Search Results (120)

The nutrient requirements of coffee plants vary according to their phenological stages, with each nutrient playing specific roles in different structures and developmental phases. This study evaluated dry matter accumulation and the concentrations of N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, and B in the leaves, branches, and reproductive organs of five Coffea canephora genotypes during three phenophases: flowering, fruit development, and fruit ripening. This work aimed to evaluate the distribution of nutrients in three phenophases in Coffeea canephora genotypes. Significant differences were observed among genotypes and phenophases. During flowering, leaves accumulated the highest amount of dry matter, but this pattern reversed in later stages, with greater accumulation in the fruits, especially during fruit ripening. The Verdim TA genotype showed the lowest dry matter accumulation in the branches across all phenophases. Genotypes A1 and Clementino presented the highest mean concentrations of P, Ca, Mg, Fe, Cu, and Zn in the leaves during the fruit development phase, while Verdim TA showed the lowest concentrations of P, K, Ca, Mn, Zn, and B. Future studies may include additional phenological stages and quantify nutrient remobilization efficiency in each genotype, contributing to improved management recommendation. Full article

Severe drought events have raised concerns regarding their effects on the phenological cycles of forest species. This study evaluates the correspondence between in situ phenophases and those detected by an unmanned aerial vehicle (UAV) in tree species coexisting within a mixed forest, with particular attention to their relationship with climatic variables. Based on 12 consecutive monthly field observations, we compared phenological developments with UAV-derived normalized difference vegetation index (NDVI) values, which were then correlated with environmental variables. The analysis revealed a convergence of inflection points and seasonal phenological shifts, likely driven by climatic factors, although distinct patterns emerged between coniferous and broadleaf species. Photoperiod (PP), vapor pressure deficit (VPD), maximum temperature (TMAX), and, to a lesser extent, precipitation (P) were the primary environmental variables influencing NDVI results, used here as a proxy for phenology. Photothermal conditions revealed seasonal asynchrony in NDVI responses between coniferous and broadleaf species, exerting a positive influence on conifers during summer, while having a negative impact on broadleaf species in spring. Validation of in situ observations with UAV-derived data demonstrated a biological correlation between canopy dynamics and NDVI values, supporting its use as a proxy for detecting phenophases at the level of individual trees. Full article

This study investigates the seasonal and floral phenology, breeding strategies, and floral morphology of Azorina vidalii, an Azorean endemic Campanulaceae with hermaphroditic, protandrous flowers, dichogamy and secondary pollen presentation. Seasonal phenology was recorded in four field populations and floral phenology in a garden population. Reproductive strategies were assessed via controlled hand pollinations in one field population. Floral morphometrics were analysed using 23 floral and five pollen traits from 121 flowers across fourteen populations throughout the Azores archipelago. Non-parametric and parametric tests, discriminant analysis, and reproductive indices were used to infer answers to this study’s goals. Results showed that temperature and humidity influenced vegetative and reproductive phenophases. The male phase was shorter than the female, likely due to pollen dynamics, and some functional overlap suggested incomplete dichogamy. Geographic variation in floral traits indicated morphological differentiation across subarchipelagos, presumably linked to environmental factors or isolation. Reproductive indices suggested a mixed mating system, partial self–incompatibility and signs of inbreeding depression. Fertilisation was absent without pollinators, and spontaneous selfing was excluded due to an absence of pollen–pistil contact during stigma retraction. These findings contribute to understanding the reproductive biology and morphologic variation in A. vidalii. The implications of these findings for the conservation of this insular plant are discussed. Full article

Gibberellic acid (GA3) may help to synchronize coffee flowering, whilst ethylene (in the form of Ethephon) may assist in advancing coffee berry maturation even when applied in the pre-flowering stage of phenophase. Functional–structural plant modeling (FSPM) can be used to help understand whole-plant responses, such as plant-scale photosynthesis. FSPM has never been used to investigate the response of coffee plants to external plant growth regulator (PGR) applications. We hypothesized that treatment with PGRs at the beginning of berry maturation (BM) during phenophase could (1) influence plant leaf area and plant photosynthesis at the end of BM and (2) assist in the uniformity of the berry maturation of seven-year-old coffee plants. Additionally, we assumed that (3) the distribution of berries over the vertical plant profile could be related to the coffee beans’ chemical quality, and that irrigated plants would have delayed maturation, but a higher yield than non-irrigated (NI) plants. To test these hypotheses, a short sustainable period of irrigation was applied six weeks before harvest. Irrigated plants were treated with GA3 or Ethephon. A combination of field measurements (leaf gas exchanges, berry collection and bean chemical analyses in relation to vertical plant strata) and computer modeling were used. At the beginning or the end of BM, coffee trees were coded using the VPlants modeling platform and reconstructed using CoffePlant3D software to compute the plant leaf area and plant photosynthesis. The greatest number of second-order red berries were found in the upper stratum, S3 (>160 cm), while slightly fewer were found in S2 (80–160 cm) belonging to the third-order axes, and the lowest number was found in S1 (<80 cm). Green berries were more representative in S2, with the greatest number belonging to the third-order axes. The participation of third-order axes in berry yield was up to approximately 37% for red berries and 25% for green berries. The greatest separation between PGRs could be seen in S2, where more berries in the Ethephon-treated plants were found than in the GA3 treated ones, while the dry mass (DM) percentage was higher in GA3 than in the Ethephon treatment. The percentage of DM in fresh mass was 17–28% in the green berries and 28–36% in the red berries. PGRs were important for homogenous berry maturity, especially GA3, which also showed the lowest total chlorogenic acid content. The NI plants showed reduced red and total berry production when compared to irrigated ones, indicating this horticultural measure is important, even during a sustainably reduced six-week period, due to preserved leaf area and plant photosynthesis, and it also increased the lipid and kahweol contents of irrigated plants when compared to NI plants, despite the maturation delay. Full article

In this study, we investigate the nutrient supply of young corn (Zea mays var. rugosa) plants using conventional biological and chemical methods, as well as the N-glycan and metabolic profile of the plant sap using the MALDI-MS. Corn plants with three different nutrient supplies were grown on sandy soil for 45 days after emergence. In treatment 1 (T1), used as a control, the plants did not receive any nutrient supplementation. Plants in treatment 2 (T2) received “ideal” N-, P-, and K-nutrient supplementation in the form of inorganic fertilizers. In treatment 3 (T3), the plants were provided with the ideal amount of P and K, and a reduced amount of N fertilizer. In addition to the amount of biomass of the young plants, macronutrient content (N, P, K, Ca, and Mg) was measured in the dry matter. We examined the amount of 0.01 M CaCl₂-soluble N fractions of the experimental soils, and the P, K, Ca, and Mg content of their ammonium lactate (AL)-soluble fractions. We were unable to statistically distinguish between T1, T2, and T3 treatments using conventional methods (in this phenophase). Metabolic profiles in the sap from young plants, captured by MALDI-MS, showed significant differences between the control, “ideal”, and N-deficient treatments. This method may also be suitable for early detection of N-deficient conditions in other plants. Full article

Climate change is affecting Mediterranean climate regions, such as California. Retrospective phenological studies are a useful tool to track biological response to these impacts through the use of herbarium-preserved specimens. We used data from more than 12,000 herbarium specimens of 29 dominant native plant species that are characteristic of 12 broadly distributed vegetation types to investigate phenological patterns in response to climate change. We analyzed the trends of four phenophases: preflowering (FBF), flowering (F), fruiting (FS) and growth (DVG), over time (from 1830 to 2023) and through changes in climate variables (from 1896 to 2023). We also examined these trends within California’s 10 ecoregions. Among the four phenophases, the strongest response was found in the timing of flowering, which showed an advance in 28 species. Furthermore, 21 species showed sequencing in the advance of two or more phenophases. We highlight the advances found over temperature variables: 10 in FBF, 28 in F, 17 in FS and 18 in DVG. Diverse and less-consistent results were found for water-related variables with 15 species advancing and 11 delaying various phenophases in response to decreasing precipitation and increasing evapotranspiration. Jepson ecoregions displayed a more pronounced advance in F related to time and mean annual temperature in the three of the southern regions compared to the northern ones. This study underscores the role of temperature in driving phenological change, demonstrating how rising temperatures have predominantly advanced phenophase timing. These findings highlight potential threats, including risks of climatic, ecological, and biological imbalances. Full article

This study investigates millerandage, a physiological disorder affecting grapes during their development. In the climate change context, millerandage can become a viticultural hazard problem causing yield drops and posing challenges regarding wine quality due to uneven ripening in grape clusters. Using the 2023 vintage data from the Research Station for Viticulture and Enology Blaj (SCDVV Blaj), Târnave wine region, Romania, we assessed the climate conditions of 2023, focusing on the adverse climatic conditions from the flowering phenophase and the observed millerandage grade that occurred as a consequence. A total of 26 grapevine cultivars were monitored, assessing millerandage grade by field observations carried out in two grapevine plantations (S1 and S2) in July (BBCH 79) and September (BBCH 87). The results show statistically significant differences, with cultivars like Ezerfurtu (Ez), Napoca (Na), and Rhin Riesling (RR) exhibiting a millerandage grade higher than 35%, while cultivars like Pinot noir (PN) and Pinot gris (PG) showed resilience, with millerandage grades below 1%. These findings highlight cultivar-specific vulnerabilities and provides insights into millerandage’s role as a climate change challenge in viticulture. Full article

Climate warming is impacting vegetation productivity and plant leaf phenology, but the precise climate drivers and windows of key leaf phenological phases, such as emergence and fall, are still not well understood. Recent intensive computational approaches based on pinpointing the optimal climate window of leaf phenophases by maximizing the signal could help to advance in this question. In this study, we assess the climate variables, the climate windows, and the type of relationship (linear or nonlinear) that drive leaf emergence and fall in 21 deciduous and 13 evergreen woody plant species inhabiting two sites in Mediterranean Spain. We used precipitation, solar radiation, and different temperature measures, including forcing and chilling, as climate variables. We found that forcing variables were the best predictors of leaf phenology, but other temperature variables, as well as precipitation and radiation, were also important. However, chilling was not a good predictor. Most selected models showed nonlinear relationships. The best thresholds for calculating forcing were different from those commonly used. In addition, the best climate window for leaf phenology was species-specific and contingent on climatic and phenological conditions. This optimum climate window often covered longer periods than those usually considered in phenology studies. Our approach could be used to assess and better forecast future plant phenological responses to climate warming. Full article

Bitter cherries (Prunus avium var. sylvestris Ser.) represent a valuable raw material in the traditional Eastern European food industry with high potential within the horticultural chain and circular economy in the context of global food security due to exceptional nutritional properties. The present study was carried out in the period 2022–2024 and had as its main purpose the evaluation of the fruit quality and production indices of some bitter cherry cultivars suitable for the technological norms specific to industrial processing. Five bitter cherry cultivars (C₁-Amaris, C₂-Amar Maxut, C₃-Amar Galata, C₄-Silva, C₅-Amara) were studied and analyzed in terms of fruit quality—morpho-physiological and organoleptic traits, and physical and chemical parameters—and general productivity—tree vigor, fruiting, and yield indices. The results highlighted a wide variability in the physical characteristics of bitter cherries, with an average weight between 3.3 and 4.9 g and the color of the skin varying from yellow with redness to dark red and blackish. Regarding the chemical attributes, antioxidant activity was relatively higher in fruits with a more intense bitter taste (89.3 μg Trolox·g⁻¹ f.w for C₂ and 89.1 μg Trolox·g⁻¹ f.w. for C₄ and C₅), a fact also found in the content total of polyphenols (with a maximum value of 743.2 mg GAE·100 g⁻¹ f.w at C₂). Total soluble solids content had an average value of 20.51°Brix and titratable acidity of 0.85 g malic acid·100 g⁻¹ f.w. The influence of local environmental factors on the productivity of bitter cherry cultivars was highlighted by significant statistical differences (p < 0.05) between cultivars. Thus, the resistance to frost in the full flowering phenophase had an average value of 86.69%, and regarding the resistance to fruit cracking, the highest percentage was found in C₁, with 99.79% unaffected fruits. The productivity index per tree had an average value of 0.24 kg per cm² trunk cross-section area. The physico-chemical properties of the fruits and the productivity of bitter cherry cultivars support the possibility of their efficient use in processing and the food industry, yielding high-quality products with nutraceutical value. Full article

The advent of precision agriculture has highlighted the necessity for the careful determination of crop phenology at increasingly smaller scales. Although remote sensing technology is extensively employed for the monitoring of crop growth, the acquisition of high-precision phenological data continues to present a significant challenge. This study, conducted in Youyi County, Shuangyashan City, Heilongjiang Province, China, employed time-series spectral index data derived from Sentinel-2 remote sensing images to investigate methodologies for the extraction of pivotal phenological phases during the primary growth stages of maize. The data were subjected to Savitzky–Golay (S-G) filtering and cubic spline interpolation in order to denoise and smooth them. The combination of dynamic thresholding with slope characteristic node recognition enabled the successful extraction of the jointing and tasseling stages of maize. Furthermore, a comparison of the extraction of phenophases based on the time-series curves of the NDVI, EVI, GNDVI, OSAVI, and MSR was conducted. The results showed that maize exhibited different sensitivities to the spectral indices during the jointing and tasseling stages: the OSAVI demonstrated the highest accuracy for the jointing stage, with a mean absolute error of 3.91 days, representing a 24.8% improvement over the commonly used NDVI. For the tasseling stage, the MSR was the most accurate, achieving an absolute error of 4.87 days, with an 8.6% improvement compared to the NDVI. In this study, further analysis was conducted based on maize cultivation data from Youyi County (2021–2023). The results showed that the maize phenology in Youyi County in 2021 was more advanced compared to 2022 and 2023, primarily due to the higher average temperatures in 2021. This study provides valuable support for the development of precision agriculture and maize phenology monitoring and also provides a useful data reference for future agricultural management. Full article

Soil arsenic (As) contamination is a global issue affecting regions worldwide. As in the soil is primarily present in inorganic forms, such as arsenite [As(III)] and arsenate [As(V)]. As is a microelement that is toxic to plants grown in As-contaminated soil. The aim of our study was to investigate the effects of increasing concentrations (0, 3, 10, 30, 90, and 270 mg kg⁻¹) of As(III) and As(V) on the As content in green pea (Pisum sativum L.) and the distribution of As among different plant parts at four phenophases (the four-node stage, beginning of flowering, green ripening, and mature stage). Another aim was to determine the percentage of total soil As available to plants under different treatments. The results indicate that the developmental stage of the pea and treatment concentration significantly influence the distribution of As among plant organs. However, the differences between the effect of inorganic As forms were less pronounced. The amount of As absorbed by the whole test plant increased with higher treatment concentrations. In the case of As(III)-treatment, As amount in the whole plant increased from 0.170 µg to 7.31 µg (I. Phenophase); from 0.294 µg to 10.1 µg (II. Phenophase); from 0.435 µg to 31.6 µg (III. Phenophase); and from 0.697 µg to 36.1 µg (IV. Phenophase). As a result of As(V)-treatment, the whole plant’s As content increased from 0.170 µg to 8.94 µg (I. Phenophase); from 0.294 µg to 17.4 µg (II. Phenophase); from 0.435 µg to 29.7 µg (III. Phenophase); and from 0.697 µg to 58.5 µg (IV. Phenophase). The concentration of As accumulated by the plant also increased over time. The proportion of As absorbed by generative parts was much smaller than that absorbed by vegetative organs. The pea seeds generally accumulated less As (maximum 7%) than the pea pods (in some cases, this reached the 10%). As the total amount of As taken up by the plant increased, the proportion of As reaching the seeds generally decreased (from 5% to 0.3% in the case of As[III]-treatment, and from 5% to 0.1% in the case of As[V]-treatment). At treatment levels where the ability of the stem to retain As increased, a maximum of 1% of the total As absorbed by the plant was found in the seeds. Depending on the treatment, 3.82–5.69% [As(V)-treatments] and 3.9–6.07% [As(III)-treatments] of the total soil As were available to the plants. The difference in the ratio of the total As content to the soluble As content was more evident at higher treatment levels (≥30 mg kg⁻¹). This value was typically lower for the As(V)-treatments. Full article

Climate change increasingly impacts urban dendroflora, affecting plant physiology and phenological phases. This paper investigates the impact of changing climatic conditions on the blooming of Fraxinus ornus ‘Globosa’, a decorative form of ash that is a significant component of green infrastructure in Novi Sad, Serbia. The research, conducted over 15 years on 42 individuals in a linear planting near a large river, analyzed temperature and precipitation effects on blooming times and inflorescence characteristics The results indicate changes in the timing of blooming, earlier than recorded in the literature, suggesting that temperature variations and changes in climatic conditions have significantly influenced the phenological phases of the selected clones of globe flowering ash. Additionally, the studied individuals showed exceptional adaptation to climate change and are not considered vulnerable. This study confirmed that this cultivar of flowering ash in urban environments is a key link in the green infrastructure of cities, functioning as green corridors along river flows as a nature-based solution. The studied cultivar is an important element of cultural heritage, contributing to the recreational potential of the linear composition of the promenade, especially during the flowering phenophase, when, in addition to its aesthetic values, it has psychological effects on users of the space, offering a calming influence due to its regular canopy and planting rhythm. Additionally, this cultivar provides important ecological functions, such as offering pollen for pollinators, thereby significantly contributing to the implementation of ecosystem services. Full article

Savannas are widespread biomes with highly valued ecosystem services. To successfully manage savannas in the future, it is critical to better understand the long-term dynamics of their productivity and phenology. However, accurate large-scale gross primary productivity (GPP) estimation remains challenging because of the high spatial and seasonal variations in savanna GPP. China’s savanna ecosystems constitute only a small part of the world’s savanna ecosystems and are ecologically fragile. However, studies on GPP and phenological changes, while closely related to climate change, remain scarce. Therefore, we simulated savanna ecosystem GPP via a satellite-based vegetation photosynthesis model (VPM) with fine-resolution harmonized Landsat and Sentinel-2 (HLS) imagery and derived savanna phenophases from phenocam images. From 2015 to 2018, we compared the GPP from HLS VPM (GPP_HLS-VPM) simulations and that from Moderate-Resolution Imaging Spectroradiometer (MODIS) VPM simulations (GPP_MODIS-VPM) with GPP estimates from an eddy covariance (EC) flux tower (GPP_EC) in Yuanjiang, China. Moreover, the consistency of the savanna ecosystem GPP was validated for a conventional MODIS product (MOD17A2). This study clearly revealed the potential of the HLS VPM for estimating savanna GPP. Compared with the MODIS VPM, the HLS VPM yielded more accurate GPP estimates with lower root-mean-square errors (RMSEs) and slopes closer to 1:1. Specifically, the annual RMSE values for the HLS VPM were 1.54 (2015), 2.65 (2016), 2.64 (2017), and 1.80 (2018), whereas those for the MODIS VPM were 3.04, 3.10, 2.62, and 2.49, respectively. The HLS VPM slopes were 1.12, 1.80, 1.65, and 1.27, indicating better agreement with the EC data than the MODIS VPM slopes of 2.04, 2.51, 2.14, and 1.54, respectively. Moreover, HLS VPM suitably indicated GPP dynamics during all phenophases, especially during the autumn green-down period. As the first study that simulates GPP involving HLS VPM and compares satellite-based and EC flux observations of the GPP in Chinese savanna ecosystems, our study enables better exploration of the Chinese savanna ecosystem GPP during different phenophases and more effective savanna management and conservation worldwide. Full article

Operational crop monitoring applications, including crop type mapping, condition monitoring, and yield estimation, would benefit from the ability to robustly detect and map crop phenology measures related to the crop calendar and management activities like emergence, stem elongation, and harvest timing. However, this has proven to be challenging due to two main issues: first, the lack of optimised approaches for accurate crop phenology retrievals, and second, the cloud cover during the crop growth period, which hampers the use of optical data. Hence, in the current study, we outline a novel calibration procedure that optimises the settings to produce high-quality $NDVI$ time series as well as the thresholds for retrieving the start of the season (SOS) and end of the season (EOS) of different crops, making them more comparable and related to ground crop phenological measures. As a first step, we introduce a new method, termed UE-WS, to reconstruct high-quality $NDVI$ time series data by integrating a robust upper envelope detection technique with the Whittaker smoothing filter. The experimental results demonstrate that the new method can achieve satisfactory performance in reducing noise in the original $NDVI$ time series and producing high-quality $NDVI$ profiles. As a second step, a threshold optimisation approach was carried out for each phenophase of three crops (winter wheat, corn, and sugarbeet) using an optimisation framework, primarily leveraging the state-of-the-art hyperparameter optimization method (Optuna) by first narrowing down the search space for the threshold parameter and then applying a grid search to pinpoint the optimal value within this refined range. This process focused on minimising the error between the satellite-derived and observed days of the year (DOY) based on data from the German Meteorological Service (DWD) covering two years (2019–2020) and three federal states in Germany. The results of the calculation of the median of the temporal difference between the DOY observations of DWD phenology held out from a separate year (2021) and those derived from satellite data reveal that it typically ranged within ±10 days for almost all phenological phases. The validation results of the detection of dates of phenological phases against separate field-based phenological observations resulted in an $RMSE$ of less than 10 days and an R-squared value of approximately 0.9 or greater. The findings demonstrate how optimising the thresholds required for deriving crop-specific phenophases using high-quality $NDVI$ time series data could produce timely and spatially explicit phenological information at the field and crop levels. Full article

The aim of this study was to determine the nitrogen requirement of maize, the optimal timing and amount of nutrient application, based on long time series data. An additional objective was to examine the response of the relative chlorophyll content of maize to nitrogen fertilisation. The examinations were carried out in a long-term field experiment at the University of Debrecen between 2016 and 2022, using two maize hybrids with different genotypes. Spatial and temporal changes in the N status of maize leaves were monitored using the Soil and Plant Analysis Development (SPAD) instrument. In addition to the non-fertilised (A₀) treatment, six fertiliser treatments were applied (spring basal fertilisation: 60 and 120 kg N ha⁻¹, A₆₀; A₁₂₀). Basal fertilisation was followed by two occasions of top-dressing at phenological stages V6 and V12, at rates of +30–30 kg N ha⁻¹ (V6₉₀ and V6₁₅₀, and V12₁₂₀ and V12₁₈₀). The CMR (Chlorophyll Meter Reading), averaged over the examined years, genotypes and fertiliser treatments, were lowest in the V6 phenological phase (40.23 ± 5.57, p < 0.05) and highest in R1 (49.91 ± 8.41, p < 0.05). A₁₂₀ fertiliser treatment increased the relative chlorophyll content by 5.11 compared to the non-fertilised treatment, 1.67 more than A60 treatment. The basal fertilisation treatment substantially increased the yield (A₆₀: +30.75%; A₁₂₀: +66.68%) compared to the A₀ treatment averaged over years and genotypes. Based on the obtained research results, a basal treatment of 120 kg N ha⁻¹ is recommended and it can be concluded that, under appropriate water supply conditions (rainfall, irrigation), nitrogen top-dressing applied in V6 phenophase results in a significant yield increase compared to basal fertilisation. Full article