02719nam a2200361 a 450000100080000000500110000800800410001910000170006024501130007726000360019030000100022650000180023652017500025465000090200465000220201365000160203565000160205165000280206765000220209565000130211765000150213065000170214565000290216265000120219165000260220365000110222965300250224065300220226565300260228765300240231365300090233765300110234614019752006-03-15       1980    bl uuuu  m   00u1 u    #d1 aMALUF, W. R.  aPhysiological aspects of low temperature seed germinating ability in tomato (Lycopersicon esculentum Mill.).  a[S.l.]: Purdue Universityc1980  a117p.  aPh.D. Thesis.  aThe inherent ability of tomato seed to germinate at low temperature is negatively correlated with oleic acid content and positively correlated with linoleic acid content in dry seeds of parent and paratially isogenic F5 lines with varying low temperature germinating abilites. Fatty acid composition does not change with time of incubation at 10oC. The proportion by which linoleic acid is higher in the cold germnating parent PI341985 (CG) over the non-cold germinating cultivar centennial (NCG) is roughly the same as the amount by which oleic acid is lower, suggesting that the primary effect of genes controlling cold germinating ability is to promite or regulate a more extensive desaturation of oleic into linoleic acid during seed development. Lower unsaturation of membrane systems in NCG would mean that membrane phase changes may occour at 10oC in NCG, but not in CG, impairing the permeability properties of the former. Pre-incubation of CG and NCG in water at 25oC for up to 24 hours prior to incubation at 10oC failed to alter the relative performance of these lines at low temperature. Activated carbon improved cold germination throughout the range of cold germinating abilites, but its effect was more pronounced in lines Ability of tomato seeds to germinate at low temperatures is not a cold-induced phenomenon, and appears to be related to fatty acid composition of cell membranes, which is predetermined in the dry seed. The primary effect appears to be the desaturation of oleic acid into linoleic acid which takes place during seed development. The extent of this desaturation is closely correlated with cold germinating ability of the line. Other oberved diferences between CG and BCG appear to represent secondary effects.  acold  adormancy breaking  agermination  aperoxidases  aplant growth substances  aprotein synthesis  atomatoes  aFisiologia  aGerminação  aRegulador de Crescimento  aSemente  aSíntese de Proteína  aTomate  aAtividade peroxidase  aBaixa temperatura  aGerminacao de semente  aQuebra de dormencia  aSeed  aTomato