WATER POTENTIAL AND FRUIT GROWTH AS MANAGEMENT INDICATORS IN TRICKLE-IRRIGATION IN 'ROCHA' PEAR

Aiming to study the physiological responses and the effect on yield and final fruit size of three irrigation treatments in a ‘Rocha’ pear orchard, climatic and crop status indicators were monitored. Irrigation amounts of 0, 98 and 265 mm were applied in the DRY, Deficit Irrigation (DI) and Maximum Water Availability (MWA) treatments, respectively. In the MWA treatment daily irrigation was applied, while in DI the irrigation was only applied when the pre-dawn leaf water potential (Ψ_PD) reached a pre-established threshold depending on the development stage of the crop (-0.5 to -0.8 MPa). The results showed an increase in tree yield with the irrigation applied (DRY=25.4 kg tree^-1; DI=29.7 kg tree^-1; MWA=31.5 kg tree^-1) without statistically significant differences between the two irrigated treatments. DI showed a superior ratio of fruits above 65 mm diameter, 10% greater TSS when compared with MWA, and the best economic result. Water use was 63% lower in DI, when compared with MWA. This irrigation treatment caused an economic benefit of 2.73 € per m³ of applied water, while this value was 7.51 € per m³ in DI.