Survey Of Nitrogen, Silicon, Phosphorous And Potasium Levels In Rice Infected And Non-Infected Fields

Abstract

Rice (Oryza sativa L) is a staple food for nearly-half of the world population contributing over 20% of total world calorie intake. In Kenya it is the third mostimportant cereal after maize and wheat. Basmati 370 is the most preferred variety but highly susceptible to rice blast disease. Rice blast, caused by Pyricularia oryzae is one of the most important rice disease causing yield loss of 70-80%. A study was carried out in Mwea Agricultural development Centre (MIA D) to determine the effect of fertilization with nitrogen, and silicon, application of rice by-product and fungicide for the management of rice blast. Soil and plant samples were collected from field that had infected and non-infected plants and analyzed for silicon and nitrogen levels. The effect of nitrogen and silicon on disease infection and yield of rice was tested using four levels of silicon fertilizer (0, 500, 1000, l500kg Silha) and nitrogen fertilizers (0, 40, 80 120kg N/ha). Each treatment was replicated four times. The experiment was laid out in split plot design with fertilizer type as main plot and fertilizer levels as sub-plot factor. Data collected comprised of disease severity score, productive tillers, number of panicles, number of filled grains, seed weight and biomass. To determine the effect of different sources of silicon from rice by-products and commercial silicate on infection of rice by Pyricularia oryzae, calcium silicate (5000Kg/ha), rice straw (2ton/ha), rice husk ash (0 .7tons/ha) and straw ash (0.6tons/ha). Basal fertilizers were added as recommended at 30 Kg K20 /ha, 58 KgP20s Iha and 80 KgN which was applied as a top dressing in two splits. Inoculums' of Pyricularia oryzae (4 x lOS conidial ml) was used to infect the rice plants and panicle blast infection was assessed using the IRRI standard.