Quinoa Photoperiod Sensitivity.

Quinoa is an Andean cereal with broad adaptation, the capacity to grow in marginal environments and high protein content and nutritional value. Originally domesticated in the Andes Mountains of South America, quinoa has been traditionally classified as a facultative short day plant, though long-day and day neutral cultivars are also currently in use. In areas of high latitudes, it is useful to identify genotypes with day length neutrality or adaptation to long day photoperiods. Five genotypes of quinoa (Titicaca, Puno, KU-2, NL-6 and Cahuil) were evaluated in growth chambers using two different photoperiod treatments; long days (LD), with 16 hours of light and 8 hours of dark, and short days (SD), with 16 hours of dark and 8 hours of light. Plant height was measured every five days from 20 to 60 days after seeding (DAS). Leaf greenness index (LGI) was calculated using a SPAD meter at 35, 45 and 55 DAS. Yield, protein and saponin content of the seed was recorded. Results showed that the quinoa were taller and higher yielding, with a greater number of leaves and a higher LGI (p<0.0001), when grown under the LD treatment compared to the SD treatment. No significant variation in protein content was observed in the seed between the two photoperiod treatments. Saponin content of the seeds was higher in SD (4.7 mg/g) compared to the LD treatment (3.1 mg/g) (p<0.0001). The highest LGI in both SD and LD treatments was recorded in the cultivar Puno. The highest yield was obtained with Titicaca at 6.5 g/plant in the LD treatment. All five genotypes of quinoa evaluated showed photoperiod insensitivity, with the plants growing in long days showing the most robust development, highest yield and lowest saponin content.