Centre for Environmental Management, Faculty of Science and Technology, Federation University Australia, Mount Helen, Victoria, Australia.
Centre for Plant Science, Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Toowoomba, Queensland, Australia.
PLoS One. 2018 Jul 5;13(7):e0199491. doi: 10.1371/journal.pone.0199491. eCollection 2018.
Nassella trichotoma (Nees) Hack. ex Arechav. (Serrated tussock) is an aggressive globally significant weed to agricultural and natural ecosystems. Herbicide resistant populations of this C3 perennial weed have emerged, increasing the need for effective wide-scale cultural control strategies. A thorough seed ecology study on two spatially distinct populations of N. trichotoma was conducted on this weed to identify differences in important environmental factors (drought, salinity, alternating temperature, photoperiod, burial depth, soil pH, artificial seed aging, and radiant heat) which influence seed dormancy. Seeds were collected from two spatially distinct populations; Gnarwarre (38 O 9' 8.892'' S, 144 O 7' 38.784'' E) and Ingliston (37O 40' 4.44'' S, 144 O 18' 39.24'' E) in December 2016 and February 2017, respectively. Twenty sterilized seeds were placed into Petri dishes lined with a single Whatman® No. 10 filter paper dampened with the relevant treatments solution and then incubated under the identified optimal alternating temperature and photoperiod regime of 25°C/15°C (light/dark, 12h/12h). For the burial depth treatment, 20 seeds were placed into plastic containers (10cm in diameter and 6cm in depth) and buried to the relevant depth in sterilized soil. All trials were monitored for 30 days and germination was indicated by 5mm exposure of the radicle and emergence was indicated by the exposure of the cotyledon. Each treatment had three replicates for each population, and each treatment was repeated to give a total of six replicates per treatment, per population. Nassella trichotoma was identified to be non-photoblastic, with germination (%) being similar under alternating light and dark and complete darkness conditions. With an increase of osmotic potential and salinity, a significant decline in germination was observed. There was no effect of pH on germination. Exposure to a radiant heat of 120°C for 9 minutes resulted in the lowest germination in the Ingliston population (33%) and the Gnarwarre population (60%). In the burial depth treatment, the Ingliston population and the Gnarwarre population had highest emergence of 75% and 80%, respectively at a depth of 1cm. Variation between the two populations was observed for the burial depth treatments; Gnarwarre had greater emergence than Ingliston from the 4cm burial depth, while Ingliston had greater emergence at the soil surface than Gnarwarre. The Gnarwarre population had greater overall germination than Ingliston, which could be attributed to the greater seed mass (0.86mg compared to 0.76mg, respectively). This study identifies that spatial variations in N. trichotoma's seed ecology are present between spatially distinct populations.
Nassella trichotoma（Nees）Hack.ex Arechav.（锯齿状丛生）是一种对农业和自然生态系统具有全球重要意义的侵略性杂草。这种 C3 多年生杂草的抗除草剂种群已经出现，这增加了对有效广泛的文化控制策略的需求。对来自两个空间上不同种群的 Nassella trichotoma 进行了彻底的种子生态学研究，以确定影响种子休眠的重要环境因素（干旱、盐度、交替温度、光周期、埋藏深度、土壤 pH 值、人工种子老化和辐射热）的差异。种子分别于 2016 年 12 月和 2017 年 2 月从两个空间上不同的种群采集；Gnarwarre（38 O 9' 8.892'' S，144 O 7' 38.784'' E）和 Ingliston（37O 40' 4.44'' S，144 O 18' 39.24'' E）。将 20 颗消毒后的种子放入培养皿中，培养皿中铺有单层 Whatman®No.10 滤纸，用相关处理溶液浸湿，然后在确定的最佳交替温度和光周期条件下培养（25°C/15°C（光照/黑暗，12h/12h）。对于埋藏深度处理，将 20 颗种子放入直径 10cm、深度 6cm 的塑料容器中，并在消毒土壤中埋藏至相应深度。所有试验均监测 30 天，根的 5mm 暴露表示发芽，子叶的暴露表示萌发。每个种群的每个处理有 3 个重复，每个处理重复 6 次，每个种群重复 6 次。Nassella trichotoma 被鉴定为非光形态发生的，在交替光照和黑暗以及完全黑暗条件下，发芽率（%）相似。随着渗透压和盐度的增加，发芽率显著下降。pH 值对发芽率没有影响。暴露在 120°C 的辐射热下 9 分钟，导致 Ingliston 种群（33%）和 Gnarwarre 种群（60%）的发芽率最低。在埋藏深度处理中，Ingliston 种群和 Gnarwarre 种群的发芽率最高，分别为 75%和 80%，埋藏深度为 1cm。在埋藏深度处理中观察到两个种群之间的变化；Gnarwarre 从 4cm 的埋藏深度的发芽率高于 Ingliston，而 Ingliston 的发芽率高于 Gnarwarre 土壤表面。Gnarwarre 种群的总体发芽率高于 Ingliston，这可能归因于更大的种子质量（分别为 0.86mg 和 0.76mg）。这项研究表明，空间上不同种群的 Nassella trichotoma 种子生态学存在差异。
