Seed Bank Dynamics Research Articles

Soil Seedbank Dynamics and Species Diversity in Pimelea-Infested Paddocks Under Pasture and Cultivated Conditions

Pasture lands, while appearing uniform in species diversity, exhibit notable variations upon closer examination. The study on Pimelea (or riceflower) seedbank dynamics revealed significant variations in seed density and distribution across soil depths, sites, years, and between pasture and cultivated paddocks in the same region of western Queensland. For the total number of germinable riceflower seeds across both the years 2019 and 2020, there is a clear distinction between pasture and cultivated paddocks. Pasture paddocks exhibited a gradual increase in total seed count from 108 seeds m−2 in 2019 to 121 seeds m−2 in 2020, resulting in a combined total of 229 seeds m−2 over the 2 years across both depths. In contrast, cultivated paddocks showed a more substantial increase, with seed counts rising from 146 seeds m−2 in 2019 to 255 seeds m−2 in 2020, resulting in a combined total of 401 seeds m−2 across both depths. Additionally, the Shannon–Wiener index at Site 1 indicated increased species diversity in the topsoil of pasture paddocks in 2020 compared to 2019, while deeper soil diversity decreased. Cultivated paddocks showed a declining trend, while pasture sites exhibited stable or increasing diversity. Pasture management generally maintained or enhanced diversity better than cultivation, especially in the topsoil layer. These findings highlight site-specific differences influenced by soil properties, land management practices, and local environmental conditions, shaping riceflower seedbank dynamics. Understanding these patterns is crucial for developing targeted management strategies to control riceflower in affected areas. Long-term field studies focusing on seedbanks are essential to develop sustainable control strategies.

Distribution of Vegetation and Soil Seed Banks Across Habitat Types in Paddy Fields Under Different Farming Practices.

Paddy field ecosystems are crucial for crop production, biodiversity conservation, and ecosystem services. Although previous studies have examined paddy field biodiversity, few have addressed how the distribution and species richness of vegetation and soil seed banks are regulated. This study investigated the distribution of wetland plants and soil seed banks in paddy fields across diverse habitat types and identified factors influencing their patterns. Surveys revealed that conventional paddy field habitats contained only a few herbicide-tolerant species (e.g., Portulaca oleracea L., Cardamine flexuosa With., and Rorippa palustris (L.) Besser). In contrast, organic paddy field habitats exhibited higher species richness and abundance. Cluster analysis and nonmetric multidimensional scaling demonstrated that soil seed bank distribution differed markedly in paddy field habitats with different farming practices and was influenced by distinct soil factors. These findings highlight the importance of understanding vegetation and soil seed bank dynamics in paddy field ecosystems to support biodiversity conservation and sustainable agriculture.

Fertility and tillage intensity affect weed community diversity and functional structure in long-term organic systems.

Knowledge of how agricultural management interacts with weed seed banks and emergent weed communities is crucial for proactive weed management. Though studies have detailed how differences in disturbance and nutrient applications between organic and conventional herbicide-based systems affect weed communities, few have focused on these same factors in contrasting organic systems. This study assessed the seed banks and emergent weed communities from the most recent crop rotation cycle (2017-2022) of a long-term experiment, which compared four organic grain and forage cropping systems differing in nutrient inputs and soil disturbance. The high fertility (HF) system received high-rate nutrient applications, low fertility (LF) received low-rate applications, enhanced weed management (EWM) focused on weed control through frequent soil disturbance, and reduced tillage (RT) prioritized soil health with less intense or frequent soil disturbance. Soil samples for greenhouse germination assays were collected at the beginning (2017) and end (2022) of the rotation to explore how these four systems influenced seed bank dynamics over time. Weed community biomass was also sampled in each crop during this time. Treatment effects on weed abundance, taxonomic diversity, and community-weighted means and functional dispersion of weed traits were analyzed with generalized mixed-effect models. The RT system had the highest weed seed bank taxonomic diversity, and EWM had the lowest. RT and LF had higher functional dispersion of traits than HF in the seed bank. Weed seed bank communities in HF and RT were characterized by short, small-seeded, and early germinating weed species. However, seed banks were also labile: Differences between systems in seed density and all other mean trait values were dependent on the crop, which preceded seed bank sampling. Likewise, differences among emergent weed communities in the four systems depended on an interaction between crop species and their planting year. Results suggest that resource availability and intensity of disturbance act as weed community assembly filters in organic cropping systems. Organic growers seeking to design systems that balance weed management and production goals can use relatively low soil disturbance and nutrient application to increase weed community taxonomic or functional diversity without necessarily increasing weed biomass or seed bank density.

Spatial–Temporal Dynamics of a Germinable Seed Bank of a Semi-Arid Vegetation in the Brazilian Northeast

Spatial–Temporal Dynamics of a Germinable Seed Bank of a Semi-Arid Vegetation in the Brazilian Northeast

Effect of soil nutrient management on soil weed seed bank dynamics across a soil fertility gradient in smallholder farms, Eastern Zimbabwe

Weed seed banks are latent biotic stress contributors to low crop production among smallholder farms. The objective of this study was to investigate effect of repeated soil nutrient amendments on weed seed bank dynamics in eastern Zimbabwe. Soil samples were taken from three farms with low, medium and high soil organic carbon (SOC) along the catena. Sampled treatments included varying combinations of compound D (7%N, 14%P, 7% K) fertiliser, cattle manure and lime. Weeds that emerged per plot were counted by species and data was tested for normality before running a linear mixed-effects model and Restricted Maximum Likelihood. Principal Component Analysis (PCA) was performed to establish the relationship between seasons, SOC, soil nutrient amendment, and emerged weeds. Significant (p < .05) species richness (Margalef index), and Shannon Weiner index were recorded in the medium (6.4g kg-1soil), high (8 g kg-1 soil) and low (< 3.9 g kg-1soil) SOC. Weed species emergence was significantly (p < .05) influenced by the level of SOC along the catena positions, representing results from the source. Emergency and abundance of weeds such as Richardia scabra, was associated with low SOC acidic sandy soils from the upper catena. However, application of nutrients (NPK+lime treatment) reduced weed species counts from 1.96±0.12 to 1.4±0.12. Cattle manure and NPK+CM treatments recorded significantly higher weed emergence, and weed biomass; compared to the control. Clearly, cattle manure treatments significantly increase the soil weed seed bank; thus, weeding intensity is likely to increase in cattle manure treated fields.

Effects of cultural practices on weed community and seedbank dynamics in a potato rotation

Effects of cultural practices on weed community and seedbank dynamics in a potato rotation

Aging seeds of weedy broomrapes and witchweeds lose sensitivity to strigolactones as DNA demethylates

Societal Impact StatementBroomrapes and witchweeds have devastating effects on crops in parts of Europe, Africa, and Asia. The key to their success is the production of copious, long‐lived seeds, which germinate in response to the perception of chemicals released by their hosts' roots. Here, it is proposed that the success of a parasite population will decrease as its seed bank ages due to the gradual decrease in sensitivity to the host signals in correlation with alterations of the seeds' epigenetic landscape, which is the set of non‐hard‐coded genetic information that influences gene function. This research provides important information toward a better understanding of parasite seed bank dynamics, which must be accounted for in future control strategies.Summary Broomrapes (Phelipanche and Orobanche spp.) and witchweeds (Striga and Alectra spp.) are obligate root parasitic weeds responsible for major crop yield losses worldwide. Their success in agricultural landscapes is attributable to their ability to produce thousands of long‐lived minute seeds that coordinate their germination with the presence of nearby hosts by perceiving host‐derived strigolactones. The processes underlying the alleged decade(s)‐long persistence in the field are understudied. Here, we used an accelerated seed aging method coupled with germination bioassays and an enzyme‐linked immunosorbent assay (ELISA), which allowed studying seed aging in Orobanchaceae in a comparative manner. We show that the losses of seed viability and germinability associated with seed aging are accompanied by a decrease in both strigolactone sensitivity and global DNA methylation. Our results also suggest that seeds of broomrapes are longer‐lived than those of witchweeds. Overall, this emphasizes the need for further research into how epigenetic mechanisms contribute to alterations in seed viability in parasitic weeds and how seed aging influences seed responses to their environment.

Weed seed bank dynamics during a three year crop rotation in Mediterranean semi-arid region (Northwestern Algeria)

Weed seed bank dynamics during a three year crop rotation in Mediterranean semi-arid region (Northwestern Algeria)

Theoretical assessment of persistence and adaptation in weeds with complex life cycles

Herbicide-resistant weeds pose a substantial threat to global food security. Perennial weed species are particularly troublesome. Such perennials as Sorghum halepense spread quickly and are difficult to manage due to their ability to reproduce sexually via seeds and asexually through rhizomes. Our theoretical study of S. halepense incorporates this complex life cycle with control measures of herbicide application and tillage. Rooted in the biology and experimental data of S. halepense, our population-based model predicts population dynamics and target-site resistance evolution in this perennial weed. We found that the resistance cost determines the standing genetic variation for herbicide resistance. The sexual phase of the life cycle, including self-pollination and seed bank dynamics, contributes substantially to the persistence and rapid adaptation of S. halepense. While self-pollination accelerates target-site resistance evolution, seed banks considerably increase the probability of escape from control strategies and maintain genetic variation. Combining tillage and herbicide application effectively reduces weed densities and the risk of control failure without delaying resistance adaptation. We also show how mixtures of different herbicide classes are superior to rotations and mono-treatment in controlling perennial weeds and resistance evolution. Thus, by integrating experimental data and agronomic views, our theoretical study synergistically contributes to understanding and tackling the global threat to food security from resistant weeds.

Flood changed the community composition and increased the importance of stochastic process of vegetation and seed bank in a riparian ecosystem of the Yellow River

Flood changed the community composition and increased the importance of stochastic process of vegetation and seed bank in a riparian ecosystem of the Yellow River

Weed Seed Banks in Intensive Farmland and the Influence of Tillage, Field Position, and Sown Flower Strips

Agricultural intensification has caused once diverse arable fields to become species-poor. Their seed banks, which are fundamental for re-establishment and maintenance of plant communities in such repeatedly disturbed environments, are now largely depleted. In order to advise farmers on the successful implementation of agri-environmental measures, as well as reduce potential subsequent costs of continued weed control, understanding seed bank dynamics in relation to aboveground vegetation is essential. We (1) investigated the change in seed bank composition in the field edge and the interior, and (2) analyzed the seed bank in flower strips and adjacent fields in relation to the aboveground vegetation on intensively managed arable farms across Germany. Low-tillage systems contained more plant species and higher seed densities in the seed bank than regularly ploughed fields. Species diversity at the field edge was higher than in the field interior, with a continuous decrease in the number of species and seed density within the first 2 m from the edge. Flower strips can lead to an enrichment of the seed bank, but it is driven by the strong rise in a few common species such as Chenopodium album. To cultivate successful flower strips, we recommend close onsite monitoring, as well as rapid intervention in the case of weed infestation.

Long-term seed bank persistence in a stochastic desert environment.

Seed banks, the collection of viable seeds in the soil, are particularly important determinants of population survival in highly variable environments. Predictions of increased stochasticity in the amount and timing of precipitation in desert environments raise the question of how seed banks of desert species will respond to climate change, and ultimately, whether these species will persist. Here, we present data from our long-term studies of germination requirements and seed bank dynamics in a rare desert gypsophile perennial, Arctomecon californica (Las Vegas bearpoppy). Arctomecon californica is a relatively short-lived plant that recruits from seed in sequences of unusually favorable years. We used germination experiments, an in situ seed bank study, and a 15-year field seed retrieval study to examine factors affecting seed bank persistence. In the germination study, a majority of seeds remained dormant, despite a wide variety of treatments, suggesting that a large proportion of the seed dispersed each year has cue-nonresponsive dormancy. Our in situ seed bank study showed that seed density varied widely between sites, among transects, and among samples within a transect. The patchiness of seeds in the soil highlights the importance of protecting large areas where A. californica populations are known to have existed in the past. The seed retrieval study provided strong evidence that this species has a long-lived seed bank in which only a small fraction of seeds (roughly 5%) become nondormant each year, allowing seed banks of this species to last up to 20 years without a seed production event. Whether this impressive life-history strategy can maintain the species in the face of climate change depends on the future frequency of the well-timed precipitation that allows for the establishment of new cohorts of adult plants.

Weed Seed Bank Density in Seven-Year-Old Conservation in No-Till System

Weed management remains a challenge when introducing new cropping systems. In Lebanon, farmers are increasingly adopting conservation agriculture (No-till) because it saves energy and reduces water and nutrient erosion. However, introducing a new system will cause a significant shift in production and management practices and is expected to produce novel weed management challenges. Thus, knowledge of soil seed banks of weeds in such systems is vital in designing effective weed management strategies. The objective of this research was to assess the size of the weed seed bank in seven-year-old conservation no-till fields. Soil samples were collected from established till and no-till fields at a depth of 0-5 cm. Transient and persistent weed seeds banks were evaluated. Results provide tangible evidence that the weed seed bank at a depth between 0-5cm in no-till system is greater than in till system. The no-till fields contained almost seven times the density of monocot and dicot weed seeds than in the conventional tilled fields. Ongoing work that builds on present results will help gain knowledge pertaining to weed seed bank dynamics in no-till system compared with conventionally tilled system.

Factors influencing the germination, establishment and distribution of

Context Little is known of the ecology of Micromyrtus minutiflora, a threatened plant species endemic to the Cumberland subregion, New South Wales, Australia. Aims To fill ecological knowledge gaps of M. minutiflora, including habitat preferences, population size and structure, survivorship; and responses to fire and disturbance to inform appropriate management practices. Methods Surveys of distribution and abundance, regeneration mode and response to fire, survivorship, size-class analysis, greenhouse germination experiments using soil blocks; and plant tissue and soil analyses. Key results Micromyrtus minutiflora was estimated to have a population of ~4.3 × 106, an extent of occurrence of ~13 000 ha and ~1.5% area of occupancy within study areas. It is strongly associated with low tree canopy cover (few trees), dispersive clay soils and Castlereagh Scribbly Gum Woodland. In the one area studied, survivorship decreased by ~15% per annum across 14 years. However, total population numbers were stable across 3 years, indicating continuous recruitment. Size distributions were unimodal and continuous from small to large plants, consistent with recruitment matching mortality. Plants lack a lignotuber and have a high shoot:root ratio. Seedling emergence was unaffected by mechanical disturbance, but heat and smoke significantly increased germination. Conclusions This species is abundant on dispersive clays but restricted to the northern Cumberland Plain in open woodland areas. It is an obligate seeder; plants are killed by fire and can flower within 2 years of germination. Implications Understanding its soil seedbank dynamics is pertinent in determining an appropriate fire regime to maintain habitat while not directly threatening populations. Populations require regular monitoring.

Assessing Seed Longevity of the Invasive Weed Navua Sedge (Cyperus aromaticus), by Artificial Ageing

Navua sedge (Cyperus aromaticus (Ridley) Mattf. & Kukenth) is a significant agricultural and environmental weed found in tropical island countries including north Queensland, Australia. It is a prolific seed producer and consequently forms a high-density seedbank, and therefore understanding the longevity and persistence of the seeds can provide critical information required for the management of this species. A laboratory-controlled artificial ageing experiment was conducted where the seeds were exposed to a temperature of 45 °C and 60% relative humidity for 125 days. Seeds were removed at various times (1, 2, 5, 9, 20, 30, 50, 75, 100 and 125 days) and their viability determined through standard germination tests. It took 20 days in the artificial ageing environment for the seeds to decline to 50% viability which indicates that Navua sedge has relatively short-lived persistent seeds. These findings will assist in developing a better understanding of the seedbank dynamics of this invasive species, allowing managers to tactically implement control strategies and prepare budgets for ongoing treatments, and have implications for the duration and success of management programs.

Seed bank dynamics and quality in the seagrass Halophila ovalis along estuarine salinity gradients—a case in the Swan-Canning Estuary

The seed bank of Halophila ovalis is crucial for resilience to disturbance through re-establishment. Understanding seasonal changes in abundance and quality of seeds in natural seed banks is critical for seed-based restoration. We selected an estuary in southwestern Australia and investigated the seasonal changes of seed distribution and viability in H. ovalis seed banks. We also adapted an X-ray viability test used for terrestrial seeds to test the viability of H. ovalis seeds. We then simulated the effect of low salinity on seed viability through a short-term indoor experiment. Seed density was significantly different between sites and seasons (0 to 43590 seeds·m-2), and the highest seed density in the seed banks was found after the reproductive season (May). The proportion of viable seeds in the seed bank was less than 22%, and was not subjected to substantial seasonal variability. The density of seeds in the seed bank decreased in spring, which indicated winter conditions were not prompt seed loss. We also predicted that extreme rainfall events and the resulting extremely low salinity would significantly reduce seed viability, and could decrease in seed germination; limit population recruitment. As it rapidly colonizes marine sediments from seeds, H. ovalis was considered an ideal seagrass for restoration purposes. Our results provide physiological information for H. ovalis seed banks to support seed-based restoration plans. Such understanding would enable accurate predictions about seagrass population resilience to extreme climate events in estuaries, where variable and extremely low salinity may limit seagrass population recovery from seeds through decreasing their viability.

A new technique for stain-marking of seeds with safranine to track seed dispersal and seed bank dynamics.

Accurate tracking of seed dispersal is critical for understanding gene flow and seed bank dynamics, and for predicting population distributions and spread. Available seed-tracking techniques are limited due to environmental and safety issues or requirements for expensive and specialized equipment. Furthermore, few techniques can be applied to studies of water-dispersed seeds. Here we introduce a new seed-tracking method using safranine to stain seeds/fruits by immersing in (ex situ) or spraying with (in situ) staining solution. The hue difference value between pre- and post-stained seeds/fruits was compared using the HSV color model to assess the effect of staining. A total of 181 kinds of seeds/fruits out of 233 tested species of farmland weeds, invasive alien herbaceous plants and trees could be effectively stained magenta to red in hue (320–360°) from generally yellowish appearance (30–70°), in which the other 39 ineffectively-stained species were distinguishable by the naked eye from pre-stained seeds. The most effectively stained seeds/fruits were those with fluffy pericarps, episperm, or appendages. Safranine staining was not found to affect seed weight or germination ability regardless of whether seeds were stained ex situ or in situ. For 44 of 48 buried species, the magenta color of stained seeds clearly remained recognizable for more than 5 months after seeds were buried in soil. Tracking experiments using four species (Beckmannia syzigachne, Oryza sativa f. spontanea, Solidago Canadensis, and Acer buergerianum), representing two noxious agricultural weeds, an alien invasive plant, and a tree, respectively, showed that the safranine staining technique can be widely applied for studying plant seed dispersal. Identifying and counting the stained seeds/fruits can be executed by specially complied Python-based program, based on OpenCV library for image processing and Numpy for data handling. From the above results, we conclude that staining with safranine is a cheap, reliable, easily recognized, automatically counted, persistent, environmentally safe, and user–friendly tracking-seed method. This technique may be widely applied to staining most of the seed plant species and the study of seed dispersal in arable land and in disturbed and natural terrestrial or hydrophytic ecological systems.

Tillage and crop establishment effects on weeds and productivity of a rice-wheat-mungbean rotation.

Weeds are one of the key threats in sustaining the productivity of the rice-wheat cropping system in the Indo-Gangetic Plains. The development of sound integrated weed management technologies requires knowledge of mechanisms that influence weed flora composition and weed seedbank dynamics. A long-term study was initiated in 2015 at Patna, Bihar, India to evaluate the effect of seven tillage and crop establishment methods on weed density, weed seedbank composition, and crop productivity in rice-wheat-mungbean rotation. All the treatments included zero-till mungbean after wheat. Tillage and crop establishment methods had differential effects on weed and weed seedbank composition. In rice, zero-till direct-seeded rice recorded 62% lower emergence of Cyperus iria, 82–90% of Echinochloa colona, and 81–83% of total weeds compared to tilled systems, but the system of rice and wheat intensification favoured E. colona. In wheat, the system of wheat intensification favoured the Phalaris minor and Solanum nigrum. Zero-till rice and wheat reduced the seedbank of Trianthema portulacastrum by 95%, and total weed seedbank by 62% compared to the system of rice and wheat intensification. Nearly, 72% of C. iria seeds, 62% of grasses, and 64% of broad-leaved weeds were in 0–15 cm soil layer. Zero-till direct-seeded rice produced a 13% lower rice grain yield than conventional puddled transplanted rice. Compared to the system of wheat intensification, zero-till wheat under triple zero-till systems produced an 11.5% higher grain yield. Managing weed seedbank is a long-term endeavour. The present study revealed that tillage and crop establishment methods influence weed density and diversity. Under zero-till rice-wheat system, rice yield decreases marginally, but the system productivity maintains due to improvement in succeeding wheat yield. This system is also helpful in reducing the weed flora density and soil weed seedbank. Regular monitoring and management of emerging pests such as armyworm (Mythimna separata) are, however, required. The study suggests that the adoption of triple zero-tillage can be a viable option for reducing the weed density and weed seedbank concurrently increasing the system productivity of the rice-wheat-mungbean cropping system in eastern Indo-Gangetic Plains.

Divergent successional trajectories of soil seed bank and post-fire vegetation in a semiarid oak forest: Implications for post-fire ecological restoration

Wildfires are a major disturbance in forest ecosystems around the world and may lead to changes in vegetation succession trajectories. This study examined the impact of time since wildfires on the successional gradients of the degraded Zagros semi-arid oak forest in Iran. Here, we investigated the role of soil seed bank in postfire understory vegetation successional trajectories after wildfires and how time-since-fire influenced plant recovery of this disturbed site. Three adjacent high severity burned areas with different fire histories and the same physiographic conditions were considered. In sampling, we surveyed both aboveground understory vegetation and soil seed bank in all the 96 plots taken along the transects of each area. Soil samples were also collected from each plot and physicochemical properties were analysed in the laboratory. Species composition in the seed bank showed divergent successional trajectories compared to the aboveground vegetation after wildfire. The diversity of soil seed banks followed a gradual decrease, while aboveground understory plants revealed an increasing trend of diversity over time. In addition, the physical and chemical composition of soils was significantly altered by fire. This study presents important insights into soil seed bank dynamics compared to the corresponding aboveground vegetation during postfire succession. The observed changes in diversity and vegetation composition after wildfire can give important insights to management strategies involving prescribed fire in the restoration efforts of highly disturbed semiarid oak forest.

"Soil Weed Seed Bank Dynamics After Two-Year of On-Farm Trials Under Conservation Agriculture in Bangladesh"

Mohammad Mobarak Hossain*, Mahfuza Begum and Moshiur Rahman Author Affiliations Department of Agronomy, Bangladesh Agricultural University, Bangladesh Received: May 02, 2022 | Published: June 09, 2022 Corresponding author: Mohammad Mobarak Hossain, Department of Agronomy, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh DOI: 10.26717/BJSTR.2022.44.007054