EFFECT OF NITROGEN AND SILICON ON MANAGEMENT OF RICE BLAST ( PYRICULARIA ORYZAE) IN MWEA IRRIGATION SCHEME OF KENYA

Abstract

Plant health is an important factor for plant growth and development. Nitrogen is essential and is usually required in large quantities by plants. However, many studies have shown that high nitrogen concentration in plant increases the severity of disease infection by plant pathogen. On the other hand, silicon though regarded as non essential element, has several benefits in crop growth. Its application to the rice plant has been shown to increase resistance to rice blast Pyriularia oryzae as well as increased crop yield. This study aimed to establish an effective level of nitrogen and silicon in the management of the rice blast disease. The experiment was carried out at Mwea Irrigation Agricultural Development (MIAD) research station in Kirinyaga District.  Seedlings were raised in the nursery before culturing in vertisol filled pots with various treatment combinations of nitrogen (40, 80 and 120 kgN ha-1) and silicon (0,500, 1000 and 1500 kgSi ha-1) in split plots and in completely randomized design (CRD). Plants were inoculated after two weeks with the  Pyricularia oryzae  spore after transplanting and disease assessed in a scale of (0-9) according to IRRI standard.  Higher rice blast was realised at 120 KgN and 0kgSi ha-1  and in the plots that had neither nitrogen nor silicon. The organic husk ash at 2ton-1 before burning and 0.7ton-1 was shown to be good source of silicon and gave results equivalent to those of 120KgN and 1000KgSi.combination.The study established that interaction of nitrogen and silicon at 80 kgN ha-1 and 1000 kgSi ha-1 was the optimal rate for management of the rice blast disease.