INTERSPECIFIC DIFFERENCES IN GROWTH AND NITROGEN UPTAKE AMONG CROTALARIA SPECIES

The interspecific differences in germination, root nodule formation, d ry matter production and nitrogen uptake were evaluated among Cvotalar ia species for the introduction as new green manure legumes. The germi nation progressed smoothly in C. juncea and C. spectabilis, but physic al scarification was neccessary in C. pallida. In the field experiment , C. juncea had a high dry weight and a great nitrogen content at the early growing stage, but a drastic defoliation and a high C-N ratio we re found at the late growing stage. C. pallida grew slowly at the earl y stage, but a high nitrogen content and an adequate C-N ratio for dec omposition were found at the late growing stage. C. spectabilis showed intermediate traits in dry matter production and nitrogen uptake. In the root-box experiment, the distribution patterns of root systems and root nodules varied among the three species. C. juncea had greater ro ot growth and nodulation compared with two other species at 35 days af ter sowing. When the three species are introduced to various cropping systems, these traits should be considered for choice as green manures .