Abstract
Doubled-haploid lines of wheat with deep and shallow root system, nine lines each, were grown in paddy fields. Grain yield of shallow-rooting 9 lines was higher than that of deep-rooting 9 lines, especially in the wet paddy field in 2002. However, the difference was not significant in the drained paddy field. The values of top dry weight and tiller number were high in the shallow-rooting lines in the wet paddy field. The grain yield was also high in shallow-rooting lines in the wet paddy field in 2003. On the contrary, grain yield was not low in the deep-rooting lines in the upland field. The values of grain yield in the wet paddy field were closely related to the groundwater level in sites where these lines were grown in the field. The regression lines show that grain yield of shallow-rooting lines was higher than that of the deep-rooting lines at the same groundwater level. Root depth index, which shows mean root depth, of the shallow rooting lines was 8.37 cm in the wet paddy field and 13.11 cm in the upland field. These values were smaller than those in the deep-rooting lines. The results suggested that shallow-rooting lines show higher tolerance to waterlodging than the deep-rooting lines.
