Evans D R, Hill J, Williams T A, Rhodes I
Welsh Plant Breeding Station, Plas Gogerddan, SY23 3EB, Aberystwyth, Dyfed, U.K.
Oecologia. 1985 Jul;66(4):536-539. doi: 10.1007/BF00379346.
Yields from five white clover/perennial ryegrass mixtures, each based on coexisting components, were compared with those produced by ten mixtures whose constituents had no previous history of coexistence. The former group consisted of five paired clover/ryegrass populations, four collected from natural pastures and one from a sown pasture, whilst the latter group comprised the same five clover populations grown in turn with each of two ryegrass companions.In the first harvest year, when artificial fertilizer plus soil mineralization supplied most of the nitrogen to this experiment, the grasses were generally favoured at the expense of the clovers. Although those mixtures based on coexisting populations had significantly lower yields the clover within these mixtures made a significantly higher contribution to their productivity. This advantage was retained into the second harvest year when it was accompanied by a correlated response in the grasses, which by then may have become dependent upon the clover for their nitrogen supply. Consequently, by the end of the second harvest year those mixtures based on coexisting populations yielded over 20% more on average, due mainly to improved early season growth. Despite considerable differences in productivity, all five clover populations gave their highest yields when grown with their matching grass.
对五种基于共存成分的白三叶草/多年生黑麦草混合物的产量，与十种成分此前没有共存历史的混合物的产量进行了比较。前一组由五对白三叶草/黑麦草种群组成，四个采集自天然牧场，一个采集自人工播种牧场，而后一组由相同的五个三叶草种群分别与两种黑麦草伴生品种轮流种植组成。在第一个收获年，当人工肥料加上土壤矿化作用为该试验提供了大部分氮素时，总体上禾本科牧草受益，白三叶草受损。虽然基于共存种群的混合物产量显著较低，但这些混合物中的白三叶草对其生产力的贡献显著更高。这种优势一直保持到第二个收获年，此时禾本科牧草也有相应反应，到那时它们可能已依赖白三叶草提供氮素。因此，到第二个收获年结束时，基于共存种群的混合物平均产量高出20%以上，这主要归功于生长季早期生长的改善。尽管生产力存在相当大的差异，但所有五个白三叶草种群与相匹配的禾本科牧草一起种植时产量最高。
