Inoculation and fertilization affect sulla performance in a new cultivation area

The forage legume sulla (Sulla coronaria (L.) Medik) establishes a host-specific nitrogen-fixing symbiotic interaction and its inoculation is mandatory where it is cultivated for the first time or not present as spontaneous species. This study aimed at investigating the effects of inoculation and fertilizer nitrogen (N) on yield performance and N-fixation ability of sulla established in a new habitat within a Mediterranean agropastoral area of Sardinia (Italy). Sulla plants, previously inoculated with peat-based inoculant, liquid inoculant and soil, and unfertilized (N0) or N100 fertilized, were sampled at full vegetative stage. Length, dry matter yield and fixed N of sulla shoots and roots were measured. Inoculation significantly affected several traits. In particular, plant DM varied from 0.5 to 3.2 g in uninoculated and inoculated plants, respectively. At N0 and using soil as inoculant, shoot fixed N reached 43 mg plant-1 whereas it was negligible in the uninoculated control. Under N100, N-fixation ability of sulla was decreased. Results highlighted that inoculation is essential for extending the cultivation of sulla in a new habitat.