Abstract
The microclimate in apple orchards is often manipulated by the use of nets against hail and/or by the presence of reflective strips, which enhance fruit color before harvest. Nets and strips cause micrometeorological changes that affect plant-environment interactions and potential evapotranspiration (ETp). In this report, the magnitude of these measures has been investigated by means of the FAO-PM equation fitted using data collected within the orchard. The experiment has been carried out in a drip irrigated apple orchard (‘Nicoter’ on M9) located in the Province of Bolzano (Italy), with a density of 4167 trees ha-1. During summer 2020, continuous measurements of meteorological data under and outside the nets were performed via two in-situ mini weather stations. Records also include the pre-harvest period, when reflective white strips have been laid on the soil surface in the alleys. In summer, hail nets reduced vapor pressure deficit by almost half. Wind speed and daily average air temperature were slightly affected by the hail nets. PAR and net radiation decreased by 26 and 21% respectively, whereas a strong increase by 48% of relative humidity was observed. Overall, a reduction of the ETp by 22% was detected under the nets. As for the effect of ground reflective strips, they slightly increased temperature in the orchard and reduced both Net radiation and the ETp, when compared to non-covered orchard sites. Such effects were mainly detected around midday. The preliminary results showed that the presence of hail nets and reflective strips affect the microclimatic conditions around the tree canopy, reducing the orchard’s water demand and consequently its irrigation requirements.