ABSTRACT
This nodulation survey consists of measuring nodulation and growth of the legume in a network of fields in the production area. In an homogeneous part of each field, a smaller plot is selected, i.e. a survey-station, where sampling is performed at two stages during legume development: at early vegetative growth with 2-4 fully expanded leaves, and during late flowering or early pod-filling when maximum nodulation has been expressed. At each stage, plants are collected from 4 random sites of the station, i.e. 2-5 neighbouring plants per site (depending on variability in samples), by excavating the root system in a 20-cm deep cubic soil volume. The plant is separated immediately from surrounding rhizospheric soil. Soil and plant samples are placed in plastic bags and stored in a cold room until further analysis. At the vegetative stage only a visual scoring of nodulation is done. At the reproductive-stage, for each individual plant, the shoot is separated from the root at the cotyledonary node; the number of nodules is recorded, and the dry weights of nodules and shoots are measured after drying at 60°C.
