ABSTRACT

Combining several cultivars within species in seed mixtures is often advocated as a means for improving crop or pasture performance. Herbage accumulation (HA) of perennial ryegrass-white clover pastures sown with a single cultivar representing different functional types of perennial ryegrass was compared with the HA of cultivar mixtures over three years in two contrasting environments (Waikato, dryland; Canterbury, irrigated) under dairy cattle grazing. Functional types were: mid-season flowering diploid, late-season diploid, and late-season tetraploid. Mixture treatments (n = 4 at each site) included all binary combinations plus the three-way combination. Mixture HA and the mean HA of the constituent cultivars did not differ for any of the mixture combinations in either environment, apart from winter in Waikato where the mid-diploid plus tetraploid mix out-yielded the mean of the individual cultivars and tended to increase total annual HA. The total annual HA of the mixtures was between 1.0 and 2.3 t DM/ha/year less than the HA of the highest-yielding individual cultivar included in the mixture in six of the eight mixture-environment combinations. While some benefits of mixtures for controlling grazing outcomes were observed, sowing individual high-performing cultivars is a better overall strategy than mixing cultivars to cover a spectrum of traits.

摘要

通常提倡在种子混合物中将多个品种在物种内结合起来作为改善作物或牧场性能的一种手段。将代表不同功能类型多年生黑麦草的单一品种播种的多年生黑麦草-白三叶草牧场的草本积累 (HA) 与乳制品下两个对比环境（怀卡托，旱地；坎特伯雷，灌溉）在三年内与品种混合物的 HA 进行比较牛放牧。功能类型为：中季开花二倍体、晚季二倍体和晚季四倍体。混合处理 ( n  = 4 在每个站点）包括所有二元组合加上三路组合。除了怀卡托的冬季，中间二倍体加四倍体混合物的产量高于单个品种的平均值，并且趋向于增加总年度医管局。在八种混合环境组合中的六个中，混合物的年总 HA 比混合物中最高产单个品种的 HA 低 1.0 至 2.3 吨干物质/公顷/年。虽然观察到混合物在控制放牧结果方面的一些好处，但播种单个高性能品种是比混合品种覆盖一系列性状更好的整体策略。