Genetics of aluminum tolerance in cowpea accessions screened in pots under the field conditions

Aluminum toxicity is a major factor limiting crop productivity on acid soils, thus posing a challenge to food production. This study assessed the level of genetic diversity for aluminum tolerance in cowpea and the intercharacter association of important traits for the effective selection of tolerant genotypes. Ten accessions of the crop were screened in pots filled with topsoil employing a 10 x 4 factorial experiment in a completely randomized design. The aluminum treatments imposed were 0, 50, 100, and 200 µM AlCl3. Results revealed significant differences among accessions for all traits studied. Aluminum treatment imposed significant differences on all traits except seeds/plant and seed yield while the interaction was significant for all traits except emergence percentage and plant height. Heritability was high (≥ 60%) for all traits except pods/plant (57.98%), and genetic advance as a percent of the mean was high (≥ 20%) for all traits except days to flowering (11.08%) and plant height (15.87%). Biplot revealed that high seed yield under aluminum stress was directly associated with high seeds/plant, a higher number of roots/plant, and high root weight/plant while higher seeds/pod was a consequence of deeper root length, late flowering, higher root weight, and higher number of roots.