Direct and Correlated Responses to Divergent Selection for Leaf Abscisic Acid Concentration in Two Maize Populations

Abstract

Abscisic acid (ABA) concentration can affect plant responses to drought and has been suggested as a selection criterion to improve drought tolerance. Divergent selection for high (H) and low (L) leaf ABA concentration was conducted under moderate drought conditions in the F 2 of maize ( Zea mays L.) single crosses Os420 × IABO78 and Mo17 × B88. Objectives of this study were to evaluate direct and correlated responses to the divergent selection. For each cross, the F 2 and the H‐ and L‐populations (H‐P and L‐P) were compared. For Os420 × IABO78, the comparison was made in one location, for 2 yr, and at three irrigation volumes (corresponding to 0, 60, and 120% of crop evapotranspiration). At all irrigation volumes, H‐P exceeded L‐P for leaf ABA concentration, drought sensitivity, leaf temperature, silk delay, and lodging resistance, while it showed lower plant height and grain yield (on average, 3.61 vs. 5.14 Mg ha −1 ). The F 2 was intermediate for most traits. Significant differences were not detected for water status traits. For Mo17 × B88, populations were compared at one irrigation volume (60% of evapotranspiration) in three environments. In all environments, H‐P was superior to L‐P for leaf ABA concentration and drought sensitivity, and it was shorter, and less productive (on average, 4.71 vs. 6.95 Mg ha −1 ). The F 2 was intermediate for leaf ABA concentration but not for grain yield. Results indicate that selection for low leaf ABA concentration led to populations with better agronomic performance than did selection for high leaf ABA concentration.