The Seasonal Dynamics of Mango’s Water Uptake in Respect to Nitrogen Fertilization

Abstract

Mango’s irrigation is typically applied regardless of the fertigation regime, mostly due to a lack of knowledge regarding the fertigation effect on plants’ water uptake. From 2017 to 2020, we investigated the seasonal dynamics of mango’s water uptake using flushing lysimeters under five different nitrogen (N) fertigation treatments: 2, 10, or 20 mg L⁻¹ of equal amounts of NH₄ and NO₃, and two additional 10 mg L⁻¹ treatments of only NH₄ or NO₃. Water uptake scaled with the tree size and atmospheric conditions, while at the same time exhibited considerable within-season variability. The 10 mg L⁻¹ produced the largest canopies, bearing the highest yield and the highest water consumption, with minor differences between the NH₄/NO₃ treatment. In all treatments, the water use increased through time, along with the tree’s growth, from ~ 5 m³ year⁻¹ tree⁻¹ in 2017 (for all treatments) and up to 9.3 m³ tree⁻¹ year⁻¹ (for 2 mg L⁻¹) or 16.3 m³ tree⁻¹ year⁻¹ (for 10 mg L⁻¹) in 2020. Daily water use ranged from 10 L tree⁻¹ in winter, climbing up to 100 L tree⁻¹ during summer in the 10 mg L⁻¹ treatment, with a large dependence on the tree’s phenology. Fruit set increased stomatal opening and led to high water use, while harvest led to stomatal closure. The findings show that nutrient availability can change mango’s water use through changes in canopy development and reproduction, implying that the fertigation scheme should be considered when planning irrigation. Phenology is also a critical factor when considering the mango’s water uptake.