Clostridium welchii isolated from intestine contents of normal and sudden death black goats is preliminarily studied by cultural performance and biochemical reaction,determination of hemolytic activity, minimum lethal dose and neutralization test of toxins.

The experiment was conducted in the green house in Hebei province in order to determine the Minimum Lethal Herbicide Dosage(MLHD) of photosynthesis inhibiting herbicide,isoproturon on five weed species and safety to the winter wheat with Plant Photosynthetic Meter(PPM).

To provide the using information of disinfectors dose in the tobacco float seedling system,the efficacies of 90% lethal dose(EC90) of 10 disinfectors were examined by carrier germicidal test on breeding substrates,including polystyrene foam trays,polyvinyl chloride plastic film and stainless blade which were inoculated with Ralstonia solanacearum.

At same time, we also knew the LD100 of konjac is 3KR and LD50 is 1.