Assessment of crop water stress index and net benefit for surface- and subsurface-drip irrigated bell pepper to various deficit irrigation strategies

This study addresses the assessment of crop water stress index (CWSI) of bell pepper (Capsicum annuum L.) and net income generated under regulated deficit irrigation (RDI), conventional deficit irrigation and partial root-zone drying (PRD) and full irrigation (I-100) using surface- and subsurface-drip systems (DI and SDI) during 2016 and 2017 in the Mediterranean region. The experimental design was split-plots with four replications. RDI was supplied with 50% of I100 during vegetative stage until flowering, then received 100% of crop water requirement. PRD50 received 50% of I-100, but from alternative laterals each watering. The results revealed that CWSI was correlated significantly (P < 0.01) and negatively with yield, yield per plant, total soluble solid, ETa, fruit weight and plant height indicating that yield of bell pepper declined with increasing CWSI values (P < 0.01). Bell pepper should be irrigated at mean CWSI value of 0.20 without any yield reduction. CWSI in the RDI and I-75 treatments were slightly greater than 0.20. Irrigation treatments had significant effect on yield and quality traits. The highest total soluble solutes were found in PRD50 and I-50. The DI I-100 treatment generated the highest net income followed by the SDI I-100 and RDI. In conclusion, RDI and I-75 appear to be good alternatives to I-100 for sustainable bell pepper production in the Mediterranean region.