International principles and standards for native seeds in ecological restoration

The growing demand for native seeds in ecological restoration and rehabilitation, whether for mining, forest, or ecosystem restoration, has resulted in a major global industry in the sourcing, supply, and sale of native seeds. However, there are no international guidance documents for ensuring that native seeds have the same standards of quality assurance that are regular practice in the crop and horticultural industries. Using the International Principles and Standards for the Practice of Ecological Restoration as a foundation document, we provide for the first time a synthesis of general practices in the native seed supply chain to derive the Principles and Standards for Native Seeds in Ecological Restoration (“Standards”). These practices and the underpinning science provide the basis for developing quality measures and guidance statements that are adaptable at the local, biome, or national scale. Importantly, these Standards define what is considered native seed in ecological restoration and highlight the differences between native seeds versus seeds of improved genetics. Seed testing approaches are provided within a logical framework that outline the many different dormancy states in native seed that can confound restoration outcomes. A “pro‐forma” template for a production label is included as a practical tool that can be customized for local needs and to standardize reporting to end‐users on the level of seed quality and germinability to be expected in a native seed batch. These Standards are not intended to be mandatory; however, the guidance statements provide the foundation upon which regulatory approaches can be developed by constituencies and jurisdictions.     

A comparative study of seed yield parameters in Arabidopsis thaliana mutants and transgenics

Because seed yield is the major factor determining the commercial success of grain crop cultivars, there is a large interest to obtain more understanding of the genetic factors underlying this trait. Despite many studies, mainly in the model plant Arabidopsis thaliana, have reported transgenes and mutants with effects on seed number and/or seed size, knowledge about seed yield parameters remains fragmented. This study investigated the effect of 46 genes, either in gain- and/or loss-of-function situations, with a total of 64 Arabidopsis lines being examined for seed phenotypes such as seed size, seed number per silique, number of inflorescences, number of branches on the main inflorescence and number of siliques. Sixteen of the 46 genes, examined in 14 Arabidopsis lines, were reported earlier to directly affect in seed size and/or seed number or to indirectly affect seed yield by their involvement in biomass production. Other genes involved in vegetative growth, flower or inflorescence development or cell division were hypothesized to potentially affect the final seed size and seed number. Analysis of this comprehensive data set shows that of the 14 lines previously described to be affected in seed size or seed number, only nine showed a comparable effect. Overall, this study provides the community with a useful resource for identifying genes with effects on seed yield and candidate genes underlying seed QTL. In addition, this study highlights the need for more thorough analysis of genes affecting seed yield.     

Foreword: International Standards for Native Seeds in Ecological Restoration

Restoration practitioners must increasingly incorporate seed procurement models and seed use planning early in project development, despite insufficient guidance about what are reasonable expectations for the sourcing and use of native seeds. This special issue presents a series of articles examining each key step in the native seed supply chain, and provides a framework for the “standards” that need to be applied to native seed batches if the native seed supply chain is to achieve the levels of reliability and transparency required. These Standards provide seed buyers, end users, and funding bodies with a level of confidence and reliability in the sourcing of quality native seeds, and a pathway toward global best practice in native seed use.     

Seed Rain in High-Altitude Restoration Plots in Switzerland

Seed rain was studied in restoration plots installed in 1985 and 1987, respectively, on an alpine downhill ski run at circa 2,500 m above sea level. The study was initiated in late autumn 1996 and completed in autumn 1998; it included temporal and spatial variation in density per m², as well as alpha diversity (species richness), and species composition of the seed rain versus that of the resident vegetation. This is the first report on post-restoration monitoring of seed rain above the timberline. Seed rain density and alpha diversity varied seasonally, with the first peak occurring immediately after spring snowmelt and the second in early autumn. The density of seed rain varied between plots and years (1,528–1,778 seeds per m² in one plot [RPF] versus 1,096–3,557 seeds per m² in another plot [RPG]). Total species number per plot was nearly twice as high in RPF as in RPG in both study years. Seed rain totaled 18 species; all but one represented either transplants introduced in restoration or colonizers established in the plots soon after restoration. Distribution of species in seed rain was largely asymmetric and only a few species provided substantial contributions. Composition of species and their respective contribution to seed rain differed between plots and was clearly influenced by performance of some species used in restoration as transplants; together they provided as much as 51% of the total seed rain. The results of the study demonstrate that restoration enhanced increase of species richness as well as seed rain in situ.     

Seed dynamics of resprouting shrubs in grassy woodlands: Seed rain,predators and seed loss constrain recruitment potential

Abstract Measuring the fate of seeds between seed production and seedling establishment is critical in understanding mechanisms of recruitment limitation of plants. We examined seed fates to better understand the recruitment dynamics of four resprouting shrubs from two families (Fabaceae and Epacridaceae) in temperate grassy woodlands. We tested whether: (i) pre‐dispersal seed predation affected seed rain; (ii) post‐dispersal seed predation limited seed bank accumulation; (iii) the size of the seed bank was related to seed size; and (iv) viable seeds accumulated in the soil after seed rain. There was a distinct difference in seed production per plant between plant families with the legumes producing significantly more seeds per individual than the epacrids. Seed viability ranged from 43% to 81% and all viable had seed or fruit coat dormancy broken by heat or scarification. Pre‐dispersal predation by Lepidopteran larvae removed a large proportion of seed from the legume seed rain but not the epacrids. Four species of ants (Notoncus ectatomoides, Pheidole sp., Rhytidoponera tasmaniensis and Iridomyrmex purpureus) were major post‐dispersal seed removers. Overall, a greater percentage of Hardenbergia (38%) and Pultenaea (59%) seeds were removed than the fleshy fruits of Lissanthe (14%) or Melichrus (0%). Seed bank sizes were small (<15 seeds m^?2) relative to the seed rain and no significant accumulation of seed in the soil was detected. Lack of accumulation was attributed to seed predation as seed decay was considered unlikely and no seed germination was observed in our study sites. Our study suggests that seed predation is a key factor contributing to seed‐limited recruitment in grassy woodland shrubs by reducing the number of seeds stored in the soil.     

Lack of adequate seed supply is a major bottleneck for effective ecosystem restoration in Chile: friendly amendment to Bannister et al. (2018)

We argue that the need for a quality seed supply chain is a major bottleneck for the restoration of Chile's native ecosystems, thus supplementing the list of bottlenecks proposed by Bannister et al. in 2018. Specifically, there is a need for defining seed transfer zones, developing standards and capacities for properly collecting and storing seeds, reducing information gaps on seed physiology and longevity, and implementing an efficient seed supply chain with certification of seed origin and quality. Without such capacities, countries are unlikely to meet their restoration commitments. Although we focus on bottlenecks in Chile, the issues we raise are relevant to other countries and thus the global agenda for ecological restoration.     

壳斗科三种植物种子大小对昆虫寄生及种子存活率的影响

种子内的寄生昆虫可以严重影响种子的发育、损害种子活力。种子足余策略理论认为大种子有利于抵御和适应昆虫寄生取食,但动物最优觅食理论推测,大种子更易遭受昆虫寄生。为对这两种对立观点进行验证,本实验以青冈、苦槠和麻栎各2个种群的种子为材料,对昆虫寄生与完好种子间的体积和萌发率进行比较,并对寄生种子萌发率与种子体积的关系进行了分析。结果显示:(1)在6个种群的种子中,只有松阳麻栎和青冈种群的寄生种子体积大于完好种子,其余4个种群的寄生种子体积小于完好种子,但这种差异不显著;(2)所有寄生种子的整体萌发率(18%)显著低于完好种子(45.66%)(P<0.001),在不同种群内,寄生种子的萌发率也分别显著低于完好种子。(3)比较同种植物体积差异显著的寄生种子的萌发率发现,大种子总比小种子具有更高的萌发率,但差异不显著;在不同植物的寄生种子间比较时,体积最大的麻栎种子萌发率显著高于体积较小的青冈和苦槠种子。研究结果表明,象虫在种子上产卵时对大种子没有选择偏好,在昆虫寄生取食严重损害种子活力的压力下,大种子比小种子具有更强的耐受力。     

江西三清山濒危植物天女花种子特性研究

研究了江西三清山天女花种子的特性,结果表明：(1)三清山天女花种群种子雨自10月初开始,10月末结束,10月中旬强度达高峰,玉京峰地段天女花种子雨持续时间较短;(2)产种率受母树冠层影响,即上层>中层>下层;种子败育率高(49.4%～100.0%);(3)主成分分析表明,乔木层盖度、大气湿度、光照因子以及土壤含水量对天女花种子发育产生显著影响。