Articles
Continuous deficit irrigation scheduling bases on trunk growth rate frequencies approach
Article number
1446_35
Pages
257 – 264
Language
English
Abstract
The accurate management of deficit irrigation scheduling needs tools that provide continuous measurements.
Trunk diameter fluctuation curves were described long ago, but derived indicators were not commonly used in olive trees.
Trunks shrink and swell in daily cycles and these curves are useful indicators.
Trunk growth rate (TGR), the difference between two daily maximums, was suggested as a water status measurement in olive trees, but its daily variability makes it difficult to use for irrigation scheduling.
Recently, weekly frequencies of several TGR ranges were suggested as an easy and sensitive approach to identify water stress conditions.
Values between -0.1 to 0.3 mm day‑1 were considered the normal range in fully irrigated conditions.
On the contrary, the increase of the appearance of values more negative than -0.3 mm day‑1 would indicate water stress conditions.
Only in conditions of very severe water stress have there been reports of false positives, with frequencies equal to full irrigated conditions.
In this level of water stress, irrigation produced a very fast increase of TGR with values commonly greater than 0.3 mm day‑1. The aim of this work was to check these results in a commercial orchard where a long period of no irrigation was performed.
The experiment was performed in a mature, hedgerow olive orchard (‘Arbequina’). Shaded water potential showed two different drought cycles during the experiment, the first moderate and the latter severe.
TGR frequencies identified correctly the first, but a false positive signal was observed in the second.
However, estimation of maximum daily shrinkage (MDS), another indicator of daily trunk diameter fluctuations, provided information to identify this period accurately.
Trunk diameter fluctuation curves were described long ago, but derived indicators were not commonly used in olive trees.
Trunks shrink and swell in daily cycles and these curves are useful indicators.
Trunk growth rate (TGR), the difference between two daily maximums, was suggested as a water status measurement in olive trees, but its daily variability makes it difficult to use for irrigation scheduling.
Recently, weekly frequencies of several TGR ranges were suggested as an easy and sensitive approach to identify water stress conditions.
Values between -0.1 to 0.3 mm day‑1 were considered the normal range in fully irrigated conditions.
On the contrary, the increase of the appearance of values more negative than -0.3 mm day‑1 would indicate water stress conditions.
Only in conditions of very severe water stress have there been reports of false positives, with frequencies equal to full irrigated conditions.
In this level of water stress, irrigation produced a very fast increase of TGR with values commonly greater than 0.3 mm day‑1. The aim of this work was to check these results in a commercial orchard where a long period of no irrigation was performed.
The experiment was performed in a mature, hedgerow olive orchard (‘Arbequina’). Shaded water potential showed two different drought cycles during the experiment, the first moderate and the latter severe.
TGR frequencies identified correctly the first, but a false positive signal was observed in the second.
However, estimation of maximum daily shrinkage (MDS), another indicator of daily trunk diameter fluctuations, provided information to identify this period accurately.
Publication
Authors
M. Sánchez-Piñero, M.J. Martín-Palomo, M. Martín, T. Carrillo, L.L. de Sosa, M. Corell, N. Medina-Zurita, A. Moriana
Keywords
maximum daily shrinkage, regulated deficit irrigation, trunk diameter fluctuations, water potential, water stress, TDR
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