Assessment of kiwifruit physiological decline: irrigation and soil management strategy to recover from waterlogging

Kiwifruit plantations reduced by 7,200 ha, equal to 30% of the total production, in Italy in recent years, as a consequence of the spread of kiwifruit vine decline syndrome (KVDS) (Sportelli, 2022). This study aims to investigate the factors involved in the onset of this syndrome as waterlogging, improper irrigation and soil management practices. The experimental trial was conducted in a yellow fleshed kiwifruit orchard (‘Zesy002’) located in Latina (Italy). Three different plots with different KVDS symptoms severity were identified (CTRL, KVDSmoderate, KVDSsevere). In order to evaluate predisposing factors to plant decline, soil characterization (telluric gases,) and water table level were performed. Daily telluric gases concentration (CO2 and CH4) was significantly higher in the KVDSsevere plot compared to the CTRL one, confirming that soil hypoxia due to waterlogging conditions is a predisposing factor of vine decline. The irrigation system in the KVDSmoderate and KVDSsevere plots was modified using two independent drip lines associated with micro-sprinklers, in order to apply an innovative water management based on soil water availability and leaf area index (LAI), that were different from the conventional management. The innovative irrigation was based on the simplified water balance and the irrigation volume applied was corrected considering the soil water content monitored by soil moisture probes at different depth. The seasonal irrigation volume applied for the different plots were 4,002, 3,890 and 4,060 m3 ha-1 in the KVDSmoderate, KVDSsevere and CTRL plots, respectively. The results revealed a general optimization in the irrigation management, with a 30% reduction in water use, compared to the average irrigation volume ordinarily applied in the Latina area. In the KVDSsevere plot, water table level was monitored along the season revealing a reduction of 30 cm compared to the previous irrigation season, thanks to the application of the innovative irrigation strategy and a drainage system.