Effects of water availability of various strains of Rhizobium on the herbage yield of Sulla (Hedysarum coronarium) in Tunisia

摘要

The forage crop Sulla has interesting possibilities in the rainier areas of Tunisia. Three field trials were set up in three different regions of Tunisia, where rainfall is a limiting factor. Inoculation of Sulla seeds before sowing and complementary irrigation both increased significantly the dry matter yield per hectare. There was a strong interaction between them : water is a limiting factor for symbiotic N fixation. Two Rhizobium strains were tested, one of European origin, which was very efficient, and an indigenous one. With complementary irrigation, both strains brought about noteworthy increases in the herbage yield (125% for the local strain, and 170% for the European strain). Without complementary irrigation, the increases were similar for the two strains, respectively 87 and 91%.