Improvement of yield, pest control and Si nutrition of rice by rice-water spinach intercropping

Intercropping is an effective agricultural practice for crop production, resource utilization, and pest control. However, aquatic crops (e.g., rice) intercropping is relatively rare. Field experiments of two years/four seasons (early and late seasons in 2012, 2013) was carried out to test the effects of rice-water spinach intercropping on yield, disease and pest control, and Si, N nutrition of rice plant in the present study. The experiment contained three treatments including rice monoculture, water spinach monoculture and rice-water spinach intercropping with three replicates by randomized block design. Results showed that rice-water spinach intercropping significantly reduced the incidence of disease and pest of rice, with a reduction of rice sheath blight by 17.3%-50.6% and rice leaf folders by 5.1%-58.2%. For yield, intercropping resulted in an increase of rice yield by 45.1%-71.7% in early season and 20.9%-34.3% in late season, but a decrease of water spinach yield by 14.1%-37.1% in early season and 3.8%-18.3% in late season. However, rice-water spinach intercropping gave a higher land equivalent ratio (1.02-1.17) therefore improved land utilization efficiency. Furthermore, intercropping significantly increased Si concentration, Si and N absorption in rice leaves in ripening stage compared with rice monoculture. Our findings suggest that rice-water spinach intercropping exhibits yield advantage for rice or total yield, improves Si nutrition of rice and provides an environmentally sound approach in controlling disease and pest.