Traits associated with higher productivity and resilience to drought-prone Mediterranean environments of coastal-lowland quinoa (Chenopodium quinoa Willd.)

Quinoa (Chenopodium quinoa Willd.) is an Andean crop that has been cultivated for over 7000 years in Andean South America. Among the five quinoa ecotypes identified, the coastal-lowland ecotype is distributed in central-southern Chile. Little is known about the phenotypic variability of this germplasm and its productive potential. In this work, we evaluated a panel of 99 self-pollinating genotypes of quinoa under rainfed and irrigated conditions in the Mediterranean area of central Chile. The aim was i) to evaluate the phenotypic variability of agronomic and leaf photosynthetic traits; ii) to assess trait responses to environmental conditions (rainfed and irrigated) and their heritability; and iii) to identify traits and genotypes associated with high yield potential and resilience in drought-prone environments. The selected genotypes were evaluated under rainfed (Hidango; 34 degrees 06' S, 71 degrees 47' W) and irrigated (Santa Rosa; 36 degrees 31' S, 71 degrees 54' W) conditions, in two growing seasons (2016/17 and 2017/18). In the most favorable environment (Santa Rosa 2016), the shoot dry weight (shoot DW) and grain yield (GY) of the different genotypes, ranged from 655 and 2787 g m-2 (average 1440 g m-2) and from 45 and 452 g m-2 (average 244 g m-2), respectively. Under rainfed conditions (at Hidango), the shoot DW and GY were reduced by 75 % and 74 %, respectively, compared to Santa Rosa 2016, but still, some genotypes produced more than 100 g m-2, with < 70 mm of precipitation, evidencing a high drought tolerance. The harvest index (HI) and grain weight (TKW) were less affected by drought; compared to Santa Rosa 2016, the reduction was 8-18 % and 25-29 %, respectively, in 2016/17 and 2017/18. Days from sowing to flowering (DSF) and from flowering to maturity (DFM) varied among genotypes and were negatively correlated with GY and HI. Under rainfed conditions, the fluorescence parameters F0 and Fm were reduced by 30 % during flowering and by 50 % during grain-filling, compared to irrigated conditions. The HI and TKW showed the highest heritability (0.69) and were highly correlated with GY in all environments. This study showed that traits associated with higher productivity and resilience of quinoa genotypes in rainfed Mediterranean environments were early maturating and with high HI, and TKW. Finally, a set of genotypes presenting a high stress tolerance index (STI), and therefore higher tolerance to drought conditions, were identified and are candidates for further research focused on the selection of parentals for more advanced breeding stages.