| dc.description.abstract | Two experiments were conducted in the field and one in the
~leenhollse to s t udy d i. f ferences in drought response in ten
varieties of common heans, collected from different ecological
zones. The bean varieties were treat.ed to two watering levels
between Jate vegetative and mid-podding stages. LeRf water and
snlut.e potentials were determined using thermocouple
psych rome t.er , while stomatal conductances, transpiration rate and
n=t. phot.osynt.het; i.crates were determined using the infra-red-gas
nnaly~er system. Relative water content, total plant biomass and
downw ar-d root penetration were also determined.
Varietal differences were observed in J.eafwater and solute
potentials, relative water content, stomatal conductance,
transpirat.ion rates, net photosynthetic rates and rates of
downward roo t growth. Ulonzo and "'hite Haricot (both landraces
from low rainfall areas) and variety GLP-I004 (developed for low
rainfall areas), maintained lower leaf water and solute
pot.onti aI s , However, they had higher stomatal conductances,
t.ransp i. rat. i on rates, ne t photosynthet i c rates, re Lative water
content and rates of downward root penetration than varieties
from high rainfall areas.
The study indicated that adaptation to drought stress in
common heans is associated with ability to adjust osmotically and
rapid downward root growth. The parameters may therefore be used
as indicators of drought resistance in beans. Relationship
between agroecology and drought resistance was also sugge | en |
