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.
