Abstract

Global climate change is altering water availability in agriculture, impacting crop yield and the accumulation of bioactive components in horticultural crops. The aim of this study was to assess how terminal drought stress affects the yield and lycopene concentration of tomato plants inoculated with arbuscular mycorrhiza. The field experiment took place at the Los Tilos Experimental Center of INIA La Platina (Buin, Región Metropolitana Santiago, Chile) during the 2020/21 growing season. Tomato plants were divided into groups with (M1) and without (M0) mycorrhizal inoculation, following a split-plot design in a randomized complete block layout (treatments: T0M0, T0M1, T1M0, and T1M1). Terminal drought stress, equivalent to a 50% reduction in irrigation water, was applied 21 days before harvest (T1), while a control group received full irrigation (T0). Measurements were taken for yield, irrigation water productivity, lycopene concentration, and soluble solids in the fruit. The lowest yield was observed in tomato plants subjected to terminal drought stress without mycorrhizal inoculation (T1M0, 53.5 t ha-1). However, plants with mycorrhizal inoculation achieved a yield of 60.1 t ha-1, with no significant differences between irrigation treatments (T0M1 and T1M1). Maximum irrigation water productivity was recorded in inoculated plants subjected to terminal drought stress (T1M1, 21.8 kg m-3). Regardless of irrigation treatment, plants with mycorrhizal inoculation exhibited a consistent lycopene concentration of 90.1 mg kg-1 in fresh fruit (T0M1 and T1M1). While the highest soluble solids concentration in fruits was observed in well-irrigated plants, no significant differences were found between water-stressed plants and those treated with mycorrhizal inoculation. Interestingly, a reduction in soluble solids near harvest was not observed in fruits of water-stressed plants treated with mycorrhizal inoculation (T1M1). Thus, further research could elucidate the positive impact of arbuscular mycorrhizal fungi by exploring the specific physiological mechanisms employed by inoculated plants to mitigate water stress.