Regulated and sustained deficit irrigation: impacts on yield components of olive trees

Nowadays, to overcome the negative impact of climatic change, the irrigation of the land occupied by olive grove is increasing.
So, deficit irrigations (DI) practices are important to reduce agricultural water use.
In this experiment, mature olive (‘Madural’) trees for oil production received full irrigation (FI), sustained deficit irrigation (SDI) and regulated deficit irrigation (RDI) and were compared to commercial olive orchard (Northeast of Portugal) in 2019. In deficit irrigation treatments, the total amount of irrigation ranged from 30 to 60% of FI, which was equivalent to a water volume of 100% of estimated evapotranspiration.
Water stress caused a significant reduction of both fresh and dry yield in all treatments except in RDI₆₀. Oil concentration was negatively affected in both, RDI and in SDI₃₀, irrigation treatments.
The highest oil yield was attained in FI (560±72.9 kg ha^‑1), the lowest yield – in SDI₃₀ (355.7±30.6 kg ha^‑1). The differences, which were observed between FI and DI treatments, were significant.
Oil yield responded linearly to the seasonal irrigation water (r²=0.92, p=0.01) with irrigation efficiency of 0.62 kg m^‑3 for oil production.
Although the results are preliminary, they showed that RDI₆₀ treatment could save 50% of water without strong effect on yield and with an economic profit similar to FI. Additionally, SDI₃₀ seems to be a good DI strategy in a situation of very low water availability for irrigation in order to mitigate adverse climate change effects.
With this strategy, the fruit and oil yields were reduced 30-37% but water savings were 70% compared to FI.

IV International Symposium on Horticulture in Europe – SHE2021

A. Fernandes-Silva, L. Canas, T. Brito, P. Marques

economic profit, Olea europaea L., oil concentration water use efficiency

https://doi.org/10.17660/ActaHortic.2021.1327.34