Effect of nitrogen, bio-fertilizer, and silicon application on yield and yield components of rice (Oryza sativa L.)

A field experiment was conducted in Neka, Mazandaran, north of Iran, to determine the effect of nitrogen (N), N sub 2-fixing bacteria (Azospirilum + Azotobacter), and silicon (Si) on rice grain yield and yield components. Treatments were N rates (0, 75, 150 kg/ha), bio-fertilizer application (inoculation with or without Azospirillum + Azotobacter), and Si rates (0, 150, 300 kg/ha). Rice grain yield was significantly affected by N rate, bio-fertilizer application and Si rate. The interaction between N rate and bio-fertilizer rate was significant for yield. With bio-fertilizer application, grain yield was significantly increased as N rate increased from 0 to 75 kg N/ha, but slightly reduced at 150 kg/ha N rate. Without bio fertilizer application, the highest grain yield was obtained in plots applied with 150 kg N/ha. Regardless of N rate and bio-fertilizer application, the highest grain yield (5287 kg/ha) was observed in plots applied with 300 kg Si/ha. Nitrogen application significantly increased plant height, tiller number per m sup 2, grain number per panicle, 1000-grain weight, biological yield, harvest index, grain N concentration, and grain N uptake across bio-fertilizer applications and Si rates. Across N and Si rates, plant height, tiller number per m sup 2, grain number per panicle, biological yield, harvest index, grain N concentration, and grain N uptake were significantly increased with bio-fertilizer application. Moreover, Si application increased significantly plant height, tiller number per m sup 2, grain number per panicle, 1000-grain weight, biological yield, harvest index, grain N uptake across bio-fertilizer applications and N rates. This study proved that bio-fertilizer application could reduce chemical N application rate with increase in rice grain yield.