03156nam a2200289 a 450000100080000000500110000800800410001910000260006024500950008626000510018130000100023250000180024252023590026065000260261965000170264565000100266265000130267265000230268565000160270865000090272465000090273365300240274265300270276665300220279365300260281565300250284115595552000-02-08       1981    bl uuuu  m   00u1 u    #d1 aSOUZA, P. I. de M. de  aRoot characteristics of selected soybean breeding populations in growth chamber and field.  aRaleigh: North Carolina State Universityc1981  a191p.  aPh.D. Thesis.  aThe root characteristics of soybean liner from three cyclyes of recurrent selection exhibiting a linear increase in yield were studied under growth chamber and field conditions (1978 and 1979). Under controlled environment conditions three technique were used: Cartons for 8-11 day old plants, 2" plastic tubes in light-tight boxes for 17 and 23 day old plants and 6" plastic tubes for 36 day old plants. In the field, roots of juvenile plants were studied through the shovelsample technique and later, for older plants, core-sample technique. Sampling dates were approximately one week apart up to beginning seed (R5) stage. In the growth chamber studies, singficant differences among lines with respect to root characteristics were observed. Many soybean entries displayed consistent behavior regardless of the method of evaluation. Tap root dry weight was the charactesitic that most often differed among entries across experiments. Differences in root characteristics appeared more frequently in a light than in a heavy planting medium, and the experimenral variation increased with both age of plant and potting medium. In the field, no consistency between years was observed in total root weight from shovel samples, and the total root weight of these young plants showed no correlation with yield but very high correlations with all shoot characteristics measured. The root characteristics of older plants (core samples) revealed that the recurrent parent D 49-249) consistently presented lower valuer root lenght and weight. No significant difference in yield among entries was observed in either experimental year. No reliable associations between root characteristics and yield were observed soybean entries. When growth chamber and field results were compared, no reliable predictive criterion was observed between root characteristics and soybean grain yields in the field. However, a few similarities between growth chamber and field root data noted with the recurrent parent, D 49-2491, which ranked at the bottom in most comparison. Due to the lack of consistency between growth chamber field results and between the two years' field experiments, and prediction fo field root characteristics or grain yield through the use of juvenile plants in growth chamber would have a very high probability od error, given our experimental conditions.  afield experimentation  aroot systems  aroots  asoybeans  aControle Ambiental  aGlycine Max  aRaiz  aSoja  aAmbiente controlado  aCaracteristica da raiz  aCondicao de campo  aEnvironmental control  aExperimento em campo