Abstract
Genetic improvement is a useful approach to increase aluminum tolerance in maize. This experiment was carried out to compare two screening techniques under greenhouse conditions and estimate the association between the results obtained for both bioassays with grain yield. Nutrient solution (NS) and pots with acid soil (AS) were utilized as screening methodologies to perform one cycle of divergent selection for aluminum tolerance in the tropical maize population SIKALQ. The four sub-populations obtained by both approaches were compared with the original and checks in a greenhouse and in multilocation field trials. Evaluation under the conditions of NS and AS showed that the populations with the best performances were those selected for aluminum tolerance under the same condition of evaluation. The variables measured in greenhouse showed good correlation and the most closely related were fresh root weight (FRW) and dry rot weight (DRW) (0.79). All of these variables showed low correlation with yield in non acid conditions (< 0.30). The correlation was more important (~ 0.50) as soil aluminum saturation increased. The best correlation was observed for visual scoring (VS) (0.68), FRW (0.47) and net root growth (NRG) (0.52).
Highlights
Acid soils comprise large agricultural areas mainly in tropical and subtropical regions (Kochian, 1995) and aluminum toxicity is one of the major factor limiting plant growth
Selection of the tolerant and sensitive seedlings in nutrient solution was based on net root growth (NRG) for individual plants, obtained by difference between final root length (FRL) and the initial root length (IRL), after grown in greenhouse for seven days in nutrient solution as described by Furlani & Furlani (1988)
Field trials were extensively used for evaluating tolerance in acid soils, they are expensive and the results are highly variable due to the natural variability in these soils and to the climatic conditions
Summary
Acid soils comprise large agricultural areas mainly in tropical and subtropical regions (Kochian, 1995) and aluminum toxicity is one of the major factor limiting plant growth. The identification of tolerant genotypes under the condition of field trials can lead to an increase in grain yield in acid soil. An alternative approach is the evaluation of genotypes under controlled environment and two main screening methodologies have been used, which are based on pots with acidic soils
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