Assessing the effect of sensor-based deficit drip irrigation regimes on crop performance of eggplant

Abstract

Due to climate change and the increasing challenge of water scarcity, irrigation of eggplants needs to optimize crop water use through deficit irrigation. However, determining the appropriate deficit irrigation level for optimal eggplant growth remains insufficiently understood, leading to potential over-irrigation. To guide improvement in irrigation water use efficiency (IWUE), this study investigated the effect of sensor-based deficit drip irrigation on performance of eggplant. The research was conducted at MUARIK using an RCBD field experimental setup. The study considered various treatments based on percentages of Field Capacity (FC): T1: 25% FC, T2: 50% FC, T3: 75% FC, T4: 100% FC, and a control with no irrigation (T0: 0% FC). Each treatment was replicated three times. The irrigation scheduling relied on daily readings from ML3 Thetaprobe sensor alongside the watermark sensor. Plant growth, yield, IWUE, Crop Water Use Efficiency (CWUE) and fruit quality were measured, and the performance of the watermark sensor against the ML3 Thetaprobe sensor was assessed using RMSE, MBE, and the Index of Agreement. Statistical analyses were performed using R Studio software at a significance level of 5%, and Tukey's multiple comparison test was applied to separate the means. The results demonstrated significant differences (p<0.05) in plant growth and crop quality parameters across the deficit irrigation levels. Likewise, crop yield and IWUE showed significant differences (p<0.05) among the deficit levels, with the highest yield of 39.1±1.10 ton/ha, CWUE of 74.75±1.8 kg/ha.mm, and IWUE of 86.81±1.2 kg/ha.mm recorded in T3. Conversely, T0 had the lowest yield and CWUE of 13.5±1.20 ton/ha and 46.5±4.1 kg/ha.mm respectively; while T1 exhibited the lowest IWUE of 43.95 ±7.1 kg/ha.mm. The study's findings indicate that irrigating eggplants at 75% FC maximizes both yield and water conservation in sandy clay loam soil. Furthermore, the use of factory-calibrated watermark sensors may not be suitable for irrigation under low soil moisture tension. Consequently, further research is recommended to explore the effects of deficit irrigation and fertilization regimes on eggplant crops.