Factors Influencing the Growth of the Root System of Etiolated Seedlings of Pisum Sativum L.

SUMMARY The growth of the root system of dark grown dwarf‐pea seedlings ceases 10–12 days after germination, even though cotyledonary reserves continue to be used for shoot growth. The cessation of root growth was not due to competition between shoot and root for cotyledonary reserves, but appeared to be the result of a depletion of essential factors which are normally supplied to the root by the light‐grown shoot. These factors included auxin, the B vitamins (thiamine and nicotinic acid) and adenine. Application of IAA in lanolin to the cut stumps of de‐shooted seedlings plus a supply of thiamine, nicotinic acid and adenine in the culture solution substituted to some extent for an illuminated shoot.