Low pH adaptation of tropical exotic acid tolerance yellow maize donor lines in sub-tropical breeding programs

Abstract

AbstractSoil acidity is one of the most important constraints to maize production in Angola, where both yellow and white maize is essential for food and feed requirements. In this study, four yellow acid soil tolerant donor lines from the International Maize and Wheat Improvement Centre (CIMMYT)—Colombia were crossed with ten yellow elite lines adapted to the mid-altitude climatic conditions developed by CIMMYT—Zimbabwe, in order to identify donor lines, which can be potential sources of acid tolerance genes in breeding programs in Angola and within the mid-altitude climatic zones. The two groups of parents were crossed using a line by tester mating design, yielding 36 crosses with sufficient seed, which were evaluated alongside six acid tolerant commercial hybrids, during the 2014–16 cropping seasons at nine sites, representing acid and non-acid soils in Angola and Zimbabwe. A significant (p < 0.05) line and line × tester effect for grain yield performance was observed across acid and non-acid conditions. Acid tolerance donor lines CY3 and CY1 showed the highest positive GCA effects for grain yield. In addition, crosses involving these two donor lines had the best yielding ability and stability under both acid and non-acid conditions. For instance, the crosses CH142464 (ZY2 × CY3) and, CH142447 (ZY2 × CY1) were the best combinations for grain yield performance under both acid and non-acid soil conditions, and were stable compared to the commercial check hybrids. Crosses involving the acid tolerant donor lines mostly flowered earlier than the commercial checks. Overall, the data showed the potential of tropically-adapted exotic yellow maize acid tolerance donor lines in improving productivity of sub-tropical maize under both low-pH and well-managed soil conditions.