Question

How much time to treat germinated rice with mercuric chloride for surface disinfection?

Answer 1

Mercuric chloride is highly antimicrobial,  with action against both  fungi and bacteria, but frequently also kills the seeds/plant materials. At low concentrations (upto 0.1 %) it is perhaps the most effective disinfective agent for seeds with soil-borne and the epiphytic fungi. So this could be the reason why some people prefer to use it as 5-20% bleach is sometimes ineffective against some fungi. But one is always safer with hypochlorite and  you could safely use 30- 50% or even up to 100% commercial bleach (nearly 4-6% sodium hypochlorite).  Mercuric chloride should really be avoided as it is highly toxic to nearly every other organism and, even worse, quickly volatises so significant quantities of its its vapour form may  be inhaled  during measurement of the solid. A number of research labs around the world have completely  banned its use.