Optimal and synchronized germination of Robinia pseudoacacia,Acacia dealbata and other woody Fabaceae using a handheld rotary tool:concomitant reduction of physical and physiological seed dormancy

The Fabaceae(legume family) is one of the largest families of plants with a worldwide distribution and a major role in agriculture and in agroforestry.A hard seed coat impermeable to water is a typical feature of several species.Physical dormancy delays and reduces germination so that mechanical,physical and chemical scarification methods have been classically used to break seed dormancy of many species.We evaluate the effectiveness of a methodology to scarify seeds of several woody Fabaceae of ecological and economical importance,including Robinia pseudoacacia and Acacia dealbata and the shrubs Cytisus scoparius,C.multiflorus and Ulex europaeus.We describe the optimized use of a handheld rotary tool(HRT),and compare its effectiveness with other scarification methods reported to break dormancy such as boiling or dry heating.Total germination and/or speed of germination were enhanced after the application of the HRT,with germination percentages significantly higher than those achieved by other methods of scarification.Based on a thorough literature review,a mode of action for the HRT is suggested which could operate by breaking the physical and physiological dormancy of treated seeds through thecombined action of coat abrasion and moderate temperatures.Considering these results,we recommend the application of this rapid,effective,low-cost and highly reproducible HRT method to break seed dormancy and enhance germination of these species and others with similar dormancy constraints.

海岸沙地肉质入侵植物对微生物群落功能与结构变化的影响

海岸沙地提供了诸多宝贵的生态系统服务,例如耕地保护、水分供应和生物多样性保护,因此海岸沙地代表了重要的栖息地保护区。因为海岸沙地环境恶劣、水资源匮乏、养分贫瘠,所以土壤微生物群落对维持植物多样性至关重要。就海岸沙地的生态系统保护而言,外来入侵植物是主要威胁。本文探讨了沿海地区入侵植物食用日中花(Carpobrotus edulis)对细菌群落功能及结构的各种影响。沙地中土壤有机质含量低,微生物活性有限,所以沙地是一种颇具挑战性的底物。因此,在评估食用日中花对生态系统的影响之前需要对细菌提取进行优化,并开展功能评估。本文首先从群落水平生理特征(CLPP)的角度,比较了采用不同土壤储量、样品量、提取液等12种提取方法对沙地群落功能活性的影响,然后又探讨了食用日中花入侵的沙地菌落功能(利用Biolog Ecoplates)与结构变化(利用PCR-DGGE)。血细胞计数发现盐溶液持续增殖了细菌细胞(P≤0.001)。主成分分析(PCA)结果显示,在有限时间框架(0–24 h)内,碳底物消耗没有显著变化。通过对比天然区与非天然区(种间)及天然区(种内)之间食用日中花入侵后的变化,发现了一种与众不同的碳底物利用模式,食用日中花入侵对群落功能的影响因地而异,而与之相辅相成的是,PCR-DGGE结果表明原沙地的菌落结构不同于食用日中花入侵后沙地的菌落结构。