Effect of cutting regime on the agronomic performance of two contrasting lines of Melilotus albus

Abstract

Two lines of Melilotus albus (Medik) of different maturity and morphological characteristics were subjected to 6 cutting regimes ranging from a single cut in March (2002) to 6 cuts between mid-October (2001) and March (2002). The yield of the late maturing, tall line, H11743 (B) was more than 13 t/ha of dry matter for the season, which was achieved with either 1 or 2 cuts. Dry matter production decreased as the number of cuts increased, with production reduced to 6 t/ha when it was cut every month between October and March inclusive. The early maturing, more prostrate genotype, Adela (E) was similarly affected by cutting regime; however, its production was lower, ranging between 4 and 6 t/ha for the season. Seed yields were not seriously affected in H11743 when it was cut until December, before allowing the plants to grow until maturity. Continuing to cut into January and February severely decreased seed yields. Seed yields for Adela were lower but followed a similar pattern to H11743. When Adela was cut every month from October until January or later it produced very little seed. Seedling regeneration closely followed seed yields, being highest (4000 seedlings/m2) with 2 cuts and being adequate (more than 2000 seedlings/m2) for both lines when the last cut was in December. Seed softened gradually over time after maturity in February, and from the end of August onwards the residual hard seed remained relatively stable at around 10% with no differences in seed softening rates between the 2 lines. The results suggest that if persistence is to be achieved, defoliation of annual Melilotus albus will have to be stopped around January or the grazing pressure will have to be substantially reduced to allow seed set and regeneration. The late maturing genotype produced more dry matter and regenerated better than the early type, regardless of cutting regime.