A study of seed lots of peas (Pisum sativum L.) differing in predisposition to pre-emergence mortality in soil

In three seed lots the condition of the cotyledons was found to be important in denning seeds predisposed to pre-emergence mortality. Such seeds readily exuded materials into seed-steep water, were rapidly infected by Pythium spp. and showed intensely stained cotyledons after being in solutions of tetrazolium chloride. In soil, infection of the cotyledons was found to occur before infection of the seedling axis and occurred in normal seed if disks of cotyledon material were placed in the soil next to the seed.
It is suggested that cotyledons influence predisposition by either increasing exudation around the seed and stimulating the fungal pathogen or by acting as a food base for the fungal hyphae which infect and kill the seedling axis.