Developing elite lines with synchronous emergence rate and strong seedling vigor for sand rice (Agriophyllum squarrosum) cultivation

Sand rice ( Agriophyllum squarrosum (L.) Moq.), an annual herbaceous species of Amaranthaceae, is a potential and climate-resilient crop. Its bet-hedging strategy in seed germination and/or seedling emergence offers survival advantages in unpredictable desert environments but poses significant challenges to its domestication and cultivation in northern China. Utilizing seeds from various sources, including natural population/wild type (Nat/WT), mutant population (the trichomeless mutant ( astcl1 ) and spontaneous mutant, Mut), F 2 mapping population of astcl1 mutant (F 2 ), and two ethyl methanesulfonate (EMS)-induced mutant libraries derived from pre-selected lines selected from the Duolunnan and Naiman populations (DLN_Mut and NM_Mut), this study aimed to identify elite lines displaying synchronous seedling emergence and strong seedling vigor. Results showed that EMS mutagenesis substantially increased the variability in seed size, seedling emergence, and vigor, with seed size positively influencing the rate and percentage of seedling emergence. Seven lines were identified with synchronous emergence rates, while 54 lines exhibited strong seedling vigor. Notably, all seven lines with synchronous emergence and 43 of the 54 lines with strong vigor were from the NM_Mut group. Furthermore, two elite lines with both characteristics were derived from the NM_Mut group. Our findings indicate that chemical mutagenesis effectively reduces the undesirable herbaceous characteristics while improving key agronomic traits. This confirms that mutagenesis breeding is feasible for de novo domestication of sand rice.