EFFECT OF HEAT AND DROUGHT STRESS IN QUINOA (Chenopodium quinoa Willd.)

Abstract

Quinoa is an Andean grain crop from South America. It is recognized due to its high nutritional value and tolerance to marginal agronomic environments. High temperature and dry environments are the primary challenges to quinoa production in the Pacific Northeast. Since the sequence of the quinoa genome in 2017, new information about abiotic stress has been published. Thus, a literature review focusing on abiotic stress in quinoa is presented. In field experiments conducted in two locations over two consecutive years under irrigated and non-irrigated conditions, high-throughput phenotyping and physiological tools were evaluated in eight quinoa genotypes. Supplementary irrigation was shown to mitigate the effect of high temperatures. Baer, Pison, and QQ74 were high yielding under both cool and hot summer temperatures. The normalized difference vegetation index was identified as a fast parameter to predict quinoa yield. In order to study the mechanisms and the effect of high temperature in quinoa, experiments were carried out in controlled conditions focusing on the effect of high temperatures on plant growth and pollen viability. Pollen viability was reduced; however, plant growth and seed yield were not affected by the high temperature, likely due to sufficient supplemental irrigation. Peroxisome abundance using as a cellular marker was evaluated in eight quinoa genotypes under heat, drought, and the combination of both. Drought and the combination of heat and drought caused significant yield losses. However, genotypes QQ74 and Pison performed better than the other six genotypes. Peroxisome abundance and hydrogen peroxide content correlated negatively with yield. Peroxisome abundance and transcription levels of genes for peroxisome fission proteins PEX11C and FIS1A could be used as markers of reactive oxygen species accumulation under abiotic stress in quinoa. Furthermore, a preliminary QTL study was presented as an appendix detecting QTL for seed size and seed color in two biparental quinoa populations. Finally, another appendix about photoperiod in quinoa showed than quinoa has a high plasticity to extreme photoperiods; hence, seed protein content and seed size were increased under short day conditions. These projects contribute to the global knowledge base for the adaptation of quinoa under abiotic stresses.