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Effective supplementation of silicon by root against stem canker of pitaya (Hylocereus polyrhizus).

Siti Nordahliawate Mohamed Sidique: Universiti Malaysia Terengganu

<div>In Malaysia, red-fleshed pitaya fruit (<em>Hylocereus polyrhizus</em>) is a high commercial value plant but prone to disease infections especially stem canker that causing plant breakdown after 3 years of growing. Therefore, our work to determine the effect of silicon nutrient (Si) application on pitaya plant growth and under biotic stress (stem canker disease) caused by <em>Neoscytalidium dimidiatum</em>. Silicon nutrient was applied once a week as root applications at the concentration of 1.5% Si (v/v), 2.5% Si (v/v) and 5% Si (v/v), which was using the grower’s conventional fertilizer applications and naturally infected. The control plants were untreated without any Si nutrient. There is a potential role of Si in delaying the development of stem canker when we observed a reduction of severity of the stem canker compare to the untreated. Results showed that the disease severity was below 10% rotted stems of pitaya plants treated with both 1.5% Si (v/v) and 2.5% Si (v/v) whereas 10–50% rotted stems of pitaya plants treated with 5% Si (v/v). The delay of the epidemic development could give more time to manage disease outbreaks and reduce the amount of fungicides usage. Additionally, the application of Si through the roots produced significantly physiological changes in the plant including increased number of new shoots, longer shoot length and early flowering. Pitaya plants also demonstrate effect of stronger and thicker stems that may retard the germination of pathogen. Silicon uptake in pitaya offer a promising outlook to improve biotic stress tolerance in a sustainable manner.</div>