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Common bean (Phaseolus vulgaris L.) is grown in regions where water deficit during reproductive development significantly reduces yield. The objective of this study was to assess morpho-physiological response to post-flowering drought stress in small red seeded common bean genotypes of diverse origin under field conditions. Forty-nine genotypes were evaluated in a 7 x 7 simple lattice design under two soil moisture regimes, non-stress (NS) and drought stress (DS) growth conditions in Gofa, Southern Ethiopia. Drought stress was initiated at flowering stage by withholding application of irrigation water. Significant differences were found among genotypes and between the soil moisture regimes except for days to flowering for the morpho-physiological traits considered. Drought stress reduced seed yield, harvest index (HI), seed per pod, seed per plant and 100-seed weight by 59%, 39%, 15%, 29% and 19%, respectively. Drought-induced reduction in seed yield of the tested genotypes ranged from 9% in ECAB-0427 to 89% in REDWOLAITA. With the highest yield of 1365.7 kg ha-1 under drought stress, ECAB-0427 was the most drought tolerant genotypes, whereas with the lowest yield of 111.9 kg ha-1, REDWOLAITA was the most sensitive genotype to the stress imposed. Superior performance of ECAB-0427 under drought stress was attributed to the maintenance of higher leaf area index (LAI) (2.8) and pod harvest index (PHI) (67.6) compared with a LAI and PHI of 0.8 and 22.1, respectively, for REDWOLAITA. Yield under drought stress was correlated with yield under non-stress (r = 0.68, p<0.01) implying that selection under drought conditions may lead to the identification of genotypes suitable for optimal conditions. Significantly higher correlation detected between GM (geometric mean) and seed yield under drought stress (r = 0.95, p<0.01) entail that the drought index can be used as one of the most important selection criteria in identifying drought resistant small red bean genotypes.

The local maize varieties are inefficient in transferring assimilates to the ear sink and as a result they are low yielding. To replace these low yielding local varieties by high yielding ones, different breeding methods have been used in Ethiopia. This study was undertaken to compare improved maize varieties released in Ethiopia for their harvest index and other important agronomic traits. Twelve improved maize varieties which were released from 1970s to 1990s in Ethiopia and 8 breeding populations were tested in a randomized complete block design at Bako Agricultural Research Centre under sub-optimum and optimum soil fertility conditions in 1997 and 1998. The analysis of variance for harvest index and other important agronomic traits showed significant differences (P<0.01) among the varieties. The mean harvest index varied from 31.1% (Bako composite) to 45.0% (BH-540), indicating wide differences among the varieties in partitioning the photosynthate into grain and vegetative plant part. The mean grain yield also varied from 4.3 t ha -1 (EAH-75) to 7.2 t ha -1 (BH-660). All the varieties released in the 1990s had a better harvest index than the old maize composites, indicating the breeding progress made was successful for both grain yield and harvest index. Further progress in maize breeding to improve harvest index and grain yield would be possible with the use of refined breeding methods and tools.

Information on heterosis and combining ability of adapted maize (Zea mays L.) inbred lines is essential to maximize their use for variety development. This study was conducted to determine heterosis and combining ability of selected inbred lines for yield and yield components. Eight inbred lines were crossed in a diallel mating system. The crosses and parents were evaluated in a randomised complete block design with three replications at Bako Research Center, Ethiopia, in 2001 and 2002. There were significant differences between the entries for measured traits. Mean mid-parent heterosis (MPH) ranged from 2.9% for days to maturity to 89.2% for grain yield and high-parent heterosis from 0.65% for ear diameter to 64% for grain yield. All crosses exhibited positive MPH for ear and plant height, ear length, kernels per row and grain yield. General and specific combining ability effects were significant for most traits. Gutto LMS 5 , CML-202 and CML-387 were good general combiners for ear and plant height, and days to maturity. Line 143-5-i was the best general combiner for grain yield. This study identified inbred lines and hybrid combinations that had desirable expression of important traits. This will be useful for the development of high yielding hybrids.

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