EFFECT OF NITROGEN FERTILIZATION ON EFFICIENCY AND REMOBILIZATION IN QUINOA CULTIVARS
Keywords:nitrogen fractionation, grain protein, crop yield, current photosynthesis, remobilization efficiency
This factorial split-plot experiment was conducted to investigate the effects of the application of time and level of nitrogen on yield, grain content, remobilization efficiency, and nitrogen consumption of quinoa cultivars. The present work has a randomized complete block design with three replications in 2018 and 2019 in Khuzestan, Iran. The experimental factors herein included four levels of nitrogen fertilizer (no fertilizer application, 100, 200, and 300 kg/ha) and different administrations: (1) 50% at base stage + 50% at six-leaf stage, (2) 50% at base stage + 25% at six-leaf stage + 25% at mid-flowering stage, (3) 25% at base stage + 50% at six-leaf stage + 25% at mid-flowering stage, and (4) 25% base stage + 25% six-leaf stage + 50% mid-flowering stage. Furthermore, quinoa cultivars Gizat, Q26, and Titicaca were selected as the sub-plots. Comparing the two-year averages, we found that with the increase in the nitrogen fertilizer, grain yield, biological yield, remobilization (R), current photosynthesis (CP), remobilization contribution (RC), remobilization efficiency (RE), nitrogen content, and grain protein increased. Meanwhile, the level and current photosynthesis contribution (CPC), agronomic and physiological efficiency of nitrogen (NAE and NUE), and grain oil content decreased. The highest biological yield (11683 kg/ha) and grain yield (5675 kg/ha) were obtained applying 200 kg/ha of nitrogen divided into 25% at base stage + 25% at six-leaf stage + 50% at mid-flowering stage for cultivar Q26. The highest RE and NUE belonged to 100 kg/ha of nitrogen, 25% of which was at base stage + 50% at six-leaf stage + 25% at mid-flowering stage for cultivar Q26. Overall, the applying 200 kg/ha of nitrogen, 25% at base + 25% at six-leaf stage + 50% at flowering stage, and use of cultivar Q26 could be recommended based on our findings.