Assessing inbred-hybrid relationships for developing drought-tolerant provitamin A-quality protein maize hybrids

Drought-tolerant early-maturing maize (Zea mays L.) inbred lines with high levels of provitamin A (PVA) and quality protein (QPM) are urgently needed for development of superior hybrids to mitigate malnutrition and to intensify maize production and productivity in sub-Saharan Africa (SSA). This study was designed to identify early-maturing inbred lines with combined tolerance to drought, elevated tryptophan, and PVA contents; to examine inbred-hybrid relationships for tryptophan and PVA accumulation; and to select hybrids with outstanding grain yield (GY) performance. A total of 64 inbred lines and six checks, plus 96 hybrids and four checks, were evaluated under drought and well-watered environments in Nigeria for 2 yr. Eighteen parental lines and 54 derived hybrids were assayed for tryptophan and PVA contents. Ten drought-tolerant inbred lines with high tryptophan and elevated PVA levels were identified in the top 10 hybrid combinations across managed drought and well-watered conditions. The inbred-hybrid relationship was significant for GY under each and across the two contrasting environments. Significant average heterosis was found for tryptophan and PVA under well-watered conditions. This indicated that the selected inbred lines could be used for developing high-yielding PVA-QPM hybrids tolerant to drought stress in SSA. The 10 top-performing PVA-QPM hybrids identified are being extensively evaluated in different locations and subsequently in on-farm trials for commercialization throughout SSA.