02483nam a2200373 a 450000100080000000500110000800800410001910000230006024501300008326000470021330000100026050000170027052015360028765000120182365000130183565000140184865000090186265000170187165000110188865000140189965000140191365000150192765000090194265000160195165300150196765300140198265300170199665300180201365300190203165300240205065300100207465300100208465300150209415586502001-11-20       1978    bl uuuu  m   00u1 u    #d1 aCARVALHO, M. M. de  aA comparative study of the responses of six stylosanthes species to acid soil factors with particular reference to aluminium.  a[Brisbane: University of Queensland]c1978  a298p.  aPhD. Thesis.  aThe present investigation was conducted to examine the comparative ability of six Stylosanthes species to tolerate acid soil infertility factors with particular reference to aluminium. Initially, a pot experiment was conducted to identify those factors limiting the growth of Stylosanthes in three acid soils from south east Queensland. All six species responded positively to lime application in the three soils, while responses to phosphate application varied with soils, species and lime rates. Lowest dry matter yield in the unlimed soils was associated with solution aluminium concentration in the saturation extract ranging from 37 to 55 uM. Maximum growth of all species occurred when the solution aluminium concentrations were reduced to the range 17 to 22 uM by the highest lime rates, which reduced the aluminium saturation of the effective CEC to less than 5 percent in all three soils. The growth response to lime was attributed to the alleviation of alluminium toxicity. Subsequent experiments conducted using sand culture that aluminium could restrict the growth of Stylosanthes species both through effects on host plant growth and on the development of an effective legume - Rhizobium symbiosis. However, plant growth was shown to be considerably more tolerant to aluminium toxicity when supplied with adequate combined nitrogen than when dependent on symbiotic nitrogen fixation. The greater sensitivity to aluminium toxicity of plants dependent on symbiotic nitrogen fixation was shown to be due to the greater...  aacidity  aagronomy  anutrition  asoil  aStylosanthes  aAcidez  aAgronomia  aAlumínio  aNutrição  aSolo  aSolo Ácido  aAlluminium  aAluminium  aFertilizacao  aFertilization  aForages plants  aPlantas forrageiras  aSoils  aSolos  aStilosante