PREDICTION OF WATER STATUS BY MEANS OF AN EMPIRICAL MODEL IN ORANGE BEARING TREES

During three consecutive years, in a citrus orchard planted with Tarocco ‘Meli’ and ‘Scirè’ on sour orange (C. aurantium L.) were verified the differences of the plant water status and the possibility to build an empirical model to estimate the ψ_pd utilizing stem water potential (ψ_md) and vapor pressure deficit (VPD_md) measured at midday.
The first results showed statistical differences during the irrigation season in the two clones water potential.
These difference permitted to separate the data of Tarocco ‘Meli’ and ‘Scirè’. As a result, two empirical models were built.
The 2^nd degree equation (ψ_pd=a+b₁ψ_md+b₂VPD_md) was obtained by considering the ψpd as dependent variable, the ψ_md and the VPD_md as explanatory variables.
ANOVA applied to the multiple regression resulted highly significant with P-value <0.000, indicating highly predictive capacity of the equation.
The multiple coefficients of correlation were R=0.783 for Tarocco ‘Meli’ and R=0.825 for Tarocco ‘Scirè’. The two models were tested with the method of the cross-validation, a technique for estimating the performance of a predictive model.
The observed data showed no statistical differences when compared to the fitted data.
The results were discussed in a relation to the application of the empirical model which estimates the ψ_pd that seems to be the best indicator of tree water status, without measuring it before dawn.

VI International Symposium on Irrigation of Horticultural Crops

F. Stagno, A. Giuffrida, F. Intrigliolo, C. Germanà, A. Continella

citrus orchard, midday and predawn water potential, environmental condition, pressure chamber

https://doi.org/10.17660/ActaHortic.2011.889.41