Tomato Yield Responses to Deficit Irrigation and Partial Root Zone Drying Methods Using Biochar: A Greenhouse Experiment in a Loamy Sand Soil Using Fresh and Saline Irrigation Water

Abstract

The impacts of regulated deficit irrigation (RDI) and partial root zone drying irrigation (PRD) on water productivity (WP), crop water response factor (Ky), and yield of tomato crop (Solanum lycopersicum) were explored in this study using fresh (0.9 dS m−1) and saline (3.6 dS m−1) water under greenhouse conditions. RDI had four ETc (crop evapotranspiration) levels, i.e., 40, 60, 80, and 100%. PRD adopted 100% ETc for all treatments with changes in its application time (first, second, third, and fourth growth stages). Biochar pyrolyzed at 450–500 °C and added at rate of 4%. The results revealed that the Ky ranged between 0.21 and 0.37, indicating that tomato can tolerate a shortage of irrigation water. The highest value of WP (191 kg m−3) was found in 40% ETc using fresh water with biochar. The highest yield (20.0 kg m−2) was obtained with the application of 100% ETc with fresh water and biochar. Biochar application did not result in favorable yields with saline water due to its high salinity (7.8 dS m−1). The use of PRD in the fourth stage with biochar and fresh water led to the highest yield (20.6 kg m−2). Finally, this study recommends the application of biochar only when fresh irrigation water is available in adequate amounts.