so , it is imperative the selection of genotypes with sexuality levels high enough to allow those crossings , which was themain aim of this research work.Materials and methods Thirty thousand Brachiaria briz antha individual plants were established in the field , af ter previous seedsowing in plastic bags , filled up with a proper soil , supplied with organic/mineral items . Plant spacing was enough to allow aclear visualization of each genotype . During the vegetative period , proper soil fertilization and weed control were performed . Atthe onset of flowering , a careful selection of �off‐type" genotypes was carried out , taking into account the following morpho‐agronomic traits : plant height , grow th habit , number of vegetative tillers , leaf blade length and width , sheath and leafhairiness , tiller diameter , leaf colour and flowering cycle . Selected individuals were transferred to greenhouse and possiblegenetic differences among them and the standard types were checked through RAPD markers ( Renganayaki et al . , ２００１) .Results and discussion Out of the ３０ ,０００ individual plants analysed in the field , only １４ (０ .０００４６％ ) showed major differencesfor the above cited forage traits , as compared to those belonging to the standard type group ( Table １) . RAPD marker analysiscarried out on them revealed that genotypes ２ , ５ and ８ are , consistently , genetically different ( Figure １ ) , probably due toprevious sexual reproduction and hopefully able to act as female parents in future crossings , aimed at the synthesis and selectionof new intra‐specific hybrids .　 Figure 1Table 1 Morphoagronomic characteristics on �o f f‐type " indiv idualsselected in a population o f Brachiaria brizantha cv . Marandu .Individual PH GH NVT LL LW SH LH TD TF TBC FC LC１ 谮１１０  SP ２０ 寣９４ X２２ %S S １３ f.５ F P L LC２ 谮９０ 篌E ６４ 寣３８ X２０ %H H ４ T.０ R G E DG３ 谮９５ 篌E ６２ 寣４５ X１８ %H H ４ T.０ R G L NG４ 谮９５ 篌E ９２ 寣５３ X１８ %H S ３ T.５ R G I NG５ 谮１２０  SP ３１ 寣３６ X１４ %S S ４ T.５ R G E DG６ 谮９７ 篌E ５８ 寣４３ X１０ %H S ２ T.５ R G L NG７ 谮１２０  E ４７ 寣５６ X１０ %H S ３ T.５ R G I NG８ 谮１２５  E ９８ 寣４３ X１１ %H S ４ T.０ R G E LG９ 谮１２５  E ５７ 寣５１ X１２ %H H ４ T.０ R G L DG１０ 祆１０５  E ７７ 寣４３ X９ H S ３ T.０ R G L NG１１ 祆１０５  E ５５ 寣５２ X１２ %H S ２ T.５ R G L DG１２ 祆１００  E ５９ 寣４８ X１５ %H S ３ T.０ R G L NG１３ 祆１０５  E ５７ 寣４４ X１２ %H S ３ T.０ R G L NG１４ 祆１１０  E ９４ 寣５４ X１２ %H S ３ T.５ R G L NG　 Observations PH ＝ plant height at ６０ days ( cm ) ; GH ＝ grow th habit ( E ＝ erect ;SP ＝semiprostra ; P ＝ prostrated) ;NVT ＝ number of vegetative tillers ;LL ＝ leaf length ( cm) ;LW ＝ leaf width ( mm ) ; SH ＝ sheath hairiness ( H ＝ hairy ; S ＝ smooth ) ;LH ＝ leafhairiness( H ＝ hairy ;S ＝ smooth) ;TD ＝ tiller diameter ( mm ) ; TF ＝ tiller format ( R ＝round ;F ＝ flat) ;TBC ＝ tiller base colour( G ＝ green ; P ＝ purple) ;FC ＝ glowering cycle( E＝ early ; I ＝ intermediate ;L ＝ later ) ;LC ＝ leaf colour ( LG ＝ light green ;NG ＝ normalgreen ;DG ＝ dark green) .Conclusions The occurrence of �off‐type" genotypesin B . briz antha population revealed to be a very rareevent ; even so , their identification , hopefully withgood sexuality levels , might be rewarding in thefuture .ReferencesAlves ER , Carneiro VTC and Araujo ACG . ( ２００１ ) . Direct evidence of pseudogamy in apomictic Brachiaria briz antha( Poaceae) . Sexual Plant Rep roduction , １４ (４ ) : ２０７‐２１２ .Lutts S , Ndikumana J and Louant BP . ( １９９１ ) . Fertility of Brachiaria ruz iz iensis in interspecific crosses with Brachiariadecumbens and Brachiaria briz antha‐meiotic behavior , pollen viability and seed set . Euphy tica , ５７ (３) : ２６７‐２７４ .Renganayaki K , Read JC and Fritz AK . (２００１) . Genetic diversity among Texas bluegrass genotypes ( Poa arachni f era Torr .)revealed by APLP and RAPD markers . Theoretical and A p p lied Genetics , １０２ : １０３７‐１０４５ .

Search for \u3ci\u3eBrachiaria brizantha\u3c/i\u3e Genotypes with Sexuality Levels High Enough to Allow Future Intra‐Specific Crossings

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Search for \u3ci\u3eBrachiaria brizantha\u3c/i\u3e Genotypes with Sexuality Levels High Enough to Allow Future Intra‐Specific Crossings

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