Pre-emergent phytotoxicity using image analysis

A simple quantitative bioassay was developed using widely available technology to determine pre-emergent phytotoxicity. Digitaria didactyla (Queensland Blue Couch Grass) was assessed by analysing digital images of the plants growing in microtitre plates for the effects of herbicides on germination. The herbicides tested were metsulfuron, triasulfuron, fluometuron atrazine, simazine and prometryn. Images of each 24-well microtitre plate (taken with a digital camera 7-10 days after planting), were analysed using a public domain image processing program, and a filter (developed using plugins available within the program) selected pixels within the green spectrum. Pixel counting took place using a spreadsheet function. To investigate the use of microtitre plates for the discovery of phytotoxic compounds within higher plants. This bioassay system allows rapid throughput of test samples with minimum handling.