The effect of inoculation on growth, nodulation and nitrogen in annual clover cultivars grown at two mediterranean locations of Sardinia, Italy

The legume's benefits are well-known and exploited in animal production systems, and the commercial availability of novel clover cultivars is an important opportunity for Mediterranean climatic areas. However, the successful performance of a legume species is strongly affected by the presence of specific rhizobia in the soil. The performances of 10 annual clover cultivars belonging to nine species, both uninoculated and inoculated, were compared at two locations in Sardinia (Italy). The rows (2 m length each) were established in autumn and seed inoculation with a selected commercial rhizobial strain was performed at sowing. In the following spring, shoot length, the number of root nodules, shoot dry matter yield and nitrogen concentration were determined on complete recovered plants. Inoculation affected shoot length, with significant differences at each site. It ranged from 7.9 to 39.7 cm. The average shoot DM production in the two locations ranged from 0.21 to 1.92 g per plant and there was a significant interaction of the location x cultivar. Inoculation significantly increased the growth of four cultivars. However, a cultivar selected in Sardinia, Trifolium brachycalycinum 'Antas', was irrespective of both location and inoculation, producing more shoot DM per plant than did the other clovers (about 1.80 g per plant). The results demonstrated that the clover agronomic performances differed among cultivars and locations. In addition, they highlighted that inoculation with a selected rhizobial strain is very useful for some clovers, suggesting that is preferable to ascertain at each site the need for clover inoculation.