VEGETATIVE AND PRODUCTIVE PERFORMANCE OF ANNUAL RESEEDING LEGUMES IN INTERCROPPING WITH DURUM WHEAT IN SEMI-ARID ENVIRONMENTS

A. Carrubba¹, P. Trapani¹, P. Quatrini² and L. Gristina¹

¹Ist. di Agronomia generale e Coltivazioni erbacee, Viale delle Scienze, 90128 Palermo, Italy

²Dip.to di Biologia cellulare e dello sviluppo, Viale delle Scienze, 90128, Palermo, Italy

Subterranean clover and annual reseeding Medicago, not only are well suitable to the Mediterranean climate, but also, due to their auto-reseeding capability may last in time and give an early sward able to protect soil from erosion. They allow to gain good results both from the productive point of view and from the quality of fourrage. Due to their morphological and physiological traits, they are suitable to the intercropping with cereals, to that they give significant deals of biologically fixed N. After the first year of intercrop, the meadows of Clover and annual Medicago obtained from the natural reseeding may be directed to forage yield, to the production of green biomass to be utilized as green manure before the seeding of some spring-summer crop (green manure), and to the formation of a permanent meadow to be sod-seeded. This work had as its goal the evaluation of the vegetative and productive behavior of some annual reseeding legumes in intercropping with durum wheat. The experiment was carried out in 1994/95 and 1995/96, using in the first year only Trifolium subterraneum ssp. brachycalycinum cv. Clare and Trifolium subterraneum ssp. subterraneum cv. Seaton Park; in the second trial year 4 annual Medicago were added: 2 Medicago rugosa (cv. Paraponto and Sapo);1 Medicago truncatula (cv. Paraggio);1 Medicago polymorpha (cv. Sephi). Both cropping systems (intercropping and pure stand) have been submitted to two N-fertilization levels. The study confirmed that the introduction of the annual reseeding legumes may represent a profitable biological resource to get the cropping inputs lower and to get the agroecological performances better. The introduction of legumes may give, besides the direct benefit on the main crop, also a not negligible residual effect on the following crops. Clover is able to stimulate the multiplication of specific Rhizobium population, even when the starting number of bacteria is very low.

Keywords: Annual legumes; reseeding; Trifolium subterraneum; Medicago spp.; intercropping; semi-arid environments.