Waterlogging-Induced Stress and Its Synergistic Effects on Peach Gummosis: Mechanisms and Mitigation Strategies

Waterlogging-induced stress significantly affects peach (Prunus persica) orchards, leading to physiological disturbances and increased susceptibility to diseases such as peach gummosis. This study investigates the synergistic effects of waterlogging and gummosis under controlled experimental conditions to determine the mechanisms linking soil saturation to disease severity. The experiment was conducted using Prunus persica cv. ‘Spring Snow’ plants grown in pots with well-drained loamy soil. Waterlogging treatments were imposed by submerging the root zone for 7, 14, and 21 days, while control plants were maintained at a 60% field capacity. Physiological responses, including root hypoxia (oxygen diffusion rate), chlorophyll content, stomatal conductance, and enzymatic antioxidant activity, were assessed. Additionally, gummosis severity was evaluated by measuring gum exudation rates and lesion development following inoculation with Lasiodiplodia theobromae.

Results revealed that prolonged waterlogging (≥14 days) significantly reduced root oxygen diffusion rates by 45%, leading to increased ethylene production and oxidative stress. Chlorophyll content and stomatal conductance declined by 32% and 41%, respectively, indicating waterlogging-induced photosynthetic impairment. Enzymatic antioxidant activity (SOD, POD, and CAT) initially increased by 25%, 18%, and 22%, respectively, but declined after 14 days, suggesting an overwhelmed defense system. The severity of peach gummosis was markedly higher under waterlogged conditions, with infected trees exhibiting 56% greater gum exudation and 48% larger lesions compared to non-waterlogged counterparts. Soil microbial analysis indicated a shift toward anaerobic and pathogenic fungal dominance in waterlogged soils, further aggravating disease incidence.

To mitigate these effects, the study evaluated the efficacy of microbial inoculants containing Bacillus subtilis and Trichoderma harzianum, as well as improved drainage practices. Trees treated with microbial amendments exhibited 38% lower gum exudation and 42% improved root recovery post-waterlogging. Additionally, trees grafted onto waterlogging-tolerant rootstocks (Prunus persica × Prunus davidiana) displayed 61% higher survival rates and 49% reduced gummosis severity compared to those on susceptible rootstocks. These findings underscore the importance of integrating water management strategies and biological control methods to minimize the adverse effects of waterlogging on peach trees. By identifying key physiological and microbial interactions, this research provides practical recommendations for improving orchard resilience under excessive soil moisture conditions.