M.Sc. Dissertation
Common bean (Phaseolus vulgaris L.) is the most important crop for the livelihoods of
smallholder farmers in Tanzania; it is the most produced pulse by small-scale farmers for
household consumption and earning income after selling surplus. Common beans are
intercropped with maize or with permanent crops such as banana or coffee and some few
farmers grow it as a sole crop. The objectives of this study were to assess the effects of
water stress on seed yield of common bean under controlled environment; and determine
the performance and adaptability of 16 genotypes at different agro-ecological
environments in Kagera Region. Two experiments were conducted during the study; one
was done in the screen-house and the other one was the field experiment. The screen
house study on yield response to water regime revealed that genotypes DAB 582, SRC 59,
IBWERA, DAB 602, SSIN 1240, Lyamungu 90, SMC 24, SMR 101, DAB 362 and
JESCA were drought tolerant with lower and high value of the Drought Susceptibility
Index (DSI) and Yield Stability Index (YSI) respectively. The analysis of variance of the
Additive Main effects and Multiplicative Interaction (AMMI) model indicated that
environments accounted for 56.9% of the total sum of square; genotypes effect explained
9.2% and the G x E interaction effect accounted 8.9% of the total sum of squares.
According the results, the GGE biplot revealed that, the genotypes SSIN 1240, SAB 659
and DAB 219, SMR 101, SMC 162 and DAB 602 showed greater stability with the
average closer to the overall average of the tested genotypes. Therefore, genotypes SMC
162, DAB 602, SSIN 1128, DAB 362 and SMR 101 were identified and recommended to
be used in future breeding program as moisture stress tolerant, good seed yield and widely
adapted in Kagera Region and similar agro ecologies.