Maize Genomics and Genetics 2025, Vol.16, No.3, 119-128 http://cropscipublisher.com/index.php/mgg 121 2.2 Current status of fresh corn production Fresh corn is a type of corn that is harvested at the milky stage and can be eaten directly or after simple processing. It mainly includes two categories: glutinous corn and sweet corn. my country is the origin of glutinous corn, so glutinous corn is often called "Chinese glutinous corn" internationally. As early as 1908, American scholar Collins introduced glutinous corn to the United States, and then gradually spread to all parts of the world. In 1944, Wallace, the founder of Pioneer Seed Company and then vice president of the United States, introduced China's rich glutinous corn germplasm resources on a large scale during his visit to China, further promoting the development of global glutinous corn breeding (Bernardo et al., 2021). Although my country has rich glutinous corn germplasm resources, related research and development started relatively late. It was not until the 1970s that systematic glutinous corn breeding was officially carried out, and a number of excellent inbred lines and hybrid varieties were successively bred, such as 'Zhongnuo No. 1', 'Zhongnuo No. 2', 'Yannuo No. 5', 'Jiongnuo No. 6', 'Lunuoyu No. 1', 'Zhongnuo 301', 'Kennian No. 1', 'Xixing Nuoyu No. 1', etc. Although these varieties have made progress in quality, the scale of cultivation is still small, mainly for picking fresh ears for consumption, and fresh consumption is still the mainstream application direction. Industrial utilization is not yet widespread, and it is only used in green consumption, quick freezing and other fields (Devasirvatham et al., 2016). Sweet corn originated in America. It can be divided into three main types according to different sweet genes: ordinary sweet type, super sweet type and enhanced sweet type. Sweet corn was commercially cultivated in the early 20th century, with the United States becoming the world's largest producer and exporter of sweet corn. Since the 1940s, the area of sweet corn cultivation in the United States has continued to expand, doubling almost every five years. Data show that by 1999, the global sweet corn planting area had reached 667 000 hectares, of which the United States had a planting area of 315 000 hectares, about 7% of the output was used for fresh consumption, and about one-third of its processed products were exported to the international market. In addition, Japan, South Korea and Taiwan also have high consumption and planting demand for sweet corn. In my country, although sweet corn breeding started early, dating back to the 1950s, its promotion and application in actual production lagged behind. It was not until the past decade that the development of sweet corn has accelerated significantly, especially in Guangdong Province, where the annual planting area has reached about 67 000 hectares, becoming one of the main areas for the development of my country's sweet corn industry. 2.3 Improvement of fresh corn quality According to the variety approval data, all regions of the country have made certain improvements in the quality of glutinous corn, and the appearance, flavor and tenderness of fresh glutinous corn are generally on the rise. Most varieties have reached the national second-level fresh glutinous corn standard, although there are no varieties that have reached the first-level standard. Breeding improvements in recent years have mainly focused on optimizing appearance traits, improving flavor, softening taste, and reducing pericarp thickness (Qureeshi et al., 2020). For example, compared with 2005, the sensory scores, flavor performance and tenderness of the varieties approved in 2009 have been improved to varying degrees, while the pericarp thickness has decreased, reflecting that the breeding direction is steadily moving towards the goal of improving the quality of fresh food. However, in terms of core quality characteristics such as smell, color and glutinousness, the overall performance has been stable since 2006, with no significant breakthroughs, and some traits have even declined slightly. This phenomenon may be related to the current insufficient utilization of germplasm resources and the fact that some breeding projects still use the "glutinous quality" improvement method of ordinary corn, which limits the space for quality improvement (Chen et al., 2023). Therefore, although the yield and quality of glutinous corn breeding have improved in recent years, in order to achieve the leap from "meeting the standard" to "high quality", it is necessary to more efficiently integrate excellent germplasm resources, optimize breeding technology routes, and promote the development of glutinous corn breeding in the direction of high quality and diversification.
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