Nitrogen Use Efficiency In Quinoa (Chenopodium quinoa) Under Organic Greenhouse and Field Conditions.

This study focuses on quinoa (Chenopodium quinoa), a pseudocereal identified by farmers in Washington State as a potentially valuable alternative grain with strong, unmet demand for regional specialty food markets.  Currently, very little quinoa is grown in Washington State and many questions regarding basic quinoa agronomy and varietal selection remain unanswered.  Here we report findings from a greenhouse study performed in Pullman, WA designed to identify quinoa cultivars with varying levels of nitrogen use efficiency.  Forty-four diverse quinoa cultivars were grown in 4L pots under three nitrogen levels with two subsamples and three replicates per treatment.  The nitrogen source was certified organic and the entire study was repeated once. Measurements of plant height and leaf chlorophyll content were taken at 30d and 45d after planting, and seed yield was measured after maturity.  Soil samples were taken at 0, 30 and 45 days after planting.  We found highly significant differences (P<0.0001) among cultivars for plant height at 45d and final seed yield.  Significant differences (P<0.05) among cultivars for leaf chlorophyll content at 15d and 30d and plant height at 30d after planting were found.  Cultivars originating from Chile and Argentina typically had higher yields than cultivars originating from Ecuador, Bolivia and Peru.  Significant GxE interactions were found for the quinoa cultivars across treatment levels. Individual cultivars with high yields in low nitrogen conditions were identified as were cultivars with relatively high yields only under conditions of high nitrogen.  We anticipate that this research will prove valuable in future selection of optimal parental cultivars for differing agronomic systems in the WSU quinoa breeding program. Additionally, a subset of 20 cultivars was planted on the WSU certified organic farm in Pullman, WA under three nitrogen management regimens in a split-block RCBD with four replicates in spring 2011.  This data will be reported as a short corollary to the above greenhouse trial.