The Effect of Rhizoctonia Induction on Leaf Thickness of Orchids Infected by Odontoglossum ringspot virus (ORSV)

Abstract

Orchids have high economic value so that they are potential to be cultivated. The species most popular with people are Dendrobium and Phalaenopsis. However, there are major obstacles that can affect orchid growth, namely viral infections. The type of virus reported to infect the most is ORSV. This viral infection can inhibit plant growth, reduce flower quality and marketability. There are also symptoms of viral infection in the form of mosaic, chlorotic, streak, and necrosis. One of the efforts to overcome viral infection is by utilizing mycorrhizae. Mycorrhizae that can be used are Rhizoctonia sp. Mycorrhizal associations in orchids can have a positive effect on nutrient absorption and host growth, so they are expected to protect orchids from viral infections. The purpose of this study was to determine the effect of Rhizoctonia induction on leaf thickness of Phalaenopsis amabilis and Dendrobium discolor infected with ORSV. The study was conducted using a factorial completely randomized design. The result of this study is that there is a difference in leaf thickness between leaves inoculated with the virus and leaves treated with mycorrhizae. Orchid leaves treated with mycorrhizae had the highest thickness, while those infected with viruses had the lowest thickness.

Study of Orchid Resistance Induction Using Rhizoctonia Against ORSV Infection Based on Anatomical Characters of Roots and Leaves

“…This was in accordance with the research of Mahfut 7 which states that the lignin in the orchid transporting bundle functions to protect the evaporation of water during the transportation of nutrients and photosynthesis products so that the lignin is thicker. In this context, the above statement was supported by the research of Arifannisa et al 9 which stated that the lignin contained in the xylem of tomato plantlets induced by salicylic acid showed a greater thickness than K.…”

“…This assumption is reinforced by the research of Mahfut et al 11 that the results of the transverse incision of the roots of the Thrixspermum subulatum orchid showed that peloton was degraded in some cortical cells with peloton not completely filling the cortical cells. This assumption was reinforced by the results of research by Arifannisa et al 9 who found two types of peloton in the dendrobium root cortex, namely peloton that filled cortical cells completely and did not completely fill cortical cells. A peloton that does not completely fill cortical cells is declared a degraded peloton.…”

“…This assumption was reinforced by the statement of Izzati et al 10 , namely the presence of pathogenic infections triggers orchids to form peroxidase enzymes in order to protect them from pathogenic infections. Meanwhile, the results of the study Arifannisa et al 9 showed that orchids induced by Rhizoctonia were able to increase peroxidase activity and stimulate lignification in the roots of the Spathoglottis plicata orchid. Therefore, in this study, the induction of orchid resistance by Rhizoctonia and ORSV inoculation triggered the orchid to increase the activity of the peroxidase enzyme, which functions to maintain the life of the orchid.…”

“…There are few studies related to OMF induction in controlling viral infection in orchids. Several previous studies only reported the effectiveness of OMF in increasing height growth, increasing the number of roots and leaves 8 , increasing leaf thickness 9 , decreasing infection symptoms and disease intensity in leaves caused by ORSV 10 , but there is no information about the effectiveness of this OMF on the anatomical structure of orchid roots and leaves.…”

“…Leaf anatomy observations: Observation and identification of leaf surface anatomical characters were carried out using the replica method 9 . The leaves that have been taken are cleaned on the top and bottom surfaces with a tissue to remove dust and dirt.…”