BREEDING FAST COOKING AND IRON BIOFORTIFIED COWPEA IN GHANA
Cowpea is a multi-purpose crop, providing food for man and livestock. It is a reliable income-generating commodity for many farmers and grain traders. However, long cooking time and low iron bioavailability are major limitations to utilization. Studies were aimed at developing high yielding, fast-cooking and iron-biofortified cowpeas possessing consumer acceptable traits. Specific activities involved morphological diversity assessment of 164 cowpea genotypes, assessment of influence of varied conditions on cooking time, diversity assessment of genotypes for cooking time for before and after storage conditions and genotype by environment (planting location) interaction on cooking time, grain iron concentration and grain yield. Other assessments include the determination of mode of inheritance and gene action for cooking time (after storage), evaluation of iron bioavailability in fast and slow-cooking cowpeas and the fabrication and validation of an experimental cooker for the evaluation of cooking time for cowpeas. Data were collected and frequency distributions, ANOVA, AMMI and combined analysis performed using SAS 9.2, Genstat 9.2 and Micrsoft excel 2013. Vegetative, reproductive and seed stage traits were useful in establishing diversity among cowpea genotypes assembled. There was significant variability among genotypes for cooking time. Minimum cook times, before and after storage, were 13 and 25 minutes respectively while the maximum cook times, before and after storage, were 460 and 770 minutes.There was a significant genotype and environment (storage conditions) interaction with significant variability within genotypes and between the two storage treatments. There was also a wide range of grain iron concentration comparable to reports in other cowpea breeding programmes. Grain iron concentration ranged from 40 to 89 mg/kg. Broad sense heritability for cooking time was 0.99 for cross C9P(B) x 11(1)-1 and 0.94 for cross TVu7687 x 11(1)-1. Narrow sense heritability for the trait was 0.84 for cross C9P(B) x 11(1)-1 and 0.88 for TVu7687 x 11(1)-1 indicating that selection for the trait can be effective and would assist breeding for fast-cooking varieties of cowpeas. Fast-cooking trait was partially dominant over the slow-cooking trait. Generation mean analysis showed that additive, dominant, additive-additive, additive-dominant and dominant-dominant gene actions were significant (p<0.001). Furthermore, cooking time, grain iron concentration and grain yield in cowpeas were significantly (p<0.001) influenced by differences in agro-ecological zones with particular reference to variation in soil iron from fields used. Cowpea genotypes F269T2L, Paddy 2A and Paddy 2B were selected for their highly stable fast cooking and high grain iron concentration abilities. Results also showed that developing fast cooking varieties through plant breeding has greater advantage over efforts to identify soil types to produce cowpeas with short cooking time. Results from the iron bioavailability study showed that cowpea genotypes with non-pigmented (white and cream) seed coats had higher bioavailable iron compared to genotypes with pigmented (brown and purple-red) seed coats. There was a non-significant difference (p>0.05) between cooking times record with the fabricated experimental cooker and the automated Mattson cooker. In addition, there was a non-significant difference (p>0.05) between standard procedures for cooking time and modified procedures for cooking time determination in cowpeas.