Evaluation of Pre-Harvest Sprouting (PHS) Resistance and Screening of High- Quality Varieties from Thirty-Seven Quinoa (Chenopodium quinoa Willd.) Resources in Chengdu Plain

Pre-harvest sprouting (PHS) will have a serious effect both on the yield and quality of quinoa (Chenopodium quinoa Willd.). It is crucial to select and breed quinoa varieties with PHS resistance and excellent agronomic traits for guidance production and utilization of quinoa. A comprehensive evaluation of the PHS resistance and agronomic traits of 37 species of quinoa resources was conducted in Chengdu Plain. The evaluation used various methods, including grain germination rate (GR), grain germination index (GI), total spike germination rate (SR), total grain germination index (SI), grey correlation analysis (GCA), cluster analysis and correlation analysis. Results showed significant differences in PHS resistance and agronomic traits amongst the 37 quinoa resources. CDU-23 was most resistant to PHS within 24 h, with a germination rate of 2.67% and 0% according to the GR and SR results, respectively. However, in the same time, CDU-31 showed the maximum susceptibility to PHS based on the SR of 31.07%, while CDU-34 was the most sensitive to PHS according to the GR of 100%. The comprehensive evaluation identified one and nine kinds of high resistance species for grain and whole spike germination, respectively. In both cases, the coefficients of variation (CV) for these parameters were 34.78% and 82.13%, respectively. GCA results showed that the magnitude of the association between each trait and yield in the thirty-seven quinoa resources was in the following order: thousand grain weight > seed length > seed area > seed width. Although the seed weight of CDU-18 reached 3.7010 g, the seed weight of CDU-5 was only 1.6030 g. However, the size of the seeds, their width and area did not correlate with their 1000-grain weight. There was a complex correlation between PHS resistance index and agronomic traits. Based on clustering analysis, thirty-seven quinoa resources were classified into three taxa. It was found that various taxa differed in PHS resistance and agronomic traits. Several comparisons of the aggregated data led to the selection of five varieties of quinoa, of which CDU-2 presented excellent agronomic qualities and strong PHS resistance. This study has provided a reference for breeding excellent quinoa varieties with PHS resistance.