02134nam a2200253 a 450000100080000000500110000800800410001910000170006024500770007726000430015430000090019750000180020652015390022465000150176365000150177865000150179365000090180865300130181765300080183065300120183865300080185065300120185865300100187014591432006-06-01       1982    bl uuuu  m   00u1 u    #d1 aNEUMAIER, N.  aCharacteristics related to differences in yield among soybean cultivars.  aColumbia: University of Missouric1982  a69p.  aPh.D. Thesis.  aSoybean [Glycine max (L.) Merrill] yields can be associated with physiological, morphological, or developmental characteristics. A three-year study was conducted to examine characteristics related to yield differences among soybean cultivars. For the first experiment, two high-yielding (Williams and Matsoy) and two low-yielding (Illini and Dunfield) cultivars were selected for study. Leaf-specific dry weight, length of the flowering-maturity period, and acetylene reduction (AR) activity at the end of the growing season differed among cultivars and were positively related to yield, while leaf area index and length of the emergence-flowering period were negatively associated with yield. Matsoy and Dunfield were selected for a grafting experiment in which the relative importance of roots and shoots, as determinants of characteristics associated with yield, was studied. Although the genotype of the shoot determined yield components, final yield was equally dependent on roots and shoots. AR rates were under the control of the roots, and as in the first experiment, Matsoy showed higher AR rates than Dunfield at the end of the growing season. However, the differences in the AR rates were not translated into differences in above-ground plant N content or above-ground DW at maturity. Matsoy flowered nine days earlier and matured four days later than Dunfield. In an attempt to test the importance of N2 fixation (AR activity) in determining yields, a third experiment was established. The soybean cultivars Matsoy and ...  aphysiology  aFisiologia  aRendimento  aSoja  aCultivar  aEUA  aSoybean  aUSA  aVariety  aYield