Determination of Water Requirements and Optimal Sowing Date for Quinoa (Chenopodium quinoa Willd.) in Selected Areas of Iraq

Experiments were conducted at the Crop Research Station in Baghdad and the Forage Research Station in Haditha during the 2021 and 2022 growing seasons. Four quinoa varieties (REGALONA, Q37, KVL-SR2, and Q21) were selected, and three sowing dates (February 1, February 15, and March 15) were tested to identify the optimal planting date and the best variety in terms of yield. The experiment was laid out in a split-plot design with three replications. The results of the combined analysis of flowering days showed significant differences (P≤0.05) between locations, planting dates, and varieties. The earliest flowering was observed in Baghdad, on the third sowing date, and in the Q21 variety, with 75, 59, and 72 days, respectively. Similar differences were observed for physiological maturity on the third sowing date (114 days) and in the Q21 variety (120 days), with REGALONA and Q21 being the shortest in duration to maturity. In contrast, Q37 and KVL-SR2 had longer maturity durations. Significant differences in plant height were observed between locations and varieties, with the highest values recorded in Haditha (157 cm), on the second sowing date (149 cm), and in the KVL-SR2 variety (168 cm). The number of heads per plant also showed significant differences across locations, sowing dates, and varieties, with the highest values observed in Baghdad, on the first sowing date, and in the Q37 variety (8, 9, and 9 heads, respectively). Grain yield exhibited significant differences as well, with the highest yield recorded in Haditha (3.510 t/ha), on the first sowing date (2.980 t/ha), and in the Q21 variety (3.620 t/ha). Based on these findings, the Q21 and REGALONA varieties, along with early sowing dates between February 1st and 15th, are recommended for quinoa cultivation in Iraq.