Plant Pathol. J. 28(2) : 164-171 (2012) http://dx.doi.org/10.5423/PPJ.OA.02.2012.0022 pISSN 1598-2254 eISSN 2093-9280 The Plant Pathology Journal © The Korean Society of Plant Pathology Effect of Foliar and Root Application of Silicon Against Rice Blast Fungus in MR219 Rice Variety Farnaz Abed-Ashtiani 1 , Jugah-Bin Kadir 1 , Ahmad-Bin Selamat 2 , Ahmad Husni Bin-Mohd Hanif 3 and Abbas Nasehi 1 1 Department of Plant Protection, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia 2 Department of Crop Science, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia 3 Department of Land management, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia (Received on February 27, 2012; Revised on May 4, 2012; Accepted on May 6, 2012) Rice blast disease caused by Magnaporthe grisea (Hebert) Barr [teleomorph] is one of the most devastating di- seases in rice plantation areas. Silicon is considered as a useful element for a large variety of plants. Rice variety MR219 was grown in the glasshouse to investigate the function of silicon in conferring resistance against blast. Silica gel was applied to soil while sodium silicate was used as foliar spray at the rates of 0, 60, 120, 180 g/5 kg soil and 0, 1, 2, 3 ml/l respectively. The treatments were arranged in a completely randomized design. Disease severity and silicon content of leaves were compared between the non-amended controls and rice plants re- ceiving the different rates and sources of silicon. Silicon at all rates of application significantly ( α = 0.05) reduced the severity of disease with highest reduction (75%) recorded in treatments receiving 120 g of silica gel. SEM/EDX observations demonstrated a significant difference in weight concentration of silicon in silica cells on the leaf epidermis between silicon treated (25.79%) and non treated plants (7.87%) indicating that Si-fertilization resulted in higher deposition of Si in silica cells in comparison with non-treated plants. Application of silicon also led to a significant increase in Si contents of leaves. Contrast procedures indicated higher efficiency of silica gel in comparison to sodium silicate in almost all parameters assessed. The results suggest that mitigated levels of disease were associated with silicification and fortification of leaf epidermal cells through silicon fertilization. Keywords : blast, Magnaporthe grisea, rice, silicon Rice (Oryza sativa L.) is among the most important crops all over the world since it is consumed as a staple as well as primary source of energy and protein (Zhang et al., 2008). In Malaysia rice is one of the major crops grown by the private and public sectors. Rice blast, caused by the fungus Magnaporthe oryzae (Couch and Kohn, 2002) (anamorph, Pyricularia oryzae Cavara), is among the most significant diseases affecting rice cultivation, since it is prevalent in most rice growing regions and causes serious yield losses (Hayasaka et al., 2008). The disease is widely distributed (85 countries) (Hajano et al., 2011) and under favorable environmental conditions it can be very disastrous (Scardaci et al., 1997). Yield and harvest losses estimated from other areas of the world have ranged from 10-30% (Tongen et al., 2006). Applying fungicide to control the disease is neither economical nor environmentally friendly. Further- more, rice blast spreads very fast and the use of resistant varieties is considered as a short term remedy. Silicon is the second element which is found in abundance in the earth's crust (Datnoff et al., 1997; Epstein, 1994; Marschner, 1995) and is a main component of plant tissues as well as cell walls, despite the fact that it is not considered as an essential nutrient for terrestrial plants (Epstein, 1994). This element can be absorbed from soil in significant amount and it is taken up by plants in the form of monosilicic acid (Mitani et al., 2005). Supply of soluble silicon in plants provides stronger, tougher cell walls which serve as a mechanical barrier against sucking and piercing insects. Also silicon can be deposited by the plants at the infection site thus inhibiting the penetration of cell walls by the attacking fungus. Rice is known as a Si-accumulator (Mitani et al., 2005) and accumulation of Si in leaves and tissues in addition to conferring resistance against fungal diseases and insect pests, can improve erectness of leaves, increase yield and alleviate water stress, salinity stress and nutrient defici- ency or toxicity stresses as well. Silicon is also considered as an environmentally-friendly element in relation to soils, fertilizers and plant nutrition (Ma and Takahashi, 2002). Based on the aforementioned it is concluded that silicon deficiency can be considered as a limiting factor for crop production. There have been plenty of reports on profitable effects of silicon in rice plantations (Ando et al., 2002; *Corresponding author. Phone) +603-8947 4845, FAX) +603-8947 4917 E-mail) kaju@putra.upm.edu.my Open Access