Agriculture and Life Sciences Division, Lincoln University, Lincoln, Christchurch, Canterbury, New Zealand.
PGG-Wrightson, Christchurch, Canterbury, New Zealand.
PLoS One. 2018 Apr 4;13(4):e0194977. doi: 10.1371/journal.pone.0194977. eCollection 2018.
Lolium perenne L. (perennial ryegrass) is the most important pasture grass species in temperate regions of the world. However, its growth is restricted in summer dry environments. Germplasm screening can be used to identify accessions or individual plants for incorporation into breeding programs for drought tolerance. We selected nine perennial ryegrass accessions from different global origins and from a range of climatic and environmental conditions. In addition, the perennial ryegrass cultivar 'Grasslands Impact' was chosen as a reference. The accessions were grown for 360 days in a controlled environment through six consecutive drought stress and recovery cycles. We observed intraspecific differences in drought stress responsiveness for shoot biomass and survival from the third stress cycle. An accession from Norway had 50% more shoot dry matter than the next best-performing accession after six drought cycles. Compared with the reference cultivar 'Grasslands Impact', shoot dry matter of the accession from Norway was more than seven times higher after six drought cycles, indicating superior performance of this ecotype under drought stress. Drought tolerance was characterized by osmotic adjustment and higher relative leaf water content at low soil moisture levels. Furthermore, the findings of this study identify solute potential as an early predictor of drought stress tolerance. These intraspecific differences can be used in breeding programs for the development of drought-tolerant perennial ryegrass cultivars.
多年生黑麦草（Lolium perenne L.）是世界温带地区最重要的牧草之一。然而，它的生长受到夏季干旱环境的限制。种质筛选可用于鉴定具有耐旱性的品系或个体植物，将其纳入到育种计划中。我们从不同的全球起源和广泛的气候与环境条件中选择了九个多年生黑麦草品系。此外，还选择了多年生黑麦草品种“草原影响”作为参考。这些品系在受控环境中生长了 360 天，经历了六个连续的干旱胁迫和恢复周期。我们观察到从第三个胁迫周期开始，在地上生物量和存活率方面存在种内对干旱胁迫的响应差异。经过六个干旱周期后，来自挪威的一个品系的地上干物质比表现第二好的品系多 50%。与参考品种“草原影响”相比，来自挪威的品系在经过六个干旱周期后，地上干物质的含量高出七倍以上，表明该生态型在干旱胁迫下具有更好的表现。耐旱性的特征是在低土壤水分水平下具有渗透调节和更高的相对叶片含水量。此外，本研究的结果表明，溶质势可以作为干旱胁迫耐受性的早期预测指标。这些种内差异可用于培育耐旱性多年生黑麦草品种的育种计划中。
