Salinity threshold value of Quinoa (Chenopodium Quinoa Willd.) at various growth stages and the appropriate irrigation method by saline water

Salinity is one of the major agricultural problems in arid and semi-arid regions. Considering the variation of plant's sensitivity to salinity during growth, a greenhouse study with completely randomized design was conducted to determine the relative salinity tolerance of Quinoa (Chenopodium quinoa Willd.) at different growth stages from seedling establishment to maturity (establishment, flowering and seed filling) by evaluating the Salinity Threshold Value (STV). Eight levels of ECi (i.e., Non-saline, 2, 4, 8, 12, 15, 20, 25 dSm(-1)) with four replications and five levels (i.e., Non-saline, 10, 15, 20, 25 dSm(-1)) with three triplications were applied at first and two last growth stages, respectively. A comparison was performed on some growth and yield parameters of plants irrigated by considering STV (T) and plants irrigated permanently by mentioned salinity levels regardless of STV (P) to choose which method (P or T) is better at each salinity level. The STV was evaluated 8, 20 and 15 dSm(-1) at each growth stage, respectively. Seedling of Quinoa was more sensitive to salinity than the mature plant. Therefore, after establishment Quinoa has the feasibility of irrigation by high-saline waters. The (P) method was suitable only if the freshwater was available during all growth period of the plant; otherwise at higher salinities irrigation should be performed by considering STV (T method) to minimize the intensity of growth and yield reduction and to prevent yield loss at very high salinities. To achieve this, if high-saline water is available it's possible to use plant propagation techniques or cultivating Quinoa simultaneously with seasonal rainfall.