Effect of phenological stages on dry matter and quality components in lucerne

Lucerne (Medicago sativa L.) is widely grown in European countries under irrigated and under rainfed conditions. Herbage production and nutritive value are related to the phenological stage of the plants at harvest. Eight cultivars were evaluated under two harvest managements (early and normal harvest, 40% of tillers at green bud and at flowering, respectively) and in two environments in Italy (Lodi and Foggia). The experiments started in 1989 at Foggia and 1990 at Lodi. Three years harvests at each site were considered. Early harvest treatment reduced dry matter (DM) yield at both locations (11.3% at Foggia and 23.6% at Lodi), ground cover index at Lodi and increased leaf:stem ratios (24.6%) at Foggia. Differences in agronomic adaptation were found among cultivars. Crude protein (CP) contents at normal harvest were lower (5.0% in leaves and 8.7% in stems) than at early harvest. Percentages of neutral detergent fibre (NDF), acid detergent fibre (ADF) and lignin (ADL) in leaves were influenced by harvesting time. As a consequence of the large interaction (year x harvest treatment x cut x cultivar), no statistically significant variations were found among cultivars in qualitative parameters of the herbage. Treatment effects on herbage quality were more evident in leaves than in stems and their contents on ADF, ADL and NDF were related to the phenological stage. Changing harvest time is more for influencing herbage quality than effective breeding. (C) 1997 Elsevier Science B.V.