Possible Role of High Temperature and Soil Biological Fertility on Kiwifruit Early Decline Syndrome

Abstract

Kiwifruit early decline syndrome is a widespread disorder that affects worldwide kiwifruit orchards. During the last few years, the seriousness and diffusion of this disorder worsened; as a consequence, in several rural areas the economic sustainability of farms was seriously affected. The early symptoms involve leaves (epinasty, chlorosis, desiccation, and abscission), fruits (decrease of number, size, and sugar content), and roots (anomalous morphology and anatomy). After symptoms occurrence, in a short time plants collapse and die: frequently this happens in the same or in the following year. Even though several phytopathological or agronomical studies have been carried out, a clear and univocal explanation of the causes and the possible remedies are yet to be understood. A field trial was carried out in an experimental kiwifruit orchard, in which several soil management practices (ridging, amendment with compost, bioinoculation with selected rhizospheric microorganisms) were tested to evaluate their effect on early decline symptoms occurrence. The analysis of plant growth parameters, root morphology and anatomy, and symptoms onset were related to environmental data (air and soil temperature, soil water tension). The results pointed to a possible role and interaction between agronomic soil management and climatic conditions as the triggering factors of kiwifruit early decline syndrome.

Effects of Short-Term High Temperature on Gas Exchange in Kiwifruits (Actinidia spp.)

“…), such as its physiology, flower, fruit composition, vine growth and yield. However, it remains unclear how high temperature affects the physiology of kiwifruits [ 22 ]. Specifically, we hypothesize that kiwifruits are susceptible to high temperature given their subtropical origin.…”

Bioactive Nitrosylated and Nitrated N-(2-hydroxyphenyl)acetamides and Derived Oligomers: An Alternative Pathway to 2-Amidophenol-Derived Phytotoxic Metabolites

“…Recently, anaerobic microsites, occurring also in well-drained soils, have been recognized as important for soil carbon persistence because they reduce microbial CO 2 release to the atmosphere [ 42 ]. Moreover, high temperatures due to climate change generate hypoxic soil conditions [ 43 ]. Thus, under field conditions, anaerobic microsites of soils, heavily loaded with nitrate and organic material [ 44 ], are suitable sites for the microbial synthesis of the nitro/nitroso compounds and the resulting polymers, especially under high-temperature conditions.…”

Enhancing soil properties through sustainable agronomic practices reduced the occurrence of kiwifruit vine decline syndrome

“…In February 2022, a mechanical excavator was used or create trenches in the inter‐row area at a depth of about 90 cm and at a distance of about 70 cm from the trunk of plants belonging to the four groups (CTRL, KVDS, SUST and SUST‐PE) (Figure S7). In this circumstance, fine roots (diameter <5 mm) taken from all groups at a depth of 30–40 cm (where kiwifruit roots are denser; Bardi, 2020; Bardi et al., 2020) were placed on Petri dishes containing potato dextrose agar (PDA) nutrient media, pre‐supplemented with ampicillin and kanamycin (Sigma‐Aldrich, St. Louis, MO, USA) and incubated at 24°C until visible colony formation. In particular, for CTRL, KVDS, SUST and SUST‐PE, 56, 84, 63 and 45 root samples, taken from three plants for each group, were analysed respectively.…”

“…Foliar symptoms of KVDS, such as epinasty, chlorosis, desiccation and abscission, are a consequence of a low root/canopy ratio because of the damage to kiwifruit root systems, in terms of reduced development, tissue breakdown and decomposition, anomalous anatomy structure and presence of necrotic areas (Bardi et al., 2020; Sofo et al., 2022). Therefore, soil mismanagement together with poor irrigation management, leading to a compacted, impermeable and hypoxic soil layer, is thought to be a major cause of kiwifruit root disruption and KVDS emergence (Bardi, 2020; Savian, Ginaldi, et al., 2020; Sofo et al., 2022).…”