Studies of the Impact of Drought Stress on Pollen Shedding and Silk Development in Maize (Zea Mays L.) to Assist Selection of Stress Tolerance Hybrids Based on Phenotypic Traits

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Maize (Zea mays L.) is the most valuable commodity crop in the United States and is second to rice in the world. With the upcoming challenges of extreme climates due to global warming, further study of abiotic stresses, including drought stress, are necessary to develop improved approaches for the selection of maize hybrids for stress tolerance. Understanding the performance under drought stress of the important growth stages, pollinating and silking, is critical for improving reproductive success of pollination and yield potential and in breeding hybrids with stress tolerance. This study investigated the impact of water stress on pollen shedding patterns, pollen quantity, pollen viability, and silk+ear growth across eight different hybrids. Assessment of pollen viability with tetrazolium compounds indicated unstable reactions and was inconsistent. However, the analysis of pollen quantity and silk growth provided direction and insights for breeding selection. By analyzing with two-way ANOVA and Emmeans functions through R studio on the pollen weight from the pollen shedding period, results showed that there was a significant difference of pollen weight among hybrids (F(7df)=2.605, p=0.0534) and treatments (F(1df)=6.165, p=0.0245). Drought significantly increased pollen weight in hybrids 11, 2, and 20, and hybrid 18 had high pollen weight in both control and stress conditions. In addition, drought reduced ear and silk growth and various silk and ear growth rates across hybrids. Among hybrids, 11, 13, 15, and 16 had greater silk+ear growth rate under drought stress. These observations provide insight regarding phenotypic traits in maize for drought stress tolerance breeding selection.

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Setter, Tim

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