PDF(Pubmed)
Abstract：
The restoration of succulent thicket (the semi-arid components of the Albany Subtropical Thicket biome endemic to South Africa) has largely focused on the reintroduction of Portulacaria afra L. Jacq-a leaf- and stem-succulent shrub-through the planting of unrooted cuttings directly into field sites. However, there has been inconsistent establishment and survival rates, with low rates potentially due to a range of factors (e.g., post-planting drought, frost or herbivory), including the poor condition of source material used. Here we test the effect of parent-plant and harvesting site on the root development of P. afra cuttings in a common garden experiment. Ten sites were selected along a ∼110 km transect, with cuttings harvested from five parent-plants per site. Leaf moisture content was determined for each parent-plant at the time of harvesting as a proxy for plant condition. Root development-percentage of rooted cuttings and mean root dry weight-was recorded for a subset of cuttings from each parent-plant after 35, 42, 48, 56, and 103 days after planting in a common garden setting. We found evidence for cutting root development (rooting percentage and root dry mass) to be strongly associated with harvesting site across all sampling days (p < 0.005 for all tests). These differences are likely a consequence of underlying physiological factors; this was supported by the significant but weak correlation (r 2 = 0.10-0.26) between the leaf moisture content of the parent-plant (at the time of harvesting) and dry root mass of the cuttings (at each of the sampling days). Our findings demonstrate that varying plant condition across sites can significantly influence root development during dry phases (i.e., intra- and inter-annual droughts) and that this may be a critical component that needs to be understood as part of any restoration programme. Further work is required to identify the environmental conditions that promote or impede root development in P. afra cuttings.
摘要：
肉质灌木丛（南非特有的奥尔巴尼亚热带灌木丛生物群落的半干旱组成部分）的恢复主要集中在通过直接种植无根插条的方式重新引入PortulacariaafraL.Jacq-一种叶子和茎-肉质灌木到田间。然而,建立和存活率不一致，低费率可能是由于一系列因素(例如，种植后的干旱，霜冻或食草动物)，包括所用原材料的不良状况。在这里，我们在普通的花园实验中测试了亲本植物和收获地点对P.afra插条根系发育的影响。沿着110公里的横断面选择了10个地点，每个站点从五个亲本植物收获的插条。在收获时确定每个亲本植物的叶片水分含量，以代替植物条件。在普通花园环境中种植后35、42、48、56和103天后，记录了来自每个亲本植物的一部分插条的根发育百分比和平均根干重。我们发现，在所有采样日（p<0.005对于所有测试）中，切割根发育（生根百分比和根干质量）与收获部位密切相关的证据。这些差异可能是潜在生理因素的结果；亲本植物的叶片水分含量（收获时）与插条的干根质量（在每个采样日）之间的显着但弱相关性（r2=0.10-0.26）支持了这一点。我们的发现表明，不同地点的植物条件可以显着影响干燥阶段的根系发育（即，年度内和年度间干旱），这可能是一个关键组成部分，需要理解为任何恢复计划的一部分。需要进一步的工作来确定促进或阻碍P.afra插条根系发育的环境条件。
