Cucumber (Cucumis sativus L.) is one of the most popular cultivated vegetable crops but it is intrinsically sensitive to cold stress due to its thermophilic nature. To explore the molecular mechanism of plant response to low temperature (LT) and the mitigation effect of exogenous nitric oxide (NO) on LT stress in cucumber, transcriptome changes in cucumber leaves were compared. The results showed that LT stress regulated the transcript level of genes related to the cell cycle, photosynthesis, flavonoid accumulation, lignin synthesis, active gibberellin (GA), phenylalanine metabolism, phytohormone ethylene and salicylic acid (SA) signaling in cucumber seedlings. Exogenous NO improved the LT tolerance of cucumber as reflected by increased maximum photochemical efficiency (Fv/Fm) and decreased chilling damage index (CI), electrolyte leakage and malondialdehyde (MDA) content, and altered transcript levels of genes related to phenylalanine metabolism, lignin synthesis, plant hormone (SA and ethylene) signal transduction, and cell cycle. In addition, we found four differentially expressed transcription factors (MYB63, WRKY21, HD-ZIP, and b-ZIP) and their target genes such as the light-harvesting complex I chlorophyll a/b binding protein 1 gene (LHCA1), light-harvesting complex II chlorophyll a/b binding protein 1, 3, and 5 genes (LHCB1, LHCB3, and LHCB5), chalcone synthase gene (CSH), ethylene-insensitive protein 3 gene (EIN3), peroxidase, phenylalanine ammonia-lyase gene (PAL), DNA replication licensing factor gene (MCM5 and MCM6), gibberellin 3 beta-dioxygenase gene (GA3ox), and regulatory protein gene (NPRI), which are potentially associated with plant responses to NO and LT stress. Notably, HD-ZIP and b-ZIP specifically responded to exogenous NO under LT stress. Taken together, these results demonstrate that cucumber seedlings respond to LT stress and exogenous NO by modulating the transcription of some key transcription factors and their downstream genes, thereby regulating photosynthesis, lignin synthesis, plant hormone signal transduction, phenylalanine metabolism, cell cycle, and GA synthesis. Our study unveiled potential molecular mechanisms of plant response to LT stress and indicated the possibility of NO application in cucumber production under LT stress, particularly in winter and early spring.
Compared with own-rooted watermelon, the influence of different rootstocks on chilling tolerance of grafted watermelon seedlings and its physiological mechanisms were studied. The results showed that grafting increased the chilling tolerance. Compared with own-rooted watermelon seedlings, the grafted watermelon seedlings had lower chilling injury index, lower electrolytic leakage (%), lower MDA content, higher chlorophyll, proline content and higher activities of superoxide dismutase, ascorbate peroxidase and dehydroascorbate reductase in leaves under low temperature stress. There was a considerable difference of chilling tolerance among different grafted watermelon seedlings due to the difference of rootstock chilling tolerance. The grafted seedlings with stronger chilling tolerance had lower electrolytic leakage (%), lower MDA content, higher proline content and higher activities of superoxide dismutase, ascorbate peroxidase, dehydroascorbate reductase in leaves than those of grafted seedlings with weaker chilling tolerance. Therefore, chilling tolerance may be related to higher antioxidative ability and membrane stability in the plants. The chilling tolerance of grafted seedlings could be properly evaluated by comprehensive physiological indexes but not a single physiological index.
In this paper,glycyrrhiza waste residues were degraded with white - rot fungi(5.776 and 1.334) and Trichoderma koningii(3.277 4) separate culture inoculation and 5.776 + 3.277 4,1.334 + 3.277 4 mixed strains inoculation.The effects of different strains on the activities of lignin - degrading enzyme,cellulase and hemicellulose enzyme and the degradation rate of lignin,cellulase and hemicellulose during the ferment of glycyrrhiza waste residues were studied.The results showed that 5.776 + 3.277 4 mixed strains inoculation were a good advantage in improving the activity and degrading rate of lignin,cellulase and hemicellulose.After fermentation for 30 days,the degradation rate of lignin,cellulase and hemicellulose were respectively 38. 52%,52.36%and 59.59%under 5.776 + 3.277 4 mixed strain inoculation.
Melon(Cucumis melo L.)is one of the important vegetable. Water stress obviously influences the yield and quality of melon. Compared with conventional irrigation and cultivation mode,the soil moisture and thermal environment,water requirement pattern are changed by drip irrigation under mulch. The results indicated that the water requirement of 8601 in seedling stage was 0.75 mm/d,4.56 mm/d in fruit expanding stage,in ripping 1.73 mm/d stage;the water requirement of Xinmi 19 at seedling stage was 0.39 mm/d,2.29 mm/d in fruit expanding stage,0.69 mm/d in ripping stage.
Zhelin Reservoir is taken as an example to give an application for the new ideal of controlling reservoir normal water level in flood season dynamically based on hydraulic uncertainty.The result is that when reservoir normal level in flood season is less than 64.426 m and the highest flood-regulating level top 70.130 m,the overtopping risk rate is 0;while it is top on 64.426 m,and is lower than 64.430 m,the risk rate increases progressively along with the rising of reservoir normal level in flood season,and the two factors have linear relation,when reservoir normal level in flood season reaches to 64.430 m,the risk rate grow abruptly.
This study is aimed at investigating the effects of exogenous selenium (Se) on the ionic equilibrium and micro-domain distribution, state transitions between photosystem I (PSI) and photosystem II (PSII), and the photosynthetic carbon assimilation efficiency of tomato ( Solanum lycopersicon L.) seedlings under the influence of salt stress. The application of 0.01 mmol•L -1 exogenous Se had no significant effects on the selective transport capacity of sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) from the roots to leaves under salt stress. It, however, significantly hindered the absorption of Na by the root system and leaves, increased the ratios of K/Na, Ca/Na and Mg/Na, and relieved the nonuniformity of micro-domain ionic distribution, thus, mitigating the ionic homeostasis imbalance and ion toxicity induced by salt stress. Additionally, the application of exogenous Se overcame stomatal limitation, regulated the state transitions between PSI and PSII, and enhanced the initial and overall activity of Rubisco as well as the activities of Rubisco activase (RCA) and fructose-1,6-bisphosphatase (FBPase). It also increased the levels of expression of nine relevant genes in Calvin cycle, which subsequently improved the concentration of photosynthetic substrates, balanced the distribution of activation energy between PSI and PSII, promoted the efficiency of CO 2 carboxylation and carbon assimilation, thereby increasing the photosynthetic efficiency of tomato seedling leaves under salt stress. Hence, the supply of exogenous Se can alleviate the inhibition of salt stress on tomato seedling growth by rebuilding ionic homeostasis and promoting photosynthetic capacity.
Tomato blight significantly threatened tomato yield and quality, making precise disease detection essential for modern agricultural practices. Traditional segmentation models often struggle with over-segmentation and missed segmentation, particularly in complex backgrounds and with diverse lesion morphologies. To address these challenges, we proposed Unet with Vision Mamba and ConvNeXt (VMC-Unet), an asymmetric segmentation model for quantitative analysis of tomato blight. Built on the Unet framework, VMC-Unet integrated a parallel feature-aware backbone combining ConvNeXt, Vision Mamba, and Atrous Spatial Pyramid Pooling (ASPP) modules to enhance spatial feature focusing and multi-scale information processing. During decoding, Vision Mamba was hierarchically embedded to accurately recover complex lesion morphologies through refined feature processing and efficient up-sampling. A joint loss function was designed to optimize the model’s performance. Extensive experiments on both tomato epidemic and public datasets demonstrated VMC-Unet superior performance, achieving 97.82% pixel accuracy, 87.94% F1 score, and 86.75% mIoU. These results surpassed those of classical segmentation models, underscoring the effectiveness of VMC-Unet in mitigating over-segmentation and under-segmentation while maintaining high segmentation accuracy in complex backgrounds. The consistent performance of the model across various datasets further validated its robustness and generalization potential, highlighting its applicability in broader agricultural settings.
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