INVESTIGATING CROP COEFFICIENTS IN DRIP IRRIGATED ORANGE TREES

During two successive years seven different crop coefficients (Kc) were applied in the management of a drip system to irrigate a mature orange grove in Sicily.
The volumes of water application were determined multiplying the evaporation from a class A evaporimeter by constant Kc values ranging from 0.4 to 0.7, and including values varying in time from 0.4 to 1.2, plus a treatment where Kc was changed according to pre-dawn xylem potential (the “physiological treatment”). The total seasonal volumes of applied water, averaged over the two years, ranged from a minimum of 2,022 m³/ha (with a constant Kc of 0.4) to a maximum of 3,548 m³/ha (with a constant Kc of 0.7). The best water use efficiency, namely the ratio of yield to applied water, was achieved in two treatments: the constant Kc 0.4 and the “physiological treatment”. The unit fruit weight was negatively correlated to the number of fruit, which however positively impacted the total production; these results give a support in finding a trade-off in citrus irrigation management between yield quantity, fruit size and water volume in order to maximize profit and save resources, and suggest that physiological indicators are a better guide to irrigation scheduling than the standard ETo x Kc procedure.

IV International Symposium on Irrigation of Horticultural Crops

C. Germanà, V. Sardo

Irrigation scheduling, ETo, pressure chamber, xylem potential, evaporimeter, WUE

https://doi.org/10.17660/ActaHortic.2004.664.32