Effect of Water Stress after Flowering Stage on Tomato Crop Yield and Soil Water Content in the Semi-Arid Peruvian Coastline

To evaluate the effects of water stress (WS) on tomato at reproductive stages four deficit irrigation (DI) treatments were established, based on the crop water requirements using the ASCE-EWRI and FAO-56 methodology. At full flowering stage irrigation treatments were reduced in 50% until the end of harvesting season. T1 (150 to 75% of FAO ETc), T2 (100 to 50% of FAO ETc), T3 (75 to 33% of FAO ETc) and T4 (50 to 25% of FAO ETc). The experiment was laid out as a Latin square design with four treatments and four replicates. The soil in the experimental site is a loam with a depth of 70 cm and the following characteristics: saturation (SAT) 43%, field capacity (FC) 27% and wilting point (WP) 13%. Soil volumetric water content at four depths (10, 20, 30 and 45 cm) was measured using a time domain reflectometry system (TDR) every 3 h. Soil volumetric water content decreased as the irrigation treatment decreased for T1, T2, T3 in the case of T4 that reached similar values to T1. Biometric destructive measurements were performed every 20 days to measure leaf area and dry mass production resulting on and LAI of 4.8, 3.2, 2.7 and 1.4 m(2) m(-2) T1, T2, T3 and T4, respectively. Coverage images were taken weekly, resulting in a maximum coverage of 80, 60, 50 and 40% for T1, T2, T3 and T4, respectively. Tomato production was significantly affected by irrigation treatment. The highest yield was obtained with T1 55.62 t ha(-1), finding significant differences between this and T2, T3 and T4 yielding 34.25, 19.81 and 17.43 t ha(-1), respectively. The three deficit treatments yielded below the national average yield (35 t ha(-1)). However, T1 produced 15 t ha(-1) additional yield, reducing water use by 90% compared to an average tomato farmer. In further research, we will use process-based mechanistic modeling to simulate the water transport dynamics under fertigation.