02272naa a2200277 a 450000100080000000500110000800800410001910000210006024501030008126000090018430000100019352014710020365000110167465000100168565000140169565000170170965300110172665300140173765300190175165300150177070000130178570000180179870000230181670000180183977301370185714567182006-03-09       2000    bl uuuu     u00u1 u    #d1 aBRIGHENTI, A. M.  aGrowth analysis of resistant and susceptible wild poinsettia biotypes to ALS inhibitor herbicides.  c2000  ap.23.  aAll natural weed populations regardless of the application of any weedkiller probably contain individual plants (biotypes) which are resistant to herbicides. Persistent herbicide use will expose the weed population to a strong selection pressure which may lead to an increase in the number of surviving resistant individuals in the population. Repeated use of imidazolinone herbicides in continuous no-till soybean selected a herbicide resistant biotype of wild poinsettia (Euphorbia herophylla) in Cafelandia country of Parana State, brazil. A comparative study of growth and development of wild poinsettia resistant and susceptible to ALS (acetolactate synthase) inhibitor herbicides was carried out at Embrapa Soja, Londrina, Parana State, Brazil. The total dry matter, leaf area, shoot dry weight, leaf dry weight, root dry weight and plant height were measured weekly 13 times, starting 14 days after sowing. Data were analyzed with a polynomial exponential function. The response variable for the whole growthperiod was estimated using 95% confidence interval. Relative growth rate, net assimilation rate, leaf weight ratio and specific leaf area decreased with plant ontogeny and behave similarly in both biotypes. The total dry matter of the plants andtheir organs as well as the leaf area and plant height exhibited similar ranges of variability in both biotypes. There no significant differences between biotypes for growth and development characteristics.  aBrazil  aweeds  aHerbicida  aResistência  aBrasil  aHerbicide  aPlanta daninha  aResistance1 aVOLL, E.1 aADEGAS, F. S.1 aGAZZIERO, D. L. P.1 aVAL, W. M. C.  tIn: INTERNATIONAL WEED SCIENCE CONGRESS, 3., 2000, Foz do Iguassu. Abstracts... Corvallis: International Weed Science Society, 2000.