Drought area expansion has a great impact on the growth and development of plants. To contribute to the water management of strawberry, this work aims to study the chronological relationship between the electrical signals and representative physiological parameters of strawberry seedlings under drought stress. This study analyzed the characteristic variables of the electrical signals; physiological parameters under drought; and control treatments. Moreover, we compared the chronological sequence of the appearance of significant differences between drought and control treatment in terms of their physiological parameters and electrical signals. The results showed that with the increase of drought treatment, the time domain parameters (peak-to-peak value, standard deviation) and frequency domain parameters (spectral of central gravity, power spectrum entropy) of the drought-treated electrical signals showed significant differences from the control on Day 2 and Day 6, respectively (p < 0.05). The root vitality of the drought treatment was significantly different from the control on Day 4 (p < 0.05); the Fv/Fm and the SPAD were significantly different (p < 0.05) on Day 7. Electrical signals first start to show a significant difference between drought and control treatment, followed by physiological parameters. Therefore, the electrical signal can be used as an early indicator of drought stress conditions. This will provide a scientific basis for the actual water management of strawberry seedlings. It also provides a methodological and theoretical basis for other studies analyzing the relationship between plant physiological parameters and electrical signals under other stress conditions.

Background and Objectives: Drought occurs more frequently in Northern China with the advent of climate change, which might increase the mortality of tree seedlings after afforestation due to hydraulic failure. Therefore, investigating water relations helps us understand the drought tolerance of tree seedlings. Electrical impedance spectroscopy (EIS) is widely used to assess the responses of plant tissues to stress factors and may potentially reveal the water relations of cells. The aim of this study is to reveal the relationships between EIS and water related parameters, produced by pressure–volume (PV) curves in lacebark pine (Pinus bungeana Zucc.) seedlings reacting to drought stress. Materials and Methods: Four-year-old pot seedlings were divided into three parts (0, 5, and 10 days of drought) before planting, the treated seedlings were then replanted, and finally exposed to post-planting drought treatments with the following soil relative water contents: (i) adequate irrigation (75%–80%), (ii) light drought (55%–60%), (iii) moderate drought (35%–40%), and (iv), severe drought (15%–20%). During the post-planting growth phase, the EIS parameters of needles and shoots, and the parameters of PV curves, were measured coincidently; thus, the correlations between them could be obtained. Results: The extracellular resistance (r_e) of needles and shoots were substantially reduced after four weeks of severe post-planting drought stress. Meanwhile, the osmotic potential at the turgor-loss point (ψ_tlp) and the saturation water osmotic potential (ψ_sat) of shoots decreased after drought stress, indicating an osmotic adjustment in acclimating to drought. The highest correlations were found between the intracellular resistance (r_i) of the shoots and ψ_tlp and ψ_sat. Conclusions: EIS parameters can be used as a measure of drought tolerance. The change in intracellular resistance is related to the osmotic potential of the cell and cell wall elasticity. Extracellular resistance is a parameter that shows cell membrane damage in response to drought stress in lacebark pine seedlings.

Plants are susceptible to a variety of abiotic stresses during the growing period, among which low temperature is one of the more frequent stress factors. Maintaining water balance under cold stress is a difficult and critical challenge for plants. Studies have shown that aquaporins located on the cytomembrane play an important role in controlling water homeostasis under cold stress, and are involved in the tolerance mechanism of plant cells to cold stress. In addition, the aquaporin gene family is closely related to the cold resistance of plants. As a major greening tree species in urban landscaping, Ligustrum× vicaryi Rehd. is more likely to be harmed by low temperature after a harsh winter and a spring with fluctuating temperatures. Screening the target aquaporin genes of Ligustrum × vicaryi responding to cold resistance under natural cold stress will provide a scientific theoretical basis for cold resistance breeding of Ligustrum × vicaryi. In this study, the genome-wide identification of the aquaporin gene family was performed at four different overwintering periods in September, November, January and April, and finally, 58 candidate Ligustrum × vicaryi aquaporin (LvAQP) genes were identified. The phylogenetic analysis revealed four subfamilies of the LvAQP gene family: 32 PIPs, 11 TIPs, 11 NIPs and 4 SIPs. The number of genes in PIPs subfamily was more than that in other plants. Through the analysis of aquaporin genes related to cold stress in other plants and LvAQP gene expression patterns identified 20 LvAQP genes in response to cold stress, and most of them belonged to the PIPs subfamily. The significantly upregulated LvAQP gene was Cluster-9981.114831, and the significantly downregulated LvAQP genes were Cluster-9981.112839, Cluster-9981.107281, and Cluster-9981.112777. These genes might play a key role in responding to cold tolerance in the natural low-temperature growth stage of Ligustrum × vicaryi.

Catalpa bungei C.A.Mey is an economically significant deciduous tree valued for timber production and landscaping applications. An efficient regeneration system is crucial for clonal propagation and serves as a foundation for future molecular breeding in C. bungei. This study established two in vitro regeneration pathways—indirect somatic embryogenesis and shoot organogenesis utilizing mature zygotic embryos as explants. Primary callus was induced from cotyledon, hypocotyl, and plumule explants. A high frequency (45.73%) of yellow-green compact callus was achieved on De-Klerk and Walton (DKW) medium supplemented with 2.0 mg/L 6-BA, 1.0 mg/L zeatin (ZT), and 0.1 mg/L NAA. Subsequent transfer to 1.5× Murashige and Skoog (MS) medium containing 1.5 mg/L 6-BA, 0.2 mg/L ZT, and 0.1 mg/L NAA yielded the highest embryogenic callus induction rate (16.67%). Embryogenic callus demonstrated bipotent potential, generating both adventitious shoots and somatic embryos under specific hormonal conditions. Histological analyses confirmed the typical developmental stages of somatic embryos, from globular to cotyledonary forms, validating the embryogenic origin of regenerated structures. Furthermore, hormone or osmotic additives such as abscisic acid (ABA), Phytagel, and polyethylene glycol 4000 (PEG4000) significantly enhanced somatic embryo induction, with Phytagel at 5.0 g/L achieving the highest rate (76.31%). For shoot organogenesis, the optimal hormonal combination of the 0.6 mg/L 6-BA, 0.4 mg/L KT, and 0.15 mg/L NAA achieved the highest bud induction rate (88.89%) and produced an average of 4.07 adventitious buds per explant. This study presents an efficient regeneration system for C. bungei, providing a practical platform for large-scale propagation and basis for biotechnological applications in woody plants.

Background: Maintaining water balance in various adversities is a difficult and critical challenge for plants. Studies have shown that aquaporins located on cytomembrane play an important role in maintaining water homeostasis under various environmental stresses. Some studies have shown that aquaporins are involved in the tolerance mechanism of plant cells under cold stress, and the aquaporin gene family is closely related to the cold resistance of plants. Ligustrum × vicaryi Rehd. plays a significant role in urban landscaping with poor cold resistance at the seedling stage and early planting stage. Screening the target aquaporin genes of Ligustrum × vicaryi related to cold resistance during natural cold stress will provide a scientific theoretical basis for cold resistance breeding of Ligustrum × vicaryi.Results: In this study, the genome-wide identification of the aquaporin gene family was performed at four different overwintering periods in September, November, January and April, and finally 58 candidate Ligustrum × vicaryi aquaporin (LvAQP) genes were identified. The phylogenetic analysis revealed that four subfamilies of the LvAQP gene family: 32 PIPs, 11 TIPs, 11 NIPs, and 4 SIPs, among which there were more genes in the PIPs subfamily than that in other plants. The key LvAQP genes were found through analyzing aquaporin genes related to cold stress in other plants and LvAQP genes expression profiles. The up-regulated key LvAQP genes were Cluster-9981.114831, Cluster-9981.104986, and Cluster-9981.120365, and the down-regulated key LvAQP genes were Cluster-9981.112839, Cluster-9981.109034, Cluster-9981.89369, Cluster-9981.110451, Cluster-9981.107281, Cluster-9981.112777, Cluster-9981.112789, Cluster-9981.122691 and Cluster-9981.88037. These genes play a key role related to cold tolerance in the nature low temperature growth stage of Ligustrum × vicaryi. Conclusions: This study systematically identified the AQP gene family in Ligustrum × vicaryi and screened for 20 differential expression LvAQP genes related to cold stress, among which 11 genes belonged to PIPs subfamily. The results of this research will lay the foundation for further biological function verification of cold resistance-related aquaporin candidate genes in Ligustrum × vicaryi, especially PIPs subfamily, and provide theoretical basis and technical support for improving seedling quality and breeding.

Understanding the dynamics of root zone soil water content is crucial for precision irrigation scheduling in protected strawberry cultivation. The HYDRUS-3D model is capable of simulating three-dimensional water flow and root water uptake. Although the model has been tested in various settings, its validation under realistic greenhouse cultivation rack systems with direct soil moisture measurements remains limited. In this study, a HYDRUS-3D model was developed to simulate root zone soil water dynamics in a greenhouse U-shaped strawberry cultivation system under both irrigated and non-irrigated conditions, with and without plastic mulch. In the first year, the model’s accuracy was evaluated using a newly developed line-scale dielectric soil moisture sensor. The simulated volumetric soil water content showed good agreement with sensor measurements across all scenarios (R² ≥ 0.8302, RMSE ≤ 0.0309, NSE ≥ 0.5979). In the following two years, we utilized the established model to schedule irrigation and investigated its water-saving effects. Model-scheduled irrigation reduced water use by 8.45–13.36% compared with conventional irrigation scheduling. No significant differences were observed in most morphological, physiological, fruit quality, or yield indicators (p > 0.05). However, occasional improvements were detected in chlorophyll content, root activity, ascorbic acid and total soluble solids. These findings demonstrate that HYDRUS-3D effectively simulates root zone water content dynamics throughout the strawberry growth cycle and serves as a practical tool for precision soil water management in greenhouse cultivation rack systems.