01627naa a2200253 a 450000100080000000500110000800800410001910000160006024500930007626000090016952009540017865000140113265000170114665000130116365000220117665000150119865000170121365000090123065300220123965300140126165300100127570000160128577300720130114576801992-11-20       1986    bl ---       0--  u    #d1 aGIMENEZ, C.  aGenetic variability in sulflower cultivars under drought. II Growth and water relations.  c1986  aExperiments were conducted between 1981 and 1983 at Cordoba, Spain to determine the morphophysiological basis for the differences in yield responses to drought of eight sunflower genotypes. There was genotypic variation in most characters examined, particularly in maximum leaf area and in leaf area duration, biomass accumulation and distribution, and in root water extraction. Long-season genotypes had greater leaf area and produced more biomass under drought conditions, exploring the subsoil down to 270 cm. Short-season genotypes restricted water extraction to the top 180 cm of the soil profile and had about half of the leaf area duration of a long-season cultivar. Evidence is presented of small differences in osmotic adjustment among genotypes. The relations between leaf area and grain yield as well as calculations of a carbon balance for the reproductive period suggest genotypic differences in photosynthetic efficiency under drought.  aleaf area  aÁrea Foliar  aGirassol  aHelianthus Annuus  aRendimento  aResistência  aSeca  aDrought resistant  aSunflower  aYield1 aFERERES, E.  tAustralian Journal of Agricultural Researchgv.37, p.583-597, 1986.