Effect of Cutting Frequency on the Change of Components in a Mixed Sward of Two Alfalfa Cultivars

[摘要] 1. An experiment was designed to investigate the effect of cutting frequency on the change of components in the alfalfa swards. Cv. Moapa (early, quick regrowth after cutting, erect type) and cv. Vernal (late, slow regrowth after cutting, prostrate type) were grown in pure and mixed swards at a density of 100 plants/m2. Two cutting schedules, 4 and 6 cuts per year, were imposed on these swards. Yield and plant number per unit area were examined at each cutting time. 2. Percentage of Vernal in the yield of the mixed swards decreased as cutting schedules advanced. The rate of decrease was greater in the 6-cut sward than in the 4-cut sward (Fig. 1). 3. Plant numbers per unit area reduced as the cutting schedules advanced both in the pure and mixed swards. The rate of reduction was much higher in the case of 6 cuts than in the case of 4 cuts (Fig. 2). 4. The reduction in plant numbers in the mixed swards was mainly due to the reduction of the plants of Vernal (Fig. 2). The surviving rate of Vernal in the mixed swards was lower than that in the pure swards, and the surviving rate of Moapa in the mixed swards was higher than in the pure swards (Fig. 3). 5. The yield of individual plant of Moapa in the mixed swards was greater than that of Vernal at every cutting time (Figs. 4 and 5). 6. It was inferred from these results that an alfalfa sward would eventually shift to a sward in which late type plants were less in number than in the original sward, and that the shift would probably be accelerated by increased cutting frequency.

[学科分类] 农业科学（综合）