Prospects of training system and deficit irrigation for increasing yield and water use efficiency of pitaya (Hylocereus spp.) in the Mediterranean region

It is well known that the water consumption of some tropical fruits is high. However, in the world and especially in agricultural areas, where the Mediterranean climate prevails, drought is defined as one of the most important abiotic stress factors that affect product patterns. For this reason, this research chose the pitaya (Hylocereus spp.) plant, which has relatively low water consumption among tropical fruit species. Three different training (Control [Pole], T and Inverted U) systems with different deficit irrigation (combined with FULL = 100%; DI75 = 75%, DI50 = 50% and DI25 = 25%) treatments in the cultivation of pitaya under greenhouse conditions; their effects on the yield, evapotranspiration, water use efficiency, irrigation water use efficiency, yield response factor and some quality parameters (fruit weight, length and width, fruit flesh hardness and water-soluble dry matter) were examined. The research was carried out in Antalya province, Turkey between 2018 and 2021 and 'Vietnamese Jaina' was used as a cultivar. Irrigation applications were carried out using drip irrigation method and the amount of irrigation water to be used in the control (FULL) treatment was calculated based on measurement values taken from the A-Class evaporation pan. The research findings revealed that the amount of irrigation water varied between 27.63 mm and 83.80 mm, and the fruit flesh value ranged between 79.36 kg cm^-2 and 105.53 kg cm^-2. In general, as the irrigation water level decreases, a decrease in fruit flesh values is also recorded. In addition, it was found that different irrigation water levels affect yield. The average yield values were found as DI75 (7169.60 kg ha^-1) > FULL (5783.90 kg ha^-1) > DI50 (4737.00 kg ha^-1) > DI25 (4376.30 kg ha^-1) ranking from high to low. Yield varied according to the training system, with the highest value recorded in the Pole (Control) System (5625.30 kg ha^-1) followed by Inverted U System (5594.90 kg ha^-1) and T System (5330.00 kg ha^-1). As an important finding for yield values, it was found that the treatment DI75 irrigation has a general superiority over the other irrigation treatments. Based on the research findings, considering the yield and quality parameters, a Pole (Control) System and an Inverted U System were recommended as a training system, respectively, along with the irrigation treatment (DI75), in which 75% of the water needed by the plant is given in greenhouse conditions considering the evaporation.