Soil microarthropods affect soil ecosystems in a manner that may contribute to balancing the goals of building soil health and controlling weeds in organic agricultural systems. While soil microarthropod feeding behavior can affect plant growth, their impacts on plant communities in agricultural systems are largely unknown. A greenhouse experiment was conducted to investigate the impacts of microarthropods on weed communities. A model weed seed bank was used in each mesocosm, which included yellow foxtail (Setaria pumila (Poir.) Roem&Schult.), giant foxtail (Setaria faberi Herrm.), Powell amaranth (Amaranthus powellii S. Watson), water-hemp (Amaranthus tuberculatus (Moq.) Sauer), common lambsquarters (Chenopodium album L.), and velvetleaf (Abutilon theophrasti Medik.). The study included three treatments: Collembola (Isotomiella minor, Schaffer 1896) abundance (none, low, high), soil microbial community (sterilized/non-sterilized), and fertilizer (presence/ absence of compost). A lab experiment examining individual weed species interactions with I. minor was conducted to elucidate the mechanisms driving the greenhouse experiment findings. Twenty seeds of each weed species were placed on moistened germination paper in containers with varying I. minor abundance levels (none, low, high, very high). Seed germination was recorded after five and seven days. In the greenhouse, the presence of I. minor increased total weed emergence during the first two weeks, but this effect diminished after three weeks. Increasing I. minor abundances generally decreased weed biomass, though this effect was greater in the non-sterilized soil. In the non-sterilized soil, I. minor presence decreased total aboveground weed biomass production by up to 23 %. The Amaranthus species, Powell amaranth and waterhemp, drove this effect with a 55 % and 32 % reduction in biomass, respectively. In tandem, the Amaranthus species had reduced abundances in the presence of I. minor. I. minor increased yellow foxtail germination in the lab, while not affecting the other weed species. This suggests that their effects on the Amaranthus weeds in the greenhouse were likely not caused by direct effects on germination, but instead through nutrient cycling or root herbivory. The proposed mechanism underlying these interactions is that I. minor can initially stimulate germination by feeding on seed coats, but when the seed coats are minimal can damage the seedling. Our findings indicate I. minor could impact weed growth in a manner that affects management decisions and outcomes.

The demand for seed-based restoration and revegetation of degraded drylands has intensified with increased disturbance and climate change. Invasive plants often hinder the establishment of seeded species; thus, they are routinely controlled with herbicides. Herbicides used to control invasive plants may maintain soil activity and cause non-target damage to seeded species. Activated carbon (AC), which has a high adsorption of many herbicides, has been incorporated into seed pellets and coatings (seed technologies) to limit herbicide damage. Though various AC seed technologies have been examined in numerous laboratory and field studies, questions remain regarding their effectiveness and how to improve it, and what causes variation in results. We synthesized the literature on AC seed technologies for dryland restoration and revegetation to attempt to answer these questions. AC pellets compared to seed coatings were more thoroughly tested in the field and generally provide strong herbicide protection. However, greater amounts of AC in seed coatings appear to increase their effectiveness. Seed coatings show more potential for use than pellets because they are less logistically challenging to use compared to pellets, but need more field testing and refinement. Results often differ between laboratory and field studies, suggesting that field studies are critical in determining realized effects. However, seedling establishment failures from other barriers make it challenging to evaluate the effectiveness of AC seed technologies in the field. AC seed technologies are an innovative tool that with continued refinement, especially if other barriers to seedling establishment can be overcome, may improve the restoration and revegetation of degraded drylands.

Microbial seed coatings serve as effective, labor-saving, and ecofriendly means of controlling soil-borne plant diseases. However, the survival of microbial agents on seed surfaces and in the rhizosphere remains a crucial challenge. In this work, we embedded a biocontrol bacteria (Bacillus subtilis ZF71) in sodium alginate (SA)/pectin (PC) hydrogel as a seed coating agent to control Fusarium root rot in cucumber. The formula of SA/PC hydrogel was optimized with the highest coating uniformity of 90 % in cucumber seeds. SA/PC hydrogel was characterized using rheological, gel content, and water content tests, thermal gravimetric analysis, and Fourier transform infrared spectroscopy. Bacillus subtilis ZF71 within the SA/PC hydrogel network formed a biofilm-like structure with a high viable cell content (8.30 log CFU/seed). After 37 days of storage, there was still a high number of Bacillus subtilis ZF71 cells (7.23 log CFU/seed) surviving on the surface of cucumber seeds. Pot experiments revealed a higher control efficiency against Fusarium root rot in ZF71-SA/PC cucumber seeds (53.26 %) compared with roots irrigated with a ZF71 suspension. Overall, this study introduced a promising microbial seed coating strategy based on biofilm formation that improved performance against soil-borne plant diseases.

Salt stress is one of the most important abiotic stress factors limiting crop production. Therefore, improving the stress resistance of seeds is very important for crop growth. Our previous studies have shown that using microcapsules encapsulating bacteria (Pontibacter actiniarum DSM 19842) as seed coating for wheat can alleviate salt stress. In this study, the genes and pathways involved in the response of wheat to salt stress were researched further. The results showed that compared with the control, the coating can improve osmotic stress and decrease oxidative damage by increasing the content of proline (29.1%), the activity of superoxide dismutase (SOD) (94.2%), peroxidase (POD) (45.7%) and catalase (CAT) (3.3%), reducing the content of hydrogen peroxide (H2O2) (39.8%) and malondialdehyde (MDA) (45.9%). In addition, ribonucleic acid (RNA) sequencing data showed that 7628 differentially expressed genes (DEGs) were identified, and 4426 DEGs up-regulated, 3202 down-regulated in the coated treatment. Many DEGs related to antioxidant enzymes were up-regulated, indicating that coating can promote the expression of antioxidant enzyme-related genes and alleviate oxidative damage under salt stress. The differential gene expression analysis demonstrated up-regulation of 27 genes and down-regulation of 20 genes. Transcription factor families, mostly belonging to bHLH, MYB, B3, NAC, and WRKY. Overall, this seed coating can promote the development of sustainable agriculture in saline soil.

With continuous innovations in wastewater treatment technology, the use of excess sludge has become a research focus. Purified-hydrocolloids obtained from aerobic granular sludge (AGS) and conventional activated sludge (CAS) have many practical applications, including waterproofing, adsorption, flame retardance, slow-release properties, and seed coating. In this study, purified-hydrocolloids extracted from CAS was used as a new seed coating, which was uniformly sprayed onto the surface of wheat seeds. Purified-hydrocolloids was most effective in resisting salt stress in wheat seedlings at a NaCl concentration of 125 mmol/L (soil salinity 2.74 g/Kg). The germination percentage, plant height, K+/Na+ ratio, soluble sugar and soluble protein contents of purifiedhydrocolloids-coated seeds increased by 13.33 %, 46.32 %, 37.25 %, 8.89 %, and 36.22 %, respectively, compared with wheat seeds without purified-hydrocolloids coating. Inhibition of O-2(-) production activity and malondialdehyde content was reduced by 38.62 % and 48.00 %, respectively. Therefore, the purifiedhydrocolloids coating had a mitigating effect on wheat seed germination and seedling growth in salt-stressed environments, and this application would be beneficial to the use of saline soil resources and the improvement of ecosystems in coastal areas.

Cryopreservation remains the technology of choice for the long-term preservation of plant germplasm. The current contribution reports on the response of seeds of N. wightii, P. vulgaris and T. indica to cryopreservation in terms of plantlet survival post cryostorage as well as examination of the external morphology of seed coats using scanning electron microscopy (SEM). Survival was determined in Petri dishes in the laboratory as well as in the soil. The results showed differential responses in seeds of the three tested species. In the case of P. vulgaris, exposure to liquid nitrogen (LN) did not adversely affect seedling emergence or characteristics of the seed coat. For N. wightii and T. indica, cracks in the seed coat that were apparent in control seeds, appeared more frequently following exposure to LN. In the case of the former species, this observation did not yield adverse consequences and seed germination rate did actually increase from 5.8 to 85.9% after LN treatment. However, in the case of T. indica, the initial growth rate of seedlings was delayed relative to the control although the germination rate was improved. It is postulated that seeds of T. indica possibly incurred additional damage to other seed components which might have led to delayed recovery.