Search Results (1,095)

Background: The beet moth, Scrobipalpa ocellatella Boyd, 1858 (Lep.: Gelechiidae), is an increasingly important pest whose climate-driven expansion threatens sugar beet (Beta vulgaris L.) production in Europe. This study aimed to characterize the structural, physiological, biochemical, and molecular responses of sugar beet to infestation. Methods: Plants were analysed using computed tomography (CT), SPAD and NDVI measurements, HPLC-based sugar analysis, FRAP and MDA assays, and RT-qPCR of antioxidant-related genes. Results: CT imaging enabled non-destructive detection of larvae (mean length: 7.32 ± 0.73 mm) and pest-induced cavities (982.20 ± 316.04 mm³). SPAD did not differ significantly among treatments, whereas NDVI was consistently reduced in infested plants, declining from 0.648 ± 0.031 in non-infested plants to 0.593 ± 0.038 in infested-treated plants and 0.611 ± 0.021 in infested-untreated plants at the first sampling. Infestation induced pronounced oxidative stress, with FRAP increasing from 14.102 ± 0.943 to 25.471 ± 0.922 µg AA eq g⁻¹ FW and MDA from 558.065 ± 21.819 to 1325.806 ± 16.762 nmol g⁻¹ FW in untreated infested plants. Antioxidant gene expression was significantly upregulated, particularly for SOD, CAT, APX, DHAR, MDAR, and GPX. Conclusions: S. ocellatella infestation triggered coordinated oxidative stress responses in sugar beet, while CT and NDVI proved useful for early damage detection. Full article

This study evaluated the effects of two silicon sources (silicic acid and Agrisil) and increasing Si concentrations on physiological responses, total polyphenol content, photochemical performance, nutrient uptake, and phenolic metabolism in sour passion fruit (Passiflora edulis Sims) grown under soilless culture conditions. The experiment was conducted in a greenhouse using increasing concentrations of Si applied through the nutrient solution. Gas exchange parameters, chlorophyll index (SPAD), chlorophyll fluorescence variables, leaf temperature, and the contents of Si, nitrogen, and total polyphenols in leaves and roots were evaluated. Moderate Si concentrations enhanced stomatal conductance and transpiration, improving intrinsic water use efficiency, and maintaining higher chlorophyll levels and photochemical performance. In contrast, higher Si concentrations increased Si deposition in leaf tissues, reduced stomatal regulation and transpiration, and increased leaf temperature. These changes were associated with reductions in chlorophyll index and photochemical performance index (PI), as well as increased F₀/Fm. Net CO₂ assimilation remained relatively stable. Silicon uptake differed between sources, with silicic acid showing faster absorption and Agrisil a more gradual release. Silicon fertilization also increased nitrogen uptake and stimulated the accumulation of phenolic compounds in roots. Overall, moderate silicon supplies enhanced physiological stability, whereas excessive accumulation imposed photochemical constraints. Full article

Spring drought is a major constraint in Mediterranean wheat production, where elevated temperatures and evapotranspiration after heading limit soil water availability during critical generative stages. This study investigated how post-heading drought reshapes the relationships between yield and multiple quality traits (a total of 22 variables) across ten bread wheat genotypes using multivariate analyses. Field experiments were conducted under rainfed and post-heading drought conditions over two growing seasons. The following traits were evaluated: yield components; flag leaf SPAD; physical, technological, and nutritional quality traits; flour color (L*, a*, b*); phenolic content; and antioxidant activity. Drought caused significant yield reductions, with SPAD, ear yield, grain and test weight emerging as key traits associated with yield formation. Water-limited conditions constrained yield formation in post-heading development stages while promoting certain quality improvements in wheat grain. PCA clearly separated drought and rainfed conditions: drought clustered with bioactive, pigment-related, and mineral traits, whereas rainfed conditions were associated with higher yield, protein content, gluten quality, and technological traits. These findings demonstrate that post-heading drought shifts wheat grain composition toward bioactive and nutritional constituents at the expense of yield-oriented and technological traits, emphasizing the need to select genotypes that sustain both yield stability and nutritional quality under increasing spring water limitations driven by climate change. Full article

Cut roses (Rosa hybrida L.) are highly sensitive to postharvest conditions, often experiencing quality losses associated with declines in SPAD values (relative chlorophyll index), color instability, Botrytis cinerea incidence, and impaired bud opening. This study aimed to evaluate the effects of different storage atmospheres, including controlled atmosphere (CA; 10% CO₂ + 3% O₂ and 6% CO₂ + 3% O₂), normal atmosphere (NA), and modified atmosphere packaging (MAP; LDPE1 (low-permeability MAP): 25 µm, 8000 cc m⁻² day⁻¹ O₂ permeability; LDPE2 (high-permeability MAP): 25 µm, 12,000 cc m⁻² day⁻¹ O₂ permeability), on SPAD values, color parameters, disease incidence, and bud development in cut rose cultivars (Rosa hybrida L.) cvs. ‘Rhodos’ and ‘Athena’ harvested in May, June, August, and November. The experiment was conducted as a factorial completely randomized design with seven biological replicates per treatment, each consisting of a single flower. Treatments were applied in combination with 1-methylcyclopropene (1-MCP, 625 ppb) and a commercial postharvest hydrating solution (Chrysal RVB, 1 mL L⁻¹) under storage conditions of 0.5 ± 0.5 °C and 80–85% relative humidity. The results indicated that CA conditions in combination with 1-MCP maintained higher SPAD values, improved color stability, and were associated with lower Botrytis incidence (p < 0.01). In addition, the low-permeability LDPE1-based MAP treatment minimized variations in hue angle (h°) and improved bud development scores, while the hydrating solution treatment promoted bud opening, particularly in cv. ‘Athena’, although its effect on disease suppression was limited. Overall, the combined application of controlled atmosphere storage and 1-MCP generally showed superior performance in maintaining postharvest quality, reducing disease incidence, and preserving the visual and physiological attributes of cut roses, with effects varying depending on cultivar and evaluated parameter. Full article

Endophytic bacteria are beneficial microbes that live within plant tissues and promote growth through nitrogen fixation, phosphate solubilization, and phytohormone production. Two endophytic isolates from bell pepper (Capsicum annuum L.) root were identified based on their morphology and biochemical properties using 16S rRNA gene sequencing. Winter barley seeds were inoculated with two PGP (plant growth-promoting) bacterial strains (C-14 and C-27), previously characterized for indole-derived compound (IDC) production, and evaluated in a pot experiment with four treatments: Treatment A1 (C-14), Treatment A2 (C-27), Treatment A3 Consortium (C-14 + C-27), and Treatment A4 (non-inoculated control). The results indicated that root and stem lengths increased in plants inoculated with bacteria compared to the uninoculated control. Among treatments, A2 produced the greatest root and shoot lengths (17.23 and 26.2 cm), while A3 showed the lowest (15.8 and 21.5 cm). SPAD values also increased by 6%, 10%, and 3.2% in Treatments A1, A2, and A3, respectively. This study clearly demonstrated that the endophytic isolates (C-14 and C-27) obtained from bell pepper roots significantly enhanced the growth of barley due to their ability of IDC production, thereby offering a promising alternate to chemical fertilizers. Full article

This study investigated the interactive effects of the culture system and carbon source on growth, shoot proliferation, and mineral nutrition dynamics in the in vitro propagation of chestnut. Explants of the ‘Akyüz’ cultivar were used in the Woody Plant Medium. Both plant tissues and culture media were analyzed for Fe, Cu, Mn, Zn, and Mg concentrations. Morphological parameters, nutrient accumulation, and depletion patterns were evaluated. The results demonstrated that the liquid culture system supplemented with sucrose significantly enhanced plant growth, chlorophyll content, callus development, and shoot multiplication. Sucrose treatments promoted higher accumulation of Fe, Cu, Zn, and Mg in plant tissues, whereas glucose treatments resulted in significantly higher Mn accumulation. Correlation and principal component analysis revealed strong positive relationships between growth parameters and Fe, Mg, Cu, and Zn, whereas Mn exhibited significant negative correlations. Among the machine learning models, Support Vector Regression showed the highest predictive performance for plant length (R² = 0.74) and SPAD (R² = 0.87). Nutrient depletion analysis showed substantial reductions in mineral concentrations in all treatments after four weeks. Overall, the combination of liquid culture systems with sucrose provides optimal conditions for chestnut micropropagation by promoting favorable nutrient interactions and minimizing antagonistic effects. Full article

Population growth, climate change, and increasing pressure on water and nitrogen resources pose major challenges for sustainable maize production. Maize yield is highly sensitive to inter-annual weather variability, yet many prediction approaches still rely on simple linear relationships and rarely integrate SPAD (Soil Plant Analysis Development)-based crop diagnostics with machine learning in multi-year nitrogen × irrigation experiments. In a three-year field experiment (2018–2020) in Hungary, we evaluated how basal and top-dressing fertilization and supplemental irrigation under contrasting water supply conditions affected the chlorophyll status and grain yield of a maize hybrid. Relative chlorophyll content was monitored using SPAD measurements at key phenological stages (V6, V12, and R1), and a multilayer perceptron (MLP) model was developed to improve yield prediction and to identify informative combinations of input variables. Five alternative scenarios (SC1–SC5) were tested by combining SPAD values with the fertilization rate, irrigation status, and crop year in different configurations, and model performance was assessed using root mean square deviation (RMSD), mean absolute error (MAE), normalized root mean square error (NRMSE), correlation (r, r²), Nash–Sutcliffe efficiency (NSE), Kling–Gupta efficiency (KGE), Kendall’s tau, and the index of agreement (d). Overall, SC4 (SPAD + fertilization + crop year + irrigation) achieved the best agreement with observed yields across most indices (e.g., r ≈ 0.93, NSE ≈ 0.86, KGE ≈ 0.90), whereas SC2 (SPAD + fertilization) produced the lowest prediction error on the independent test subset, indicating the most robust generalization. Basal fertilization with 60 and 120 kg N ha⁻¹ significantly increased yield in 2019 and 2020, while irrigation generally enhanced yield except for the 30 kg N ha⁻¹ top dressing applied at the V6–V12 stages. These results demonstrate that coupling SPAD measurements with MLP modeling and multi-criteria performance evaluation can support more efficient, site-specific nitrogen and irrigation decisions and help stabilize maize yields under variable climatic conditions. Full article

The performance of single-photon avalanche diodes (SPADs) is highly dependent on the operating temperature, while traditional SPAD models neglect the self-heating effect induced by avalanche current during long-term device operation, leading to insufficient prediction accuracy. This paper proposes an electro-thermal coupled SPAD simulation model that self-consistently integrates the transient thermal effects of the avalanche process with temperature-dependent electrical parameters, including junction capacitance, breakdown voltage, impact ionization coefficients, and Shockley–Read–Hall (SRH) recombination rates. The complete electro-thermal coupled model is constructed based on Sentaurus-TCAD thermal simulation and Virtuoso circuit simulation and implemented via the Verilog-A language. Simulation results demonstrate that after the device operates for 100 μs under repeated avalanche-quenching processes, the self-heating effect causes a 0.34 V shift in breakdown voltage, increases the device dead time by 3.34 ps, and simultaneously reduces the photon detection probability and elevates the dark count rate. This study conducts a systematic investigation into the performance degradation mechanism of SPAD devices induced by the self-heating effect, laying a theoretical foundation at the device self-heating level for subsequent research on the electrothermal interaction between quenching circuits and device bodies. Full article

Winter cover crops (WCCs) are effective at reducing N losses from temperate agroecosystems. Although extensive research on WCCs has demonstrated numerous benefits, overall adoption rates in the Midwest U.S. remain low. We evaluated an alternative to WCC’s ability to reduce nitrate (NO₃⁻)-N leaching; that is, adding an inexpensive, easy-to-apply, form of labile carbon (C) as a soil amendment intended to immobilize N and mitigate leaching. In the autumn in a typical maize–soybean rotation, we added crude glycerol (a C-rich, biodiesel byproduct) and hypothesized that glycerol carbon (C_glyc) would immobilize N and have no effect on crop growth. More specifically, C_glyc was broadcast applied at three rates (0, 216, and 866 kg C ha⁻¹ y⁻¹) and combined factorially with six spring-applied fertilizer N rates (0, 56, 112, 168, 224, and 280 kg N ha⁻¹) at two sites. In response, we measured: soil profile NO₃⁻-N, leached NO₃⁻-N, crop health (via SPAD), yield, and maize agronomic optimum N rate (AONR). C_glyc reduced spring soil profile NO₃⁻-N by 14–24% across site-years, but had highly variable and non-significant effects on NO₃⁻-N leaching. C_glyc had an inconsistent impact on crop SPAD and yield, with C_glyc increasing AONR by ~63 kg N ha⁻¹ (or 31–40%) at one of two sites. Our results show promise for using labile C as a “liquid cover crop” soil amendment. Future studies should explore greater labile C application rates and alternate application timing in order to fine-tune the balance between environmental benefits and crop productivity. Full article

The aim of the study was to determine, under field conditions, the effects of O₃, H₂O₂, and fungicide protection on potato late blight severity, SPAD values, tuber yield, and mineral composition, and additionally to assess whether the number of ozone applications modifies selected tuber quality traits. Two complementary field experiments were conducted in 2017 and 2018. In the main experiment, control, fungicide protection, ozone fumigation, and foliar H₂O₂ treatments were compared with respect to late blight severity, SPAD response, yield, and macro- and micronutrient contents in tuber peel and flesh. In the supplementary experiment, single, double, and triple ozonation were compared in relation to starch content, vitamin C concentration, and tuber mineral composition. Fungicide treatment most effectively limited late blight symptoms, particularly at later assessment dates, and was associated with the highest tuber yield. SPAD values, yield, and several mineral traits were strongly dependent on the study year, indicating a major contribution of environmental conditions. The response to O₃ and H₂O₂ was selective and less stable than that observed under fungicide protection. In the supplementary experiment, the number of ozone applications did not significantly affect starch content. Vitamin C concentration depended mainly on the study year, whereas tuber mineral composition depended mainly on year and tissue type. The results indicate that, under field conditions, fungicide protection remained the most effective option for limiting late blight and achieving the highest tuber yield, whereas O₃ and H₂O₂ should be regarded as factors capable of modifying selected plant and tuber traits, but not as direct substitutes for standard chemical protection. Full article

Nitrogen use efficiency (NUE) is a major determinant of maize (Zea mays L.) productivity and sustainability, yet the regulatory changes associated with modern breeding remain incompletely understood. Here, we used breeding-era transcriptomic data from 137 elite Chinese maize inbred lines to identify transcriptional regulators associated with maize NUE. Breeding-era expression shifts in NUE effector genes were modest but tissue-specific, pointing to pathway-level transcriptional rewiring during modern breeding. Focusing on the first leaf above the uppermost ear at silking, we identified 69 breeding-era-responsive genes, including 10 transcription factors, and prioritized ZmSPL19 through Pearson correlation analysis with curated NUE-related genes. ZmSPL19 expression declined during modern breeding and showed a nitrate-repressed expression, with lower transcript abundance under nitrogen-sufficient conditions and rapid downregulation upon nitrate resupply. Loss of ZmSPL19 function promoted primary root elongation, biomass accumulation, leaf nitrogen content, soil–plant analysis development (SPAD), photosynthetic rate, kernel number, and grain yield under nitrogen-sufficient conditions. These results identify ZmSPL19 as a breeding-associated negative regulator of growth and yield formation under nitrogen-sufficient conditions and support the value of a breeding-informed strategy for discovering regulators with potential relevance to maize NUE improvement. Full article

Background/Objectives: The dark green leaf color trait in bunching onion (Allium fistulosum L.) is an important agronomic trait closely associated with market value; however, its genetic basis remains poorly understood. This study aimed to identify quantitative trait loci (QTLs) associated with leaf color using SPAD values as a phenotypic indicator. Methods: An ${\mathrm{F}}_2$ population derived from a cross between the dark green line YSG1go and the light green line Asagikei-KUJYO was used. A linkage map was constructed based on RNA-seq-derived SNP markers, and SPAD values were measured for QTL analysis. Results: The linkage map consisted of eight linkage groups with a total length of 2103.0 cM and 765 mapped markers. SPAD values showed significant differences between the parental lines, with high broad-sense heritability ($H^2$ = 0.76), indicating a strong genetic contribution to this trait. Multiple significant QTLs were detected on chromosomes 4 and 5, each explaining 27.4–38.1% of the phenotypic variance. The direction of allelic effects differed among QTLs, suggesting that favorable alleles are distributed between the parental lines. In addition, genes related to chloroplast protein translation were identified within the QTL regions. Conclusions: SPAD values are a suitable indicator for genetic analysis of leaf color in bunching onion, and the QTLs identified in this study provide valuable information for molecular breeding aimed at improving dark green leaf color. Full article

Micronutrient limitation and rhizosphere imbalance often constrain the productivity and quality of leafy vegetables in intensively managed greenhouse soils. This study evaluated the effects of conventional fertilization (CK), micronutrient supplementation (Mi), and micronutrient supplementation combined with a compound microbial inoculant (MM) on bur clover (Medicago polymorpha L.) yield, quality, rhizosphere chemical properties, and soil microbial communities. Compared with CK, Mi increased yield by 26.53%, whereas MM increased yield by 40.77%. MM also significantly increased SPAD, soluble protein, and soluble sugar, while reducing plant nitrate content by 22.86%; Mi had no significant effect on nitrate reduction. MM decreased soil pH from 8.62 to 8.34 and increased EC, available P and K, water-soluble Ca, Mg, and K, and available Zn and B, indicating improved rhizosphere chemical conditions. Mantel analysis showed that yield and plant nitrate were significantly associated with several soil variables. MM also markedly reshaped rhizosphere microbial communities, with clear treatment separation for both bacteria and fungi. The bacterial community was significantly explained by selected soil variables, whereas the fungal model was not significant. Overall, micronutrient supplementation mainly promoted yield, while its combination with microbial inoculation further improved rhizosphere conditions, crop quality, and nitrate control. Full article

Increasing planting density is a common strategy to raise soybean yield, yet it often intensifies light competition within the canopy, leading to diminishing returns at high densities. Optimizing row spacing to improve canopy light distribution and light use efficiency is therefore key to increasing yield under dense planting. This study examined the combined effects of planting density and row spacing on canopy light interception, distribution dynamics, and yield in a drip-irrigated soybean system. A two-year field experiment (2024–2025) was conducted in Shihezi, Xinjiang, using three density levels (D1: 210,000; D2: 330,000; D3: 450,000 plants ha⁻¹) and two row spacing patterns (RS1: alternating wide–narrow rows of 20 + 55 cm; RS2: uniform 38 cm rows). Results demonstrated that plant density establishes the baseline for yield, while row spacing modulates light utilization and unlocks yield potential under high-density conditions. The RS1 treatment increased SPAD values in upper leaves by 6.06% at the R6 growth stage compared to the RS2 treatment. At the R5 stage, the RS1 treatment increased radiation use efficiency (RUE) by an average of 6.44%. This planting pattern alleviated photosynthetic decline in dense canopies and conferred a distinct yield advantage. The highest yield was achieved under the D2 treatment, which was 8.44% and 6.71% higher than that under the D1 and D3 treatments, respectively. In conclusion, integrating moderate plant density with optimized wide–narrow row spacing improves canopy light capture and utilization, synergistically enhancing yield and resource use efficiency. This approach offers a practical strategy to overcome the yield plateau in high-density soybean production systems. Full article

To clarify the regulatory mechanism of NLA on tomato plant architecture and fruit quality, wild-type (WT), nla mutant (narrow leaf angle), and NLA overexpression lines (OE1, OE2) were used as materials, and the study was carried out through genetic analysis, phenotypic and quality determination, and gene expression analysis. The results showed that the tomato leaf angle is controlled by a single gene with semi-dominant inheritance. The nla mutant forms a compact plant architecture due to reduced cell volume at the leaf angle. During vegetative growth, it exhibited significantly increased plant height and decreased stem diameter and crown width. During reproductive growth, it showed significantly higher height of the first inflorescence node and a significantly higher number of the first flowering node. The nla mutant maintained a higher SPAD value during the whole growth period. Mutation of NLA had no significant effect on soluble solids content, but significantly increased flavonoid and titratable acid contents. Meanwhile, the compact architecture optimizes plant spatial distribution, and higher flavonoid content improves antioxidant capacity. Molecular mechanism analysis combined with GA quantification showed that the nla mutant exhibited significantly higher contents of bioactive GA₁ and GA₄, which were closely associated with up-regulated expression of GA biosynthetic genes SlGA20ox1 and SlGA20ox2, as well as down-regulated expression of GA catabolic genes SlGA2ox4 and SlGID1.This study provides a theoretical basis for high-photosynthetic-efficiency breeding and high-quality cultivation of tomato. Full article