An accurate and effective single-seed moisture selection method based on nuclear magnetic resonance (NMR) in maize

Kernel moisture content (KMC) is important for maize grain development, harvest, and storage. Breeders always consider KMC as a necessary indicator when conducting breeding programs. The fact that a large number of samples are required for the typical breeding process necessitates the development of accurate, high-throughput, and non-destructive detection techniques for KMC. Here, we proposed an effective method based on nuclear magnetic resonance (NMR) spectroscopy to track moisture variation in maize kernels and select offspring with low KMC at harvest. Both moisture mass and content could be accurately measured via regression analysis (R2 = 0.9924 and 0.9139, respectively). Magnetic resonance imaging technology was also applied to monitor the spatial distribution of moisture in individual kernels and ears. On the other hand, with two generations of KMC selection experiments, we demonstrated the effectiveness of the proposed method. KMC was measured for selfcrossing kernels of two elite hybrids, namely Zhengdan958 and Xianyu335, and partial kernels were classified into a high-kernel-moisture group (HMG) or low-kernel-moisture group (LMG). The progenies were then selected for kernels having a high KMC in HMG and low KMC in LMG. After selection, KMCs in LMG were significantly lower than those in the HMG in both hybrids at generations F2 and F3. Finally, phenotypic response surveys revealed that KMC selection significantly affected the flowering time. Our results demonstrate the effectiveness of the NMR-based platform for optimizing KMC trait, with potential applications in maize breeding programs.