Plant G protein γ subunits have multiple functions in growth and development processes and in abiotic stress responses. Few functions of Gγ in horticultural crops have been revealed thus far. In this study, the potential function of CsGG3.1-2, one of the two alternative splice variants of Gγ gene CsGG3.1 in cucumber (Cucumis sativus L.), was investigated using transgenic plants overexpressing antisense CsGG3.1-2 under the control of the 35S promoter. The tolerance to chilling stress in transgenic plants was significantly decreased. Cold stress-related physiological parameters and the expression of CBFs and their downstream target genes were then measured. Compared with WT, the maximum efficiency of photosystem II (Fv/Fm), antioxidative enzymes activities, soluble protein, and proline accumulation decreased significantly in transgenic plants treated with cold stress, whereas the malonaldehyde (MDA) content increased. However, the overexpression of antisense CsGG3.1-2 did not affect the induction of cold-inducible genes. Quantitative real-time PCR (qPCR) analysis showed the increased expression of CBF genes and their downstream target genes in transgenic plants, suggesting that CsGG3.1-2 affects cold responses via CBF-independent pathways in cucumber. At the same time, the sucrose and fructose contents decreased in transgenic plants under both normal and cold conditions. These findings suggest that soluble sugar deficiency is associated with chilling sensitivity in transgenic plants, and CsGG3.1-2 may have a role in regulating carbohydrate metabolism in cucumber.

Due to its sensitivity to cold temperatures, cucumber growth is substantially constrained by suboptimal temperature stress in northern China’s off-season production systems. Suboptimal temperatures severely repress the nutrient absorption, growth, and yield formation of vegetables in solar greenhouses during winter and early spring in China. Alginate oligosaccharides (AOSs) are anionic acidic polysaccharides derived from brown algae, known for promoting plant growth and alleviating abiotic stress. In this study, we aimed to investigate the effects of different nutrient solution concentrations combined with AOS on the growth and nutrient uptake of cucumber seedlings under suboptimal temperatures (15/8 °C, day/night). Potted ‘Jinchun 4’ cucumber seedlings grown in coconut coir were treated with 0.5×, 1.0×, or 1.5× strength of Hoagland solution alone (N0.5, N1, N1.5), or with 30 mg·L⁻¹ AOS (A0.5, A1, A1.5). The results showed that the growth attributes and nitrogen (N) accumulation of cucumber plants of N1 and N1.5 were significantly higher than those of N0.5. Additionally, plants of A0.5 exhibited significantly higher plant height, chlorophyll a content, root surface area, root volume, root vitality, N metabolism enzyme (NR, GDH, GS) activities, and N accumulation, than those under N0.5, N1, or N1.5. Moreover, compared to A0.5, the net photosynthetic rate, total root length, root surface area, root N content, leaf nitrate reductase activity, root glutamate dehydrogenase activity, and N accumulation of A1 and A1.5 were significantly higher than those of A0.5. Correlation analysis revealed strong linkages between root morphology traits and tissue N content. In summary, under suboptimal temperature conditions, the application of AOS improved cucumber seedlings’ nutrient absorption and growth more efficiently than merely raising nutrient levels, as it enhanced root surface area, root vitality, and N metabolic enzyme activities.

The large-span insulated plastic greenhouse is a highly promising horticultural facility. The design parameters and configuration of structural components significantly impact their safety and load-bearing performance. However, current research in this field remains insufficient. In this study, the deformation, stress distribution, and stability of large-span insulated plastic greenhouses with different structural configurations were investigated using the finite element method. Subsequently, the ultimate bearing capacity of large-span insulated plastic greenhouses with varying ridge heights was examined. The research indicated that the greenhouse with a plane truss and double-layer tie rod exhibited the smallest deformation and stress in its members, as well as the highest ultimate load-bearing capacity. The analysis revealed that the installation of double-layer tie rods not only enhanced the collaborative effect of arch frames within the structural calculation unit but also reduced displacement along the Z direction, effectively mitigated the $\mathrm{P}-∆$ effect, reduced out-of-plane bending stress, and improved the ultimate load-bearing capacity. Ridge height affected the load-bearing capacity of the greenhouse structure. However, a higher ridge height did not necessarily result in a stronger ultimate load-bearing capacity. The greenhouse structure with a ridge height of 5 m demonstrated the maximum ultimate load-bearing capacity, capable of bearing 1.98 times the initial load. This study provides theoretical support for the configuration of structural components of large-span insulated plastic greenhouses and offers a scientific basis for the optimal design of ridge height.

Alginate oligosaccharides (AOSs) have been shown to be effective in enhancing crop growth. However, their functions in horticulture crops and growth-promoting mechanisms remain insufficiently characterized. This study employed pot cultivation experiments to investigate the effects of AOS root drenching (0, 15, 30, 45 mg·L⁻¹) on tomato (Solanum lycopersicum L.) seedling growth, photosynthetic performance, and phytohormone accumulation. The results showed that AOS promoted the leaf count per plant, leaf area of the youngest fully expanded leaves, shoot and root dry mass, chloroplast pigment contents and photosynthetic rate of tomato seedlings. And the 30 mg·L⁻¹ treatment consistently showed optimal efficacy, in which tomato seedlings also exhibited a significantly longer total root length, a larger root surface area and a greater number of root tips compared to the control. Phytohormone profiling revealed that AOS differentially regulated shoot/root phytohormones as follows: increasing auxins/cytokinins (CKs)/GA₁₉ content in shoots and Indole-3-acetic acid (IAA)/CKs/1-aminocyclopropane-1-carboxylic acid (ACC) content in roots, while decreasing root Jasmonic acid (JA)/5-deoxystrigol (5DS) contents. Finally, these findings demonstrate that AOS enhances tomato growth by coordinately reprogramming phytohormone homeostasis.