Search Results (908)

Plant genders could express different functional strategies to compensate for different reproductive costs, as females have an additional role in fruit and seed production. Secondary sexual dimorphism (SSD) expression is frequently greater under stress than under optimal growth conditions. The early gender identification in papaya may help to reduce orchard costs because the most desirable fruit shape is formed by hermaphrodite plants. We hypothesized that (a) gender ecophysiological phenotyping can be an alternative to make gender segregations in papaya seedlings, and (b) such gender segregation will be more efficient after a short drought exposure than under adequate water conditions. To test such hypotheses, seedlings of two papaya varieties (‘Candy’ and ‘THB’) were exposed to two kind of treatments: (1) water shortage (WS) for 45 h, after which they were well watered, and (2) continuously well-watered (WW). Study assessed the ecophysiological responses, such as stomatal conductance (g_s), SPAD index, optical reflectance indices, morphological traits, and biomass accumulation in females (F) and hermaphrodites (H). In WS treatment, the SSD was expressed in 14 of 18 traits investigated, while in WW treatment, the SSD was expressed only in 7 of 18 traits. As tools for SSD expression, g_s and simple ratio pigment index (SRPI) must be measured on the first or second day after the imposed WS was interrupted, respectively, while the other parameters must be measured after a period of four days. In some traits, the SSD was expressed in only one variety, or the response of H and F plants were of opposite values for two varieties. The choice of the clearest responses of gender segregation in WS treatment will be greenness index, combination of normalized difference vegetation index (CNDVI), photochemical reflectance index (PRI), water band index (WBI), SRPI, leaf number, leaf dry mass, and leaf mass ratio. If the WW conditions are maintained for papaya seedling production, the recommendation in gender segregation will be the analysis of CNDVI, carotenoid reflectance index 2 (CRI2), WBI, and SRPI. The non-destructive optical leaf indices segregated papaya hermaphrodites from females under both water conditions and eventually could be adjusted for wide-scale platform evaluations, with planned space arrangements of seedlings, and sensor’s set. Full article

Diffuse speckle contrast analysis (DSCA), also called speckle contrast optical spectroscopy (SCOS), has emerged as a groundbreaking optical imaging technique for tracking dynamic biological processes, including blood flow and tissue perfusion. Recent advancements in single-photon avalanche diode (SPAD) cameras have unlocked exceptional sensitivity, time resolution, and high frame-rate imaging capabilities. Despite this, the application of large-format SPAD arrays in speckle contrast analysis is still relatively uncommon. This study introduces a pioneering use of a large-format SPAD camera for DSCA. By harnessing the camera’s high temporal resolution and photon-detection efficiency, we significantly enhance the accuracy and robustness of speckle contrast measurements. Our experimental results demonstrate the system’s remarkable ability to capture rapid temporal variations over a broad field of view, enabling detailed spatiotemporal analysis. Through simulations, phantom experiments, and in vivo studies, we validated the proposed approach’s potential for cerebral blood flow and functional tissue monitoring. This work highlights the transformative impact of large SPAD cameras on DSCA, setting the stage for breakthroughs in optical imaging. Full article

Peanut cultivation is widely practiced using plastic mulch film, resulting in the accumulation of microplastics/nanoplastics (MPs/NPs) in agricultural soils, potentially negatively affecting peanut growth. To investigate the effects of two polystyrene (PS) sizes (5 μm, 50 nm) and three concentrations (0, 10, and 100 mg L⁻¹) on peanut growth, photosynthetic efficiency, and physiological characteristics, a 15-day hydroponic experiment was conducted using peanut seedlings as the experimental material. The results indicated that PS-MPs/NPs inhibited peanut growth, reduced soil and plant analyzer development (SPAD) values (6.7%), and increased levels of malondialdehyde (MDA, 22.0%), superoxide anion (O₂⁻, 3.8%) superoxide dismutase (SOD, 16.1%) and catalase (CAT, 12.1%) activity, and ascorbic acid (ASA, 12.6%) and glutathione (GSH, 9.1%) contents compared to the control. Moreover, high concentrations (100 mg L⁻¹) of PS-MPs/NPs reduced the peanut shoot fresh weight (16.1%) and SPAD value (7.2%) and increased levels of MDA (17.1%), O₂⁻ (5.6%), SOD (10.6%), POD (27.2%), CAT (7.3%), ASA (12.3%), and GSH (6.8%) compared to low concentrations (10 mg L⁻¹) of PS-MPs/NPs. Notably, under the same concentration, the impact of 50 nm PS-NPs was stronger than that of 5 μm PS-MPs. The peanut shoot fresh weight of PS-NPs was lower than that of PS-MPs by an average of 7.9%. Additionally, we found that with an increasing exposure time of PS-MPs/NPs, the inhibitory effect of low concentrations of PS-MPs/NPs on the fresh weight was decreased by 2.5%/9.9% (5 d) and then increased by 7.7%/2.7% (15 d). Conversely, high concentrations of PS-MPs/NPs consistently reduced the fresh weight. Correlation analysis revealed a clear positive correlation between peanut biomass and both the SPAD values as well as Fv/Fm, and a negative correlation with MDA, SOD, CAT, ASA, and GSH. Furthermore, the presence of PS-MPs/NPs in roots, stems, and leaves was confirmed using a confocal laser scanning microscope. The internalization of PS-MPs/NPs within peanut tissues negatively impacted peanut growth by increasing the MDA and O₂⁻ levels, reducing the SPAD values, and inhibiting the photosynthetic capacity. In conclusion, the study demonstrated that the effects of PS on peanuts were correlated with the PS size, concentration, and exposure time, highlighting the potential risk of 50 nm to 5 μm PS being absorbed by peanuts. Full article

Accurate and non-destructive monitoring of leaf chlorophyll content (LCC) is essential for assessing crop photosynthetic activity and nitrogen status in precision agriculture. This study introduces a phenology-aware machine learning framework that combines hyperspectral reflectance data with various regression models to estimate leaf chlorophyll content (LCC) in cotton at six key reproductive stages. Field experiments utilized synchronized spectral and SPAD measurements, incorporating spectral transformations—such as vegetation indices (VIs), first-order derivatives, and trilateration edge parameters (TEPs, a new set of geometric metrics for red-edge characterization)—for evaluation. Five regression approaches were evaluated, including univariate and multivariate linear models, along with three machine learning algorithms: Random Forest, K-Nearest Neighbor, and Support Vector Regression. Random Forest consistently outperformed the other models, achieving the highest R² (0.85) and the lowest RMSE (4.1) during the bud stage. Notably, the optimal prediction accuracy was achieved with fewer than five spectral features. The proposed framework demonstrates the potential for scalable, stage-specific monitoring of chlorophyll dynamics and offers valuable insights for large-scale crop management applications. Full article

Maize–soybean intercropping is widely practised to improve land use efficiency, but shading from maize often limits soybean growth and productivity. Melatonin, a plant signaling molecule with antioxidant and growth-regulating properties, has shown potential in mitigating various abiotic stresses, including low light. This study investigated the efficacy of applying foliar melatonin (MT) to enhance shade tolerance and yield performance of soybean under intercropping. Four melatonin concentrations (0, 50, 100, and 150 µM) were applied to soybean grown under mono- and intercropping systems. The results showed that intercropping significantly reduced growth, photosynthetic activity, and yield-related traits. However, the MT application, particularly at 100 µM (MT₁₀₀), effectively mitigated these declines. MT₁₀₀ improved plant height (by up to 32%), leaf area (8%), internode length (up to 41%), grain yield (32%), and biomass dry matter (30%) compared to untreated intercropped plants. It also enhanced SPAD chlorophyll values, photosynthetic rate, stomatal conductance, chlorophyll fluorescence parameters such as Photosystem II efficiency (ɸPSII), maximum PSII quantum yield (Fv/Fm), photochemical quenching (qp), electron transport rate (ETR), Rubisco activity, and soluble protein content. These findings suggest that foliar application of melatonin, especially at 100 µM, can improve shade resilience in soybean by enhancing physiological and biochemical performance, offering a practical strategy for optimizing productivity in intercropping systems. Full article

Foliar fertilization is an effective practice that improves both the yield and quality of maize, a crop with high and specific micronutrient demands. This study hypothesized that foliar application of Fe, Cu, Mn, Mo, Zn and B would improve grain size and quality in GS210 maize compared to the control. The single-factor field experiment was conducted in 2023–2024 on Haplic Cambisol (Eutric) soil, under a variety of meteorological conditions. The application of Zn and B fertilizers significantly increased the soil plant analysis development (SPAD) index. Yield components (number of grains per ear, thousand-grain weight) and grain yield increased significantly following Zn foliar application compared to the control. Zn application increased grain yield by 0.59 t ha⁻¹ and 0.49 t ha⁻¹ in 2023 and 2024, respectively. Smaller but beneficial effects were observed with Cu and B applications. In contrast, the effects of fertilization with other micronutrients (Fe, Mn, Mo) were less pronounced than anticipated. Biochemical analyses revealed that foliar fertilization with Fe, Cu and Mo increased total phenolic content and antioxidant capacity, while Fe and Mo enhanced carotenoid accumulation, and Cu and B significantly influenced grain color parameters. The study highlights the potential of foliar fertilization to improve maize performance and grain quality, despite possible antagonisms between micronutrients. Full article

Optimizing irrigation and the targeted use of plant growth regulators are key strategies to improve productivity in citrus systems under water-limited conditions. This study evaluated the effects of three irrigation levels (4.44, 5.18, and 7.77 mm day⁻¹) combined with variable doses of naphthaleneacetic acid (NAA) and gibberellic acid (GA₃) on physiological and productive responses in Citrus aurantiifolia. The treatment with 7.77 mm irrigation and moderate doses of NAA (100 mg L⁻¹) and GA₃ (80 mg L⁻¹) increased yield by 38% (6.2 kg/plant), and it enhanced photosystem II photochemical efficiency (F_v/F_m = 0.82), chlorophyll index (SPAD = 62), and fruit weight by 15%. In contrast, high hormone doses under water deficit reduced leaf water potential and impaired physiological performance, leading to lower productivity. These findings support the combined use of regulated deficit irrigation and hormonal biostimulation as a sustainable strategy to enhance key lime yield and resource efficiency in semi-arid environments. Full article

Accurately estimating leaves’ relative chlorophyll contents (widely represented by Soil and Plant Analysis Development (SPAD) values) across growth stages is crucial for assessing crop health, particularly in regions characterized by varying sowing dates. Unlike previous studies focusing on high-resolution UAV imagery or specific growth stages, this research incorporates satellite-derived texture indices (TIs) into a SPAD value estimation model applicable across multiple growth stages (from tillering to grain-filling). Field experiments were conducted in Jiangsu Province, China, where winter wheat sowing dates varied significantly from field to field. Sentinel-2 imagery was employed to extract vegetation indices (VIs) and TIs. Following a two-step variable selection method, Random Forest (RF)-LassoCV, five machine learning algorithms were applied to develop estimation models. The newly developed model (SVR-RBF_VIs+TIs) exhibited robust estimation performance (R² = 0.8131, RMSE = 3.2333, RRMSE = 0.0710, and RPD = 2.3424) when validated against independent SPAD value datasets collected from fields with varying sowing dates. Moreover, this optimal model also exhibited a notable level of transferability at another location with different sowing times, wheat varieties, and soil types from the modeling area. In addition, this research revealed that despite the lower resolution of satellite imagery compared to UAV imagery, the incorporation of TIs significantly improved estimation accuracies compared to the sole use of VIs typical in previous studies. Full article

Background: Conventional practices for the cultivation of “Cipollotto Nocerino” spring onion are mainly based on growers’ experience, and up to 250 kg/ha for N is commonly furnished among growing cycles. Facing the issue of reduced availability of natural resources for crop production (for example mineral resources), we investigated the optimization of the productivity. Methods: In our research, we tested the use of depletion nutrient supply strategy (CAL-FERT^®) to enhance fertilization in accordance with the principle of sustainable agriculture included in the Farm to Fork strategy. In our study, besides the common initial fertilization, three different strategies for cover fertilizations have been elaborated with the support of CAL-FERT^® software. The treatments were as follows: (i) commercial standard fertilization as control (named CF); (ii) fertilization equivalent to 50% of the N applied in the control (named F-50); (iii) fertilization corresponding to 25% of the N applied in the control (named F-25); and (iv) strongly reduced fertilization compared to the control (named F-0). The parameters investigated included the following: plant height, yield, SPAD index, nitrogen use efficiency, dry matter, soluble solid content, and pyruvate contents in bulbs and leaves. Nitrogen content was also analyzed for both hypogeous and epigeous apparatuses. Results: Among the most interesting vegetative results, plant height and SPAD readings were reduced only by the extreme treatment F-0 compared with the other treatments at 104 days after planting. Regarding qualitative and productive parameters, the treatments F-50 and F-25 showed the highest yield without prejudging Soluble Solid Content and reducing pungency. Conclusion: In nutritional experiments, onion could be considered as a crop model to investigate quality in vegetables due to its consumption as fresh product and for its particular response, in terms of yield and quality, to fertilization. The use of simulation software can support the identification of strategies to reduce the nutrient supply without any detrimental effect on yield and other vegetative and qualitative parameters in onion crops. Full article

The use of mineral fertilisers has increased in recent years, but this has had a negative effect on the environment, including causing the water in rivers and lakes to become too rich in nutrients, a process known as eutrophication. Current research focuses on producing fertiliser materials that are environmentally friendly. The aim of this study was to examine the impact of novel specialised organic-mineral fertilisers (OMFs: NP 24-12, NP 10-10, and NP 10-10 Zn⁺) on the yield and chemical composition of maize. These fertilisers were compared with a control (no fertiliser) and with other fertilisers (mixture of commercial fertilisers (MCFs): NP 24-12 and NP 10-10) that were used as a reference. All fertilisers increased the SPAD index at the fifth leaf unfolded stage of maize, with the majority (apart from OMF NP 10-10) also increasing it at the panicle emergence stage. MCF NP 10-10 had the most positive effect on the plant height, while OMF NP 10-10 had the least positive effect. All fertilisers had a positive effect on maize growth and development, with MCFs NP 10-10 and NP 24-12 having by far the strongest effect on increasing crop yields. The yield of plants fertilised with OMFs NP 24-12, NP 10-10, and NP 10-10 Zn⁺ was lower than the yields of plants fertilised with MCF NP 24-12 and MCF NP 10-10. OMF NP 10-10 caused a greater increase in the contents of all elements, and OMF NP 24-12 caused a greater increase in most elements (except P and Ca) in maize than MCFs did at an identical NP ratio. OMF NP 10-10 Zn⁺ was found to have a significant impact on the mineral composition of maize, resulting in a decline in Ca and P levels, along with a notable increase in Mg, Zn, and Cu concentrations. The most significant differences were observed for Cu and Zn. The OMFs, notably NP 24-12 and NP 10-10, exhibited a comparatively diminished acidifying impact in comparison with the MCFs. The application of fertilisers resulted in a significant increase in soil nutrient levels, with most fertilisers increasing the soil N, P, and Zn contents. Additionally, the OMFs led to an increase in Cu. However, MCFs NP 24-12 and NP 10-10 reduced the soil Cu and Mn contents. Studies should include other species as they have different needs. Field experiments are also needed. Full article

This study presents a hybrid adaptive control strategy that integrates genetic algorithm (GA) optimization with an adaptive neuro-fuzzy inference system (ANFIS) for precise thermal regulation of single-photon avalanche diodes (SPADs). To address the nonlinear and disturbance-sensitive dynamics of SPAD systems, a performance-oriented dataset is constructed through multi-scenario simulations using settling time, overshoot, and steady-state error as fitness metrics. The genetic algorithm (GA) facilitates broad exploration of the proportional–integral–derivative (PID) controller parameter space while ensuring control stability by discarding low-performing gain combinations. The resulting high-quality dataset is used to train the ANFIS model, enabling real-time, adaptive tuning of PID gains. Simulation results demonstrate that the proposed GA-ANFIS-PID controller significantly enhances dynamic response, robustness, and adaptability over both the conventional Ziegler–Nichols PID and GA-only PID schemes. The controller maintains stability under structural perturbations and abrupt thermal disturbances without the need for offline retuning, owing to the real-time inference capabilities of the ANFIS model. By combining global evolutionary optimization with intelligent online adaptation, this approach improves both accuracy and generalization, offering a practical and scalable solution for SPAD thermal management in demanding environments such as quantum communication, sensing, and single-photon detection platforms. Full article

Straw returning inhibits tillering at the early stage of rice growth and thus affects grain yield. Sulfur-coated urea (SCU) has been expected to increase nitrogen use efficiency (NUE) and yield, save labor input, and reduce environmental pollution in crop production. Nevertheless, the sulfur coatings of SCU are easy to break and then shorten the nutrient release cycle. Whether there was a complementary effect between straw returning and SCU in NUE and grain yield had remained elusive. To investigate the effects of straw returning combined with the application of SCU on NUE and rice yield, a two-year field experiment was conducted from 2022 to 2023 with three treatments (straw returning combined with conventional urea (SRU), no straw returning combined with SCU (NRS), straw returning combined with SCU (SRS)). We found that straw returning combined with the application of SCU increased rice yield and NUE significantly. Compared with SRU and NRS, SRS treatments significantly increased grain yield by 14.61–16.22%, and 4.14–7.35%, respectively. Higher effective panicle numbers per m² and grain numbers per panicle were recorded in NRS and SRS treatments than SRU. SRS treatment increased nitrogen recovery efficiency by 79.53% and 22.97%, nitrogen agronomic efficiency by 18.68% and 17.37%, and nitrogen partial factor productivity by 10.51% and 9.81% compared with SRU and NRS treatment, respectively. The enhanced NUE in SRS was driven by higher leaf area index, SPAD value, net photosynthetic rate, carbon metabolic enzyme (RuBP and SPS) activity, nitrogen metabolic enzyme (NR, GS, and GOGAT) activity, sucrose and nitrogen content in leaves, and nitrogen accumulation in plant during grain filling. Moreover, the improved yield in SRS was closely related to superior NUE. In conclusion, straw returning combined with application of SCU boosted grain yield and NUE via enhanced carbon–nitrogen metabolism during the late growth period in rice. Full article

Biochar and seaweed fertilizers could improve soil quality and promote plant growth. However, the key soil factors and microbial mechanisms that drive maize growth in coastal saline–alkali soils remain unclear. A soil culture experiment was designed with four treatments—no organic fertilizer (CK), single seaweed fertilizer (F), single biochar (B), and combined application of seaweed fertilizer and biochar (BF)—to investigate the effects of biochar and seaweed fertilizer on maize growth and its mechanism. The results showed that B and BF significantly increased maize aboveground biomass by 8.86% and 17.28% compared to CK, respectively. The soil organic carbon, total nitrogen, available nitrogen, available phosphorus, available potassium content, and pH of B and BF were significantly increased. Bacterial diversity increased under B and BF, while fungal richness decreased under BF. The changes in the fungal community were mainly affected by soil available nitrogen, but there was no significant correlation between bacterial communities and these indicators. Pearson correlation analysis suggested that the bacterial Chao1 index was significantly positively correlated with maize growth indicators, soil available phosphorus, and available potassium, as well as the bacterial PD whole tree index with leaf area and available phosphorus. The fungal Shannon index was significantly negatively correlated with maize plant height, leaf area, SPAD, aboveground biomass, and soil total nitrogen and available nutrients. Overall, biochar and seaweed fertilization could significantly promote maize growth by improving soil chemical properties and microbial communities in coastal saline–alkali soils. Full article

This study aimed to evaluate the impact of intercropping Brassica oleracea. with three perennial grasses (Poa pratensis L., Lolium perenne L., and Festuca rubra L.) under varying levels of iron (Fe) availability (Fe0, Fe1 and Fe5) in nutrient solutions. The research focused on biomass accumulation, photosynthetic efficiency, root development, nutrient uptake, and oxidative stress response. In the absence of Fe, Brassica sp. exhibited chlorosis, reduced biomass, and increased ferric chelate reductase (FCR) enzyme activity as an adaptive response. Brassica plants intercropped with Poa sp. maintained higher chlorophyll (Chl) levels and photosystem II efficiency (F_v/F_m values), mitigating Fe deficiency effects. Catalase activity and polyphenol production varied with intercropping species, indicating differential stress response mechanisms. Intercropping improved Zn, Mn, and P accumulation, with Poa sp. facilitating greater Zn and Mn uptake. Intercropping Brassica sp. with specific grass species offers potential agronomic benefits by improving Fe use efficiency, mitigating stress, and enhancing nutrient uptake. Future research should focus on optimizing intercropping combinations for sustainable agricultural practices. Full article

Calcareous soils, characterized by high pH and calcium carbonate content, often limit the availability of essential nutrients for crops such as rice (Oryza sativa L.), reducing yield and nutritional quality. In this study, we evaluated the effect of the halotolerant yeast Debaryomyces hansenii on the growth, nutrient uptake, and phosphorus acquisition mechanisms of rice plants cultivated in calcareous soil under controlled greenhouse conditions. Plants inoculated with D. hansenii, particularly via root immersion, exhibited significantly higher SPAD chlorophyll index, plant height, and grain yield compared to controls. A modest increase (~4%) in dry matter content was also observed under sterilized soil conditions. Foliar concentrations of Fe, Zn, and Mn significantly increased in plants inoculated with D. hansenii via root immersion in non-sterilized calcareous soil, indicating improved micronutrient acquisition under these specific conditions. Although leaf phosphorus levels were not significantly increased, D. hansenii stimulated acid phosphatase activity, as visually observed through BCIP staining, and upregulated genes involved in phosphorus acquisition under both P-sufficient and P-deficient conditions. At the molecular level, D. hansenii upregulated the expression of acid phosphatase genes (OsPAP3, OsPAP9) and a phosphate transporter gene (OsPTH1;6), confirming its influence on P-related physiological responses. These findings demonstrate that D. hansenii functions as a plant growth-promoting yeast (PGPY) and may serve as a promising biofertilizer for improving rice productivity and nutrient efficiency in calcareous soils, contributing to sustainable agricultural practices in calcareous soils and other nutrient-limiting environments. Full article