EFFECTS OF ORGANIC AND INORGANIC FERTILIZER WITH REDUCED NITROGEN LEVEL ON GROWTH, NITROGEN USE EFFICIENCY, SEED YIELD AND QUALITY TRAITS OF Chenopodium quinoa

The objectives of the present investigation were to assess the effects of fertilizer type (organic and inorganic), reduced nitrogen rate and their interaction on growth, nitrogen use efficiency, seed yield and quality traits of quinoa crop. A two-year field experiment was conducted, using a split split-plot design with three replications. Main plots were devoted to two fertilizer types (compost and Ammonium nitrate), sub-plots to three N rates (71.4, 142.8 and 214.2 kg N/ha), and sub sub-plots to 37 quinoa genotypes. Mean seed yield/ha (SYPH) across seasons was 4728 kg/ha when using the Compost, while it was 1884 kg/ha when using Ammonium nitrate. Superiority of organic to mineral fertilizer in SYPH was accompanied by superiority in seed yield/plant (SYPP) (94.88%), inflorescence weight (317.1%), 1000-seed weight (24.69%), inflorescence diameter (86.27%), biological yield/plant (BYPP) (41.94%) and harvest index (HI) (37.47%). Quinoa plants under the organic fertilizer were more N efficient than under the mineral fertilizer by 95.85% for economic nitrogen use efficiency (NUEe), 39.80% for biological nitrogen use efficiency (NUEb) and 8.83% for nitrogen utilization efficiency (NUTE). The seed contents of protein, oil and ash were higher under organic fertilizer than under chemical fertilizer by 13.35, 3.82 and 19.06%, respectively. Reduction of nitrogen rate from 214.2 kg N/ha caused a significant reduction in SYPH (13.25 and 15.35%), SYPP (9.17 and 13.75%), BYPP (0.07 and 4.60%), HI (9.11 and 9.63%), inflorescences/plant (9.60 and 17.58%) under 142.8 and 71.4 kg N/ha, respectively. Reduction in such traits was more pronounced under mineral than organic fertilizer. The highest SYPH was recorded under the highest N rate of organic fertilizer, but the lowest was recorded under the lowest N rate of chemical fertilizer. The highest NUEe and NUEb values were recorded under the lowest N rate in the organic fertilizer.