Kangnongyu8009: a new high-yield maize variety developed through amalgamation of temperate and tropical germplasm

Maize (Zea mays) is China's most important cereal crop, playing a crucial role in national food security.According to the National Bureau of Statistics, in 2024 China's maize planting area reached 44.74 million hectares with a total output of 294.92 million tons, accounting for 37.5% and 41.74% of the national grain planting area and total grain yield, respectively (National Data of China, h t t p s : / / d a t a .s t a t s .g o v .c n ) .The growing demand from livestock production, food processing, and bioenergy industries has continuously driven the need for higher maize yields (FAO statistics, https://www.fao.org/faostat/en).As one of China's major maize-producing regions, the Huang-Huai-Hai Plain commonly employs a winter wheat-summer maize double-cropping system.Although this practice substantially enhances grain production efficiency, it also compresses the effective growing period of maize, thereby increasing its vulnerability to