Each of the four objectives was addressed through an independent study. The findings from each study are presented separately.
6.2.1 Participatory Plant Breeding: Assessment of Farmers’ Perceptions and Preferences in Cowpea Varieties in Mozambique
Participatory rural appraisal and participatory varietal selection were carried out in Bilene, Boane and Chibuto districts and the market survey conducted in open markets and food stores in Maputo. The following information was obtained:
• Cowpea is an important crop produced for its leaves and grain for household consumption and the market.
• Accessibility to markets was the major driving force determining the aim of production and the relative importance of different cowpea products between districts.
• The major aim of production in districts located far away from the major markets was household consumption while in district located near major markets was income generation.
• Cowpea grain and leaves were important across districts but differed between districts; grain was the most important product for farmers located in districts that were far away from the major markets while leaves were more important for farmers located near the major markets.
• Drought was the most important production constraint indicated by farmers followed by aphids, bruchids and viral diseases.
• Farmers used various criteria to select a cowpea variety. High grain yield was indicated to be the most important selection criterion followed by high leaf yield, large seed size and earliness. Results indicated that high grain yield was not always the major criterion used by farmers to select
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cowpea varieties. Potential marketability of the variety was also an important criterion determining the selection of a variety.
6.2.2 Assessment of cowpea genotypes for variability in drought tolerance Variability in drought tolerance among two-hundred sixteen (216) genotypes (136 early and 80 late) was studied by growing the genotypes under drought stressed and non-stressed conditions at Chókwè during the 2008 off-season (June – October). The following information was obtained:
• Genetic variability for drought tolerance existed amongst the tested germplasm.
• The two-hundred and sixteen genotypes were clustered into four groups according to their yielding ability under drought stressed and non-stressed conditions and their drought tolerance. These groups were: high yielding-drought tolerant genotypes (group A), high yielding- drought susceptible genotypes (group B), low yielding-drought tolerant genotypes (group C) and low yielding-drought susceptible genotypes (group D).
• Genotypes INIA-24, INIA-120, IT96D-610, Tete-2, Sh-50 and UC-524B were examples of high yielding-drought tolerant types; genotypes INIA- 11C, INIA-11D, INIA-51, INIA-42F, IT85F-3139, VAR-50B, IT83D-442, Massava-5, N’diambour, Xingove and Zimbabwe were examples of high yielding-drought susceptible types; genotypes IT98K-1111-1, IAR- 8/7, KVx403 and KVx525 were examples of low yielding-drought tolerant while IT82E-18, IT95M-303, CP-2, KVx-421 and Massava-11 were examples of low yielding-drought susceptible types.
• Stress tolerant index was strongly and positively correlated with drought-stressed and non-stressed yield, mean productivity and geometric mean productivity.
• Stress tolerance index was the best quantitative criterion for assessing cowpea genotypes for drought tolerance because it enabled identification of high yielding-drought tolerant genotypes.
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• Multivariate analysis using drought-stressed and non-stressed yield and quantitative indices of stress tolerance was a useful method for assessing the variability of cowpea genotypes for drought tolerance.
6.2.3 Gene action controlling drought tolerance, yield and yield related traits
The gene action controlling drought tolerance, yield and yield related traits was studied using 28-F2 populations generated from an 8x8 half diallel and their parents grown under drought stressed and non-stressed conditions at Chókwè and Umbeluzi. Results from the study revealed that:
• Additive gene action was more important than non-additive in controlling drought tolerance (stay-green), days to flowering, number of pods per plant, number of seeds per pod and hundred seed weight.
• Additive gene action was more important than non-additive in controlling yield under non-stressed conditions while under drought-stressed conditions non-additive gene action was more important.
• The number of pods per plant was the only yield related trait that positively correlated with yield.
• Direct selection for yield would be possible under non-stress conditions while under drought conditions yield improvement would be possible by selecting for number of pods per plant
• Genotype IT93K-503-1 was the most desirable to use as a parent in genetic improvement for drought tolerance, yield and number of pods per plant while INIA-41 was the most desirable to use as a parent in genetic improvement for drought tolerance and hundred seed weight
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6.2.4 Genotype × environment interaction and grain yield stability of cowpea genotypes when grown under drought stressed and non-stressed conditions in Sothern Mozambique
Genotype x Environment interaction and stability of grain yield of 48 cowpea genotypes was investigated in two locations (Chókwè and Umbeluzi) under drought-stressed and non-stressed conditions during three seasons (2009 main season, 2009 off-season and 2010 main season) in southern Mozambique. A 4×12 α-lattice design with three replications was used at Umbeluzi during 2009 main and off season while at Chókwè two replications were used in all seasons.
The data was analyzed using the GGE biplot. Results from the study indicated that:
• Genotype-by-environment interactions were present.
• Genotypes adapted to specific and a wide range of environments existed.
• Genotypes IT-18, INIA-51, INIA-51A and Nhavanca were adapted to high yielding and drought stressed and non-stressed environments while VAR- 11D was adapted to low yielding environment. All these genotypes produced the highest yields but were unstable across environments.
• High yielding and stable genotypes included INIA-23A, INIA-81D, INIA- 24, INIA-25, INIA-16 and INIA-76.
• The lowest yielding genotypes included Bambey-21, INIA-36, INIA-12 and Monteiro. Genotype INIA-12 was unstable while the rest were stable.
• Chókwè was a high yielding environment and ideal for identifying high yielding genotypes but not adequate for selection since it was not representative of an average environment. Umbeluzi was a low yielding environment and was not ideal for selection.
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