Pisum Sativum Nodules Research Articles

The effect of ethrel on nodulation inPisum sativum L.

Nodulation of inoculated pea plants was severely inhibited when ethrel (2-chloroethane phosphonic acid) was applied to the roots. The inhibition was evident at ethrel concentrations of 2 ppm and above. Ethrel applied to the foliage at 10 ppm also depressed nodulation. At least part of the effect of ethrel on nodulation came from its inhibition of root growth.

A Cotyledonary Inhibitor of Root Nodulation in Pisum sativum

AbstractRoot nodule formation was studied in 11‐day‐old seedlings of Pisum sativum L. cv. Alaska, which were inoculated with Rhizobium leguminosarum at the time of planting. On intact plants an identical nodulation pattern was observed in the lateral roots attached to the two xylem strands connected to the cotyledons. When one cotyledon was removed before germination, however, a highly significant increase in nodultion was observed on the lateral roots attached to the xylem strand which no longer was connected to a cotyledon. Excision of one cotyledon also caused an alteration in the radial location of root nodules on the primary root. Under these conditions there was a distinct promotion of nodular proliferations in the root cortex opposite the primary phloem poles. The fact that removal of one cotyledon increased nodulation on the lateral roots but had no effect on the rhizobial infection of lateral root hairs suggested that a cotyledonary inhibitor acts at a step between the infection process and the appearance of a macroscopic nodule. The data were interpreted in terms of an inhibitor of cortical cell division which is translocated from the cotyledons to the developing root via the phloem.