The System of Rice Intensification (SRI), a method of rice production developed to sustainably increase productivity in the crop’s cultivation, also appears to have a pest control effect.
In a study over five years and eight locations in India, researchers found that grain yield was higher using SRI on all study sites, while there were lower incidences of a number of key pests and higher levels of natural enemies in SRI plots.
While plant hoppers, stem borers and gall midges were seen at lower levels in SRI plots, there were greater numbers of whorl maggots (the larvae of shore flies) and thrips. However, crops produced using SRI had higher levels of cellulose, hemicellulose and silica — characteristics associated with resistance to pest damage — than those grown using other methods.
Over the course of the study, damage due to stem borers ranged from 7 to 34% on SRI sites, and 13-51% in conventional fields. Crucially, there were fewer pest species present overall in SRI plots.
Consistent findings
SRI uses early plant establishment and lower plant density in a defined grid pattern, combined with the use of organic fertilisers and controlled water use. It was originally tested in Madagascar, and has seen impressive results in reduction in seed requirements and water usage.
The findings of the current study, led by a team from the Indian Institute of Rice Research, were backed up by meta-analysis of previous work on SRI and pests, which consistently showed reduced damage and higher yields.
“SRI practices establish a micro-environment in the crop canopy that is less conducive to the growth and multiplication of insect pests,” wrote the researchers in the journal Agronomy.
“The effect of such an environment is complemented by SRI rice plants having higher silica content in leaves and stalks and a greater number of natural enemies in the plot. These factors lead to lower pest incidence and less crop loss.”
