Peas grown in media with elevated plant-available silicon levels have higher activities of chitinase and beta-1,3-glucanase, are less susceptible to a fungal leaf spot pathogen and accumulate more foliar silicon

Pea seedlings grown for 5 weeks in a growing medium amended with potassium silicate fertiliser had significantly greater activities of the enzymes chitinase and beta-1,3-glucanase in leaf extracts compared with those grown in coir-based control mix, prior to challenge by a foliar pathogen. Additionally, fewer lesions developed on pea leaves inoculated with the fungal pathogen Mycosphaerella pinodes 5 weeks after growth in the Si-amended mix. Plant-available Si, as monosilicic acid, in the Si-amended mix was more than five times that in the control mix. Peas accumulated nearly twice as much silicon (w/w dried foliage) after 3 weeks growth in an alternative potting mix amended with silicon from rice hull derivatives, as those grown in a conventional perlite/sand medium as control. The monosilicic acid content of the rice hull mix was approximately three times greater than that of the perlite/sand mix. There were no significant differences in dry weights between plants from control and Si-amended mixes. The results suggest associations in pea between available silicon in growth media, accumulation of Si within the plant, early activation of host defences and subsequent resistance to fungal pathogens, with potential for reduction and control of diseases.