Search Results (18)

‘Green island’ symptoms in the form of vivid green, round spots visible on the senescent leaves of many plants and trees are mostly the results of pathogenic colonization by fungi, and the greenish tissue is often dead. Therefore, this study investigates whether green spots observed on senescent Norway maple (Acer platanoides L.) leaves were still alive and photosynthetically active. The appearance of ‘green islands’ on the leaves of young Norway maple trees was observed from the autumn of 2019 to 2022 in an urban forest (Bialystok, eastern Poland). However, in the late summer (September) of 2023 and 2024, mostly tar spots caused by the fungus Rhytisma spp. on maple leaves could be observed, with only a few leaves having ‘green island’ symptoms. The percentage of ‘green island’ areas on senescent leaves observed during the 4 years (2019–2022) was influenced by a year of sampling (p < 0.001). A non-destructive physiological analysis of chlorophyll, flavonoids, and nitrogen balance index (NBI) in leaves revealed that these parameters were significantly lower in ‘green islands’ than in the summer leaves, but higher than in the senescent yellow area of the autumn leaves. In the case of anthocyanins, their level was significantly higher in ‘green islands’ than in yellow areas, although, in the summer leaves, anthocyanins were undetectable. The amount of chlorophyll and most photosynthetic parameters were significantly (p < 0.05) reduced in the ‘green islands’ of the senescent leaves compared to the mature green leaves. However, these parameters were significantly higher in the ‘green islands’ than in senescent yellow leaves. Carotenoid content in the ‘green island’ and yellow areas of senescent leaves were at the same level, twice as higher than in summer leaves. Green mature leaves and the ‘green islands’ on senescent leaves had the same structure and anatomy. The main differences concerned the chloroplasts, which were smaller and had less grana and starch grains, but had more plastoglobuli in ‘green island’ cells. The cells building the mesophyll in the yellow area of the leaf deteriorated and their chloroplasts collapsed. Epiphytes were present on the adaxial epidermis surface in all types of samples. Full article

Rational management of scarce water resources is necessary. These resources are not utilised effectively. Therefore, the efficacy of irrigation management at the field level can be enhanced, and the irrigated areas can be expanded through rigorous irrigation management. By estimating water requirements in a straightforward, realistic, precise and feasible manner, achieving optimal water consumption for quality production and profitability is possible. In the context of the development of water resources in tropical and hot climates such as Ghana, estimating water demand assists farmers in planning and adjusting their requirements over time. This study assessed the water requirements of a greenhouse banana during the dry season to assure year-round cultivation, as Ghana has two primary seasons: wet and dry. The estimate was predicated using WSN and the JDL–Mivar data fusion model, which was dependent on the determination of perspiration. The results were contrasted with the existing literature, considering both climatic and biological data and other parameters during the cultivation period due to the model’s ability to fuse datasets. The study determined that the optimal indoor temperature for banana cultivation was 38.1 °C, while the minimum threshold was set at 21 °C. Significant differences and fluctuations in the maximal daily transpiration rates were observed in the water requirements for ‘WN’ values, which ranged from 25 to 50 m³/(ha·J). Banana plants require an intake of 10–20 litres of water per day during their growth season, according to the data collected from the WSN moisture sensor. The banana plants transpired between 100 and 600 kilogrammes of water for every kilogramme of dry matter produced during the humid climate, as indicated by the transpiration ratio, which ranged from 100 to 600. The Leaf Area Index (LAI) fluctuated from 3.3 in June to 4.89 in December. Our proposed method for monitoring bananas in a greenhouse will provide the cultivator with precise information about the bananas that are cultivated within the greenhouse environment. The optimal Leaf Area Index is between 3.6 and 4.5 for bananas to achieve their maximum yield potential. The relative humidity for bananas is typically around 80%, ranging from 65% to 75% during the night and approximately 80% during the day. Full article

Urban green spaces (UGSs) are critical in providing essential ecosystem services (ESs) that enhance the quality of life of urban communities. This study investigated the synergies and trade-offs between structural characteristics of urban trees and their ecosystem services and their implications for urban park management within Yurim Park, Daejeon, South Korea, using the i-Tree Eco tool. The study specifically focused on regulating and supporting services, assessing diversity, air pollution removal, carbon sequestration, and avoiding runoff. A systematic review of urban park management practices complemented the empirical analysis to provide comprehensive management recommendations. The findings of a total of 305 trees from 23 species were assessed, revealing moderate species diversity and significant variations in structural attributes, such as diameter at breast height (DBH), leaf area index (LAI), and crown width (CW). These attributes were found to be strongly correlated with ES outcomes, indicating that healthier and larger trees with extensive canopies are more effective in providing benefits such as pollution removal, runoff reduction, and carbon sequestration. However, the study also identified trade-offs, particularly regarding volatile organic compound (VOC) emissions, which can contribute to ground-level ozone formation despite the trees’ pollution removal capabilities, sensitivity to water stress, requirements for shade and cooling effects, and impacts on water yield. The results highlight the importance of strategic management practices to balance these trade-offs, such as selecting low-emitting species and employing incremental pruning to enhance pollutant removal while minimizing VOC emissions. Additionally, the findings underscore the significance of tree placement and landscape patterns in optimizing year-round benefits, particularly in reducing urban heat island effects and enhancing energy efficiency in adjacent buildings. The study concludes that while urban parks like Yurim Park offer substantial ecological and environmental benefits, continuous monitoring and adaptive management are essential to maximize synergies and mitigate trade-offs. The insights provided on species selection, tree placement, and landscape design offer valuable guidance for urban planners and landscape architects aiming at enhancing the effectiveness of urban parks as nature-based solutions for sustainable urban development. Full article

Urban air pollution poses a significant threat to human health, with metropolitan areas particularly affected due to high emissions from human activities. Particulate matter (PM_x) is among the most harmful pollutants to human health, being composed of a complex mixture of substances related to severe pulmonary conditions. Urban green spaces play a vital role in mitigating air pollution by capturing PM_x, and it is essential to select plant species with a high capacity for PM_x accumulation to effectively enhance air quality. This study aimed to evaluate and compare the accuracy of two PM_x quantification methods—light microscopy and filtration—which demonstrated a high correlation (R² = 0.72), suggesting that both methods are reliable for assessing PM_x accumulation on leaves. Light microscopy allowed for the visualization of PM_x deposition, revealing the species warranting further analysis using the filtration method. Among the species analyzed, Euonymus japonicus, Ligustrum lucidum, Alnus glutinosa, Rubus ulmifolius, and Laurus nobilis demonstrated the highest total PM_x accumulation, exceeding 50 µg cm⁻², making them particularly valuable for air pollution mitigation. This study examined the correlation between leaf traits such as specific leaf area (SLA), leaf area (LA), leaf dissection index (LDI), and leaf roundness and PM_x accumulation across the 30 different plant species. A multiple linear regression analysis indicated that these leaf traits significantly influenced PM_x accumulation, with SLA and LA showing negative correlations and leaf roundness exhibiting a positive correlation with PM_x deposition. In conclusion, this study highlights the importance of selecting plant species with specific leaf traits for effective air quality improvement in urban environments particularly in highly polluted areas, to enhance air quality and public health. Full article

The potential microclimatic effects of street trees are influenced by their ecological characteristics, planting patterns, and street orientations, especially in subtropical hot and humid areas. To investigate these effects, four typical street tree species in Guangzhou were selected for study during the transition seasons: Khaya senegalensis, Terminalia neotaliala, Ficus microcarpa, and Mangifera indica. Air temperature (AT), relative humidity (RH), solar radiation (SR), surface temperature (ST), wind speed (WS), and the leaf area index (LAI) were monitored. The cooling effects of these four species and the resulting improvements in human thermal comfort (HTC) were assessed. The influences of tree planting patterns and street orientations on cooling benefits were systematically analyzed. The results indicate that, during transition seasons, the four street trees, on average, can block 96.68% of SR, reduce AT by 1.45 °C and ST by 10.25 °C, increase RH by 5.26%, and lower the physiologically equivalent temperature (PET) by 8.34 °C. Terminalia neotaliala, reducing AT and PET by 1.76 °C and 12.4 °C, respectively, offers the greatest potential for microclimate improvement. Among the four tree species, the variations in ST (ΔST) and PET (ΔPET) were minimal, at only 0.76 °C and 0.25 °C, respectively. The average differences in AT and PET between inter-tree and under-tree environments were 0.06 °C and 0.98 °C, respectively. The AT reduction rate was 1.7 times higher in the double-row planting pattern compared to the single-row planting pattern. Street trees planted in the northwest–southeast (NW-SE) orientation exhibited a 16.96% lower WS reduction than those in other orientations. The northeast–southwest (NE-SW) orientation showed the least potential to enhance human thermal comfort. Compared to NE-SW, the northwest–southeast (NW-SE) orientation achieved twice the rate of AT reduction, while the north–south (N-S) orientation improved it by 1.3 times. This data analysis aids in assessing the impact of green infrastructure on urban climates and demonstrates the year-round microclimatic benefits of street trees. Full article

In Korea, greenhouses are traditionally used for crop cultivation in the winter. However, due to diverse consumer demands, climate change, and advancements in agricultural technology, more farms are aiming for year-round production. Nonetheless, summer cropping poses challenges such as high temperatures, humidity from the monsoon season, and low light conditions, which make it difficult to grow crops. Therefore, this study aimed to determine the best planting time for summer tomato cultivation in a Korean semi-closed greenhouse that can be both air-conditioned and heated. The experiment was conducted in the Advanced Digital Greenhouse, built by the National Institute of Agricultural Sciences. The tomato seedlings were planted in April, May, and June 2022. Growth parameters such as stem diameter, flowering position, stem growth rate, and leaf shape index were measured, and harvesting was carried out once or twice weekly per treatment from 65 days to 265 days after planting. The light use efficiency and yield per unit area at each planting time was measured. Tomatoes planted in April showed a maximum of 42.9% higher light use efficiency for fruit production and a maximum of 33.3% higher yield. Furthermore, the growth form of the crops was closest to the reproductive growth type. Therefore, among April, May, and June, April is considered the most suitable planting time for summer cultivation, which is expected to contribute to reducing labor costs due to decreased workload and increasing farm income through increased yields. Future research should explore optimizing greenhouse microclimates and developing crop varieties tailored for summer cultivation to further enhance productivity and sustainability in year-round agricultural practices. Full article

The installation of solar facilities is increasing rapidly in the Mojave Desert USA, with the largest facility in North America (3227 ha) currently being built 30 km north of Las Vegas, NV. At the state level, Nevada (USA) has developed an energy plan to diversify its energy portfolio by 2030 with green energy representing 50% of the energy produced. Although solar is considered a clean energy, it does require significant amounts of land and as such may have negative consequences at the habitat and ecosystem levels. A multi-year study was conducted to assess the impact a photovoltaic facility in the Mojave Desert had on the growth and physiological response of two native shrubs (Ambrosia dumosa and Larrea tridentata) growing inside and outside the facility. These species were selected because they were the dominant species at the site and are representative of desert scrub communities throughout the Mojave Desert. At the time of construction, native plants and washes were left intact inside the solar facility. The solar panel arrays were separated at either 8 m or 10 m. Plants were selected for monitoring on the basis of location: at the panel drip line, below the panels, or midway between panel rows. Abiotic factors, including PAR, reference evapotranspiration, precipitation, soil water in storage, and infiltration, were monitored bi-monthly. The growth and physiological status of the plants were assessed by monitoring leaf water potential, chlorophyll index, canopy temperatures, non-structural carbohydrates in the roots and stems, leaf tissue ion concentrations, stem elongation, and seed production. Plants at the bottom edges of the panels received more precipitation due to runoff from the panels, which led to increased soil moisture in the long spacing but not the short spacing. The lower soil water in storage in the short spacing was related to greater growth and higher soil water extraction. Although the area under the panels provided shade in the summer and warmer temperatures in the winter, the incoming PAR was reduced by as much as 85%, causing plants growing under the panels to be spindly with lower canopy volume (L. tridentata, p = 0.03) and seed yield (A. dumosa, p = 0.05). Ambrosia plants remained green in color year-round (not going into winter dormancy) inside the facility and had elevated levels of starch in their roots and stems compared with plants growing at the outside control sites (p < 0.001). Larrea growing outside the facility had lower xylem water potentials compared with those inside the facility (p < 0.001), lower chlorophyll index (p < 0.001, Ambrosia as well), and lower stem elongation (p < 0.001), supporting the conclusion that both Larrea and Ambrosia performed better inside the facility. Shifts in δ¹³ C suggested greater water-use efficiency at the locations with the least amount of soil water in storage. Our results support the installation of solar facilities that minimize the impact on native plants and wash connectivity (ecovoltaics), which should translate into a reduced negative impact at the habitat and ecosystem levels. Basedon our results, energy companies that embrace ecovoltaic systems that take an engineering and biological approach should provide acceptable environments for desert fauna. However, corridors (buffers) will need to be maintained between solar facilities, and fences will need to have openings that allow for the continuous flow of animals and resources. Full article

Potential evapotranspiration (PET) indicates if a cultivation area is suitable for planting. Currently, site-specific PET models that are based on large geographic regions are vulnerable to inaccurate predictions as a result of climate change and sudden changes in the environmental abiotic stressors that affect plant growth. For the aim of promoting the papaya Sinta F1 cultivar, the study optimized the standard Thornthwaite PET model by integrating three advanced physics-based metaheuristics and evolutionary computing, namely atom search (ASO), differential evolution (DE), and multiverse (MVO) optimizers. The PET value was optimized through minimization as a function of air temperature, light intensity, heat index, and extended heat index. As the PET value approaches 0, it indicates that there is more soil-water content that can be absorbed by plants. Based on the four cultivation treatments (uncontrolled, ASO, DE, and MVO) exposed in three replicates within 90 days, the ASO-optimized Thornthwaite PET-treated (ASO_Th) papaya plants resulted in the highest chlorophyll a and b concentrations, densest stomatal density, concentrated root and stem xylem and phloem vessels, considerable root and stem length, most formed leaf count, and strongest action potentials coming from stem membrane for both light and dark periods. This proves the applicability of the intelligent process in modifying the Thornthwaite model for plant growth promotion. Also, through the developed ASO_Th, the stem length and thickness ratio was improved for mechanical stability to facilitate more branching leaves and potential fruits during the fruiting stage, and the chlorophyll a and b ratio was enhanced, which naturally extended the light energy band for photosynthesis. Overall, the newly developed ASO_Th model may be used to grow papaya seedlings year-round anywhere on Earth if there is a control system to regulate the environmental setting inside the growth chamber. Full article

Wheat (Triticum aestivum L.) is a key food crop, accounting for approximately 765 million tons produced worldwide. The present study evaluated 16 wheat genotypes using 19 morphological and phenological traits, 16 molecular markers (Inter Simple Sequence Repeats and Start Codon Targeted; ISSR and SCoT) and rbcL and matK plastid gene barcoding. The 16 wheat genotypes showed significant genetic variation using the markers assayed. Cell plot of phenological parameters revealed significant differences among the 16-day-old seedlings of wheat genotypes at Z1.1 growth stage. Collectively, W2 genotype had the lowest shoot length (SL), length of first internodes (LFI) and leaf area (LA) values, while W8 genotype had the highest diameter of first internode (DFI) and LA values. Furthermore, W7 genotype had the maximum plant biomass (PB) and leaf width (LW) values. Geometric models grouped wheat kernels into “rounded” and “nearly elongated”. Estimates of heritability (H²) for these morphological characters ranged from 4.93 to 100%. The highest H² values were recorded for root number (RN) (100%) followed by SL (88.72%), LFI (88.30%), LA (87.76%) and Feret diameter (86.68%), while the lowest H² value was recorded for DFI (4.93%). Furthermore, highly significant genotypic and phenotypic correlations were also observed among those traits. Reproducible fingerprinting profiles and high levels of polymorphism (PPB%) of SCoT (95.46%) and ISSR (82.41%) were recorded, indicating that they are effective tools for detecting genetic variation levels among wheat genotypes. The informativeness of markers were measured through estimation of polymorphic information content (PIC), resolving power (RP) and marker index (MI). The RP and PPB% of SCoT were significantly higher compared to those of ISSR. Comparatively, the two molecular markers were effective for studying genetic diversity among wheat genotypes, but SCoT markers were more informative. Moreover, based on the two chloroplast DNA regions (rbcL and matK), MatK was found to be more reliable for differentiating among T. aestivum genotypes. Taken together, using all the studied attributes, a clear taxonomic relationship can be used to identify T. aestivum species and improve their pragmatic production and development. Full article

The oil palm (OP) Elaeis guineensis is a robust feeder of nutrients and necessitates the adjustment and adequate allocation of nutrients for optimum growth and yields. Therefore, information on leaf nutrient concentrations during the immature stage is essential for maximal OP yield at the mature stage. Currently, in Malaysia, fertilizer by the standard practice application (Treatment 1; T1) is considered a cost-effective fertilization practice in terms of fertilization cost and the overall cost per palm oil tree per hectare. However, there is an idea to further reduce the costs of fertilizers and labour per hectare to make it more cost-effective. Therefore, the present study aims to develop a novel biochemical fertilizer by testing the Universiti Putra Malaysia (UPM) biochemical fertilizer (Treatment 2; T2) in the immature OP. Since the use of T1 has been well established in Malaysia, the present study is to compare the leaflets’ nutrient levels (nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), and boron (B)) and vegetative parameters (frond length (FL), frond number of leaves (FNL), frond width (FW), frond thickness (FT), chlorophyll index (CI), and the canopy of immature OP by using T2 to compare with those in T1. This study was conducted 6 to 48 months after planting (MAP) at the Telang OP plantation, Kuala Lipis (Pahang), from January 2015 to December 2018. Based on the chemical levels of the pre-treatment soil samples collected at the weeded circle area in January 2015 in the two depths (0–15 cm and 15–30 cm), there was no significant difference (p > 0.05) in all 11 chemical parameters (pH, total N, organic carbon (Org C), total P, available P (Av P), cation exchange capacity (CEC), exchangeable K, (Ex K), exchangeable Ca (Ex Ca), exchangeable Mg (Ex Mg), exchangeable aluminium (Ex Al) and B between T1 and T2. This indicated that the chemical levels in the OP soils in both T1 and T2 would not be significant factors when T1 and T2 were applied. All six leaflets’ nutrient levels showed at least ‘Optimum’ or ‘Excessive’ compared to the established guideline using T1 and T2. Overall, there was no significant (p > 0.05) difference in all the above six leaflets’ nutrient levels and six vegetative parameters between T1 and T2 based on the t-Test, multiple linear stepwise regression analysis, and correlation analysis. These results suggested that rates of T1 and T2 applied in this study are enough to provide the amount of nutrients needed to support the OP vegetative growth during the immature period. The estimated cost savings for the combination of T2 fertilizers per hectare (RM 1113.43 or 250 USD) and reduction of the number of rounds (RM 133.85; or 30 USD) of T2 fertilizer application would give a sum of total cost savings of at least RM 1247.25 (280 USD) per hectare. If only based on the T2 fertilizer per hectare, the economic benefit of the total cost saving is estimated to be at least 10.6%. In summary, this study recommends the utilization of T2 as a novel, cost-effective, and alternative biochemical fertilizer treatment for better management of immature OP plantations in Malaysia. Full article

Conventional methods of crop mapping need ground truth information to train the classifier. Thanks to the frequent acquisition allowed by recent satellite missions (Sentinel 2), we can identify temporal patterns that depend on both phenology and crop management. Some of these patterns are specific to a given crop and thus can be used to map it. Thus, we can substitute ground truth information used in conventional methods with agronomic knowledge. This approach was applied to identify irrigated permanent grasslands (IPG) in the Crau area (Southern France), which play a crucial role in groundwater recharge. The grassland is managed by making three mows during the May–October period, which leads to a specific temporal pattern of leaf area index (LAI). The mowing detection algorithm was designed using the temporal LAI signal derived from Sentinel 2 observations. The algorithm includes some filtering to remove noise in the signal that might lead to false mowing detection. A pixel is considered a grassland if the number of detected mows is greater than 1. A data set covering five years (2016–2020) was used. The detection mowing number was conducted at the pixel level, and then the results were aggregated at the plot level. An evaluation data set including 780 plots was used to assess the performances of the classification. We obtained a Kappa index ranging between 0.94 and 0.99 according to the year. These results were better than other supervised classification methods that include training data sets. The analysis of land-use changes shows that misclassified plots concern grasslands managed less intensively with strong intra-parcel heterogeneity due to irrigation defects or year-round grazing. Time series analysis, therefore, allows us to understand different management practices. Real land-use change in use can be observed, but long time series are needed to confirm the change and remove ambiguities with heterogeneous grasslands. Full article

This research was conducted to select the most suitable winter forage crop varieties for silage in reclaimed land located in the Midwest of Korea by investigating the soil environment, crop growth characteristics, dry weight, and forage value according to growth stage. The slightly alkalescent soil was characterized by a pH of 7.41–7.84, by an electrical conductivity (EC) of 1–2.5 dS/m, and by 440–934 mg/kg of available phosphate. Barley showed the highest chlorophyll content in the heading stage and milk stages, while oats and triticale reached the highest content in the milk and dough stage. In both years, triticale achieved the highest leaf area index (LAI), reaching 4.3–4.8. In addition, triticale showed the highest percentage of dry matter and the highest dry weight in the milk stage. Forage value was the best in the heading stage for all cereal crops; however, its quality decreased as the growth stage proceeded. This study suggests cultivating triticale, which showed high adaptability to reclaimed soil and climatic conditions, as well as good growth and dry weight when harvested between the milk and dough stages. These results indicate that triticale can be cultivated all year round in salty soil and these data can be useful to increase forage production in reclaimed soil. Full article

Akebia trifoliata (three-leaf akebia) has long been used as a medicinal herb and has the potential to be used in diverse ways, especially as a fruit crop. However, efforts to domesticate and cultivate new varieties for commercial use are only in their infancy. Here, we evaluated the genetic diversity of 29 genotypes, which were previously selected from a natural population consisting of 1447 genotypes and exhibiting high resistance to fungal diseases and a smooth peel of A. trifoliata using 85 genome-specific single sequence repeat (SSR) markers. We also characterized variation in 19 phenotypic traits and nutritional components. Large variation in phenotypic traits and nutritional components was observed, especially in vitamin C, seed/pulp, and fruit color. Correlation analyses revealed that many phenotypic traits and nutritional components were significantly correlated. A principal component analysis identified five principal components, which explained 83.2% of the total variation in the data. The results of the SSR analysis revealed that 80 of the 85 SSR markers were polymorphic; the total number of alleles amplified was 532. The expected heterozygosity was 0.672, and Shannon’s information index was 1.328. A Ward dendrogram and unweighted pair group method with arithmetic mean dendrogram revealed high diversity among the 29 genotypes and suggested that the measured morphological and nutritional traits were genetically independent of disease resistance and texture traits, as well as SSR marker loci. Finally, our results suggest that additional rounds of selection from the selected population, despite its small size, could be effective for the development of new A. trifoliata fruit cultivars. Full article

Lettuce (Lactuca sativa L.) is a leafy vegetable cultivated widely for its fast and year-round production and its beneficial phytochemical content, which may be boosted further by plant biostimulants that are considered eco-sustainable means for enhancing horticultural crop production. A greenhouse experiment was carried out to evaluate the yield and qualitative parameters of two differently pigmented lettuce cultivars grown in a floating raft system either untreated or treated (leaf, root or leaf/root application) with vegetal protein hydrolysates (PHs). For foliar application (F), lettuce plants were sprayed at a dose of 3 mL L⁻¹, whereas for root application, 0.15 (T1) or 0.3 (T2) mL L⁻¹ was applied to the nutrient solution alone or in combination with foliar spray (T1 + F and T2 + F) with the same foliar concentration. Bio-morphometric and production data were collected after harvest. Physiological and plant nutrition assays included leaf gas exchange, leaf fluorescence, SPAD index, mineral content, carotenoids, total phenols, total ascorbic acid content and antioxidant activities. Cultivar-specific reactions to biostimulant application were noted: whilst the green pigmented cultivar thrived under nutrient solution applications and recorded higher yield by 82.7% (T1) or (T1 + F) and 71.7% (T2), the red cultivar thrived under combined treatments, yielding 55.4% (T2 + F) higher than control and providing the most concentrated phytochemical content. These latter treatments also engendered the highest SPAD index, F_v/F_m ratio, CO₂ assimilation, stomatal conductance and transpiration. In addition, the T2 + F treatment boosted ‘Canasta’ hydrophilic antioxidant activity (21.9%) and total ascorbic acid (5.6-fold). Nutrient solution treatments alone proved advantageous when compared to foliar treatments, while mixed treatments proved genotype-specific. New research on genotype specificity of biostimulant effects is warranted for future use, in order to rationalize biostimulant application modes and dosages. Full article

Leaf shape is closely related to economics of leaf support and leaf functions, including light interception, water use, and CO₂ uptake, so correct quantification of leaf shape is helpful for studies of leaf structure/function relationships. There are some extant indices for quantifying leaf shape, including the leaf width/length ratio (W/L), leaf shape fractal dimension (FD), leaf dissection index, leaf roundness index, standardized bilateral symmetrical index, etc. W/L ratio is the simplest to calculate, and recent studies have shown the importance of the W/L ratio in explaining the scaling exponent of leaf dry mass vs. leaf surface area and that of leaf surface area vs. leaf length. Nevertheless, whether the W/L ratio could reflect sufficient geometrical information of leaf shape has been not tested. The FD might be the most accurate measure for the complexity of leaf shape because it can characterize the extent of the self-similarity and other planar geometrical features of leaf shape. However, it is unknown how strongly different indices of leaf shape complexity correlate with each other, especially whether W/L ratio and FD are highly correlated. In this study, the leaves of nine Magnoliaceae species (>140 leaves for each species) were chosen for the study. We calculated the FD value for each leaf using the box-counting approach, and measured leaf fresh mass, surface area, perimeter, length, and width. We found that FD is significantly correlated to the W/L ratio and leaf length. However, the correlation between FD and the W/L ratio was far stronger than that between FD and leaf length for each of the nine species. There were no strong correlations between FD and other leaf characteristics, including leaf area, ratio of leaf perimeter to area, fresh mass, ratio of leaf fresh mass to area, and leaf roundness index. Given the strong correlation between FD and W/L, we suggest that the simpler index, W/L ratio, can provide sufficient information of leaf shape for similarly-shaped leaves. Future studies are needed to characterize the relationships among FD and W/L in leaves with strongly varying shape, e.g., in highly dissected leaves. Full article