Gains in grain yield of released maize (Zea mays L.) cultivars under drought and well-watered conditions

Abstract

Maize (Zea mays L.) grain yield is severely constrained by drought and this study was conducted to assess gains in grain yield and other traits of released maize cultivars. Twenty-three maize cultivars plus a check were evaluated under drought and well-watered conditions at Zaria and Kadawa during 2015/2016 and 2016/2017 dry seasons. The 24 cultivars were evaluated using 6 x 4 lattice design with three replications. Genotypes differed significantly for all measured traits except anthesis-silking interval (ASI), husk cover, and number of ears per plant under drought, and ASI, husk cover, and ear aspect under well-watered conditions. Under drought, grain yield ranged from 2251 kg ha−1 for SAMMAZ 31 to 4938 kg ha−1 for SAMMAZ 19, with a genetic gain of 1.93% yr−1. Under well-watered conditions, grain yield varied from 3082 kg ha−1 for SAMMAZ 37 to 5689 kg ha−1 for SAMMAZ 51, with the same genetic gain found under drought conditions. Grain yield reduction as a result of drought was 28.4% and performance under drought predicted performance under well-watered conditions better than vice versa with regression coefficient value of 0.8. Grain yield had significant correlations with all measured traits under both water conditions, except for husk cover, plant and ear heights under drought. Our data revealed that substantial genetic gains have been made in breeding for high grain yield cultivars under drought and well-watered conditions over a period of 16 years in Nigeria.

Genetic Gains from Selection for Drought Tolerance during Three Breeding Periods in Extra-Early Maturing Maize Hybrids under Drought and Rainfed Environments

“…The significant mean squares detected for GY and most measured traits for the 60 extra-early hybrids under both drought and well-watered conditions suggested high genetic variability among the hybrids under both moisture stress and optimal growing conditions. The significant Env × hybrid (period), and period mean squares indicated that the hybrids performed differently under contrasting moisture conditions within different periods and that the environments and the periods were distinct enough to reveal the differences among the genotypes [10,25,39]. These results also suggested large variability in environmental factors particularly soil type (water holding capacity) and rainfall amount [40], as well as temperature ranges during the growing seasons at the experimental site, particularly at Ikenne.…”

“…It was believed that assessment of the genetic improvement in terms of grain yield and related agronomic traits from one breeding period to the other during the past two decades could be beneficial in identifying important traits to accelerate genetic gains in the hybrid development program [22,23]. However, the direct relationship between grain yield potential and related traits of the drought-tolerant extra-early hybrids developed during the three breeding periods [24] had not been assessed to understand the rationale behind the huge investments in the breeding program [25]. It is therefore of vital importance to determine the extent of progress made in breeding for extra-early hybrids tolerant to drought in the specified breeding periods.…”

Gains in Genetic Enhancement of Early Maturing Maize Hybrids Developed during Three Breeding Periods under Striga-Infested and Striga-Free Environments

“…Information on trait association is important for designing effective breeding programs for maize genetic enhancement [22]. The significant and negative correlations obtained for grain yield and Striga damage and number of emerged Striga plants at 8 and 10 WAP implied that these characters were important for yield improvement under Striga infestation.…”

Accelerated Genetic Gains in Early-Maturing Maize Hybrids following Three Periods of Genetic Enhancement for Grain Yield under Low and High Soil-Nitrogen Environments

“…Several authors [10][11][12][13][14][15] have reported genetic gain studies for comparisons of older and newer cultivars under different environments, and they have significantly contributed to better understanding of the breeding progress of maize cultivars developed during different periods [16,17]. Results of genetic gain studies have revealed significant increases in grain yield between generations of cultivars.…”