Total phenolic content and allelopathic effect of soil incorporation of Praxelis clematidea on emergence and growth of plants.
Praxelis (Praxelis clematidea R.M. King & H. Rob.) is an invasive weed in many cropping systems in Thailand. It is an annual weed in Asteraceae. This study aimed to study on total phenolic content in dry praxelis and allelopathic effect of soil incorporated with dry praxelis plants in appropriate concentration and application time for weed control without crop injury. The results showed that total phenolic content from extracted praxelis with 50% methanol was greater when non-incubation treatment was applied. Total phenolic content without incubation was 12.3 and 29.3% greater than 24 and 72 hours incubation, respectively. The praxelis concentration of 1:10 provided the greatest inhibition on emergence and growth of Digitaria ciliaris and Bidens pilosa followed by concentrations of 1:20, 1:40, and 1:80, respectively. The praxelis concentration of 1:20 was used for testing an appropriate application time for transplanted lettuce. The results showed that allelochemicals of soil incorporated with praxelis were greater on 3, 5 and 7 days after soil incorporation (DAI) and lesser toxicity was found after 7 DAI. Therefore, the use of allelopahic effect of soil incorporated with praxelis for weed control depended on allelochemicals, application time, concentration, and transplanting time. This study can be developed and utilized as an alternative weed control method in crop production systems for reduced herbicide use.