Evaluation of Cowpea Genotypes for Drought Tolerance Using the Pot Screening Approach

Background: Tolerance to drought is crucial for cowpea producers in Northern Ghana, where the bulk of the crop is produced

Aims: To assess Five cowpea genotypes for their tolerance to drought at various stages of development.

Study Design: Randomized complete block design was used for the study.

Place and Duration of Study: The study was carried out in pots over a three-month period at the Savanna Agricultural Research Institute, Tamale-Northern Ghana.

Methodology: The study made use of factorial experiment in randomized complete block design using two factors (genotypes and water stress regimes). Treatment combinations were replicated three times. Genotypes were subjected to moisture stress at either the vegetative, flowering or pod filling stages. A well-watered control was included.

Results: Though the analysis of variance indicated significant main effects for genotype and moisture stress for a number of traits studied, no significant interactions between the two factors were evident for the traits studied. Moisture stress significantly reduced the number of pods per plant and grain yield. Moisture stress imposed during the vegetative phase has the most significant reduction in grain yield and number of pods per plant compared to the irrigated control. In general, the correlation coefficients were weak and not statistically significant. All the significant correlation coefficients were positive and were found between grain yield and its components. Also, the relationship between susceptibility to moisture stress and yield potential was investigated by correlation and regression analysis. This study indicated a significant positive relationship between susceptibility to moisture stress and yield potential.

Conclusions: No single genotype was found to be most tolerant to drought for all the three growth stages in which drought was imposed. The study, therefore, emphasised the difficulty in combining high yield potential and drought tolerance in development cowpea genotypes.