Grain quality in Maize (Zea mays L.): breeding implications for short-season drought environments

Abstract

Total and extractable starch, oil, protein, and amino acids of maize (Zea mays L.) are important to farmers and ranchers because of their various end uses including ethanol and feedstock nutrition. The objectives of this study were: (1) to evaluate grain quality traits in different water regimes and (2) to discuss the implications for breeding maize quality cultivars in water stressed (WS) environments. Ninety-four partial diallel crosses including 47 diverse maize inbreds and checks were tested in 12 WS, well watered (WW), and random drought (RDT) environments in 2013 and 2014. The changes in mean grain extractable (<1.33 %) and total starch (<0.74 %), oil (<2.2 %), cysteine (<2.91 %) and lysine (<2.81 %) contents in WS and RDT were small while the changes in grain protein (+6.58 % in WS and +3.46 % in RDT) and methionine (+4.41 % in WS and −1.86 % in RDT) content were large compared to WW environments. Additive genetic variance was most important across stresses and the largest variance was estimated in WS environments. The narrow-sense heritability (h ²) was found to be high (>0.40) for all traits in WW environments except for grain protein and amino acid contents. The mid-parent hybrid correlation was strong (>0.62) for all traits across stresses except for amino acid content (<0.55). The stress environments were largely associated for grain oil and total and extractable starch contents (>0.60). However, they were less associated with grain protein content and amino acid content (<0.49). Therefore, while breeding for better ethanol maize varieties could be based on multi-location testing in WS environments, breeding for healthier feedstock protein products could be conducted across environments.