**1. Introduction**

Maize (*Zea mays* L.), commonly referred to as maize holds a prominent and cherished status as one of the world's most essential crops. Its importance extends beyond geographical borders, influencing cultures, economies, and dietary habits worldwide. Maize, serving as a staple food source for humans, providing nourishment, supporting livelihoods, a fermentation substrate, and a valuable commodity in numerous industrial applications [1], particularly in its dry grain form, occupies a critical role on the global scale. Wheat, maize, and rice are the primary staple cereals worldwide, each cultivated on approximately 200 million hectares. Corn, frequently referred to as maize, underwent domestication more than 9000 years ago within the southern Mexico/Mesoamerica region [2]. Together, these three primary global staple cereals, namely wheat, rice, and maize, make up a substantial portion of the human diet, accounting for approximately 40 percent of the world's calorie intake and 35% of protein consumption [3]. Maize fulfills a versatile and continually evolving function within the global agricultural and food systems, making substantial contributions to food and nutrition security [4, 5]. About 56% of its output is used as livestock feed, while one-fifth finds application in non-food sectors, and 13% is designated for human consumption. Notably, maize is distinguished by its high starch content, constituting roughly 65% of its composition [6]. Currently, maize has risen as a viable alternative to rice and wheat. Around 35% of its harvest is directed toward human consumption, while 25% serves as feed for poultry and cattle, and another 15% is used in food processing [1]. It has achieved the status of a significant global commodity, with 15% of the world's maize production currently being exported, marking an increase from the 11% reported in the previous decade [3]. It is on the verge of overtaking wheat as the most heavily traded cereal. Leading net-exporting nations such as the USA, Brazil, Argentina, Ukraine, and Romania are consistently shipping substantial quantities, ranging from 5 to 54 million metric tons annually [7]. Over the last century, maize yield has surged by a factor of eight, thanks to innovations in yield per plant and plant density optimization achieved through harnessing heterosis.

Throughout history, maize has been a quintessential subject in the realms of genetics, developmental biology, physiology, and, more recently, genomic research. The genetic investigation of *Zea mays* L. commenced with Edward East's pioneering research in 1908, which explored topics like inbreeding depression and hybrid vigor. A significant advancement in cytogenetics occurred in the 1940s when transposable elements (TEs) were discovered, as exemplified by Barbara McClintock's pioneering work [8]. In 2009, the first maize genome was made public [9]. Then, Jiao et al. [10] embarked on a re-sequencing project focused on the B73 maize variety. This effort revealed that a substantial 74% of its genome is comprised of long-terminal repeat retrotransposons (LTRs), which predominantly contribute to its enlarged size in comparison to other grass species. The main factor responsible for the maize genome's expansion relative to other grasses is the widespread increase in LTRs [10]. The cumulative cytogenetic, genetic, and genomic studies of maize have yielded rich insights into its genome's structure, function, and evolution. Resequencing wild relatives, traditional landraces, and improved maize lines, and aligning them with the reference genome, suggests that introgression from wild relatives contributes to post-domestication maize diversity. Through this method, genes with a wide range of biological functions that experienced selective pressure during the domestication process have been pinpointed [11].

The foundation of maize breeding relies on leveraging heterosis, which involves genome-wide allelic interactions, interactions among quantitative trait loci (QTLs), and inter-genomic interactions that occur when the two parental genomes combine in the F1 hybrid. The functional understanding of many maize genes, especially those linked to heterosis, is less advanced compared to other cereal crops, notably wheat and rice. Integrating whole-genome markers into genomic-based breeding represents

### *Enhancing Maize (*Zea mays *L.) Crop through Advanced Techniques: A Comprehensive Approach DOI: http://dx.doi.org/10.5772/intechopen.114029*

a viable approach for improving maize breeding and holds significant promise. Genomic selection (GS) serves as a notable illustration of this genomic design breeding strategy as it does not require an extensive comprehension of gene functions or the precise assessment of each marker's efficacy [12]. In this contemporary genomics era, the integration of various strategies and methodologies promises to boost maize productivity. This includes the amalgamation of modern genomics, phenomics, gene editing, synthetic biology, and the utilization of AI technology. The integration of an extensive array of maize omics data, spanning genomics, phenomics, epigenomics, transcriptomics, proteomics, and metabolomics, will form a vital foundation for machine learning approaches to build network models illustrating the interactions among various genetic components. In the context of a maize breeding program, a key strategic approach for achieving the desired goals of increased production and enhanced quality traits revolves around reducing the frequency of hybridizations while maximizing the incorporation of superior alleles. Swift progress toward trait enhancement objectives can be attained by executing two or three iterations of small-scale population development, thereby making the most of the available genetic diversity. This chapter highlights the importance of incorporating comprehensive strategies to enhance maize production, utilizing various modern techniques such as molecular breeding, marker-assisted selection (MAS), GS, the role of genome editing (CRISPR-Cas), and transgenic approaches. Additionally, the chapter delves into prospects and significant challenges in the field of maize improvement.
