Effect of Drought Stress, Biofertilizer and Potassium Nano Fertilizer on Leaf Area Index, 1000-Seed Weight, Harvest Index and Quality of Quinua (Chenopodium quinoa Willd) Seed

In order to investigate the effect of drought stress, biofertilizer and potassium Nano fertilizer on quinoa plant, a split-factorial experiment was conducted in a randomized complete block design with three replications in Ahmadabad Mostofi, Tehran, Iran in two growing seasons (2017-2018 and 2018-2019). The studied factors included drought stress at four levels (-0.015 (control), -0.3, -0.6 and -0.9 MPa) as the main factor and two biofertilizer factors (a combination of Nitrogen-fixing bacteria and mycorrhiza fungi at four levels (non-application (control) and 1, 2 and 3%) and potassium Nano fertilizer at two levels (non-application (control) and application) as sub-factors were factorially placed in sub-plots. The results showed that the highest leaf area index (3.38), 1000-seed weight (2.56 g) and harvest index (31.7%) is attainable in normal irrigation condition and application of potassium Nano fertilizer. The highest potassium (0.115%), iron (154.0 mg/100 g dry matter), and grain carbohydrates (76.8%) contents were obtained under normal irrigation condition with application of 3% biofertilizer and application of Nano fertilizer and the lowest ones were obtained under condition of severe stress with non-application of biofertilizer and non-application of potassium Nano fertilizer. With increasing stress intensity, the mean calcium and magnesium of the seed decreased from 0.273% and 0.240% in normal irrigation conditions to 0.145% and 0.142% in severe stress conditions, respectively. Drought stress increased and decreased quinoa protein and seed oil, respectively, but the application of biofertilizer and potassium Nano fertilizer improved them. Therefore, both under normal irrigation and drought stress conditions, the use of 3% biofertilizer and potassium Nano fertilizer is recommended to improve the quality of quinoa seed.