Julius-Kühn-Archiv (Mar 2012)
Quantifying herbicide injuries in maize by use of remote sensing
Abstract
Maize breeders and plant protection companies require early information about negative side effects of herbicides on maize plants to identify cultivars which are susceptible to specific herbicide agents. Experiments were conducted in 2005 and 2006 to quantify herbicide injuries in maize. In 2005, sulfonylurea type herbicides and an untreated control were established in a susceptible and an insusceptible maize cultivar at University of Bonn, Research Station Dikopshof. Multispectral images were taken via airborne remote sensing after herbicide application. The normalized difference vegetation index (NDVI), an indicator for crop vitality, was calculated. Biomass was assessed before harvest. Yield was mapped at harvest. In 2006, 12 maize cultivars were sown in strips at Dingbuchenhof, near Erkelenz. Plots with an untreated control and plots with two doses of a sulfonylurea type herbicide were established square to the direction of the maize strips. Maize vitality was observed by visual ratings after spraying. Multispectral images were taken via airborne remote sensing and NDVI was calculated. In 2005, corn and straw biomass was significantly reduced in the treated plots within the susceptible cultivar. NDVI values and crop yields were reduced in the plots treated with sulfonylurea type herbicides. High correlations between NDVI- and yield values were calculated. However, no differences were assessed in the insusceptible maize cultivar. In 2006, overdoses of the sulfonylurea type herbicide caused vitality losses in almost all cultivars. Observations on crop vitality from visual ratings corresponded in many cases with the vitality values (NDVI) measured with remote sensing. Visual ratings can be influenced by individual estimation mistakes. By contrast, remote sensing enables numerically discrimination of herbicide injury in entire maize fields. This kind of measure may be helpful to accelerate the detection process of maize cultivars that are susceptible to herbicides.
Keywords
