Abstract

Aim of the study: The objective of this study was to determine the salinity tolerance threshold of Amaranthus cruentus L. and evaluate its performance under various salinity conditions. Additionally, this research explored the feasibility of expressing the salinity threshold as pore water salinity (ECw), which can be estimated using a capacitance probe in combination with the mathematical model proposed by Hilhorst (2000) (ECwHi). The ultimate goal was to enhance salinity management strategies for sustainable agricultural practices. Area of the study: Faculty of Agronomy Sciences of the University of Chile, Santiago, Chile. Materials and Methods: The trial evaluated the development of A. cruentus irrigated with water of electrical conductivity levels of 1.75, 2.5, 5, 8, 10, and 15 dS m-1 over a complete crop cycle (5 months). The variables measured included stem water potential, stomatal conductance, plant and panicle height, biomass, and yield. ECw was measured using suction lysimeters, while ECwHi was estimated using data from a GS3 capacitance probe and a mathematical model. Main results: No significant differences were found in stem water potential, plant and panicle height, biomass, or yield, except at 15 dS m-1. Based on these results, a salinity tolerance threshold of 5.64 dSm-1 was determined for the electrical conductivity of a saturated extract (ECe). A strong correlation (R² > 0.8) between ECw and ECwHi was found, however the accuracy of this relationship decreased as the electrical conductivity increased from 3 to 14 dS m⁻¹. Thus, calibration is recommended for use with this specific model. Research highlights: The study showed that Amaranthus spp. is a viable option for saline conditions, and underscore the importance of precise salinity management for sustainable agricultural practices.