Genotype by light quality interaction on the growth and development of quinoa (Chenopodium quinoa) and the crop response to salinity

Quinoa (Chenopodium quinoa Willd.) is a highly nutritious crop with remarkable tolerance to drought and salinity, making it a promising model for developing resilient crops. In model plant species, photoreceptors have been shown to mediate abiotic stress responses. Although quinoa’s tolerance mechanisms have been extensively investigated, the influence of light on its growth and stress responses remains largely unexplored. This study evaluated the effects of broad-spectrum white light supplemented with narrow-bandwidth light on quinoa vegetative development under non-saline and moderate salinity conditions. Four genotypes were tested: two commercial varieties and two local Ecuadorian landraces. Light quality influenced physiological responses in a genotype-dependent manner. Supplemental far-red light promoted greater plant height under both control and salt conditions. Supplemental red light enhanced biomass accumulation under control conditions but not under salinity, suggesting that red light–mediated growth promotion may be constrained by higher salinity. Conversely, supplemental blue light mitigated the negative effects of salinity on growth, indicating a potential role as a positive mediator for salt tolerance in the species. The presence of salt altered several light-driven responses,  supporting an interaction between responses to light and salt stress signaling. Our findings highlight the importance of incorporating light-related variables into quinoa stress physiology research which could ultimately provide breeding insights to enhance crop resilience through targeted photoreceptor breeding.