Field Crop 2024, Vol.7, No.3, 158-170 http://cropscipublisher.com/index.php/fc 159 quality, aiming to enhance the nutritional value and economic benefits of maize through scientific management (Ciampitti and Vyn, 2013). This study aims to evaluate the impact of various agronomic practices on the protein and starch content of maize. By synthesizing findings from multiple studies, the objective is to identify effective strategies for enhancing the nutritional quality and industrial utility of maize. This study assesses the influence of different agronomic practices on the protein content and amino acid composition of maize, explores how these practices affect the starch content and its properties, and provides recommendations for future research and practical applications to improve maize quality through agronomic interventions. By achieving these goals, this study hopes to offer practical technical guidance to agricultural producers, provide a scientific basis for improving maize quality and yield, and contribute to the optimization of maize cultivation for better nutritional outcomes and industrial applications. 2 Overview of Maize Composition Maize (Zea mays L.) is a staple crop with significant nutritional and industrial value. Its composition primarily includes carbohydrates, proteins, lipids, and essential minerals. The two major components of maize that are often the focus of agronomic studies are protein and starch, both of which are crucial for its nutritional and industrial applications. 2.1 Protein content in maize Maize contains protein, and the specific content may vary depending on the maize variety and growing conditions. Generally, maize has a protein content of about 8.5%. For example, every 100 grams of maize contains approximately 8.5 grams of protein. This protein is important for human physiological functions such as growth and tissue repair. Protein content in maize is a critical factor for both human consumption and animal feed. The concentration of protein in maize grains can be influenced by various agronomic practices. For instance, the application of nitrogen fertilizer has been shown to increase grain yield, which can inversely affect protein concentration unless the yield increase is directly due to nitrogen application (Mason and D'croz-Mason, 2002). Additionally, irrigation practices can enhance the biological value of protein, although higher nitrogen application rates may alter the amino acid balance, potentially reducing the nutritional value of the protein (Mason and D'croz-Mason, 2002). 2.2 Starch content in maize Maize has a high starch content, making it a primary source of carbohydrates. The starch content may vary depending on the maize variety and maturity, but generally, it is over 70%, which is significantly higher than other grains such as rice. In every 100 grams of maize, starch constitutes the majority, providing a substantial amount of energy. Starch is the predominant carbohydrate in maize, making it a vital component for both food and industrial uses. The composition of starch, particularly the amylose-to-amylopectin ratio, can be influenced by environmental conditions and agronomic practices. For example, environmental factors such as solar radiation and temperature during the grain filling period can significantly affect the amylose/starch ratio (Martínez et al., 2019). Fertilization with nitrogen and sulfur, as well as modifications in the source/sink ratio through defoliation and plant thinning, have been studied, but these practices did not produce significant changes in starch composition (Martínez et al., 2019). However, increases in minimum temperature during early grain filling were associated with decreases in starch percentage and increases in the amylose/starch ratio (Martínez et al., 2019). 2.3 Factors affecting maize composition Factors influencing the composition of maize include genetics, environment, and agronomic practices. Different varieties of maize exhibit differences in nutritional components, such as protein, starch, and fat content. Growing conditions, including soil, climate, irrigation, and fertilization, significantly impact the growth and development of maize, thereby affecting its nutritional content. As maize matures, its nutritional composition also changes.
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