DETERMINATION OF THE PRACTICAL CULTIVATION COEFFICIENT OR IRRIGATION FACTOR IN CHERIMOLIA ORCHARDS (Annona cherimola Mill.) USING SOIL SENSORS

Given the growing water scarcity and the need to make cherimoya (Annona cherimola Mill.) cultivation more sustainable, this study proposes using soil sensors to increase irrigation water use efficiency (EUAr) without compromising fruit yield or quality. The objective was to determine the practical crop coefficient (KcS) or irrigation factor by using capacitance probes to continuously determine the dynamics of water absorption from the soil by the crop. To this end, a completely randomized block design trial was conducted over two seasons, incorporating two irrigation treatments: the control (To) and cherimoya trees irrigated according to the FAO-56 Penman-Monteith (Kc-ETo) methodology, as established by the Food and Agriculture Organization of the United Nations (FAO). This approach utilized data obtained from soil sensors and the interpretation of management guidelines for efficient irrigation. Crop productivity and resource use efficiency were assessed. Likewise, relationships between crop phenology and changes in the normalized difference vegetation index (NDVI) were explored to determine curves that estimate the optimal KcS for the season. The use of sensors resulted in a notable increase in EUAr in both seasons, reaching a maximum of 68 % compared to the methodology proposed by FAO. No significant differences were detected between treatments in terms of yield or fruit size. The optimal mean and 70th percentile values of the crop coefficient (KcS) obtained were 0.43–0.47 for the flowering stage, 0.66–0.73 for the fruit set stage (start of fruit growth), and 0.43 for the fruit growth stage until harvest. Likewise, when reference evapotranspiration exceeded 2.25 mm per day, there was a clear difference in soil water depletion between levels above and below the irrigation threshold. Finally, it was observed that the crop absorbed the most water between 13:00 and 16:00 hours.