02451nam a2200385 a 450000100080000000500110000800800410001910000180006024500800007826000450015830000100020350000180021352015420023165000110177365000130178465000130179765000130181065000130182365000140183665000120185065000220186265000160188465000170190065000090191765000120192665300140193865300110195265300130196365300210197665300150199765300120201265300140202465300150203865300120205315480671993-02-16       1989    bl uuuu  m   00u1 u    #d1 aSPEHAR, C. R.  aThe genetics of aluminium tolerance in soya beans Glycine max (L.) Merrill.  aCambridge: University of Cambridgec1989  a124p.  aPh.D. Thesis.  aAluminium toxicity is a widespread problem in the soils of most tropical areas of the world and is a major constraint in the establishment of stable farming systems. Even when soil fertility is improved, the roots of cultivated plants tend to be confined to the ploughed layer making the crop more vulnerable to dry spells. Crops with relatively high tolerance to aluminium are therefore needed and one of these crops, for wich a ready market exists, is the soya bean. This project started with a series of field experiments to evaluate the variability in aluminium tolerance of soya bean varieties which originated from various breeding programmes to adapt the crop to tropical regions of Brazil. Based on varietal performance, as measured by grain yield and mineralcomposition in the presence of high and low levels of aluminium, nine contrasting varieties were chosen for crossing schemes. A diallel cross and some backcrosses were obtained for the genetic studies. The genetics of aluminium tolerance was studied in these crosses by diallel and generation mean analyses in field and hydroponics experiments. The field experiments were conducted in the Centro de Pesquisa Agropecuaria dos Cerrados - CPAC, Planaltina, DF, Brazil. The F2 hybrids were used to determine the segregation patterns for tolerance to aluminium indicated by grain yield and mineral composition. The same crosses were tested in high-and low-aluminium areas and their relative performance was analysed. Previous experiments indicated that soya bean varieties...  aBrazil  abreeding  agenetics  asoybeans  atoxicity  aAlumínio  aCerrado  aGenética Vegetal  aGlycine Max  aMelhoramento  aSoja  aToxidez  aAluminium  aBrasil  aCultivar  aDistrito Federal  aPlanaltina  aSoybean  aTolerance  aTolerancia  aVariety