In Vitro and Greenhouse Evaluation of Silicon Compounds Against Ascochyta Blight Pathogens and Physiological Responses in Pea

Ascochyta blight is a serious disease that affects pea plants worldwide. It is caused by different species of the Ascochyta, Phoma and Boeremia genus. This study identified Ascochyta blight isolates obtained from Colombian Central Andes pea crops and evaluated the interaction between the effects of silicon (Si) compounds (potassium (KSi) and calcium (CaSi) silicates) on the growth of isolates obtained from Ascochyta blight lesions, disease progression and plant physiology (stomatal conductance, growth and chlorophyll) in pea plants. In an in vitro experiment (E1), the study tested two types of Si compounds on the growth of three isolates of the pathogen. In the greenhouse experiment (E2), pea plants were treated with potassium silicate (KSi) and infected with two isolates, AMn01 and AMn03. The study found three types of isolates (AMn01, AMn02, and AMn 03) that were obtained from infected pea leaves. All three were identified as part of the Didymella genus, with AMn01 and AMn03 being closely related to Didymella lethalis and Didymella pinodella . In E1, KSi and CaSi inhibited the mycelial growth of all three isolates, with KSi (32%) being more effective than CaSi (12%). In E2, KSi, especially when applied to the soil (KSi-S: 2.20), reduced disease severity in pea plants infected with AMn01 (KSi-S: 2.49 vs. control inoculated without Si (cp+): 2.67) and AMn03 [KSi-S: 1.92 vs. cp+: 2.44]. KSi‑S (213.66 CO 2 · m −2 ·s −1 ) improved stomatal conductance compared to cp+ plants (136.14 mmol CO 2 · m −2 · s −1 ). These findings suggest that D. pinodella and D. lethalis can also be causal agents of pea Ascochyta blight in Colombia. The use of Si, especially KSi, could help to manage the disease and improve plant physiology. Further field tests are required to confirm the role of Si in sustainable pea farming.