Crop weed interactions under environment stress - A review

Crops and weeds compete with each other for the resources like water, light, nutrients etc. Due to human interventions climate is changing with increase in CO₂, ozone concentration and temperature variation. Physiological basis for variation in the competing ability of crops and weeds is their C₃ and C₄ photosynthetic pathways. Increase in CO₂ alone favors C₃ crops and weeds, but any simultaneous increase in temperature will benefit C₄ crops and weeds. Tropospheric ozone also reduces crop yield and some weeds like purple nutsedge are less sensitive to ozone. Efficient cultivars and herbicides are necessary to control weeds under changing environments.