Persistence of morphologically diverse lucerne under continuous stocking and intensive grazing

Abstract

Grazing tolerance of lucerne is an attribute of growing interest worldwide. A breeding method relying on direct selection for persistence under continuous stocking and intensive grazing was here applied to germplasm first selected for the presence of positive traits, hoping to combine an effective selection procedure with the advantages of a favourable morphology. Progenies belonging to diversified plant ‘models’, previously synthesised, were evaluated under sheep grazing in 2 trials in northern Italy with reference to a tolerant and an intolerant check variety. The reliability of the assessment according to recommended standard procedures was ensured by the recorded difference in persistence of the 2 checks. Two semi-prostrate models proved very tolerant to grazing, and another, semi-erect model proved partly tolerant. When the spring biomass was measured before grazing imposition, the grazing-tolerant models showed lower values than the other models and the checks, but they featured the highest biomass after the grazing seasons in both trials, owing to their outstanding tolerance. The best germplasm will be used to develop grazing-tolerant varieties. The most tolerant models displayed a long cold-season rest. Nonetheless, they could also be of interest in areas with relatively mild winters, for instance in mixtures with winter-active annual species, or in intercropping situations. Based on reported evidence, germplasm selected under intensive grazing and continuous stocking is expected to retain its tolerance under more rational management systems.