02126nam a2200217 a 450000100080000000500110000800800410001910000200006024501070008026000160018730000100020350000660021352015420027965000170182165000140183865000100185265000130186265300140187565300100188965300090189914732872023-10-19       1976    bl uuuu  m   00u1 u    #d1 aSILVA, J. B. da  aInfluence of preplant tillage systems for continuous corn production on the potential weed population.  a1976.c1976  a76 p.  aDissertação (Mestrado) - Purdue University, West Lafayette.  aField and greenhouse experiments were carried out in two lacations and three different soils to study the influence of preplant tillage systems for continuous corn productions on the potential weed population of untreated and herbicide treated plots and on the weed seed distribution throughout the soil depth. At the Feddun-Purdue Agricultural Center, Bedford, Indiana, on a Bedford silt Loam, 3 replications of conventional tillage-spring plowed, chisel plant, coulter plant, coulter plant plowed once, till plant and till plant plowed once were maintained under continous corn productions during the period of 1968-1973 and left fallow in 1974 to evaluate the weed population in plots treates during the same period with atrazine 3.0 kg/ha, atrazine 2.0 + alachlor 1.5 kg/ha and untreated. At the Pinney-Purdue Agricultural Center, Wanatah, Indiana on both tracy Sandy Loam and Runnymede Loam, 4 replications of conventional tillage-spring plowed. chisel plant and coulter plant were kept under continous corn productions during the period of 1969-1974 and left fallow in 1975 to evaluate the weed populations in plots treated during the 6 year period with atrazine 3.0 kg/ha, atrazine 2.0 + alachlor 1.5. kg/ha, simazine 2.0 + alachlor 1.5 kg/ha and untreated. Besides recording weeds in the fields six soil samples were taken from each untreated plot in all the tillage systems and locations for a seed-depth study in the greenhouse. The influence of tillage systems on the weed populations of untreated plots was primarily on (...)  aErva Daninha  aHerbicida  aMilho  aZea Mays  aHerbicide  aMaize  aWeed