In this study, the physiological response of potted apple trees to combined drought and heat stress was evaluated. After establishing different levels of soil water availability, the trees were exposed to a five-day simulated heatwave with daily maximum temperatures of 40 degrees C. Stem water potential, leaf gas exchange, chlorophyll fluorescence, and tree transpiration were monitored before, during and after the combined application of heat and water stress, therefore providing insights into the extent and rapidity of the recovery. Drought caused stomatal closure that limited net photosynthesis and transpiration both at leaf and at tree level, leading to structural damage through leaf loss. On drought-stressed plants, chlorophyll fluorescence was significantly reduced by heat stress, suggesting additional leaf damage although net photosynthesis was not lower than under drought stress alone. On the other hand, well-watered trees showed low midday stem water potentials and high transpiration rates during the heatwave, while net photosynthesis was not affected. Water use efficiency of well-watered trees at 33 degrees C was reduced to 60 % of that at 23 degrees C. After the heatwave, transpiration rate in well-watered trees immediately declined to pre-stress levels, underscoring the strong atmospheric control on transpiration in apple trees. In drought-stressed trees, predawn stem water potential reached pre-stress values already on the first day of recovery. Stomatal conductance, net photosynthesis, and chlorophyll fluorescence, however, required a longer period to recover, indicating that drought stress induced transient hydraulic limitations. Nevertheless, all parameters fully recovered within five days after the end of the heatwave, showing that apple trees can withstand periods of combined heat and drought stress. The key role of water in modulating the response to heat stress highlights the need for improved irrigation management in apple orchards under climate change.

Addressing saline soil issues while ensuring agricultural productivity requires innovative technologies. This study investigated the impact of adding an innovative remediation preparation, specifically leguminous compost containing 50 g (LCT+CS-1), 100 g (LCT+CS-2), or 150 g of corn silk kg-1 (LCT+CS-3), to saline soil (ECe = 11.05 dS m-1) on soil characteristics and fenugreek plant performance during the 2022/2023 and 2023/2024 seasons. All organic supplementations significantly improved soil organic matter content, nutrient levels, and enzyme activities (urease, acid and alkaline phosphatase, and catalase) while reducing soil pH and Na+ content compared to the control. These results reflected decreased Na+ content, oxidative stress indicators (hydrogen peroxide and superoxide radicals), and oxidative damage (leaf electrolyte leakage and malondialdehyde levels) in fenugreek plants. On the other hand, leaf integrity (chlorophyll and carotenoid contents, membrane stability index, and relative water content) and nutrient contents improved. Furthermore, K+/Na+ ratio, osmoregulatory compounds (soluble sugars and proline), antioxidant levels (glutathione, ascorbate, phenols, and flavonoids), and antioxidant activity increased notably. Thus, notable increases in plant growth and yield traits and seed quality (trigonelline, nicotinic acid, total phenols, and flavonoids) were achieved. LCT+CS-2 was the most effective treatment for saline soil (ECe = 11.05 dS m-1), alleviating salinity effects and improving fenugreek growth, yield, and seed quality traits.

Simple Summary: To reduce the influence of chemical fertilizers and pesticides on the cultivation of Fritillaria taipaiensis P. Y. Li, this study adopted the application of microbial fertilizer to mitigate soil damage and enhance the plant's stress resistance. In this experiment, the growth index, enzyme activity, and gene expression of F. taipaiensis leaves were measured by applying nitrogen-fixing bacteria. The results showed that nitrogen-fixing bacteria could promote the growth and development of F. taipaiensis. This study not only provides a theoretical foundation for the subsequent cultivation technology of F. taipaiensis but also provides a new idea in terms of the realization of green planting of Chinese medicinal materials. The widespread application of chemical fertilizers and pesticides has resulted in environmental pollution. With the growing emphasis on ecological agriculture in traditional Chinese medicine, microbial fertilizers are increasingly recognized for their potential. The aim of this study is to investigate the effect of inoculating nitrogen-fixing bacteria on the soil (yellow loam, river sand, and organic fertilizer in a 2:1:1 ratio) of Fritillaria taipaiensis, with a focus on the leaf changes in terms of physiological parameters, antioxidant enzyme activity, and corresponding gene expression levels. The experiment involved three nitrogen-fixing bacteria, namely Rahnella aquatilis, Pseudomonas chlororaphis, and Paenibacillus stellifer, with a total of eight treatment groups. The objective was to assess how these bacterial treatments influenced physiological parameters, photosynthetic characteristics, pigment content, and both antioxidant enzyme activities and gene expression in the leaves of F. taipaiensis. The experimental results demonstrated statistically significant reductions (p < 0.05) in malondialdehyde (MDA) content and stomatal limitation value (LS) in F. taipaiensis leaves under treatment conditions relative to the control group (CK). The most substantial decreases were observed dual-inoculation with R. aquatilis and P. stellifer (N5), showing reductions of 38.24% and 20.94% in MDA and LS compared to CK values. Additionally, leaf area, leaf thickness, stem thickness, plant height, photosynthetic parameters, pigment content, soluble sugars, soluble proteins, proline levels, and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) exhibited varying degrees of increase. Compared to the CK group, the SOD, POD, and CAT activities of the N5 group increased by 141.06%, 160.59%, and 106.23%, respectively. The relative gene expression patterns of SOD, POD, and CAT corresponded with the trends observed in their respective antioxidant enzyme activities. Pearson correlation analysis further demonstrated that leaf area and net photosynthetic rate (Pn) were significantly correlated with respect to SOD, POD, and CAT activities, as well as their corresponding gene expression levels. In conclusion, inoculation with nitrogen-fixing bacteria improved the growth and stress tolerance of F. taipaiensis, with the combined application of Rahnella aquatilis and Pseudomonas stellifer yielding the most effective results. This study establishes that different rhizosphere nitrogen-fixing bacteria, either individually or in combination, influence the photosynthetic characteristics, physiological and biochemical parameters, and protective enzyme systems of F. taipaiensis. These findings provide a theoretical foundation for the selection of nitrogen-fixing bacteria as biofertilizers in the artificial cultivation of F. taipaiensis and highlight their potential application in the cultivation of traditional Chinese medicinal materials.

Waterlogging, or excessive accumulation of water in the soil, poses significant stress to riparian ecosystems and agroforestry, especially with increasing global rainfall. Cenchrus fungigraminus is a vital agricultural resource, biomaterial, and super-energy plant with high resistance and adaptability. This study examined its morphological and physiological responses under root and above-ground waterlogging for up to 30 days. Results showed that waterlogging significantly inhibited growth, reducing membrane permeability, and root activity, and accelerating leaf senescence (P < 0.05). Despite this, C. fungigraminus achieved 100 % survival after 30 days of waterlogging. The plant adapted to the hypoxic environment by enhancing oxygen channels through cortex cell loosening, lysigenous tissue formation, and adventitious root development. It also activated defense mechanisms, increasing the activities of antioxidant enzymes (SOD, POD, and CAT), levels of non-enzymatic antioxidants (AsA and GSH), osmotic regulators (SS, SP, and Pro), and anaerobic respiratory enzymes (PDC, ADH, and LDH), and hormones (ABA, IAA, GA, and ETH). Under two levels of waterlogging depth, the plant initially adopted the LowO2 escape strategy (LOES), but over time, it transitioned to the Low-O2 quiescence strategy (LOQS), while still retaining some features of the LOES. Our results revealed that C. fungigraminus demonstrates strong adaptability to waterlogging, especially in response to root waterlogging. By employing anatomical adjustments and exceptional cellular defense mechanisms, the species effectively mitigates damage, establishing itself as an excellent forage grass for slope protection under waterlogged conditions. These results offer valuable guidance for selecting waterlogging-tolerant species to restore and rehabilitate degraded riparian ecosystems in the Yellow River Basin, optimize land use in waterlogging-prone areas, and advance the genetic improvement of waterlogging tolerance in other forage varieties.

The study aimed to determine how the physiological responses of the sunflower (Helianthus annuus L.) plant were affected by prolonged drought stress, salinity stress, and boron application, as well as to assess the recovery dynamics following re-watering. The experimental design included well-watered (WW 80% watering), drought stress (DS, 20% watering) salinity stress (SS, 0 control and 13 dS m-1), boron toxicity (Na2O5B2O3.10H2O, at different doses of 0 and 8 mg L-1) and re-watering after a long-term period of drought stress (24 days). The well-irrigated (80% WW) treatment, which included all factors as a the non-stressed control treatment during the experiment was carried out with five replications. Morphological, physiological and biochemical analyses of plants were measured at four time points: at the 10th and 24th days after the onset of the drought stress period and after re-watering, at 2nd and 7th days following. The relative membrane permeability was increased and relative water content was decreased because drought and salinity stress limited water availability and caused an imbalance in the water status of the leaves and stem of the plant. Even though high levels of Na+ and Cl- ions interfered with essential nutrient uptake under drought stress and boron application, Ca+2 ion levels in the leaves significantly increased in the leaves of plants in areas treated with drought, salt, and boron after re-watering. Extended or intense drought and salinity conditions harmed the phloem and xylem tissue cells of the stem by changing cell size and density, which in turn disrupted biochemical processes, including the functioning of water channels under challenging circumstances. Particularly under conditions of salt and drought stress, the vascular bundles in the plant stem were observed to either shrink significantly or assume an irregular shape. Long-term drought reduced relative water content (RWC) values, resulting in plant dehydration and increased osmotic pressure (RMP) in leaf cells, further exacerbated by salinity and drought stress. The plant attempted to regain some of its characteristics in response to these severe stress conditions after re-watering. However, 24 days after the long dry period, even if watering was re-applied, the growth power of the plant was reduced due to the disturbance in membrane permeability as a result of excessive cell damage.

Drought is one of the most severe environmental stresses affecting soybean growth and development, especially in arid and semi-arid areas. The aim of this experiment is to evaluate the effect of regulated deficit irrigation during the vegetative stages on soybean plants and determine the amount irrigation water can be reduced without affecting the physiological parameters, the crop phenology, and the yield of the soybean crop. The field experiments were conducted during two irrigation crop seasons (2021 and 2022) in Louata, Morocco. The results showed that regulated deficit irrigation regimes during the vegetative stages was combined with high temperatures and low air humidities during the beginning of flowering and the pod filling stage during 2021 in comparison with 2022, especially for 25% CWR (crop water requirements). Regulated deficit irrigation regimes reduced the stomatal conductance by 46% and 52% respectively during the first and second growing seasons by limiting CO2 intake for the Calvin cycle. The stomata closure increased the leaf temperature and affected the functioning of the photosynthetic apparatus by damaging the chlorophyll pigments and impairment of electron transport chains in chloroplasts. The transition from regulated deficit irrigation to 100% CWR at the beginning of flowering (R1) compensated for the photosynthetic loss, improved the growth and development of soybean plants and enhanced the yield and its components for 50% and 75% CWR. The adaptative mechanism such as the remobilization of the carbon reserved in the stems and leaves (vegetative tissues) to the grains improved the grain yield by 36.7% during 2021 and by 32.2% during 2022 and. This consequently improved the water use efficiency, the water productivity of soybean for 50% and 75% CWR and contributed to water saving with an average of 60 mm per growing season. (c) 2024 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC- ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

To comprehensively understand the toxic effects and ecological risks of microplastics on major economic tree species, a pot experiment was conducted using polylactic acid (mPLA) microplastics as the test object to explore the effects of different concentrations (0.1%, 0.5%, 1%, 5%, 10%, w/w, mass fraction) of microplastics on the growth and physiological characteristics of mulberry trees. The study results showed that, compared with the control group, the biomass, total chlorophyll content, and net photosynthetic rate of mulberry trees in the mPLA treatment group were significantly reduced under high concentration (10%) treatment; the activities of SOD and CAT and the MDA content were significantly increased by 50.00%, 47.83%, and 60.87%, respectively, at a 10% concentration. The results indicate that the toxic effects of microplastic addition on mulberry trees are related to the type and concentration of microplastics. High concentrations of mPLA can damage the photosynthetic system of plants, affecting photosynthesis, causing oxidative damage and thus inhibiting the growth of mulberry plants.

This study investigated the infestation of tomato plants by the plant-parasitic nematode, M. incognita, and its accurate detection by plant electrophysiology (PE). Dedicated tests were done on whole plants to record electrophysiological signals from nematode infested and uninfested plants and to establish a trained model indicating nematode-induced stress. Monitoring nematode-induced stress by PE confirmed the results obtained by assessing root galls and quantifying xylem sap 3 to 4 weeks after infestation. The machine learning model captured the stress intensities and the time course of plant damage caused by nematodes. Stress caused by second-stage juveniles (J2) infestation appeared 3 to 5 days after infestation (DAI), whereas stress caused by egg infestation was detected 5 to 7 days later (10-13 DAI). For the first time, the real-time effectiveness of nematicides was recorded in further tests. Nematode infested plants treated preventatively with cyclobutrifluram (TYMIRIUM (R) technology) showed a delayed and short (about 3 days) period of low stress intensity, whereas infested but untreated plants showed a period of maximum stress for about 12 days. In addition, depending on the type of application (preventative or curative), different modes of biological activity of IRAC group N-2 and N-3 nematicides (fluopyram, abamectin) could be captured by PE signalling. PE offers a new way of monitoring plant health in real time, which is particularly valuable for accessing 'invisible' pests, such as plant-parasitic nematodes in the soil.

Diesel spills and nuclides pollution cause global ecosystem and human health problems. The remediation of contaminated soil using woody plants has received considerable attention. Differences in plant species and sex can lead to differences in tolerance to various stressors. We aimed to investigate the response of male and female seedlings of Populus cathayana and Salix babylonica to diesel and Sr2+ stress and to compare the enrichment characteristics of Sr2+ in trees. Male and female seedlings of P. cathayana and S. babylonica were treated with diesel fuel and 0, 10 (low), and 100 (high) mg Kg(-1) of Sr2+. Results showed that P. cathayana and S. babylonica had good enrichment characteristics and tolerance. S. babylonica had a more robust tolerance and ability to remediate contaminated soil than P. cathayana. The defense mechanisms of both female seedlings in response to stress were similar, while males showed different defense strategies. Male trees had higher Sr2+ enrichment capacity, antioxidant enzymes, soil enzyme activity, and soluble matter content, indicating that males had higher tolerance capacity than females. Under diesel stress alone, the reduced photosynthetic rate of male seedlings of P. cathayana was mainly limited by stomatal factors, and their photosynthetic system was more tolerant to diesel. POD and APX activities, as well as alkaline phosphatase and urease activities in the soil, were significantly higher in S. babylonica seedlings than in P. cathayana, indicating that S. babylonica seedlings were more resistant to diesel pollution. At low concentrations of the Sr2+ complex, diesel and Sr2+ showed antagonistic effects in reducing the damage caused by stress. As the Sr2+ concentration increased, damage to the plants manifested primarily through synergistic enhancement. The results of this study provide a scientific basis for the remediation of diesel fuel and nuclides contaminated soils using woody plants.

Nitrogen deposition and drought significantly influence plant growth and soil physicochemical properties. This study investigates the effects of nitrogen deposition and water stress on the growth and physiological responses of Quercus dentata, and how these factors interact to influence the overall productivity. Two-year-old potted seedlings were selected to simulate nitrogen deposition and water stress. Nitrogen was applied at rates of 0 kgha-1year-1 (N0) and 150 kgha-1year-1 (N150). The levels of water stress corresponded to 80% (W80), 50% (W50), and 20% (W20) of soil saturation moisture content. High nitrogen (N150) significantly increased stem elongation and stem diameter by enhancing photosynthetic parameters, including P n (W80) and G s (W50), and maintained higher water use efficiency. Under drought conditions, nitrogen enhanced leaf water content, stabilized electrical conductivity, regulated antioxidant enzyme activity, and increased the accumulation of proline. However, under severe drought, nitrogen did not significantly improve biomass, highlighting the critical role of water availability. Additionally, increased nitrogen levels enhanced soil enzyme activity, facilitated the uptake of crucial nutrients like K and Zn. Mantel tests indicated significant correlations between soil enzyme activity, water use efficiency, and leaf Fe content, suggesting that nitrogen deposition altered nutrient uptake strategies in Q. dentata to sustain normal photosynthetic capacity under water stress. This study demonstrates that nitrogen deposition substantially enhances the growth and physiological resilience of Q. dentata under W50 by optimizing photosynthetic efficiency, water use efficiency, and nutrient uptake. However, the efficacy of nitrogen is highly dependent on water availability, highlighting the necessity of integrated nutrient and water management for plant growth.