Effect of Additive Intercropping Series of Sunflower with Basil, under Saline and Fresh Water Irrigation Regimes on their ‎Yield and Advantage Indices

Additive intercropping series of sunflower and basil have been laid out under salty and fresh water irrigation management with the aim of achieving the highest yield and intercropping advantage as a result of intercropping the two plants. An experiment has been performed at Zabol University during two cropping years (2018 and 2019). Fresh water (ECe = 3.9 dS.m-1) and saline water (ECe = 1.1 dS.m-1) have been taken from the Hirmand River and a local well, respectively. The irrigation water regimes are fresh water, salt water, and an alternating usage of salty and fresh irrigation water. In addition, five types of intercropping patterns are considered the sub-factors (100% sunflower (4 plants/m2), 100% basil (80 plants/m2), 100% sunflower+ 50% basil, 50% sunflower + 100% basil and 100% sunflower + 100% basil. The results show that the interaction between intercropping patterns and different irrigation regimes has had a significant effect on 1000 seed weight, seed yield, harvest index, oil yield of sunflower, dry weight, and essential oil yield of basil plants. In response to all irrigation regimes, the highest value of total land equivalent ratio (1.37-1.45) and intercropping advantage (0.29 - 0.48) has occurred as a result of cultivating 50% sunflower + 100% basil, thereby appearing as a good model of intercropping. The results show that intercropping patterns can be effective in modulating the negative effects of saline irrigation water on plant yield.