03025nam a2200253 a 450000100080000000500110000800800410001910000130006024500890007326000160016250000450017852023640022365000120258765000130259965000190261265000140263165000350264565000130268065000140269365300160270765300150272365300190273865300140275713174082011-07-21       2001    bl uuuu  m   00u1 u    #d1 aJANK, L.  aSection for enhanced agronomic attributions in Setaria Sphacelata (Schumacher) Moss.  a2001.c2001  aTese (Doutorado), University of Florida.  aThere is a demand for a wider range of adapted, improved warm-season grasses in Florida because the cool winters affect the productin and persistence of many existing cultivars. A breeding program was conducted in Florida to study the breeding potential and adapttion of the tropical forage grass Setaria sphacelata (Schumacher) moss to these conditions. Eight populations were developed from 1997 to 1999 using half-sib family selection methodology. Six of the populations were developed in Gainesville, one in Ona and one in Quincy. In 1999 and 2000, these populations were compared in two wide-spaced an two close-spaced experiments in Gainesville. The methodology of halfsib family selection using detached culms for intermating selected populations in  isolation was useful for setaria breeding, because it allowed completion of one cycle of selection  per year, it maintained variability and it avoidd inbreedin. Results of population comparisons showed that selection for leaf  width ws successful. The width of leaves, leaf percentage, leaf: stem ratio, and whole-plant crude protein (CP) concentration were increased,  while leaf dry mattr yield,  in vitro organic matter digestibility (IVOMD) and other measured morphological characteristics were unchanged. Stem and total dry matter yields were decreased. Selection for head number did noto significantly increase the number of heads and decreased plant height, leaf width, inflorescence lenght,  total, leaf and stem dry matter yield, leaf percentage and leaf: stem ratio in one or both cycle. Seed production, CP and IVOMD were not affected. Selection for  regrowth after grazing reduced plant height, inflorescence lengh and seed production. Selkction for frost tolerance was successful in enhancing winter survival at Gainesville and rduced canopy and inflorescence height and leaf dry matter yield in one or two cycles. It did  not affect leaf width, inflrescence lenght, head number, total or stem dry matter production  or leaf: stem ratio. The germplasm of S. sphacelata was plastic enough that changes in morphological and agronomic traits due to selection  and  breeding were achived. Setaria has promise for use as a forage plant  in Florida, but concerns regarding pest susceptibility and winter persistence  remain to be resolved before this species may be commercialized in the state.  aFlorida  apastures  aplant breeding  aGramineae  aMelhoramento Genético Vegetal  aPastagem  aSeleção  aAdaptação  aAdaptation  aEstados Unidos  aSelection