Maize Genomics and Genetics 2025, Vol.16, No.1, 10-19 http://cropscipublisher.com/index.php/mgg 14 In addition to its stress tolerance, L9/T7 also showed high yield stability across different environments. The grain yield of this line ranged from 1.28 to 3.5 t/ha, with the highest yield recorded under well-watered conditions (Matongera et al., 2023b). The ability of L9/T7 to perform consistently across diverse environmental conditions underscores its potential as a reliable fresh-eating maize line with enhanced quality and stress resistance. 4.3 Implications for future breeding The identification of the superior maize line L9/T7 has significant implications for future breeding programs. This line's high yield potential and stress tolerance make it an excellent candidate for developing new hybrids that can thrive in various environmental conditions. By incorporating L9/T7 into breeding programs, it is possible to create maize hybrids that not only meet the nutritional needs of consumers but also withstand the challenges posed by climate change (Chen et al., 2012; Matongera et al., 2023a). Furthermore, the genetic diversity and trait associations observed in L9/T7 can be leveraged to enhance the genetic base of fresh-eating maize. The line's favorable GCA and SCA effects suggest that it can be used to produce hybrids with improved grain yield, nutritional quality, and stress resistance (Matongera et al., 2023a; 2023b). This will contribute to the sustainability and productivity of maize production, ensuring a stable food supply for future generations. 5 Findings from Field Trials and Evaluations 5.1 Yield and quality traits The performance of different maize lines in terms of yield, sweetness, and kernel appearance was rigorously evaluated under various conditions. For instance, hybrids such as L230, L613, and L5*18 demonstrated high specific combining ability (SCA) effects for yield under combined drought and heat stress (CDHS), indicating their potential as superior lines for yield (Chiuta and Mutengwa, 2020). Additionally, the study on multi-nutrient maize revealed that hybrids like L10/T7 and L9/T7, which combined zinc-enhanced lines with normal nutritional backgrounds, exhibited high grain yield and desirable secondary traits under both stress and non-stress conditions (Matongera et al., 2023a; Yang and Li, 2024). In terms of quality traits, the evaluation of pro-vitamin A maize hybrids under Striga hermonthica infestation and low soil nitrogen conditions identified hybrids such as TZEEIOR 217×TZEEIOR 197 and TZEEIOR 245×TZEEIOR 195 as top-yielding under stress conditions (Makinde et al., 2023). These hybrids not only maintained high yield but also exhibited superior kernel appearance and sweetness, making them suitable for fresh consumption. 5.2 Stress resistance performance The performance of maize lines under stress conditions, such as drought and salinity, was a critical aspect of the evaluations. The study on drought and heat stress tolerance identified inbred lines L30, L6, L5, L17, and L2 as having good combining ability for yield under CDHS, suggesting their robustness in stressful environments (Chiuta and Mutengwa, 2020). Similarly, the evaluation of maize inbred lines under optimal and drought stress conditions highlighted that lines like Nub60, Nub32, Nub66, and GZ603 exhibited high drought tolerance, maintaining relatively high grain yield under both normal and stress conditions (Balbaa et al., 2022). Moreover, the research on stacking tolerance to drought and resistance to Striga hermonthica demonstrated that DTSTR hybrids out-yielded commercial hybrids by 13%-19% under managed drought stress and by up to 70% under Striga-infested conditions (Menkir et al., 2020). This indicates that these hybrids possess significant resilience to multiple stress factors, making them ideal candidates for cultivation in stress-prone regions. 5.3 Significant correlations Key correlations between quality and stress resistance traits were identified, providing insights into the selection of superior maize lines. For instance, the study on genetic diversity and inter-trait relationships in tropical extra-early maturing quality protein maize revealed a strong association between grain yield and traits like plant height and ear height under low soil nitrogen stress (Abu et al., 2021; Li and Huang, 2024). This suggests that selecting for these secondary traits could indirectly enhance grain yield under stress conditions.
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