Interpretation of genotype-environment-nitrogen management interactions in the early maturing sorghum (Sorghum bicolor (L.) Moench) region of China

Sorghum (Sorghum bicolor (L.) Moench) is an important cereal crop in arid and semiarid regions. However, research on sorghum cultivation has lagged behind that of major field crops, and few information is available on the interaction of sorghum genotype, environment, and nitrogen fertilization on sorghum yield. Hence, a two-year field experiment included six varieties, and four nitrogen treatments were conducted at six sites in the spring-sown and early maturing regions of China. The results showed that yield variations between years and among sites, varieties, and fertilization were highly significant (P < 0.05). While the interaction between nitrogen fertilization and year showed significance in some cases, all other interactions were either significant or highly significant. Environment (including year, location, and year-location interaction) contributed the most to total yield variance (45.26%), followed by genotype (23.40%). Nitrogen and its interaction with the environment accounted for only 2.54% of the total variance, while nitrogen fertilization, variety, and their interaction with the environment contributed 6.69%. Although nitrogen fertilization showed no significant impact on sorghum yield in most cases, topdressing 300 kg ha−1 urea around the growing point differentiation stage consistently resulted in higher yields, with few exceptions. Rainfall showed a crucial determinant of nitrogen topdressing efficiency, underscoring its importance in nitrogen fertilization treatments. Topdressing proved to be a widely applicable fertilization practice in the current research areas, albeit optimal when soil moisture conditions are favorable. In unfavorable soil conditions or with excessive nitrogen doses, topdressing might lead to a yield penalty. In addition, the effect of nitrogen fertilization on sorghum production may be influenced by genotype, but further research is still necessary. Our research findings provide a conducive reference for nitrogen fertilization in sorghum production in similar regions.