Seed Dispersal Research Articles

Seed dispersal mechanism of Erythronium japonicum in Northeast China

Seed dispersal is recognized as a very important stage in the life history of plant sexual reproduction. Seed dispersal directly determines whether plant seeds can reach the favorable germination sites and ensure the successful germination of seeds subsequently which is the first stage of plant seedling establishment. The final dispersal location of seeds with diplochory usually requires the joint decision of two stages including primary seed dispersal and secondary seed dispersal. The seed dispersal of Erythronium japonicum by ants was investigated in three different habitats. The effect of seed maturity on seed fate and the effects of elaiosome removal and water immersion on seed dispersal in the wild were studied. The results showed that eight species of ants were involved in E. japonicum seed dispersal in the three habitats. The seed handling efficiency and the number of seeds transported by ants were affected by the composition of ant community and the size of ant population. There was a strong correlation between the seed dispersal distance and the body length of ants. Small ants may have expanded their foraging range through fierce struggle. The immature E. japonicum seeds will also be handling by ants, indicating that the seed elaiosome mature prior to seeds. We found elaiosome plays an important role in the dispersal of E. japonicum seeds, and it can also be used as a “handle point” for smaller ants. The components of elaiosome are not easily soluble in water, which can avoid the loss of the attraction of E. japonicum seeds to ants due to the rain during the seed dispersal process.

Highlighted articles for March 2022.

Highlighted articles for March 2022.

Reproductive and leaf morpho-anatomy of the Australian alpine podocarp and comparison with the Australis subclade

ABSTRACT Podocarpus lawrencei (Mountain Plum Pine) is an endemic Australian conifer species and morphologically, ecologically, and genetically close to P. nivalis, P. gnidioides, P. totara, P. acutifolius, and P. laetus. The reproductive biology and seed cone morpho-anatomy of P. lawrencei and the Australis subclade is not well understood. This study describes the detailed reproductive morpho-anatomy of P. lawrencei and compares it with these related species of Australis subclade. Seed cone reproductive developmental stages, morpho-anatomical features of the seed cones and leaf were investigated using histology, light, and scanning electron microscopy. Seed cone initiates with a terminal bud in late July, and the reproductive cycle takes 1 or more than 1 year (12–16 months) to complete. The ovule is inverted and ovule inversion is present. The reproductive cycle of this group of podocarps takes more than 1 year to complete. The seed cone of P. lawrencei has a fused non-fleshy epimatium (green-brown seed) with a brightly coloured reddish receptaculum. The seed cone shows morphological and anatomical similarity with P. nivalis in particular and no significant morpho-anatomical difference with other Australis subclade species. The brightly coloured fleshy cones of Australis subclade suggest frugivory and zoochory for dispersal of seeds. More extensive population genetic studies are required to evaluate the genetic structure, diversification, and historical biogeography of Australis subclade. This study provides a primary base from which to evaluate the genetic structure of all the species in this clade.

Spatial Distribution of Polyphenolic Compounds in Corn Grains (Zea mays L. var. Pioneer) Studied by Laser Confocal Microscopy and High-Resolution Mass Spectrometry.

Desirable changes in the biochemical composition of food plants is a key outcome of breeding strategies. The subsequent localization of nutritional phytochemicals in plant tissues gives important information regarding the extent of their synthesis across a tissue. We performed a detailed metabolomic analysis of phytochemical substances of grains from Zea mays L. (var. Pioneer) by tandem mass spectrometry and localization by confocal microscopy. We found that anthocyanins are located mainly in the aleurone layer of the grain. High-performance liquid chromatography in combination with ion trap tandem mass spectrometry revealed the presence of 56 compounds, including 30 polyphenols. This method allows for effective and rapid analysis of anthocyanins by plotting their distribution in seeds and grains of different plants. This approach will permit a more efficient screening of phenotypic varieties during food plant breeding.

Drivers of Ecological and Evolutionary Disruptions in the Seed Dispersal Process: Research Trends and Biases

As the sole opportunity for most plants to move, seed dispersal influences the biodiversity and functioning of plant communities. Global change drivers have the potential to disrupt seed dispersal processes, affecting plant communities and ecosystem functions. Even though much information is available on the effects of seed dispersal disruption (SDD), we still lack a comprehensive understanding of its main causes at a global scale, as well as the potential knowledge gaps derived from research biases. Here we present a systematic review of biotic and abiotic SDDs to ascertain the global change drivers addressed, dispersal modes impacted, plant processes affected, and spatial focus of existing research on this topic up-to-date. Although there are many modes of dispersal and global change drivers in temperate and tropical ecosystems worldwide, research efforts have predominantly addressed the effect of alien species for biotic seed dispersal in temperate systems and oceanic islands as well as how defaunation of bird or mammal dispersers has affected seed removal in the Neotropics. SDD studies were also biased toward forest ecosystems, with few in shrublands or grasslands. Finally, the effects of climate change, ecological consequences at the whole community level, and evolutionary changes were largely unrepresented in SDD studies. These trends are likely due to a combination of true geographic and ecological patterns in seed dispersal and global change and bias in research focus. We conclude that increased research investment in the less-studied systems and a better understanding of potential synergies and feedback between multiple global change drivers will be important to forecast the threats to plant biodiversity and those ecosystem functions derived from seed dispersal in the Anthropocene.

Accurate paternal and maternal immigrant gene flow analysis over three mast years detects relative levels of gametic heterogeneity components in a natural population of Abies firma

ABSTRACT To consider and evaluate the effectiveness of strategies for genetic variation preservation of populations of targeted species, it is important to examine which components of gametic heterogeneity have a greater impact on the genetic diversity of the next generation. Here, we investigated gene dispersal patterns in dispersed seeds and the relative levels of genetic diversity and differentiation for within-population and immigrant groups of both paternal and maternal gametes in a natural population of Abies firma during three reproductive events (mast years). Accurate paternity and maternity analyses, genotyping 630 seeds (1,260 tissue samples) and 331 candidate adult trees in total, were performed by analyzing 12 nuclear microsatellite loci of both diploid biparental embryos and haploid maternal megagametophytes. We found that 53.7% of paternal gametes and 15.3% of maternal gametes were of immigrant origin, indicating substantial gene flow for both parentages. Of the three components of gametic heterogeneity (immigration, parentage, and year) of the seeds, differences in gene-flow categories (within-population vs. immigrant gametes) showed the largest variation (mean F ST = 0.030). Differences in gametes between paternal and maternal parentages had the second-largest variation (0.012), and variation among three mast years was the lowest (0.006). Diverse immigrant gametes derived from nearby populations at the landscape level and the differences in paternal and maternal reproductions of adult trees are considered to make the main contributions to the overall genetic variability of dispersed seeds of A. firma.

The Relationships of Habitat Conditions, Height Level, and Geographical Position with Fruit and Seed Traits in Populations of Invasive Vine Echinocystis lobata (Cucurbitaceae) in Central and Eastern Europe

In climbing plants, fruits can be formed at different heights, depending on the height of external support. However, the effect of height on fruit and seed traits in invasive vines of Cucurbitaceae has not been intensively studied so far. In Europe, Echinocystis lobata, a North American member of Cucurbitaceae, is considered one of the most abundant invasive alien plants spreading in natural riparian forests, thickets, and tall herbs, whereas it is a rare species in urban woodlands. In this study, we tested the variability of selected fruit and seed traits of E. lobata in connection with habitat origin (natural, semi-natural, and anthropogenic), habitat type (using the EUNIS habitat classification), height (the distance between the fruit and the ground), and geographical position. The study was conducted in 2018 in 65 sites located in Latvia, Lithuania, Poland, and Slovakia. In each study site, a random sample of 10 fresh mature fruits of E. lobata was collected from subsequent 0.50 m intervals of height. The length, the width, and the weight of the fresh fruits, as well as the total number of seeds and number of undeveloped seeds per fruit, were examined. Moreover, the well-developed seeds from selected study sites were weighed. The statistical analysis showed the significant effect of habitat origin, habitat type, and height on most of the studied fruit and seed traits. The largest range of height (from 0.00 to 4.00 m) was observed in two types of habitats (F—heathland, scrub, and tundra; and G—woodland, forest, and other wooded land). The total number of seeds per fruit was positively correlated with the length, width, and weight of the fresh fruits. The fruits were a little heavier and bigger in natural habitats located in the northeast of the study area. The distribution of fruits at different heights may contribute to better dispersal of seeds by animals and wind, and may also better protect the seeds from being eaten by granivorous animals. The defence against seed-eating animals is expected to be stronger in semi-natural habitats, as well as on banks and shores of inland surface waters, where the seed production is the highest. The influence of seed traits on seed germination and seedling survival in various habitats and their importance in the invasiveness of E. lobata require further study.

Effects of temperature on seed dormancy and germination of the coastal dune plant Viola grayi: germination phenology and responses to winter warming.

In temperate sand dunes, rising air temperature from climate change could not only further elevate surface soil temperatures during summers, but also drastically change the range of soil temperatures in other seasons. Winter warming may shift the timing of seed germination of dune species that require cold stratification for dormancy release. We assessed the effects of temperature on dormancy and germination of Viola grayi seeds and evaluated whether winter warming could affect its germination phenology by conducting germination experiments and analyzing soil temperature data in cold and warm winters. Viola grayi seeds were dormant when dispersed in spring. One-month moist-chilling treatment (4°C) effectively released dormancy, while short, intermittent lower temperatures (alternating 20°/5°C) did not. Continuous higher temperatures induced secondary dormancy in nondormant seeds. During a cold, snowy winter, the surface soil temperatures of the sand dune remained at 0°-2°C for approximately 1 month owing to the accumulated snow, while the period of such stable low soil temperatures was much shorter during a warm, less-snowy winter, and the highest soil temperature reached 20°-25°C. These results suggest that dispersed seeds germinate in the following spring after winter chilling, but they may remain dormant after warm winters. With winter warming, seed dormancy of V. grayi seeds could be prolonged and the associated germination delayed. Assessing the minimum requirements for dormancy release and the potential to form persistent soil seed banks is important for judging the necessity and urgency of conservation efforts for temperate dune species.

Seed dispersal by spider monkeys in logged and unlogged sites in the Calakmul tropical humid forest, Mexico / Dispersión de semillas por monos araña en sitios talados y no talados en el bosque húmedo tropical de Calakmul, México

Seed dispersal by animals can be negatively affected by selective logging, but effects such changes in critical food resource, quality of food resources and food availability on seed dispersal and seedling recruitment, remains poorly understood. We investigated how selective logging, impacts the quantity of seed dispersal, focusing on highly frugivorous primate Ateles geoffroyi yucatanensis in Calakmul, Mexico. We assessed whether seed dispersal by the spider monkey differs between a logged and an unlogged site in the Calakmul tropical humid forest, Mexico. We recorded seeds in monkey faeces, including those deposited in latrines under sleeping trees (aggregated seed dispersal) and those dispersed across the forest (scattered seed dispersal) during a 5-mo period. The use of sleeping tree was similar in both forest conditions, averaging (± SD) 4.5 ± 4.3 weeks. They deposited 15,853 seeds (1–35 mm in length) from 20 tree species under sleeping trees, but seed abundance was 2.2 times higher in unlogged forests. Scattered seed dispersal (997 seeds from nine species) followed the opposite pattern, with 2.3 times more seeds in logged forests. The number of seeds and species per faecal sample did not differ between forest types, averaging 9.4 ± 20.2 seeds from 1.0 ± 0.8 seed species. Most (95%) scatter-dispersed seeds were undamaged in both forest types. These findings suggest that primate quantity seed dispersal is not limited in logged forests, potentially contributing to the recovery of these managed forests.

Lost mutualisms: Seed dispersal by Sumatran rhinos, the world’s most threatened megafauna

AbstractDiverse assemblages of seed‐dispersing megafauna once existed in Asian rainforests, but are now almost solely represented by elephants. Asia's rhinos persist in remnant, ecologically extinct populations and the most threatened of these is the Sumatran rhino, Dicerorhinus sumatrensis. To understand the seed dispersal role of Sumatran rhinos, we consolidated information on fruit consumption, seed dispersal, and fruit traits from a 2‐month field study (Sumatra), local ecological knowledge (Peninsular Malaysia), and published and unpublished accounts. We evaluated differences between the taxa and traits of fruits dispersed by rhinos and elephants, and identified other dispersers of megafaunal‐syndrome fruits that were rhino‐dispersed. At least 79 plant species were dispersed by rhinos: overstorey plants (trees and climbers; 78% of species) had large, usually “mammal‐colored,” fruits and seeds, and were mainly drupes and berries; 61% of these were megafaunal‐syndrome fruits (>4 cm wide). Understorey plants (herbs, shrubs, and small trees) had small, often capsular, fruits and seeds that are potentially dispersed following the “foliage‐is‐the‐fruit” hypothesis. Rhinos were the only known disperser for 35% of the megafaunal‐fruit genera. The highest dispersal overlap shown was with elephants: fruits dispersed by rhinos tended to be capsular and were smaller than fruits dispersed by both elephants and rhinos. Given these findings and the different foraging and ranging behavior of Sumatran rhinos and elephants, we suggest that these megafauna had important differences in their seed dispersal roles. Asian rainforests have, therefore, lost an important seed dispersal mutualist. Conservation efforts should aim to protect and restore the ecological function of these unique creatures.Abstract in Indonesian is available with online material.

The effects of defaunation on plants' capacity to track climate change.

Half of all plant species rely on animals to disperse their seeds. Seed dispersal interactions lost through defaunation and gained during novel community assembly influence whether plants can adapt to climate change through migration. We develop trait-based models to predict pairwise interactions and dispersal function for fleshy-fruited plants globally. Using interactions with introduced species as an observable proxy for interactions in future novel seed dispersal networks, we find strong potential to forecast their assembly and functioning. We conservatively estimate that mammal and bird defaunation has already reduced the capacity of plants to track climate change by 60% globally. This strong reduction in the ability of plants to adapt to climate change through range shifts shows a synergy between defaunation and climate change that undermines vegetation resilience.

Plant canopy may promote seed dispersal by wind

Seed dispersal has received much research attention. The plant canopy can intercept diaspores, but the effect of the plant canopy (the aboveground portion of a plant consisting of branches and leaves) on dispersal distance has not been explored empirically. To determine the effect of plant canopy on seed dispersal distance, a comparison of diaspores falling through open air and through plant canopy was made in a wind tunnel using three wind speeds and diaspores with various traits. Compared with diaspores falling through open air, the dispersal distance of diaspores falling through plant canopy was decreased or increased, depending on wind speed and diaspore traits. When falling through a plant canopy, dispersal distance of diaspores with thorns or those without appendages was promoted at low wind speed (2 m s−1), while that of diaspores with low wing loading (0.5 mg mm−2) and terminal velocity (2.5 m s−1) was promoted by relatively high (6 m s−1) wind speed. A plant canopy could increase seed dispersal distance, which may be due to the complicated updraft generated by canopy. The effect of maternal plants on seed dispersal regulates the distribution pattern and the species composition of the community.

Pollinators and seed dispersers of espinheira-santa (Monteverdia ilicifolia - Celastraceae), a Brazilian medicinal plant

Espinheira-santa (Monteverdia ilicifolia) is a native plant of Brazil widely used in folk medicine because it has several therapeutic properties. Regarding the pollination biology and seed dispersal of this species, there is no information available in the literature. In this study, pollinators and dispersers of M. ilicifolia were observed and identified, as well as the behavior of these biological agents during the period of flowering and fruiting. In addition, the frequency of pollinator visits and the efficiency of the seed disperser were recorded. It was verified that in espinheira-santa, pollination is carried out by diptera and by hymenoptera. Among the main groups of pollinators are the flies, being Lucilia eximia, Limnophora sp. and Eristalis sp. the most frequent, and the wasps, in which Brachygastra mellifica, Polistes canadensis, Mischocyttarus sp. and one species of the Tiphiidae family were the most frequent. Eight species of birds consumed diaspores (arils with seeds), acting as dispersers of this species. However, the following birds were more efficient in the dispersion of seeds: Tangara sayaca, Elaenia sp. and Pipraeidea bonariensis. In this sense, M. ilicifolia is a species that has entomophilous pollination and ornithochoric dispersion.

Assessing short and long‐term variations in diversity, timing and body condition of frugivorous birds

Seed dispersal by frugivorous bird species involves a fine temporal tuning between fruiting plants and birds. However, this interaction may be severely threatened by anthropogenic climate and land‐use change, which may result in phenological mismatches and pervasive ecological consequences for avian communities. In this study, we evaluate changes at long (~40 years) and short‐time (seasonal) spans in an avian frugivore community using a snapshot resampling. Particularly, we focus on changes in composition, abundance, migratory timing (i.e. phenology) and physical condition in relation to variations in fruit supply. We used bird and fruit data collected during 1981–1983 and 2019–2021 in a Mediterranean scrubland site in Doñana Natural Area, SW Spain. Our findings indicate a profound transformation of species composition, bird phenology and body condition: in ~40 years, the avian community showed a 66% and 18.4% decrease of the abundance of wintering and seed‐disperser species, respectively. Seasonal abundance peaks were advanced for at least one month in the 9 out of 11 frugivorous bird species included in the analyses. Avian body condition during the migratory passage has worsened, with fewer individuals showing a high‐fat percentage now than in the past. Finally, we report a fruit production decrease of almost half in 2019–2021 compared to 1981–1983, probably linked to habitat encroachment by pine trees and replacement of fleshy‐fruited shrubs. Vegetation encroachment and climate change are the most plausible explanations for the observed changes in the avian community, but the relative importance of these factors is yet unknown. Our results at a local scale mirror the dramatic consequences of global change affecting the diversity, phenology and physical condition of frugivorous bird species reported in multiple studies across the globe. The loss of frugivores may trigger feedback mechanisms in which seed dispersal is disrupted, leading to impaired recruitment of fruiting plants and hence less food availability for the avian community.

Determining the effects of LFHV-PEF treatment on the water distribution and vigor of aged rice seeds using LF-NMR

This study aimed to investigate the effect of low-frequency high-voltage pulsed electric field (LFHV-PEF) treatment on the germination of aged rice seeds. Aged rice seeds were subjected to LFHV-PEF treatment with different electric field strengths, and low-field nuclear magnetic resonance (LF-NMR) was performed to acquire the LF-NMR data of rice seeds at different germination periods during a standard seed germination test to analyze their internal patterns of water state and distribution. Optimal treatment conditions were determined based on the physicochemical data collected during germination, and the improvements in seed vigor were verified. The findings indicated that during germination, the contents of bound and semi-bound water within the aged rice seeds initially increased and then decreased, whereas free water and total water contents increased continuously and rapidly. Side peaks were also observed within the seeds. Under the LFHV-PEF treatment, the semi-bound water within the seeds was more easily converted to free water, and the water absorption rate, germination potential, germination rate, germination index, and vigor index of these seeds improved. Further, the optimal electrical field strength was 12 kV. By analyzing the internal patterns of water state and distribution in seeds, the mechanism by which electric field treatment improved seed vigor was elucidated, thus, providing theoretical support and data evidence for research on water absorption during the germination of rice seeds, and methods for improving seed vigor. Keywords: aged rice seeds, germination, water phase, seed vigor, LF-NMR, LFHV-PEF DOI: 10.25165/j.ijabe.20221504.7590 Citation: Cheng E S, Song P, Hou T G, Wu L Y, Zhang B H. Determining the effects of LFHV-PEF treatment on the water and vigor of aged rice seeds using LF-NMR. Int J Agric & Biol Eng, 2022; 15(4): 190–196.

Multi-step locally expansion detection method using dispersed seeds for overlapping community

The local expansion method is a novel and promising community detection algorithm. Just based on part of network information, it can detect overlapping communities effectively, but some problems exist such as seed node aggregation, poor quality and inaccurate community coverage. Therefore, we propose a local expansion overlapping community detection algorithm based on dispersed seeds. There are four essential parts of this algorithm: 1) We firstly generate non-overlapping partitions of the network, and locate seed nodes with the largest influence in their own partition by using a new index of node influence, which combines the information centrality of nodes and the number of k-order neighbors. 2) Secondly, on the condition of the neighborhood overlap measure maximization, seed nodes merge unseeded nodes to generate a preliminary seed community; 3) Then based on the community conductance gain, the allocated nodes are screened and the free nodes are assigned to the seed community; 4) In the end, a node-community similarity based on common connection edge is proposed to re-allocate new free nodes and obtain the final community structure. This method can make the community distribution more proper and the coverage more reasonable. The experimental results on some artificial data and real network data show that the algorithm performs well on overlapping community indicators such as EQ and ONMI, while the community detection results are more stable.

Active metabolism during desiccation of the desiccation tolerant short-lived seeds of Poincianella pluviosa (DC.) L. P. Queiroz

Abstract: During embryogenesis and seed filling, developing seeds are metabolically highly active, while at the desiccation stage of tolerant seeds a decreased metabolism is expected. Seeds of Poincianella pluviosa present an extensive maturation cycle (11 months), longer than seed storability at room temperature (8 months). The metabolic profile of these seeds was characterized during maturation and drying, focusing in their role on seed behavior after shedding. Distinct responses of the embryonic axes and cotyledons to drying were observed depending on the developmental stage. Low proportions of tricarboxylic acids intermediaries until maturity indicated a low respiratory metabolism prior to the desiccation stage. Changes in shikimate, 4-coumarate, and quinate proportions suggest a metabolic shift towards the synthesis of chlorogenate isomers, found in high proportions in dispersed seeds. High proportions of lactate and glycerol were observed in immature seeds after artificial drying, but also in naturally dried axes of dispersed seeds. This suggests an active metabolism prior to drying and an osmotic stress under hypoxia, mechanisms that were never described before in desiccation-tolerant seeds. The results indicated that P. pluviosa seeds are dispersed with an incomplete metabolic switch-off, which can be related to their short lifespan.

From domestication syndrome to breeding objective: insights into unwanted breakup in common beans to improve shattering

Context Agronomical traits like loss of seed dispersal targeted by ancient human selection are an important milestone of crop domestication. Evolution in plant species is a result of natural and human selection at the time of domestication. Evolution leads to continued improvement of adaptive traits in almost all plant species. Aims Pod shattering, one of the examples of convergent evolution, is defined as breaking up of the pod shell enabling the successful dispersal of seeds mainly in wild species. Since the available climate change models predict an increase in aridity, it is expected that the losses on account of shattering will be aggravated, especially in dry areas. Methods Histological studies and biochemical parameters are increasingly used as surrogates for pod shattering response as they provide key inputs for selecting contrasting genotypes based on differential lignification, role of pectin, fibre, cellulose and total carbohydrate content as well as enzymes such as endopolygalacturonase and β-glucanase and hormones. Key results There is diversity for level of shattering, with race Nueva Granada showing higher rates of pod shattering as compared to the Durango and Jalisco races. Genomics has helped identify several genes or quantitative trait loci (QTL) such as PDH-1, St-1, SHAT-1, WRKY1 and MYB26 that are implicated in various traits related to pod shattering. Conclusions Plant breeders need to introgress shattering resistance into commercial varieties to mitigate the imminent yield losses. Implications This requires an in-depth knowledge of mechanistic, physiological, biochemical and the underlying genetic basis of pod shattering resistance.

Disruption of a Keystone Interaction Erodes Pollination and Seed Dispersal Networks

Disruption of a Keystone Interaction Erodes Pollination and Seed Dispersal Networks

种子散布位置对格氏栲幼苗根系形态及生长特征的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 种子散布位置对格氏栲幼苗根系形态及生长特征的影响 DOI: 10.5846/stxb202102060385 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（31700550，31770678）；福建省自然科学基金（2019J01367）；福建省林业科技推广项目（2018TG14-2） Effect of seeds dispersal position on the root morphology and growth characteristics of Castanopsis kawakamii seedlings Author: Affiliation: Fund Project: The National Natural Science Foundation of China (31700550；31700678)；the Nature Science Fund of the Fujian Province Science and Technology of China(2019J01367); the Science and Technology Promotion of Project Forestry Bureau of the Fujian Province (2018TG14-2) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:种子从母株掉落于地面萌发后，其根系在不同散布位置（凋落物上层、土壤表层和凋落物下层）的生长形态影响幼苗定居及建成，而目前对其根系形态及生长特征的了解并不充分，限制了对幼苗根系在不同散布下适应策略的理解。为此，以格氏栲（Castanopsis kawakamii）为研究对象，通过模拟种子在凋落物中位置，设置凋落物上层（种子下层铺垫2 cm和4 cm凋落物，U2和U4处理）、土壤表层与凋落物下层（种子上层覆盖0、2、4、6 cm和8 cm凋落物，CK、D2、D4、D6和D8处理）等3种散布，探讨不同散布位置对格氏栲幼苗根系9个生长指标的影响。结果表明：（1）种子散布位置对幼苗根干物质质量具有显著影响，D2处理达最大值。（2） D2处理的幼苗根长、根表面积、根尖数、分枝数和比根长高于其它处理；根系平均直径在D6处理达最大值。（3）相关分析表明根长、根表面积、根尖数、分枝数和比根长与根系平均直径呈显著负相关关系。（4）对根系9个生长指标提取主成分后聚类为4个类群，D2与D4处理各划分一类；U2与U4处理划分一类，其余三个处理划分一类。综上所述，凋落物浅层覆盖（D2处理）适宜格氏栲根系生长；凋落物上层（U2和U4处理）种子萌生根根系受凋落物阻隔作用阻止其与土壤接触，而一旦根系与土壤接触，生长速度加快；土壤表层（CK处理）受地表光照及水分条件限制及凋落物深层覆盖（D6和D8处理）的幼苗受深层凋落物产生的机械阻碍力影响，通过调整对根干物质质量的投入和根系形态可塑性来适应种子散布。因此，在幼苗根系快速生长阶段，通过人为干扰方式，适当调节森林凋落物厚度，以促进格氏栲幼苗在林内更新。 Abstract:The seeds of Castanopsis kawakamii fallen from the mother trees on the forest floor, after germination its root morphology under different dispersal positions (seeds on top of litter, seeds without litter, and beneath litter) may affect the seedlings settlement and establishment. Unfortunately, how the seed dispersal positions affect the seedlings root systems, especially for the morphology and growth characteristics, remains insufficiently understood. The lack of information limits the understanding of root adaptive strategy in different dispersal positions. Hence, we took C. kawakamii as research object by simulating the seeds position in litter, and set up three seeds dispersal positions including seeds on top of litter (2 cm and 4 cm litter under seeds, U2 and U4 treatments), soil surface (without litter, CK treatment), and seeds beneath litter (seeds were covered by 2, 4, 6, 8 cm litter, D2, D4, D6 and D8 treatments), aiming to explore the effect of seed dispersal positions on nine growth indices of root for C. kawakamii seedlings. The results showed that (1) there was a significant difference in root dry mass of C. kawakamii seedlings among different seed dispersal positions. Root dry mass of D2 treatment was higher than other treatments, whereas of U4 treatment was the lowest. (2) The root length, root surface area, root tips number, root forks number and specific root length of D2 treatment were higher than those of other treatments; whereas the root average diameter reached the maximum under D6 treatment. (3) Correlation analysis showed that root length, root surface area, root tips number, root forks number and specific root length had significantly negative correlation with root average diameter. (4) We extracted principal components from nine root growth indices and then clustered them into 4 groups. D2 and D4 treatments were separately divided into two groups; U2 and U4 treatments were divided into one group, and the other three treatments were divided into one group. We concluded that seeds beneath litter (D2 treatment) was the most suitable growth pattern for root growth of C. kawakamii. The U2 and U4 treatments of seeds on top of litter mainly prevented roots from contacting with soil via litter barrier; whereas when it contacted with the soil, the root growth rate was accelerated. Seedlings grew in the soil surface (CK treatment) with the restricted light and water conditions, and its root grew in D6 and D8 treatments was inhibited due to mechanical hindrance of deep litter. These factors led the seedlings to regulate the investment of root dry mass and root morphological plasticity to adapt the seed dispersal positions. Therefore, we should properly remove litter by human interference during root rapid growth stage to promote the regeneration of C. kawakamii seedlings in the natural forest. 参考文献 相似文献 引证文献