Dehydration-avoidance responses of tepary bean lines differing in drought resistance

Four tepary bean (Phaseolus acutifolius) lines were studied for the responses of the dry matter accumulation and partitioning, the growth characteristics of the root and the shoot genotypes, and the potential seed yield to drought. Comparatively, two lines were high (NE # 8A and NE # 19) and two lines (NE # 5 and NE # 7) were low in the seed yield under well-watered conditions. The two high yielding lines remained higher in the seed yield than the two low yielding lines under drought conditions. NE # 19 is characterized by a deep root penetration and a balanced root : shoot growth pattern, along with the greatest mass of root in the deepest soil profile. Its leaves exhibited sensitive stomates in response to drought stress. Except for having less depth of its root penetration, NE # 8A was very similar to NE # 19. NE # 8A showed less reduction than NE # 19 in the potential seed yield as affected by the water deficit. It appeared to use less soil water, suggesting operating sensitive stomates. However, the RWC of NE # 8A leaves showed more reduction than NE # 19 in response to the drought. NE # 19 could cope with more severe water stress due to its deeply penetrating root along with the sensitive stomates of the leaf genotype.