Dear Pankaj Kumar Mishra, To screen the resistance of soybean germplasm to Macrophomina phaseolina I suggest you try the toothpick inoculation technique. This was developed in Maize for stalk rot pathogens and has been successfully used in soybean working with Diaporthe Stem canker. See Keeling for the work on Stem Canker. But basically the toothpicks are boiled in distilled water to eliminate inhibitors and then Saturated in potato dextrose broth and cultured with the fungus for testing in a sterilized mason jar. The inoculation is done by puncturing the stem with a dissecting pin and inserting the inoculated toothpick into the hole made by the dissecting pin. The lesions are measured and rated to give the resistance levels of the screened germplasm. The advantage of this technique is the large numbers it can handle and uniformity of the procedure. Results using it have been remarkably consistent. Good luck Paul Reed Hepperly

Dear Pankaj Kumar Mishra,

To screen the resistance of soybean germplasm to Macrophomina phaseolina you need collect isolate from your area and classify it to high or low virulence according to screen several genotypes. 

How to identify the high and low virulence isolates.

Please attach some references if you have.

Thank you

I would suggest that besides using the standard toothpick inoculation that the test be initiated at full flower and that a standard period of drought stress be applied using some sort of rain shelter.

The drought stress at maturity is critical as a predisposing factor.

You will also need to develop a rating scale using pattern coverage of symptoms on the split stems. The ability of storing the dry sclerotia will be useful for your studies.

Many of genotypes that can resist these types of disease have an ability not to senesene at normal maturity which is called stay green trait. Good luck