Agronomic performance of elite drought tolerant maize (<i>Zea mays</i> L.) hybrids under natural disease inoculation in the rainforest of Nigeria.

Abstract

The tropical rainforest agroecology is highly vulnerable to a myriad of plant disease infections and the likelihood that farmers would adopt a new maize cultivar largely depends on its resistance to the common diseases. In the present study, a set of newly developed single cross drought tolerant maize hybrids were evaluated under natural disease inoculation and their performance for grain yield, breeder’s traits, and response to infections by four cosmopolitan foliar diseases were assessed. A trial comprising 96 experimental hybrids and 4 hybrid checks were planted over two rainy seasons at Ikenne using a 10 x 10 triple-­‐lattice design. Hybrids differed significantly (p < 0.0001) for grain yield and other measured traits. Significant hybrid x year interaction was also observed for all traits except plant aspect. Ranking of mean grain yields of hybrids between the two years revealed moderate but highly significant correlation (r = 0.50, p < 0.0001). All measured traits except curvularia were negatively and significantly correlated (r = -­‐0.16 to -­‐0.58, p < 0.0001) with grain yield. Mean grain yields ranged between 2,282 and 6,132 kg ha-^­‐1 with a trial mean of 4,509 kg ha-­^­‐1. The top five yielders exceeded the best drought tolerant check (M1026-­‐7; 5,485 kg ha-­^­‐1) by a least 2 standard errors whereas the top 20 hybrids produced significantly higher yields than the best commercial check (Oba 98; 4,150 kg ha-­^­‐1) and had mostly favorable scores for the breeder’s traits and response to foliar disease infections. Promising high yielding and drought tolerant hybrids that have appreciable resistance to common foliar diseases can be selected among the tested genotypes.