Vegetation regeneration on natural terrain landslides in Hong Kong: direct seeding of native species as a restoration tool

Landslides are common in tropical and subtropical regions with hilly terrains and heavy rainstorms, which cause significant economic, ecological, and social impacts. Natural forest succession is usually slow on landslide scars due to poor soil structure and the lack of seeds of woody plant seeds, and often comes with a higher risk of repeated landslide. Ecological forest restoration has recently been suggested as an effective alternative to restore the exposed landslide scars, however, a comprehensive study to identify effective landslide restoration strategies remains lacking, particularly associated with seed treatment methods and species selection. Here we evaluated the effectiveness of different seed coating treatments of both pioneer and later successional tree species of different seed sizes on seed germination in a one-year study on three landslides in Hong Kong. Our results show that bare seeds had germination rates of 17 to 67% across all selected species (n=7). Biochar-dominant seed coating formulation boosted an additional 9.33 (SE= 0.04) in seed germination rate, while the clay-dominant seed coating formulation did not show significant effect on germination. Our results also show that medium and large-seeded non-pioneer species have significantly higher germination rates than pioneer species. These results collectively suggest that direct seeding using a biochar seed coat is a manageable and useful method to enhance tree seed germination—an essential first step to restore the forests after landslide disturbances in Hong Kong, with potential to be extended to other humid tropical and subtropical forests.

Chitosan oligosaccharide alleviates the growth inhibition caused by physcion and synergistically enhances resilience in maize seedlings

The use of biopesticides has gradually become essential to ensure food security and sustainable agricultural production. Nevertheless, the use of single biopesticides is frequently suboptimal in agricultural production given the diversity of biotic and abiotic stresses. The present study investigated the effects of two biopesticides, physcion and chitosan-oligosaccharide (COS), alone and in combination, on growth regulation and antioxidant potential of maize seedlings by seed coating. As suggested from the results, physcion significantly inhibited the growth of the shoots of maize seedlings due to the elevated respiration rate. However, COS significantly reduced the growth inhibition induced by physcion in maize seedlings by lowering the respiration rate and increasing the content of photosynthetic pigments and root vigor, which accounted for lower consumption of photosynthesis products, a higher photosynthetic rate and a greater nutrient absorption rate. Thus, an improved growth was identified. As indicated from the in-depth research, the application of physcion and COS combination is more effective in down-regulated the malondialdehyde (MDA) content by facilitating the activities of the antioxidative enzymes (i.e., superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (G-POD)). Such results indicated that the combined use of physcion and COS neither affected the normal growth of maize seedlings, but also synergistically improved the antioxidant potential of the maize plants, resulting in plants with high stress resistance. Thus, the combined use of physcion and COS by seed coating in maize production has great potential to ensure yield and sustainable production of maize.

Use of Biostimulants: Towards Sustainable Approach to Enhance Durum Wheat Performances

The use of biostimulant (BS) holds a promising and environmental-friendly innovation to address current needs of sustainable agriculture. The aim of the present study is twofold: (i) assess the potential of durum wheat seed coating with microbial BS (‘Panoramix’, Koppert), a mix of Bacillus spp., Trichoderma spp., and endomycorrhiza, compared to two chemical products (‘Spectro’ and ‘Mycoseeds’) through germination bioassay, pot and field trials under semi-arid conditions, and (ii) identify the most effective method of BS supply (‘seed coating’, ‘foliar spray’, and ‘seed coating + foliar spray’) under field conditions. For this purpose, three modern durum wheat cultivars were tested. ‘Panoramix’ was the most efficient treatment and enhanced all germination (germination rate, and coleoptile and radicle length), physiological (relative water content, chlorophyll content, and leaf area), and agro-morphological (plant height, biomass, seed number per spike, thousand kernel weight, and grain yield) attributes. Unexpectedly, the individual application of ‘Panoramix’ showed better performance than the combined treatment ‘Panoramix + Spectro’. Considering the physiological and agro-morphological traits, the combined method ‘seed coating + foliar spray’ displayed the best results. Principal component analysis confirmed the superiority of ‘Panoramix’ treatment or ‘seed coating + foliar spray’ method. Among tested durum wheat cultivars, ‘Salim’ performed better especially under ‘Panoramix’ treatment, but in some case ‘Karim’ valorized better this BS showing the highest increase rates. Based on these study outcomes, ‘Panoramix’ might be used as promising sustainable approach to stimulate durum wheat performance.

Superabsorbent Polymer Seed Coating Reduces Leaching of Fungicide but Does Not Alter Their Effectiveness in Suppressing Pathogen Infestation

Superabsorbent polymers (SAPs) applied to soil have been recognized as water reservoirs that allow plants to cope with periods of drought. Their application as a seed coat makes water available directly to the seeds during their germination and early growth phase, but on the other hand, it can affect the efficiency of plant protection substances used in seed dressing. In our experiments, we evaluated the effect of seed coating with SAP on fungicide leaching and changes in their effectiveness in suppressing Fusarium culmorum infestation. Leaching of fungicide from wheat seeds coated with SAP after fungicide dressing, as measured by the inhibition test of mycelium growth under in vitro conditions, was reduced by 14.2–15.8% compared to seeds without SAP coating. Germination of maize seeds and growth of juvenile plants in artificially infected soil did not differ significantly between seeds dressed with fungicide alone and seeds treated with SAP and fungicide. In addition, plants from the seeds coated with SAP alone grew significantly better compared to untreated seeds. Real-time PCR also confirmed this trend by measuring the amount of pathogen DNA in plant tissue. Winter wheat was less tolerant to F. culmorum infection and without fungicide dressing, the seeds were unable to germinate under strong pathogen attack. In the case of milder infection, similar results were observed as in the case of maize seeds.

Influence of Trichoderma harzianum- seed Coating on the Biochemical Characteristics of Wheat (Triticum aestivum L.) Under Salt Stress

Salt stress is one of the main limitations to Triticum aestivum productivity all around the world. An experiment was conducted to assess the effect of Trichoderma harzianum seed coating on germination and seedling development of wheat under salt stress (60 and 120 mM NaCl). The seeds of six wheat cultivars, namely Shafaq-06, Punjab-11, Millet, Seher, Pirsabik, and Aari were seed coated with Trichoderma (taken from NARC Pakistan) at the rate of 2 x 107 CFU using PelGel for 24 h. After air-drying at room temperature for 12 h, the coated seeds were sown in small pots. Experimentation was laid out in a completely randomized design with three replications. The data for various biochemical attributes were collected after 30 d of germination to test the seed and seedling vigor, respectively. Trichoderma harzianum seed coating reduced the amount of hydrogen peroxide, catalase, Malondialdehyde, and increased protein content, Ascorbate Peroidase, and total phenolics under salt stress advocating that its use is effective in the cultivation of crops in saline areas because it inhibits oxidative damage by triggering various phenolic compounds and scavenging proteins.

Hydrogel Alginate Seed Coating as an Innovative Method for Delivering Nutrients at the Early Stages of Plant Growth

Seed coating containing fertilizer nutrients and plant growth biostimulants is an innovative technique for precision agriculture. Nutrient delivery can also be conducted through multilayer seed coating. For this purpose, sodium alginate with NPK, which was selected in a preliminary selection study, crosslinked with divalent ions (Cu(II), Mn(II), Zn(II)) as a source of fertilizer micronutrients, was used to produce seed coating. The seeds were additionally coated with a solution containing amino acids derived from high-protein material. Amino acids can be obtained by alkaline hydrolysis of mealworm larvae (Gly 71.2 ± 0.6 mM, Glu 55.8 ± 1.3 mM, Pro 48.8 ± 1.5 mM, Ser 31.4 ± 1.5 mM). The formulations were applied in different doses per 100 g of seeds: 35 mL, 70 mL, 105 mL, and 140 mL. SEM-EDX surface analysis showed that 70 mL of formulation/100 g of seeds formed a continuity of coatings but did not result in a uniform distribution of components on the surface. Extraction tests proved simultaneous low leaching of nutrients into water (max. 10%), showing a slow release pattern. There occurred high bioavailability of fertilizer nutrients (even up to 100%). Pot tests on cucumbers (Cornichon de Paris) confirmed the new method’s effectiveness, yielding a 50% higher fresh sprout weight and four times greater root length than uncoated seeds. Seed coating with hydrogel has a high potential for commercial application, stimulating the early growth of plants and thus leading to higher crop yields.

Optimizing wheat seed treatment with entomopathogenic fungi for improving plant growth at early development stages

Aim of study: Entomopathogenic fungi (EPF) are biocontrol agents, plant growth promoters, and increase tolerance to biotic-abiotic stresses. In this study we investigated the factors associated to the application method, which are crucial for the interaction between the fungus and the host plant at initial crop growth stages. Area of study: The study was performed in Cordoba (Spain) Material and methods: Three experiments were performed to investigate: (i) the effect of different concentrations of the surfactant Tween® 80 (0, 0.5, 1, 5, and 10%) on wheat seed coating with conidia of Metarhizium brunneum and seed and conidia viability; (ii) the performance of wheat seedlings at first growth stages after their inoculation with Beauveria bassiana or M. brunneum via seed coating or soil drenching; and (iii) the role of soil sterilization and seed disinfection on leaf concentration of chlorophyll (SPAD) and B. bassiana or M. brunneum colonization. Main results: Tween® 80 concentration linearly improved seed coating (up to 127%) without altering wheat seeds and fungal conidia germination. Seedling length of inoculated plants was significantly increased with B. bassiana and M. brunneum (67% and 46%, respectively) via seed coating. Seed disinfection was key to achieve an enhancement in wheat SPAD (10-18%) with B. bassiana or M. brunneum concerning Control, that combined with sterilization of soil showed the highest endophyte colonization rates (up to 83.3% with both fungi) Research highlights: The surfactant concentration, application method, seed disinfection, and soil sterilization are key parameters to improve the potential benefits on the EPF-plant relationship.

Comparative Performances of Beneficial Microorganisms on the Induction of Durum Wheat Tolerance to Fusarium Head Blight

Durum wheat production is seriously threatened by Fusarium head blight (FHB) attacks in Tunisia, and the seed coating by bio-agents is a great alternative for chemical disease control. This study focuses on evaluating, under field conditions, the effect of seed coating with Trichoderma harzianum, Meyerozyma guilliermondii and their combination on (i) FHB severity, durum wheat grain yield and TKW in three crop seasons, and (ii) on physiological parameters and the carbon and nitrogen content and isotope composition in leaves and grains of durum wheat. The results indicated that the treatments were effective in reducing FHB severity by 30 to 70% and increasing grain yield with an increased rate ranging from 25 to 68%, compared to the inoculated control. The impact of treatments on grain yield improvement was associated with higher NDVI and chlorophyll content and lower canopy temperature. Furthermore, the treatments mitigated the FHB adverse effects on N and C metabolism by resulting in a higher δ13Cgrain (13C/12Cgrain) and δ15Ngrain (15N/14Ngrain). Overall, the combination outperformed the other seed treatments by producing the highest grain yield and TKW. The high potency of seed coating with the combination suggests that the two microorganisms have synergetic or complementary impacts on wheat.