Influence of height at cutting on dry matter yield of red clover (Trifolium pratense L.). I. First season

Horacio López T. 1, Mario Silva G.2 y Alejandra Pascual V.3

During 1983/84, at the La Platina Experimental Station (33º34' lat. S, 70º38' long. W; 625 m.o.s.I.), INIA, Santiago, the effect of height at cutting on red clover (Quiñequeli cv.), was evaluated. The pasture was sown in May 1984, at arate of 20 kg/ha of inoculated seed and fertilized with 53.4 kg P/ha and 16 kg N/ha. A complete factorial of 3 x 3 x 3 (cuts at 40, 50 and 60 cm height, in all combinations), in randomized blocks, with three replications was used. Plot size was 6 x 2 m. Results were analized for net growth rate (TeN), net assimilation rate (TAN) and dry matter yield, expressed as standing herbage (FITOP), photosynthesizing herbage (FITOF) and weed herbage (FITOMAL). Net growth rate increased as height at cutting increased, although as season went on and due to higher temperatures and radiation, the relative increment of respiration rate was higher than photosynthesis, disminishing this parameter. Net assimilation rate showed an inverse relationship, and the most efficient treatments were those cut at a lower height. Weed herbage was low, so that standing and photosynthesizing herbage were very similar. In both cases, there were significatives differences (P < 0.05) in the three cuts, with lower yields for the treatments cut at less height. The treatment cut permanently at a height of 60 cm, yielded 4.5 ton D.M./ha more, in photosynthesizing herbage, than the treatment cut permanently at 40 cm (P < 0.05). Finally, in a forth cut, the effect of treatments on residual growth of the pasture was analized.

1 Estación Experimental La Platina (INlA), CasilIa 439, Correo 3, Santiago, Chile.
2 Asesor Area Producción Animal, INIA y Profesor U. de C-hile, Fac. Ciencias Agrarias y Forestales, Ese. de Agronomía, Depto Prod. Animal, Casilla 1004, Santiago, Chile.
3 Rucalhue 1739, Las Condes, Chile.