Chapter 7 - Quinoa

Abstract

Quinoa cultivation expanded from South America to many countries in the past decades. Most of this expansion was based on trial and error, but future breeding and crop management necessitates a better understanding of the crop’s physiology. Even though there were significant advances at the plant and leaf at physiological level, a crop level of understanding is mostly lacking. Quinoa is a short-day plant with a wide geographic range of cultivation in its native environments, and this is expressed as high variation in photoperiod and temperature sensitivity, facilitating its adaptation to new environments. In contrast to other grain crops, its phasic development is also significantly affected by radiation and water deficits. Preliminary evidence suggests the late reproductive phase is the critical period for yield determination and, given quinoa’s semideterminate nature, grain number sensitivity to environment continues until late grain filling. Quinoa is promoted as highly tolerant to water deficit, however, analysis of Yield vs ETc data shows an upper limit of 13.3kghamm− 1, and maximum transpiration efficiencies range from ~ 35 to ~ 6 kg ha mm− 1, with increasing ETc. These values are low compared not only to cereals but also oil crops such as sunflower and canola. And significant gaps in water limited yields are detected deserving further exploration. The dynamics of nitrogen (N) uptake and distribution between organs and contribution to grain N is shown, and a N dilution curve was fitted to data from several experiments allowing for the estimate of crop N demand. N utilisation efficiency is high under low N but decrease fast with increasing N uptake, and this decrease is not explained by changes in grain N concentration but by a low N harvest index. Evidence of sink limitations to yield in highly productive environments suggests that increased partitioning to reproductive organs through breeding could result in both increases in potential yield and N utilisation efficiency because a positive association between N harvest index and harvest index is observed. Finally, there is yet little knowledge about responses to heat and waterlogging stresses, both limiting factors for quinoa expansion and production sustainability.