Anthocyanins endow tomatoes with richer nutritional characteristics. This study provides a comprehensive evaluation of the anthocyanin-rich tomato germplasm black ‘Pearl,’ which features an appealing purple flesh. The high levels of anthocyanins, antioxidant enzymes, vitamin C, and vitamin E confer a strong total antioxidant capacity. The organic acid and soluble sugar content in flesh are slightly lower, and it has a mild bitterness, with storage characteristics inferior to red-fleshed tomatoes. The correlation analysis between transcriptomics and metabolomics indicates that multiple structural genes and transcription factors in the anthocyanin biosynthetic pathway actively regulate the synthesis of anthocyanins. UPLC-ESI-MS/MS analysis of mature fruits identified a total of 43 types of anthocyanins, including six novel anthocyanins such as petunidin-3-O-rutinoside-5-O-rhamnoside and petunidin-3-O-feruloyl-xyloside-rutinoside. This study enriches our understanding of anthocyanin synthesis and metabolites in tomatoes, while the unique anthocyanins present in black ‘Pearl’ provide important genetic resources for the future development of high-quality, anthocyanin-rich tomato varieties.

Strawberries are vulnerable to postharvest microbial contamination, with gray mold from Botrytis cinerea being significant. Plasma-activated water (PAW) is a promising sustainable food sterilization method. This study evaluated PAW's efficacy in inhibiting postharvest strawberry microbial infections, delaying gray mold, and assessing quality, exploring its potential as an alternative to fungicides. Results showed PAW inhibited B. cinerea growth and delayed decay during storage. PAW reduced pathogenic-related genes in B. cinerea (BCBCG1, BCATG1, BCSTR2, BCSOD1) while enhancing defense-related genes in strawberries (FaPAL, FaPOD, FaCHI, FaGLU). To counteract PAW-induced reactive oxygen species (ROS), antioxidant-related genes (FaSOD, FaCAT, FaAPX, FaGR) are upregulated with increased enzyme activities. PAW treatment was associated with enhanced defense responses and redox homeostasis in strawberry fruit, potentially contributing to increased resistance to B. cinerea infection. In addition, PAW helped maintain strawberry quality during storage, thereby extending its shelf life.

Tomato leaf mold caused by Cladosporium fulvum (C. fulvum, syn. Passalora fulva) is one of the most devastating diseases affecting tomatoes. C. fulvum evolves very fast. Cultivars containing Cf that are resistant to C. fulvum are easily infected by newly differentiated physiological races. In this study, physiological and biochemical indicators of Cf-12 plants and knockout lines Slcf-12-28 were determined, and transcriptomic analysis was performed after inoculation to elucidate the molecular mechanism of the incompatibility interaction between Cf-12 and C. fulvum. The results showed that Cf-12 could quickly recognize the effectors secreted by C. fulvum and induce a large number of reactive oxygen species at the infection site, which led to a rapid increase in antioxidant enzyme activities and the accumulation of antibacterial substances such as phenylalanine ammonia-lyase, phytoalexin, lignin, phenols, and flavonoids during secondary metabolism. At the same time, it induces the upregulation of AOS, AOC and OPR in the JA synthesis pathway, and activates the expression of early resistance response genes initiated by JA. Finally, local hypersensitive necrosis occurred in the cells around the infection points of C. fulvum, limiting further infection of C.fulvum. In conclusion, these results contribute to further understanding of the molecular mechanism of the incompatibility interaction between Cf and C. fulvum.

Abiotic and biotic stresses threaten crop yield. Grafting promotes the resistance of vegetables to environmental stresses. However, rootstocks with enhanced resistance to multiple stressors are scarce and potential mechanisms remain obscure. Here, we screened a tomato rootstock 'QZ71' with resistance to salt, saline-alkali, drought stress, Fusarium oxysporum and Phytophthora capsici root rot. Compared with the self-root grafted cultivar 'STG2', rootstock grafting showed increased resistance to single and combined salt and P. capsici stress. Salt alone had a greater effect than P. capsici infection alone, and the adverse impact was worsened under combined stresses. Moreover, grafting-enhanced resistance was related to maintaining K+/Na+ homeostasis, increasing defensive enzyme activities and lignin biosynthesis and activating the expression of their associated genes. Importantly, grafting significantly increased SA content and the expression of SA signalling marker genes, including SlNPR1 and SlPR-1. Conversely, SA-deficient mutant NahG rootstock grafting obviously attenuated the resistance by inhibiting the expression of ion transporters, defence enzymes, lignin synthesis and SA signalling marker genes. Together, our findings demonstrated, for the first time, that the excellent tomato rootstock QZ71 enhanced resistance to single and combined salt and P. capsici stress by activating the SA signalling pathway, highlighting the importance of rootstock selection in improving crop performance.

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 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.

Tomatoes are frequently challenged by various pathogens, among which Phytophthora capsici (P. capsici) is a destructive soil-borne pathogen that seriously threatens the safe production of tomatoes. Plant growth-promoting rhizobacteria (PGPR) positively induced plant resistance against multiple pathogens. However, little is known about the role and regulatory mechanism of PGPR in tomato resistance to P. capsici. Here, we identified a new strain Serratia plymuthica (S. plymuthica), HK9-3, which has a significant antibacterial effect on P. capsici infection. Meanwhile, stable colonization in roots by HK9-3, even under P. capsici infection, improved tomato growth parameters, root system architecture, photosynthetic capacity, and boosted biomass. Importantly, HK9-3 colonization significantly alleviated the damage caused by P. capsici infection through enhancing ROS scavenger ability and inducing antioxidant defense system and pathogenesis-related (PR) proteins in leaves, as evidenced by elevating the activities of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and chitinase, β-1,3-glucanase, and increasing the transcripts of POD, SOD, CAT, APX1, PAL1, PAL2, PAL5, PPO2, CHI17 and β-1,3-glucanase genes. Notably, HK9-3 colonization not only effectively improved soil microecology and soil fertility, but also significantly enhanced fruit yield by 44.6% and improved quality. Our study presents HK9-3 as a promising and effective solution for controlling P. capsici infection in tomato cultivation while simultaneously promoting plant growth and increasing yield, which may have implications for P. capsici control in vegetable production.

The development of environmentally friendly slow-release fertilizers with effective water retention is an urgent need in modern agriculture. Although biochar can improve soil fertility as a nutrient carrier, it suffers from poor slow-release performance and water retention. Conversely, soy protein hydrogels, characterized by their hydrophilic nature with three-dimensional cross-linked networks, can retain large amounts of water and facilitate the slow release of fertilizers and water due to their high specific surface area. Hence, a novel slow-release composite material with high water retention was prepared by introducing bamboo biochar into a soy protein–based hydrogel (SPB) network through graft copolymerization. The findings indicated that the bamboo biochar promoted the SPB cross-linked network density, which improved the swelling rate of SPB materials and soil water-holding capacity. Moreover, SPB-2–4

Drought limits crop growth and yield. Inoculation with plant growth-promoting rhizobacteria (PGPR) emerges as a promising strategy to protect crops against drought. However, the number of drought-tolerant PGPR is limited, and the regulation mechanisms remain elusive. Here, we screened a novel drought-tolerant PGPR strain Paenibacillus polymyxa HL14-3 with high drought-tolerance potential and efficient colonization ability. P. polymyxa HL14-3 inoculation effectively alleviated drought-induced growth inhibition and oxidative stress and improved the root system architecture in cucumber. Furthermore, P. polymyxa HL14-3 improved stomatal closure and leaf relative water content, reducing water loss in cucumber under drought stress. Importantly, P. polymyxa HL14-3 inoculation enhanced drought tolerance in cucumber by inducing abscisic acid synthesis, which was counteracted by root irrigation with the ABA synthesis inhibitor fluridone. Together, our results demonstrate that P. polymyxa HL14-3 inoculation enhances drought tolerance in cucumber by triggering ABA-mediated stomatal closure, providing an effective drought-tolerant PGPR for promoting agricultural production in arid areas.

Effective colonization on plant roots is a prerequisite for plant growth promoting rhizobacterias (PGPR) to exert beneficial activities. Light is essential for plant growth, development and stress response. However, how light modulates root colonization of PGPR remains unclear. Here, we found that high red/far red (R/FR) light promoted and low R/FR light inhibited the colonization and growth enhancement of Serratia plymuthica A21-4 (S. plymuthica A21-4) on tomato, respectively. Non-targeted metabolomic analysis of root exudates collected from different R/FR ratio treated tomato seedlings with or without S. plymuthica A21-4 inoculation by UPLC-MS/MS showed that 64 primary metabolites in high R/FR light-grown plants significantly increased compared with those determined for low R/FR light-grown plants. Among them, 7 amino acids, 1 organic acid and 1 sugar obviously induced the chemotaxis and biofilm formation of S. plymuthica A21-4 compared to the control. Furthermore, exogenous addition of five artificial root exudate compontents (leucine, methionine, glutamine, 6-aminocaproic acid and melezitose) regained and further increased the colonization ability and growth promoting ability of S. plymuthica A21-4 on tomato under low R/FR light and high R/FR light, respectively, indicating their involvement in high R/FR light-regulated the interaction of tomato root and S. plymuthica A21-4. Taken together, our results, for the first time, clearly demonstrate that high R/FR light-induced root exudates play a key role in chemotaxis, biofilm formation and root colonization of S. plymuthica A21-4. This study can help promote the combined application of light supplementation and PGPR to facilitate crop growth and health in green agricultural production.

Salinity stress badly restricts the growth, yield and quality of vegetable crops. Plant growth-promoting rhizobacteria (PGPR) is a friendly and effective mean to enhance plant growth and salt tolerance. However, information on the regulatory mechanism of PGPR on vegetable crops in response to salt stress is still incomplete. Here, we screened a novel salt-tolerant PGPR strain Pseudomonas aeruginosa HG28-5 by evaluating the tomatoes growth performance, chlorophyll fluorescence index, and relative electrolyte leakage (REL) under normal and salinity conditions. Results showed that HG28-5 colonization improved seedling growth parameters by increasing the plant height (23.7%), stem diameter (14.6%), fresh and dry weight in the shoot (60.3%, 91.1%) and root (70.1%, 92.5%), compared to salt-stressed plants without colonization. Likewise, HG28-5 increased levels of maximum photochemical efficiency of PSII (Fv/Fm) (99.3%), the antioxidant enzyme activities as superoxide dismutase (SOD, 85.5%), peroxidase (POD, 35.2%), catalase (CAT, 20.6%), and reduced the REL (48.2%), MDA content (41.3%) and ROS accumulation in leaves of WT tomatoes under salt stress in comparison with the plants treated with NaCl alone. Importantly, Na+ content of HG28-5 colonized salt-stressed WT plants were decreased by15.5% in the leaves and 26.6% in the roots in the corresponding non-colonized salt-stressed plants, which may be attributed to the higher K+ concentration and SOS1, SOS2, HKT1;2, NHX1 transcript levels in leaves of colonized plants under saline condition. Interestingly, increased abscisic acid (ABA) content and upregulation of ABA pathway genes (ABA synthesis-related genes NCED1, NCED2, NCED4, NECD6 and signal genes ABF4, ABI5, and AREB) were observed in HG28-5 inoculated salt-stressed WT plants. ABA-deficient mutant (not) with NCED1 deficiency abolishes the effect of HG28-5 on alleviating salt stress in tomato, as exhibited by the substantial rise of REL and ROS accumulation and sharp drop of Fv/Fm in the leaves of not mutant plants. Notably, HG28-5 colonization enhances tomatoes fruit yield by 54.9% and 52.4% under normal and saline water irrigation, respectively. Overall, our study shows that HG28-5 colonization can significantly enhance salt tolerance and improved fruit yield by a variety of plant protection mechanism, including reducing oxidative stress, regulating plant growth, Na+/K+ homeostasis and ABA signaling pathways in tomato. The findings not only deepen our understanding of PGPR regulation plant growth and salt tolerance but also allow us to apply HG28-5 as a microbial fertilizer for agricultural production in high-salinity areas.

Long-distance signals play a vital role in plant stress response. γ-aminobutyric acid (GABA) has been proposed to be a signal and protects crops against diverse stresses. However, whether GABA acts as a long-distance signal to plant response to stresses remains unknown. Here, we found that the GABA content in cucurbita rootstocks, especially figleaf gourd, was significantly higher than that in cucumber. Figleaf gourd rootstock obviously enhanced cold tolerance and GABA accumulation in roots, xylem sap and leaves of grafting cucumber seedlings. Conversely, GABA synthesis inhibitor 3-mercaptopropionic acid (3-MPA) irrigation was more effective than its foliar application in inhibiting grafting-induced cold tolerance. Moreover, fluorescence microscopy confirmed that GABA can be transported from root to shoot through the xylem when the roots of grafted seedlings were fed with fluorescein isothiocyatate-labeled GABA under normal and cold stress conditions. Importantly, 3-MPA irrigation attenuated grafting-induced cold tolerance, as revealed by a decline in the GABA accumulation, the transcripts of ICE1, CBF1 and COR47, the activities of the antioxidant enzymes, and an increase in stomatal aperture. Collectively, our findings strongly support that GABA functions as a novel long-distance signal in figleaf gourd rootstock-induced cold tolerance of grafted cucumber seedlings by modulating CBF-signalling pathways, antioxidant system and stomatal aperture, providing new evidence for long-distance signaling-mediated cold response of plants.

Pyroxasulfone (PYS) is an isoxazole herbicide favored for its high activity. However, the metabolic mechanism of PYS in tomato plants and the response mechanism of tomato to PYS are still lacking. In this study, it was found that tomato seedlings had a strong ability to absorb and translocate PYS from roots to shoots. The highest accumulation of PYS was in the apex tissue of the tomato shoots. Using UPLC-MS/MS, five metabolites of PYS were detected and identified in tomato plants, and their relative contents in different parts of tomato plants varied greatly. The serine conjugate, DMIT [5, 5-dimethyl-4, 5-dihydroisoxazole-3-thiol (DMIT)] &Ser, was the most abundant metabolites of PYS in tomato plants. In tomato plants, the conjugation of thiol-containing metabolic intermediates of PYS to serine may mimic the cystathionine β-synthase-catalyzed condensation of serine and homocysteine (in the pathway sly00260 sourced from KEGG database). This study ground breakingly proposed that serine may play an important role in plant metabolism of PYS and fluensulfone (whose molecular structure is similar to PYS). PYS and atrazine (whose toxicity profile is similar to PYS but not conjugate with serine) produced different regulatory outcomes for endogenous compounds in the pathway sly00260. Differential metabolites in tomato leaves exposed to PYS compared with the control, including amino acids, phosphates, and flavonoids, may play important roles in tomato response to PYS stress. This study provides inspiration for the biotransformation of sulfonyl-containing pesticides, antibiotics and other compounds in plants.

Soil salinity severely limits crop yield and quality. Grafting onto tolerant rootstocks is known as an effective means to alleviate salt stress. The present study was planned to find out the potential roles, mechanisms and applications of luffa rootstock to improve salt tolerance of grafted cucumber plants. Here, we screened a highly salt-tolerant luffa rootstock by evaluating the growth, photosynthetic performance, antioxidant defense and the accumulation of Na+ and K+ under salt stress. Reciprocal grafting between cucumber and luffa showed that luffa rootstock significantly improved the salt tolerance of cucumber plants, as evidenced by higher fresh weight, photochemical efficiency (Fv/Fm), and lower relative electrical conductivity (REC), which was closely associated with the decreased accumulation of Na+ and increased the accumulation of K+ in shoots of luffa grafted cucumber seedlings, leading to a lower Na+:K+ ratio in shoot when compared with self-grafted cucumber. Furthermore, grafting with intermediate stock of luffa also sufficiently alleviated cucumber salt stress by reducing Na+ accumulation in shoot and the whole plant but increasing Na+ accumulation in interstock and root under salt stress, fully proving the salt tolerance depending on the capacity of luffa interstock to limit the transport of Na+ from the root to the shoot. More importantly, luffa rootstock improved the growth, yield and quality of grafted cucumber plants grown in pots in solar greenhouse as revealed by increased net photosynthetic rate, plant height, leaf number, yield, Vitamin C and soluble sugar but decreased titratable acid under both salinity and normal conditions. Together, these results, for the first time, clearly demonstrated that luffa,a new highly salt-tolerant rootstock, enhances salt tolerance and improves yield and quality of grafted cucumber plants by reducing sodium transport to the shoot.

NAC transcription factors (TFs) play an important role in the plant resistant response to biotic and abiotic stresses. However, the functions of the most NAC TFs are still unknown, especially in tomato. Here, we identified and functionally characterized an NAC TFs, SlNAP1, in tomato, and found that SlNAP1 was significantly induced by salt stress. Under 150 mM NaCl treatments, morphological indexes of SlNAP1 over-expressed (SlNAP1-OE) transgenic tomato lines were significantly better than the wild-type (WT) plants. The content of Na+ in leaves and roots of SlNAP1-OE transgenic plants decreased, while the K+ content in leaves, roots, and stems increased compared with WT plants. The expression of the salt stress-related genes (NHX1, HKT1;2 and SOS1) in SlNAP1-OE plants were also significantly up-regulated under salt stress. The SOD, POD and CAT activities and the expression level of antioxidant oxidase synthesis genes of SlNAP1-OE lines were significantly increased. In addition, the SlNAP1-OE lines accumulated less MDA, H2O2 and O-2(center dot-), improved antioxidant defense systems which contributed to increase salt tolerance. In summary, our data suggest that SlNAP1 positively regulates salt tolerance in tomato by regulating ion homeostasis and ROS metabolism.

Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (Fol) is a common disease that affects tomatoes, which can cause the whole plant to wilt and seriously reduce the production of tomatoes in greenhouses. In this study, the morphological indexes, photosynthetic performance and incidence rate of NSY50 under Fol infection were evaluated. It was found that NSY50 could improve the growth of tomato seedlings and significantly reduce the incidence rate of Fusarium wilt. However, the molecular mechanism of NSY50 that induces resistance to Fusarium wilt is still unclear. We used transcriptomic methods to analyze NSY50-induced resistance to Fol in tomatoes. The results showed that plant defense related genes, such as PR and PAL, were highly expressed in tomato seedlings pretreated with NSY50. At the same time, photosynthetic efficiency, sucrose metabolism, alkaloid biosynthesis and terpene biosynthesis were significantly improved, which played a positive role in reducing the damage caused by Fol infection and enhancing the disease tolerance of seedlings. Through transgenic validation, we identified an important tomato NAC transcription factor, SlNAP1, which was preliminarily confirmed to be effective in relieving the detrimental symptoms induced by Fol. Our findings reveal that P. polymyxa NSY50 is an effective plant-growth-promoting rhizosphere bacterium and also a biocontrol agent of soil-borne diseases, which can significantly improve the resistance of tomato to Fusarium wilt.

To investigate the mechanisms used by plant-growth-promoting rhizobacteria (PGPR) to protect plants under pathogen attack, we studied the effects of Paenibacillus polymyxa NSY50 on promoting the photosynthetic performance, carbon assimilation, and antioxidant metabolism of cucumber seedling leaves under the Fusarium wilt stress. Results showed that the inoculation of Fusarium oxysporum f. sp. cucumerinum (FOC) significantly decreased the net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO 2 concentration (Ci), and transpiration rate (Tr); markedly reduced the chlorophyll content and the maximal quantum yield of photosystem II photochemistry ( F v / F m ); and suppressed the growth of cucumber seedlings. However, pre-treatment with NSY50 significantly enhanced photosynthesis and minimized the harmful effects on photosynthesis caused by the FOC. Moreover, the contents of sucrose, fructose, and total soluble sugars in the leaves under the NSY50 + FOC treatment were further increased by 34.08%, 14.61%, and 4.40% compared with those under FOC treatment, respectively. In addition, the key enzymes in sucrose metabolism, such as sucrose phosphate synthase, sucrose synthase, acid invertase, and neutral invertase, exhibited significantly higher activities and related gene expression than in the other treatments. Furthermore, pre-treatment with NSY50 apparently enhanced the antioxidant enzyme activities and decreased the MDA and H 2 O 2 contents in the leaves. Hence, NSY50 can promote plant growth and alleviate FOC-induced damage by increasing photosynthetic efficiency, elevate sucrose metabolism, and antioxidant capacity in cucumber seedlings.

2020年11月1日-2021年2月28日,在河南郑州地区对冬春季双膜双被装配式日光温室内外温度、光照和湿度小气候进行测定,以探明其温光性能.在温室内外分别布置环境自动记录仪,每台记录仪均连接温湿度传感器和光照传感器,实现数据的自动监测与传输.结果表明:观测期内,温室内旬平均气温为11.4～21.4℃,旬平均最低气温为9.4～16.7℃;温室内0.1m深处旬平均土壤温度为15.4～22.9℃,旬平均最低土壤温度为15.0～22.1℃,温室内外最大气温差和土温差分别为17.0℃和15.6℃.全年最冷时段(1月上旬)温室外旬平均最低气温为-7.9℃,0.1m处土壤温度旬平均最低值为2.2℃,而此时段温室内旬平均最低气温和0.1m处土壤温度旬平均最低值分别达到9.9℃和15.8℃.11月-翌年2月,温室内光照度逐渐增大,晴天光照度在2000～220001x,11月、12月、1月和2月晴天日平均透光率分别为42％、52％、49％和45％,12月透光率最高,不同月份透光率存在明显差异;阴天温室光照度在300～40001x,各月阴天日平均透光率分别为34％、35％、36％和33％,透光率差异不明显.11月下旬-1月下旬,温室内夜间湿度为95.4％～99.0％,夜间叶片沾湿时长占比为89.1％～99.5％,温室内湿度大.观测结果说明双膜双被结构日光温室在黄淮地区冬春季具有较好的保温性能,有利于进行喜温果菜类的越冬生产,具有一定的推广应用价值,但是存在温室透光率偏低、光照弱等问题.

Cadmium (Cd) is highly toxic to both plants and humans.Light plays crucial roles in plant growth, development and stress responses, but how light functions in plant Cd response remain unclear.Here,we found that Cd treatment significantly induced the expression of PHYB but not PHYA and CRY1 in leaves and roots of cucumber. Correspondingly,compared with white light (W) during Cd stress,red light(R) increased Cd sensitivity,whereas blue light (B) enhanced Cd tolerance as evidenced by decreased Cd-induced chlorosis, growth inhibition, photosynthesis inhibition and chloroplast ultrastructure damage.Furthermore,B markedly increased the transcripts and activities of the antioxidant enzymes including ascorbate peroxidase (APX),catalase (CAT),superoxide dismutase (SOD) and glutathione reductase (GR),as well as glutathione (GSH) content and GSH1 expression, resulting in hydrogen peroxide (H2O2) and superoxide (O2.–) reduction,but R treatment showed the opposite trend. Moreover, R and B markedly up-regulated and down-regulated the expression levels of Cd uptake and transport genes including IRT1, NRAMP1 and HMA3, leading to more and less Cd accumulation than the W-treated plants in both shoots and roots, respectively under Cd stress. Collectively, our data clearly demonstrate that R and B function antagonistically to regulate Cd tolerance in cucumber via modulating the photosynthesis, antioxidant defense system and Cd uptake, providing a novel light quality control strategy to enhance crop Cd tolerance and food safety.

为促进河南省塑料大棚的标准化发展,科学指导其设计和建造,以《温室结构荷载设计规范》中规定的河南省18个地区钢骨架塑料大棚为研究对象,利用Ansys Workbench软件分别建立了不同跨度下(8、10、12、14 m)7种常用拱架材料设计的塑料大棚模型,对比了河南省18地区不同跨度不同拱架材料塑料大棚在不同荷载组合下的节点最大应力,筛选出控制荷载和最不利荷载组合,然后利用最不利荷载组合下的承载能力极限状态验算了其安全性,给出了河南省塑料大棚拱架材料规格选型建议.结果表明:河南省18地区中,栾川、南阳、商丘和固始4地塑料大棚的控制荷载是雪荷载,最不利荷载组合为永久荷载+1.2×不均匀雪荷载,其他14地区塑料大棚的控制荷载为风荷载,最不利荷载组合为永久荷载+1.0×风荷载.在河南省18地区中,风荷载是塑料大棚的首要不利荷载,对塑料大棚的安全性影响最大,其次是雪荷载.在建立24个塑料大棚模型,模拟计算河南省18地区最不利荷载组合的节点最大应力,共432组安全性验算分析的基础上,提出了适用于河南省18地区不同跨度塑料大棚不同风荷载等级下的材料规格选择建议,具有广泛的适用性.

黄瓜枯萎病是制约黄瓜生长发育及产量的重要生物胁迫因素.近年来,黄瓜生产过程中土地长期高度集约化、高复种指数以及不合理的施肥、灌溉等措施造成土壤微生物区系失衡,导致黄瓜枯萎病危害日趋严重.植物根际促生菌(PGPR)不仅能改善黄瓜根际微生物区系结构,促进黄瓜生长发育,还能通过自身作用或诱导黄瓜产生系统抗性以有效防治黄瓜枯萎病.综述了PGPR促进植物生长和防治病害的作用机制,以及利用PGPR防治黄瓜枯萎病的研究进展,以期为PGPR在黄瓜生产中的应用研究提供参考.