Abstract
Genetic variation abundance, high genetic advance coupled with high heritability estimates presents the most suitable condition for selection. Ninety-five hybrids generated from elite and new inbred lines crossed using half diallel mating design were evaluated under diverse environments. The objectives were to estimate genetic variances, heritability of traits and genetic advance and to determine correlations of grain yield and its component characters in maize hybrids. Analysis of variance revealed significant differences among genotypes for all traits studied except for ear rots. Estimates of phenotypic coefficient of variation were slightly higher than genotypic coefficient of variation for all traits suggesting low influence of environment in the expression of these traits. High heritability and genetic estimates were recorded for grain yield (79%; 30.27%), plant height (85%; 102.42%) and ear height (86%; 117.15%) whilst high heritability and low genetic advance were observed for anthesis date (87%; 5.8%), texture (75%; 8%) and ear position (71%; 0.23%). Correlation between environments using grain yield data revealed existence of a very strong positive correlation between CIMMYT2 and RARS2 suggesting that the sites have the same discriminating effect. Correlation among traits revealed that grain yield had significant (P < 0.05) positive correlation with plant height and ear height. Similarly, plant height had significant and positive correlation with ear height while ear position was positively correlated to ear height. Path analysis showed that plant height, ears per plant and ear position had positive direct effects on grain, while anthesis date, ear height, ear position, grain moisture content at harvest and texture indirectly influenced grain yield. These characters’ contribution to grain yield is important and the strong association with grain yield implied that these can be used as secondary traits to indirectly select for grain yield performance in this set of germplasm across all the environments.
Highlights
Maize (Zea mays L.) plays a crucial role in food security and livelihoods of people in the sub-Saharan Africa (SSA) (Kassie et al, 2017)
The traits analyzed in this study include: grain yield (GYD), anthesis date (AD), ear height (EH), plant height (PH), stem lodging (SL), root lodging (RL), husk cover (HC), moisture content (MC), anthesis silking interval (ASI), ear position (EPO), texture (TEX) and ear per plant (EPP) were significant at (P < 0.05) except for ear rots (ER)
Heritability ranged from 20% to 87% with higher estimates recorded for plant height (85%), anthesis date (87%), ear height (86%), grain yield (79%), texture (75%) and ear position (71%) and anthesis silking interval (55%)
Summary
Maize (Zea mays L.) plays a crucial role in food security and livelihoods of people in the sub-Saharan Africa (SSA) (Kassie et al, 2017). Maize yield in SSA average is 2.1 tons per hectare which is much lower compared to world average of 5.6 tons per hectare (FAOSTAT, 2017). Abiotic stresses such as heat, drought and poor soils with low nitrogen hinder maize productivity in the region (Makumbi et al, 2018; Das et al, 2019). In the current study the focus was on estimating genetic parameters of hybrids evaluated under diverse environments. Genetic parameters such as genetic variability and heritability estimates are crucial in improving selection efficiency and jas.ccsenet.org. Selection of best genotypes using grain yield alone under stress conditions is not effective but can be improved via improvement of yield component traits such as anthesis date, anthesis silking interval, plant height, ears per plant among others (Mhike et al, 2012)
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