Citation: Maˇ cki´ c, K.; Baji´ c, I.; Peji´ c, B.; Vlaji´ c, S.; Adamovi´ c, B.; Popov, O.; Simi´ c, D. Yield and Water Use Efficiency of Drip Irrigation of Pepper. Water 2023, 15, 2891. https://doi.org/10.3390/w15162891 Academic Editor: Xinchun Cao Received: 25 May 2023 Revised: 4 August 2023 Accepted: 7 August 2023 Published: 10 August 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). water Article Yield and Water Use Efficiency of Drip Irrigation of Pepper Ksenija Maˇ cki´ c 1, *, Ivana Baji´ c 2 , Borivoj Peji´ c 1 , Slobodan Vlaji´ c 2 , Boris Adamovi´ c 1 , Olivera Popov 2 and Dejan Simi´ c 3 1 Faculty of Agriculture, University of Novi Sad, Trg Dositeja Obradovi´ ca 8, 21102 Novi Sad, Serbia; pejic@polj.uns.ac.rs (B.P.); borisa@polj.uns.ac.rs (B.A.) 2 Institute of Field and Vegetable Crops Novi Sad, Maksima Gorkog 30, 21101 Novi Sad, Serbia; ivana.bajic@nsseme.com (I.B.); svlajic89@gmail.com (S.V.); oliveraa.popov@gmail.com (O.P.) 3 Agricultural Institute of Republic of Srpska, Knjaz Miloša 17, 78000 Banja Luka, Bosnia and Herzegovina; dejansymic@yahoo.com * Correspondence: ksenija@polj.uns.ac.rs Abstract: Drip irrigation is gaining importance in mitigating the consequences of water scarcity even in regions with abundant rainfall. The transition from surface to subsurface drip irrigation is accompanied by numerous problems. To overcome these issues, shallow subsurface drip irrigation can be potentially used as an effective drought control tool that brings additional benefits compared to conventional surface drip irrigation techniques. This research investigated the effects of different cal- culations of daily crop water requirements, reference evapotranspiration (ETo), and pan evaporation (Eo) on the yield and water use efficiency of pepper irrigated with a surface and shallow subsurface drip irrigation system. The experiment was conducted in field conditions in the Vojvodina region, the northern part of Serbia. The irrigation scheduling was based on the water balance approach. The calculated evapotranspiration rate was about 400 mm for the pepper growing period, regardless of the calculation method. The highest yield of pepper and evapotranspiration water use efficiency was obtained on the Eo variant with surface drip irrigation. However, irrigation water use efficiency showed no statistical significance concerning the calculation of evapotranspiration and irrigation type. The results indicated that both calculation methods and irrigation types can be used in pepper production, but priority should be given to pan-evaporation-based calculation. Keywords: kapia pepper; drip irrigation; shallow subsurface drip irrigation; pan evaporation; reference evapotranspiration 1. Introduction Pepper (Capsicum annum L.) is widely used for human nutrition as fresh or processed. The global production is estimated to be 35.9 million tonnes with an average yield per hectare of 17.5 t [1]. It is the second largest crop in Serbia after potatoes, with 9974 ha in 2020 with an average yield of 10 t ha -1 [2]. The kapia type of pepper, distinguished by its red color, conical shape, thinner wall, and thicker skin in the middle, is traditionally used in Balkan cuisine. The soil water status is the most important factor in kapia pepper pro- duction because the pepper is highly sensitive to water shortage. In vegetable production, pepper is regarded as one of the most vulnerable crops to water stress [1]. Sufficient water supply is essential throughout the crop cycle for high yields and quality [3,4], and in such conditions, the yield of kapia pepper can reach over 40 t ha -1 [5]. Pepper is especially sensitive to water shortage during the flowering and fruiting stages, but also to excessive soil moisture and poor soil aeration. Although bell pepper is frequently produced with extensive irrigation, this practice does not result in improved plant growth or fruit yield; however, a mild deficit in irrigation strategies could be considered since no impact on fruit yield and quality despite the reductions in plant water status, growth, and leaf gas exchange was determined [4]. Irrigation planning is therefore a key factor in pepper water management. Water 2023, 15, 2891. https://doi.org/10.3390/w15162891 https://www.mdpi.com/journal/water