Limited persistence of perennial ryegrass (Lolium perenne L.) in dairy pastures is a significant issue in parts of New Zealand. The contribution of plant genetic background to this problem is not well understood. Temporal changes were investigated in genotypic and phenotypic composition of two perennial ryegrass cultivars (Nui SE and Alto AR37, older and newer cultivars respectively) sown as fields plots at three locations. Samples from survivor populations collected annually over 6 years from each location were established in a field nursery, analysed by simple sequence repeat (SSR) markers and assessed for vigour, leaf morphology and tiller number. SSR‐based estimates of the statistic G′_ST indicated no significant (p > .05) genetic differentiation between survivor populations and plants grown from remnant seed (ex‐seed) after 5 years, and no significant change (p > .05) in within‐population genetic diversity for either cultivar at any location. SSR analysis of endophytic fungus (Epichloë festucae var. lolii) type revealed only limited ingress of off‐type ryegrass volunteers into plots at two locations. Vigour scores of survivor plants were not significantly (p > .05) different among plants collected from different locations and ex‐seed plants. Leaves on ex‐seed plants were longer (p < .001) than those on the survivor plants after four but not 6 years and may reflect a short‐term response to climatic conditions experienced in the field nursery. Our results suggest that the reported poor ryegrass persistence is not driven by changes in population genetic structure and that the sown cultivars survived and remained true to type.

中文翻译：

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牧草年龄对多年生黑麦草基因型和表型的影响

奶牛牧场中多年生黑麦草（黑麦草perenne L.）的持久性有限是新西兰部分地区的重要问题。植物遗传背景对这一问题的贡献尚不十分清楚。研究了在三个地点作为田地播种的两个多年生黑麦草品种（Nui SE和Alto AR37，分别为旧和新品种）的基因型和表型组成的时间变化。在野外苗圃中建立从每年从每个位置收集的6年以上幸存者种群的样本，通过简单序列重复（SSR）标记进行分析，并评估其活力，叶片形态和分till数。的统计信息的基于SSR-估计G' _ST表明没有显著（p > .05）5年后，幸存者种群与从残留种子（种子）生长出来的植物之间的遗传分化 ，任何位置上任一品种的种群内遗传多样性均无显着变化（p > .05）。内生真菌的SSR分析（稻香festucae变种lolii）类型在两个位置处显示断型黑麦草志愿者只有有限的进入到地块。 在不同地点收集的植物和种子植物中，存活植物的活力得分没有显着差异（p > .05）。种子植物上的叶子更长（p （<0.001），而不是四年但不是六年后的幸存植物，可能反映了对田间苗圃的气候条件的短期反应。我们的结果表明，所报告的不良黑麦草持久性不是由种群遗传结构的变化驱动的，播种的品种存活下来并保持真实的类型。