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Combining Ability and Heterotic Effects in Newly Developed Early Maturing and High-Yielding Maize Hybrids under Low and Recommended Nitrogen Conditions
1 Department of Agronomy, Faculty of Agriculture, Kafrelsheikh University, Kafr El-Sheikh, 33516, Egypt
2 Department of Biology, Faculty of Science, Umm Al-Qura University, Makkah, 24372, Saudi Arabia
3 Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
4 Department of Biological Science, College of Science, University of Jeddah, Jeddah, 21589, Saudi Arabia
5 Department of Biology, College of Science, Buraydah, 51452, Saudi Arabia
6 Department of Plant Production, Genetic Branch, Faculty of Environmental and Agricultural Sciences, Arish University, El-Arish, 45511, Egypt
7 Department of Geography and Environmental Sustainability, College of Humanities and Social Sciences, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh, 11671, Saudi Arabia
* Corresponding Author: Mohamed M. Kamara. Email:
(This article belongs to the Special Issue: Integrative Approaches to Plant Stress Responses under Changing Climate Conditions)
Phyton-International Journal of Experimental Botany 2025, 94(1), 101-122. https://doi.org/10.32604/phyton.2025.058033
Received 09 September 2024; Accepted 07 November 2024; Issue published 24 January 2025
Abstract
Nitrogen (N) is a crucial nutrient vital for the growth and productivity of maize. However, excessive nitrogen application can result in numerous environmental and ecological problems, such as water pollution, biodiversity loss, and greenhouse gas emissions. Therefore, breeding maize hybrids resilient to low nitrogen conditions is crucial for sustainable agriculture, especially under low nitrogen conditions. Consequently, this study aimed to evaluate the combining ability and heterosis of maize lines, recognize promising hybrids, and study gene action controlling key traits under low and recommended N stress conditions. The half-diallel mating design hybridized seven maize inbreds, resulting in 21 F1 hybrids. These hybrids, along with two high-yielding commercial hybrids (SC10 and TWC310), were evaluated in field trials under recommended (290 kg/ha) and low N (166 kg N/ha) conditions. Significant variations were observed among assessed hybrids for all measured traits, with non-additive gene action being predominant for grain yield and its related characteristics under recommended and low N conditions. Inbred lines P105 and P106 were recognized as effective combiners for earliness, with P105 also excelling in shorter plant height and lower ear placement. In addition, P101, P102, and P104 were identified as good combiners for increasing grain yield and related attributes under low N conditions. The crosses P105 × P106 and P106 × P107 demonstrated outstanding heterotic effects for earliness, while hybrids P101 × P102 and P102 × P104 exhibited remarkable heterotic effects for grain yield low nitrogen stress conditions. These promising hybrids could be considered for commercial use after further evaluation. Strong positive correlations were found between grain yield and ear height, plant height, number of kernels per row, and 1000-grain weight, highlighting their importance for indirect selection to enhance the grain yield of maize under low N stress conditions.Keywords
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