ABSTRACT
Quinoa (Chenopodium quinoa ), a herbaceous annual, has been widely
cultivated in recent years because of its high nutritional value and
strong tolerance to abiotic stresses. The study was conducted at two
planting densities (LD, 10 plants/m2; HD, 65
plants/m2) on ameliorated coastal mudflats in Jiangsu
Province, China (118° 46′ E, 32° 03′ N). The results showed soil
salinity and organic matter were higher in the HD than LD treatment, and
salinity of the rhizosphere soil was higher than that of the
non-rhizosphere soil. Quinoa grown in HD was taller, with thicker stalks
and lower yields per plant, but higher yield per unit area. Amplicon
sequencing showed that Proteobacteria , Bacteroidota andAcidobacteria were the dominant bacterial phyla. Regarding the
rhizosphere soil, the Shannon index was higher in the HD than LD, andProteobacteria and Bacteroidota were more abundant in the
HD treatment. Fifty-one differential metabolites were identified by
metabolomic assays, belonging to 14 annotated metabolic pathways.
S-adenosylmethionine was the most
abundant and up-regulated metabolite (fold change >1.67),
and was more abundant in the roots from the LD than HD treatment.
Docosahexaenoic acid was more abundant in the HD than LD treatment, and
was down-regulated metabolite. In conclusion, planting density was an
important factor affecting quinoa yield; compared with unplanted soil,
planting quinoa at low density increased the content of the important
metabolite S-adenosylmethionine in the root system of quinoa, and high
density cultivation of quinoa increased soil salinity and microbial
abundance and diversity.