Cytokinin Content during Early Stages of Legume-Rhizobial symbiosis and effect of hypothermia

The effects of pea (Pisum sativum L.) seedling inoculation with nodule bacteria (Rhizobium leguminosarum bv. viceae) and hypothermia on the content of cytokinins (Ck) in seedling roots during 8 days after external factor action were studied. As soon as a day after inoculation with Rh. leguninosarum, the content of Ck in the seedling roots increased, especially in the root zone most susceptible to infection (0-20 mm from the tip); this not only affected growth of the whole roots but also determined the initiation of nodule primordia. Hypothermia (8A degrees C) reduced the content of CK as soon as in a day. After 5 and 8 days of hypothermia, the content of Ck in inoculated plants was approximately twice higher than in non-inoculated plant roots.