Impact of mulching and high salinity water irrigation on mango: a preliminary study in Mediterranean environment

The cultivation of mango (Mangifera indica L.) is increasingly spreading in the Mediterranean basin, but it faces significant challenges, including limited water availability and the use of low-quality water during the irrigation season. These issues are further intensified by the impacts of climate change, making it essential to adopt crop and soil management strategies that optimize and preserve this resource. A common management strategy in the Mediterranean environment involves cultivating mango plants on raised beds covered with black plastic mulch. The study aimed to assess the impact of mulching on soil temperature, moisture and salinity, as well as on the eco-physiological behaviour, yield, and fruit quality of mango plants irrigated with very high salinity water during an irrigation season. The experiment was conducted in a 4 -year-old mango orchard (cv. Keitt) near Palermo, Italy. Two soil management strategies were compared: black plastic mulch and unmulched soil, both combined with very high salinity water irrigation (4 mS/cm). Results indicate that, within the first 5 cm of soil depth, the temperature differences between the two experimental conditions were particularly marked. Unmulched soil showed a higher daily temperature excursion, reaching 50°C during the season. At depths between 5 and 10 cm, unmulched soil recorded temperatures above 40°C, while mulched soil did not exceed 32°C. Mulching plays a crucial role in maintaining lower and more stable soil temperatures, especially on days characterized by high air temperatures. The mulched soil also had a higher volumetric water content, probably due to reduced evaporation and a more uniform water distribution in the soil profile. An increase in soil electrical conductivity was observed in the unmulched soil over the season, suggesting a potential surface salt accumulation caused by evaporation. However, at a depth of 25-30 cm, no significant differences were observed between the two experimental conditions. Regarding the net photosynthesis rate, as well as yield and fruit quality parameters, the plants responded similarly under the two different management strategies. Despite mango being notoriously sensitive to saline conditions, plants irrigated with very high salinity water maintained a high photosynthetic activity. In addition, fruits achieved an average weight of 750 g and a total soluble solids content of 15 °Brix, according to the quality standards required by the European market. The results of the study are promising, but the data collected will need to be further validated in the next season to assess the long-term impact of mulching and salt accumulation in the soil.

Aknowledgment: this research was funded under Action 2 of the “Budget Strategico del Dipatimento SAAF” of the University of Palermo prot. 206917 – 18/12/2023.