The increasing demand for sustainable agricultural practices has intensified interest in soilless cultivation systems. However, hydroponics is unable to provide mechanical support for plant roots, and traditional soilless cultivation substrates mostly suffer from poor water retention capacity, rapid nutrient loss, and difficulty in precise control. Hydrogel-based soilless cultivation substrates show great potential for application due to their excellent water absorption, water retention and adjustable transparency. In this study, P(AM-co-NIPAM)/gelatin composite hydrogels with adjustable pore structures, mechanical strength and transparency were obtained by regulating the concentration of crosslinker. Soybean seedlings were grown on these substrates to evaluate the effects of hydrogel properties on root and shoot growth. The results demonstrate that hydrogels with optimized crosslink density possess superior mechanical properties, enhanced water retention capacity, and adequate transparency, facilitating both robust plant growth and high-resolution root system observation. We found that under the MBA content of 0.05 %, the hydrogel matrix could significantly promote the growth of aerial part and root system of soybean seedlings, and was conducive to the colonization of root bacteria. This work highlights the potential of controlled hydrogel matrices in soilless cultivation as a sustainable solution to improve root growth environments, enhance resource utilization, and enable dynamic root system studies. Given their adjustable structure and compatibility with plant growth, such hydrogels may also serve as promising candidates for future application in soilless crop production systems, particularly in scenarios where water and substrate optimization are critical to sustainable agricultural practices.

Soil salinization has become one of the major problems that threaten the ecological environment. The aim of this study is to explore the mechanism of salt tolerance of hybrid walnuts (Juglans major x Juglans regia) under long-term salt stress through the dynamic changes of growth, physiological and biochemical characteristics, and anatomical structure. Our findings indicate that (1) salt stress inhibited seedling height and ground diameter increase, and (2) with increasing salt concentration, relative water content (RWC) decreased, and proline (Pro) and soluble sugar (SS) content increased. The Pro content reached a maximum of 549.64 mu g/g on the 42nd day. The increase in superoxide dismutase (SOD) activity (46.80-117.16%), ascorbate peroxidase (APX) activity, total flavonoid content (TFC), and total phenol content (TPC) under salt stress reduced the accumulation of malondialdehyde (MDA). (3) Increasing salt concentration led to increases and subsequent decreases in the thickness of palisade tissues, spongy tissues, leaves, and leaf vascular bundle diameter. Upper and lower skin thickness, root periderm thickness, root diameter, root cortex thickness, and root vascular bundle diameter showed different patterns of change at varying stress concentrations and durations. Overall, the study concluded that salt stress enhanced the antireactive oxygen system, increased levels of osmotic regulators, and low salt concentrations promoted leaf and root anatomy, but that under long-term exposure to high salt levels, leaf anatomy was severely damaged. For the first time, this study combined the anatomical structure of the vegetative organ of hybrid walnut with physiology and biochemistry, which is of great significance for addressing the challenge of walnut salt stress and expanding the planting area.

Beyond ecological and health impacts, invasive alien plant species can generate indirect and direct costs, notably through reduced agricultural yields, restoration, and management of the invaded environment. Acacia dealbata and Ailanthus altissima are invasive plant species that cause particularly significant damage to the railway network in the Mediterranean area. The allelopathic properties of Mediterranean plant species could be used as nature-based solutions to slow down the spread of such invasive plant species along railway borders. In this context, a mesocosm experiment was set-up: (i) to test the potential allelopathic effects of Cistus ladanifer, Cistus albidus, and Cotinus coggygria leaf aqueous extracts on seed germination and seedling growth of A. dealbata and A. altissima; (ii) to evaluate whether these effects depend on the extract dose; and finally, (iii) to estimate whether these effects are modified by soil amendment. Leaf aqueous extracts of the three native plant species showed negative effects on both seed germination and seedling growth of the two invasive species. Our results show that the presence of allelochemicals induces a delay in seed germination (e.g., A. dealbata germination lasted up to 269% longer in the presence of high-dose leaf aqueous extracts of C. coggygria), which can lead to a decrease in individual recruitment. They also highlight a decrease in seedling growth (e.g., high-dose C. coggygria leaf aqueous extracts induced a 26% decrease in A. dealbata radicle growth), which can alter the competitiveness of invasive species for resource access. Our results also highlight that compost addition limits the inhibitory effect of native Mediterranean plants on the germination of invasive alien plants, suggesting that soil organic matter content can counteract allelopathic effects on invasive alien plants. Thus, our findings revealed that the allelopathic potential of certain Mediterranean plant species could be a useful tool to manage invasive plant species.