High-Throughput Phenotyping to Evaluate Heat Stress Response in Quinoa.

Quinoa is a nutritionally dense annual seed crop originating from the Andes Mountains of South America. Sensitivity to high temperatures has been reported as a serious obstacle to global expansion of quinoa. Temperatures above 35^› C during anthesis have been shown to significantly reduce quinoa grain yield. The objective of this study was to evaluate heat tolerance in diverse quinoa genotypes. 112 genotypes were evaluated at anthesis for 12 days in a greenhouse simulation experiment with a maximum temperature of 40^› C for 2 hours/day. Leaf greenness index (LGI) was quantified using a SPAD meter for each genotype. Of the original 112 genotypes, 68 produced seeds under heat-stressed conditions. The variety “Kaslaea” produced the highest yield (9.93 g/plant) and the variety “Cahuil” had the largest seed (3.37 mm²) under greenhouse conditions.  A set of eight genotypes were selected based on LGI for a subsequent field trial. Four (Baer, QQ74, Pison, and BGQ 352) were potentially heat tolerant with a mean decrease in LGI of 19.31 between day 12 and day 0, and four (17 GR, 3 UISE, La Molina and Japanese Strain) were considered sensitive to heat with a reduction in LGI of 60.11. The eight genotypes were grown at two field sites in 2016 under both heat-stressed and non heat-stressed conditions, and irrigated and dryland conditions, and evaluated for several indirect heat tolerance traits. These genotypes are currently being further evaluated using chlorophyll fluorescence imaging (CFI) to 38 ^›C in the WSU Phenomics facility with a FluorCam 2701 LU camera.  Different chlorophyll parameters will be measured with CFI. We will determine whether the eight genotypes selected previously for LGI in the greenhouse are correlated with the results obtained from the field experiment and the phenomics data. Our results will validate the capacity to generate a new tool for phenotyping quinoa at high temperatures.