Millions of tons of pesticides are applied annually in agriculture. Among them, herbicides originating from agricultural run-off can contaminate soils, surface and ground waters with severe toxic effects on humans. In order to control the spread of these compounds, it would be reasonable to make a rational use of them, limiting their employment to the bare necessities. Estimating the level of their presence in areas which must be treated and balancing, before any further indiscriminate treatment, the amount of herbicide needed to avoid the growth of weeds represent the only winning strategy in this sense. For this reason, an experimental device able to evaluate the effect of herbicides on the physiological status of the crops was built and tested. By measuring the intrinsic fluorescence of photosynthetic apparatus, the instrument can provide with important information about general plant conditions, properly addressing all further treatments on the crops. For the measurements, the ratio between two fluorescence emissions (at 684 and 735 nm) was assumed as indicator of long-term stress, demonstrating to increase proportionally to herbicide concentration and regardless of the chemical class of herbicides tested. The source of chlorophyll fluorescence was a laser with a wavelength of 457 nm and a power output of 200 mW, enough powerful to generate signals which can be measured at a distance of 15 meters. A telescope and a sensitive ICCD camera collected and detected the fluorescence emission, respectively. Interferential filters were used to select the fluorescence signals at 684 nm and 735 nm. A photomoltiplicator, with a spectral range of 185 ÷ 900 nm, completed the instrument set up. The instrument is intended for the in field assessment of toxic herbicide levels.
LASER-BASED FLUORESCENCE SENSOR FOR THE ASSESSMENT OF HERBICIDE LEVELS IN CULTIVABLE AREAS
2010
Abstract
Millions of tons of pesticides are applied annually in agriculture. Among them, herbicides originating from agricultural run-off can contaminate soils, surface and ground waters with severe toxic effects on humans. In order to control the spread of these compounds, it would be reasonable to make a rational use of them, limiting their employment to the bare necessities. Estimating the level of their presence in areas which must be treated and balancing, before any further indiscriminate treatment, the amount of herbicide needed to avoid the growth of weeds represent the only winning strategy in this sense. For this reason, an experimental device able to evaluate the effect of herbicides on the physiological status of the crops was built and tested. By measuring the intrinsic fluorescence of photosynthetic apparatus, the instrument can provide with important information about general plant conditions, properly addressing all further treatments on the crops. For the measurements, the ratio between two fluorescence emissions (at 684 and 735 nm) was assumed as indicator of long-term stress, demonstrating to increase proportionally to herbicide concentration and regardless of the chemical class of herbicides tested. The source of chlorophyll fluorescence was a laser with a wavelength of 457 nm and a power output of 200 mW, enough powerful to generate signals which can be measured at a distance of 15 meters. A telescope and a sensitive ICCD camera collected and detected the fluorescence emission, respectively. Interferential filters were used to select the fluorescence signals at 684 nm and 735 nm. A photomoltiplicator, with a spectral range of 185 ÷ 900 nm, completed the instrument set up. The instrument is intended for the in field assessment of toxic herbicide levels.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
