Response of quinoa (Chenopodium quinoa Willd.) to differential drought stress in the Bolivian Altiplano: Towards a deficit irrigation strategy within a water scarce region

Abstract

A controlled drought stress experiment was carried out on Quinoa in the Bolivian Altiplano. The Bolivian Altiplano is a vast inter Andean basin at an average altitude of 3850 m.a.s.l. The climatic and soil conditions put severe constraints on crop production in this region. Quinoa (Chenopodium quinoa Willd.), a traditional Andean pseudocereal, is remarkably well adapted to the unfavorable growth conditions and has high nutritional value. Due to limited and highly variable rainfall during the growing season, yields are unstable. Irrigation of quinoa during the frost free period is a way to increase and stabilize yields. However, given the water scarcity in the region, deficit irrigation with flexible guidelines is the only option. To develop guidelines for deficit irrigation, a lysimeter experiment under a rain shelter with eight water application treatments was carried out in Viacha (Bolivia). The treatments consisted in provoking water stress during the six sensitivity stages and during the total season. The reference treatment was fully irrigated quinoa. During the season, biomass evolution, root length and weight, applied irrigation water and drainage were monitored. At the end of the season the grain yield, water use efficiency (WUE) and harvest index (HI) were determined. In times of water stress before or during flowering, the above ground biomass production was delayed and the logistic shape of the growth curve got interrupted. Remarkably, root growth was not inhibited in these treatments, which provoked temporal increases in root to shoot ratio (RSlength) during stress periods. However, the effects in RSlength had disappeared at harvest. On the other hand, treatments with continuous stress, stress during pre-flowering, stress during flowering and stress during the pasty grain phase, resulted in significantly lower total yields and low WUE. Treatments with stress during the initial vegetative stages gave rise to the highest WUE. The HI was a rather constant index for all treatments except for the treatment with continuous stress and stress during the pasty grain phase. In order to stabilize quinoa yields in the Bolivian Altiplano in a sustainable way, water should be regarded as the main limiting production factor and research should further focus on optimal WUE and deficit irrigation. This research * Corresponding author: VLIR-UDC Research Associate Tel. +32 16 32 97 54 Fax +32 16 32 97 60 Sam.Geerts@biw.kuleuven.be a K.U.Leuven, Faculty of Bioscience Engineering Laboratory for Soil and Water Management Celestijnenlaan 200 E B-3001 Leuven Belgium b Universidad Mayor de San Andres (UMSA) Facultad de Agronomia Av. Heroes del Acre 1850 La Paz Bolivia