Modulating shallot bulb bioactive compounds and water use efficiency through automatic precision fertigation

Abstract Shallots are the main horticultural commodities in Indonesia, and are mostly cultivated in wetlands with a high use of water and fertilizer. Sustainable water use strategies, along with improving the quality of shallot bulbs produced, are very important to implement in order to be able to adapt to the threat of global climate change. This study aimed to evaluate the effect of precision irrigation methods based on evapotranspiration (ET) values on the water use efficiency (WUE) and chemical compounds of shallots in dry land cultivation. The experiment used a complete randomized block design with three irrigation treatments and six replicates. Irrigation was applied based on the ET value (ETb), twice the ET value with a fixed schedule (2ETb), and twice the ET value using a soil moisture sensor (S). All the experimental treatments were performed using an automatic irrigation machine (Nutrigads). The highest WUE (18.76 kg/m 3 ) was achieved through irrigation using a soil moisture sensor (treatment S). GC-MS analysis was performed to determine the profiles of different bioactive compounds in the shallot bulbs. ETb treatment induced the highest levels of organoleptic compounds, while 2ETb treatment increased its anti-microbial properties, and S treatment increased metabolite compounds related to abiotic stress. The results of this study support the use of targeted irrigation methods to improve sustainable water use and shallot bulb quality in dry-land cultivation.