Determining basil production functions under simultaneous water, salinity, and nitrogen stresses

Abstract One of the priorities in the management of agricultural inputs, such as water and fertilizers, involves investigating the variations in the crop yields under actual field conditions, subjected to the effects of various simultaneous stresses. The current study is mainly aimed at investigating the simultaneous effects of triple water, salinity, and nitrogen stresses on basil, Mazandaran mass cultivar, and determining its production functions in such situations. The study was conducted at Doshan Tappeh Agricultural Experiment Station with an area of one ha in Tehran, Iran. A factorial experiment was conducted in the form of a randomized complete block design with different irrigation levels as the main treatment. In addition, two sub-treatments, i.e., salinity and fertilization, were conducted in three replications by a water and soil laboratory in 2016 and 2017. The irrigation treatments included full irrigation (FI) in 100% (W1) and deficit irrigation (DI) in 80% (W2), 60% (W3), and 40% (W4) of crop water requirements. The salinity treatment involved 1.175 ds m−1 (S1) (control treatment), 3 ds/m (S2), and 5 ds/m (S3), while the fertilization treatment involved 100% (F1) (control treatment), 75% (F2), and 50% (F3) of the recommended fertilizer requirement. Overall, results indicated that under a constant fertilizer treatment, the rise in the salinity and water stress reduced the basil yield, while under the water-fertilizer double stress, the basil yield rate first decreased and then had a notable increase. By applying water and salinity stresses, the crop yield experienced a steeper reduction under the water stress than the salinity stress. Contrary to expectations, fertilization reduced basil yield under these conditions.