Review of seed pelletizing strategies for arid land restoration

Seed enhancement technologies for sustainable dryland restoration: Coating and scarification

High temperatures, soil salinity, a lack of available water, loose soils with reduced water holding, and low soil fertility are obstacles to restoration efforts in degraded drylands and desert ecosystems. Improved soil physical and chemical properties, seed germination and seedling recruitment, and plant growth are all proposed as outcomes of seed enhancement technologies (SETs). Seed priming, seed coating, and seed scarification are three SETs' methods for promoting seed germination and subsequent plant development under unfavorable environmental conditions. Various subtypes can be further classified within these three broad groups. The goals of this review are to (1) develop a general classification of coating and scarification SETs, (2) facilitate the decision-making process to adopt suitable SETs for arid lands environments, and (3) highlight the benefits of coating and scarification SETs in overcoming biotic and abiotic challenges in ecological restoring degraded dryland. For rehabilitating degraded lands and restoring drylands, it is recommended to 1) optimize SETs that have been used effectively for a long time, particularly those associated with seed physiological enhancement and seed microenvironment, 2) integrate coating and scarification to overcome different biotic and abiotic constraints, and 3) apply SET(s) to a mixture of seeds from various species and sizes. However, more research should be conducted on developing SETs for large-scale use to provide the required seed tonnages for dryland restoration.

Microbial seed coating: An attractive tool for sustainable agriculture

Seed coating is considered one of the best methods to promote sustainable agriculture where the physical and physiological properties of seeds can be improved to facilitate planting, increase growth indices and alleviate abiotic and biotic stresses. Several methods of seed coating are used to attain good application uniformity and adherence in the seed coating process. Seed coating has been tested in seeds of various plant species with different dimensions, forms, textures, and germination types. Plant beneficial microorganisms (PBM), such as rhizobia, bacteria, and fungi inoculated via seed inoculation can increase seed germination, plant performance and tolerance across biotic (e.g., pathogens and pests) and abiotic stress (e.g., salt, drought, and heavy metals) while reducing the use of agrochemical inputs. In this review, the microbial seed coating process and their ability to increase seed performance and protect plants from biotic and abiotic stresses are well discussed and highlighted in sustainable agricultural systems.

Rock structures improve seedling establishment, litter catchment, fungal richness, and soil moisture in the first year after installation

Grasslands are essential natural and agricultural ecosystems that encompass over one-third of global lands. However, land conversion and poor management have caused losses of these systems which contributed to a 10% reduction of net primary production, a 4% increase in carbon emissions, and a potential loss of US $42 billion a year. It is, therefore, important to restore, enhance and conserve these grasslands to sustain natural plant communities and the livelihoods of those that rely on them. We installed low cost rock structures (media lunas) to assess their ability to restore grasslands by slowing water flow, reducing erosion and improving plant establishment. Our treatments included sites with small and large rock structures that were seeded with a native seed mix as well as sites with no seed or rock and sites with only seed addition. We collected summer percent cover for plants, litter, and rock and spring seedling count data. We also collected soil for nutrient, moisture, and microbial analysis. Within the first year, we found no change in plant cover between rock structures of two rock sizes. We did find, however, an increase in soil moisture, litter, fungal richness, and spring seedling germination within the rock structures, despite a historic drought. This work demonstrates that rock structures can positively impact plants and soils of grasslands even within the first year. Our results suggest that managers should seriously consider employing these low-cost structures to increase short-term plant establishment and possibly, soil health, in grasslands.

Challenges and Strategies for Sustainable Mangrove Management in Indonesia: A Review

Mangroves are an important ecosystem that provides valuable social, economic, and environmental services. Indonesia has placed mangroves on its national priority agenda in an important effort to sustainably manage this ecosystem and achieve national climate commitments. However, mangrove management is faced with complex challenges encompassing social, ecological, and economic issues. In order to achieve the government’s commitments and targets regarding mangrove restoration and conservation, an in-depth study on and critical review of mangrove management in Indonesia was conducted herein. This work aimed to provide a comprehensive analysis of the challenges and strategic recommendations for sustainable mangrove management in Indonesia. SWOT analysis was carried out to understand the strengths, weaknesses, opportunities, and threats related to mangrove management in Indonesia. To address these gaps, we reviewed the existing policies, current rehabilitation practices, environmental challenges, and research and technology implementations in the field. We found that strategies on mangrove ecosystem protection, such as improving the function and value of mangrove forests, integrating mangrove ecosystem management, strengthening political commitments and law enforcement, involving all stakeholders (especially coastal communities), and advancing research and innovations, are crucial for sustainable mangrove management and to support the national blue carbon agenda.

Solutions in microbiome engineering: prioritizing barriers to organism establishment

Microbiome engineering is increasingly being employed as a solution to challenges in health, agriculture, and climate. Often manipulation involves inoculation of new microbes designed to improve function into a preexisting microbial community. Despite, increased efforts in microbiome engineering inoculants frequently fail to establish and/or confer long-lasting modifications on ecosystem function. We posit that one underlying cause of these shortfalls is the failure to consider barriers to organism establishment. This is a key challenge and focus of macroecology research, specifically invasion biology and restoration ecology. We adopt a framework from invasion biology that summarizes establishment barriers in three categories: (1) propagule pressure, (2) environmental filtering, and (3) biotic interactions factors. We suggest that biotic interactions is the most neglected factor in microbiome engineering research, and we recommend a number of actions to accelerate engineering solutions.

A global review of seed enhancement technology use to inform improved applications in restoration

Seed-based restoration often experiences poor success due to a range of edaphic and biotic issues. Seed enhancement technologies (SETs) are a novel approach that can alleviate these pressures and improve restoration success. Broadly, SETs have been reviewed for agricultural and horticultural purposes, for specific types of SETs such as coating or priming, or for focal ecosystems. However, information is lacking for SETs within a restoration focused context, and how they are being used to alleviate certain barriers. This review aimed to synthesise the current literature on SETs to understand what SETs are being tested, in which sectors and locations they are being tested, what issues are faced within restoration using SETs, and how SETs are being used to approach these issues. Priming was highlighted as the main SET investigated. Inoculation, pesticide application and magnetic fields were also commonly tested (SETs we termed 'prospective techniques'). SET research mainly occurred in the agricultural sector. More recently, other sectors, such as restoration and rangeland management, have increased efforts into SET research. The restoration sector has focused on extruded pelleting and coating (with activated carbon), in combination with herbicide application, to overcome invasive species, and coating with certain additives to alleviate edaphic issues. Other sectors outside restoration were largely focused on evaluating priming for overcoming these barriers. The majority of priming research has been completed on crop species and differences between these species and ecosystems must be considered in future restoration efforts that focus on native seed use. Generally, SETs require further refinement, including identifying ideal additives and their optimum concentrations to target certain issues, refining formulations for coating and extruded pelleting and developing flash flaming. A bet-hedging approach using multiple SETs and/or combinations of SETs may be advantageous in overcoming a wide range of barriers in seed-based restoration.

Dalziell E, Trudgen MS, Bateman AM, Erickson TE. Global change impacts on arid zone ecosystems: Seedling establishment processes are threatened by temperature and water stress

Recruitment for many arid-zone plant species is expected to be impacted by the projected increase in soil temperature and prolonged droughts associated with global climate change. As seed dormancy is considered a strategy to avoid unfavorable conditions, understanding the mechanisms underpinning vulnerability to these factors is critical for plant recruitment in intact communities, as well as for restoration efforts in arid ecosystems. This study determined the effects of temperature and water stress on recruitment processes in six grass species in the genus Triodia R.Br. from the Australian arid zone. Experiments in controlled environments were conducted on dormant and less-dormant seeds at constant temperatures of 25°C, 30°C, 35°C, and 40°C, under well-watered (Ψsoil = -0.15 MPa) and water-limited (Ψsoil = -0.35 MPa) conditions. Success at three key recruitment stages-seed germination, emergence, and survival-and final seed viability of ungerminated seeds was assessed. For all species, less-dormant seeds germinated to higher proportions under all conditions; however, subsequent seedling emergence and survival were higher in the more dormant seed treatment. An increase in temperature (35-40°C) under water-limited conditions caused 95%-100% recruitment failure, regardless of the dormancy state. Ungerminated seeds maintained viability in dry soil; however, when exposed to warm (30-40°C) and well-watered conditions, loss of viability was greater from the less-dormant seeds across all species. This work demonstrates that the transition from seed to established seedling is highly vulnerable to microclimatic constraints and represents a critical filter for plant recruitment in the arid zone. As we demonstrate temperature and water stress-driven mortality between seeds and established seedlings, understanding how these factors influence recruitment in other arid-zone species should be a high priority consideration for management actions to mitigate the impacts of global change on ecosystem resilience. The knowledge gained from these outcomes must be actively incorporated into restoration initiatives.

Wetland Restoration with Hydrophytes: A Review

Restoration cases with hydrophytes (those which develop all their vital functions inside the water or very close to the water surface, e.g., flowering) are less abundant compared to those using emergent plants. Here, I synthesize the latest knowledge in wetland restoration based on revegetation with hydrophytes and stress common challenges and potential solutions. The review mainly focusses on natural wetlands but also includes information about naturalized constructed wetlands, which nowadays are being used not only to improve water quality but also to increase biodiversity. Available publications, peer-reviewed and any public domain, from the last 20 years, were reviewed. Several countries developed pilot case-studies and field-scale projects with more or less success, the large-scale ones being less frequent. Using floating species is less generalized than submerged species. Sediment transfer is more adequate for temporary wetlands. Hydrophyte revegetation as a restoration tool could be improved by selecting suitable wetlands, increasing focus on species biology and ecology, choosing the suitable propagation and revegetation techniques (seeding, planting). The clear negative factors which prevent the revegetation success (herbivory, microalgae, filamentous green algae, water and sediment composition) have to be considered. Policy-making and wetland restoration practices must more effectively integrate the information already known, particularly under future climatic scenarios.

Modern Seed Technology: Seed Coating Delivery Systems for Enhancing Seed and Crop Performance

The objective of modern seed-coating technology is to uniformly apply a wide range of active components (ingredients) onto crop seeds at desired dosages so as to facilitate sowing and enhance crop performance. There are three major types of seed treating/coating equipment: dry powder applicator, rotary pan, and pelleting pan with the provisions to apply dry powders, liquids, or a combination of both. Additional terms for coatings produced from these types of equipment include dry coating, seed dressing, film coating, encrustments, and seed pelleting. The seed weight increases for these different coating methods ranges from <0.05% to >5000% (>100,000-fold range). Modern coating technology provides a delivery system for many other materials including biostimulants, nutrients, and plant protectants. This review summarizes seed coating technologies and their potential benefits to enhance seed performance, improve crop establishment, and provide early season pest management for sustainable agricultural systems.

Immersion Freezing of a Scots Pine Single Seed in a Water-Saturated Dispersion Medium: Mathematical Modelling

Forest owners will be able to solve the problem of protecting small forest seeds from mechanical and atmospheric influences during aerial sowing, as well as the problem of manufacturing capsules in the field, saving financial, time and material resources. The process of creating a capsule by freezing the seed in a water-saturated dispersed system—immersion freezing—allows you to organize the technological properties of forest seeds depending on the initial requirements. In most cases, the quality of the seed capsule is determined by the thermophysical and mechanical properties of the components. The technological process of obtaining seed capsules for aerial seeding and the choice of freezing modes is based on a priori mathematical modeling of heat-and-mass transfer processes. The main purpose of the study is to predict the duration of the seed freezing process in a capsule with a water-saturated dispersed medium, depending on the external temperature conditions, the geometric parameters of the capsule and the seed. The cooling agent is carbon dioxide. The research is based on the use of numerical modeling methods on the platform COMSOL Multiphysics. A mathematical model is proposed that allows us to obtain the dynamics of the distribution of temperature and moisture content fields in the dispersed system and seed depending on a complex of geometric and thermophysical factors. The time of immersion freezing of the capsule with the common pine seed for the conditions considered should be in the range of 150 to 250 s.