Apple trees rainfall interception during the leafed and leafless phases of the annual cycle

For apple orchards cultivated in semi-arid climates, the study of rain water distribution into the three main fractions - “throughfall”, “stemflow”, and “interception” by the trees - is very relevant to enhance the sustainability of apple growing and water resources. This is particularly true in the current climate change scenario. Therefore in this study, measurements of rainfall, throughfall, stemflow, and interception were carried out between January and December 2022 in an apple orchard located in the Aures (northeastern Algeria). The results revealed that the rain received by the orchard (200.7 mm) was reduced by 40.7% compared to the 20-year average (2000-2019). In addition, the fraction of throughfall and stemflow were around 78.8% and 2.5%, respectively, whereas the average interception fraction was 18.7% of the total rainfall with a significant difference between the leafed and leafless phases of the annual tree cycle. The models generated in the present study showed that throughfall occurred when the amount of rainfall was higher than 1.6 and 0.3 mm during leafed and leafless phases, respectively. Furthermore, rainfall triggered the stemflow when its intensity was higher than 5.0 and 10.9 mm during the leafless and leafed phases, respectively. The results of our study revealed that rainfall with less than 5 mm produced little or no throughfall and stemflow in apple orchards, and this highlighted the necessity of adopting irrigation in these regions, particularly during the leafed phase.