Effect in Hydroponics of Nitrogen and Aluminium Toxicity on Tropical Maize

Maize (Zea mays L.) is the most important cereal crop for most countries in the sub-Saharan Africa. Nitrogen (N) deficiency and aluminium (Al) toxicity are among the abiotic stresses leading to low maize productivity. Lack of N and Al toxicity in soil entails, in most cases, application of nitrogenous fertilizer and lime to ameliorate N deficiency and Al toxicity in the soil respectively. However, excessive application of nitrogenous fertilizers and lime may lead to environmental pollution and unavailability of nutrients due to increased pH respectively. To maximize yields and profits, the use of maize genotypes with high N-use efficient which are tolerant to Al toxicity presents a sustainable approach in this scenario. The objectives of this study were therefore i) to evaluate the effect of varying concentrations of N and Al in hydroponics, on genotypic responses of tropical maize and ii) the prospects of selecting genotypes with dual ‘N use efficient’ and ‘Al tolerant trait’. An experiment was carried out in a 9 x 3 x 2 factorial scheme under hydroponic conditions with nine maize genotypes (CML 538, CZL 113, CML 134, CML 537, CML 312, CML 489, CZL 112, CZL 0814 and CML 444) submitted to three nitrogen doses (0, 21.3 and 42.6 mg L-1) and two aluminum doses (0 and 20 mg L-1), completely randomized design with two replicates. Results showed a significant difference among the genotypes with CZL 0814 genotype identified as the best performing genotype in hydroponics across N and Al concentration levels. However, consideration of variance components showed that N main effect contribution on genotypic performance was lower compared to Al and genotypic main effects. These results imply that availability of N for plant uptake could have been affected by the availability of Al in solution. Evaluation for dual trait, N use efficiency (NUE) and Al tolerant requires assessing genotypes for N stress factor and further subject the candidate genotypes to Al stress or vice versa.