Performance and yield stability of maize hybrids in stress-prone environments in eastern Africa

Identification and deployment of high-yielding and stress-tolerant maize hybrids adapted to stress-prone agro-ecologies is important for improving the food security and livelihoods of smallholder farmers in eastern Africa.The objectives of this study were to(i)assess the performance of maize hybrids under well-watered and drought stress conditions;(ii)evaluate grain yield stability of 65 intermediate-maturing and 55 early-maturing hybrids in 24 well-watered locations and seven drought stress locations;and(iii)identify representative and/or discriminative testing locations for increasing genetic gains for the target traits.There were significant differences for grain yield among early-and intermediatematuring hybrids tested under well-watered and drought stress environments.Among the early-maturing hybrids,the top 10 hybrids produced 46.8%–73.9%and 31.2%–42.1%higher mean grain yields than the best commercial check under drought and well-watered conditions,respectively.Among the intermediate-maturing hybrids,the top 10 hybrids produced 25.2%–47.7%and 8.5%–13.5%higher grain yield than commercial checks under drought stress and well-watered conditions,respectively,suggesting improvement in the levels of drought tolerance in both early-and intermediate-maturing hybrids.GGE biplot analysis and a bi-segmented regression linear method identified specific early-maturing and intermediate-maturing hybrids that performed well under both well-watered and drought stress conditions.These hybrids could be recommended for commercial production in eastern Africa.Kakamega in Kenya was found to be the most representative and highly discriminating site among well-watered testing locations,while Kabuku in Tanzania was the least representative of test locations.For testing under drought stress conditions,Kiboko in Kenya was identified as the most representative location.This information could be useful for allocating resources and streamlining CIMMYT maize hybrid testing in eastern Africa.

Color of Corn Grains and Carotenoid Profile of Importance for Human Health

The increasing on the levels of carotenoids in staple foods of broad human consumption is one of the strategies of food biofortification programs, mainly due to the importance of these compounds to human health on the prevention of vitamin A deficiency. Maize is a major staple food due to its high consumption in regions where problems of Vitamin A deficiency are of great relevance. Maize biofortification programs have made progress in determining the amounts of carotenoids in grain of thousands of accesses. This work aimed at studying the influence of the color of the grains in the profile of carotenoids in four different Brazilian genotypes. The selection of ears within the same genotype was based on a color scale, considering the lighter (lightest yellow) in one group and the most colorful (darkest orange) in another group. Significant interactions (p 0.05) between the color of the grains and the genotypes for all the variables were detected in addition to genetic variability for both groups (lightest yellow and darkest orange). The colored ears of corn showed a high level of total carotenoids (TC) and fractions in RS 535 and RS 445, and the colorful ears of genotype RS 535 showed 300% more α + β carotenes (μg·g-1) in relation to lighter of this same material. The results of this study showed the influence of genotype on the grain color and content of carotenoids, indicating that breeders have the flexibility to make selection of some genotypes based on grain color, reducing cost and time compared to laboratory methods used for the screening of genetic materials.