i mean to ask callus not callu.............

In general, growth regulators (NAA and 2,4-D) are most important  to induce callus.   friable callus, critical cell density or number, medium composition,  as well as physical conditions are important to initiate suspension culture.

but in this concern, 1mg/l 2,4-D or NAA at a level of  less than 1 mg/l is enough to initiate callus.

this site helps:http://www.pharmatutor.org/articles/tissue-culture-of-endangered-brahmi

I agree with Dr. Metwally Bekhit.

Regards

SM Najim