Leaf Morphological Characteristics Research Articles

The Optimum Gamma Irradiation Dose for Inducing Changes in Aglaonema Morphology

The Optimum Gamma Irradiation Dose for Inducing Changes in Aglaonema Morphology

Evaluation of Phenotypic and Genetic Characteristics of Dryobalanops aromatica (Dipterocarpaceae) Seedlings Growing in Peat and Mineral Media

The selection of tree species suitable for restoration in diverse site conditions is still a challenge. Therefore, this study aimed to analyze the phenotypic and genetic characteristics of Dryobalanops aromatica seedlings growing in mineral soil media and peat media. Phenotypic characteristics were evaluated by analyzing the growth performance, leaf morphological characteristics, leaf color, and chlorophyll content, while genetic characteristics were evaluated by using microsatellite markers. The study revealed that seedlings planted in peat media exhibited greater height and shoot length growth, although the difference was not statistically significant compared to those in mineral soil media. However, seedlings in mineral soil media displayed a significantly higher survival rate than those in peat media. Peat-grown seedlings had higher chlorophyll content in their leaves, while mineral soil-grown seedlings displayed a lighter green leaf color based on digital analysis. Genetic analysis indicated a high genetic diversity of overall D. aromatica seedlings (He = 0.635) and unclear genetic structure between the two media. Overall, these findings demonstrate the successful adaptation of D. aromatica seedlings to peat media, positioning them as a promising choice for peatland restoration.

Ecotypic Variation in Leaf Thermoregulation and Heat Tolerance but Not Thermal Safety Margins in Tropical Trees.

To avoid reaching lethal temperatures during periods of heat stress, plants may acclimate either their biochemical thermal tolerance or leaf morphological and physiological characteristics to reduce leaf temperature (Tleaf). While plants from warmer environments may have a greater capacity to regulate Tleaf, the extent of intraspecific variation and contribution of provenance is relatively unexplored. We tested whether upland and lowland provenances of four tropical tree species grown in a common garden differed in their thermal safety margins by measuring leaf thermal traits, midday leaf-to-air temperature differences (∆Tleaf) and critical leaf temperatures defined by chlorophyll fluorescence (Tcrit). Provenance variation was species- and trait-specific. Higher ∆Tleaf and Tcrit were observed in the lowland provenance for Terminalia microcarpa, and in the upland provenance for Castanospermum australe, with no provenance effects in the other two species. Within-species covariation of Tcrit and ∆Tleaf led to a convergence of thermal safety margins across provenances. While future studies should expand the number of provenances and species investigated, our findings suggest that lowland and upland provenances may not differ substantially in their vulnerability to heat stress, as determined by thermal safety margins, despite differences in operating temperatures and Tcrit.

Leaf growth pattern and morphology of Sauropus androgynus (L.) Merr. in tropical lowland

Chikurmanis or katuk (Sauropus androgynus (L.) Merr.) is a traditional leafy vegetable that is consumed widely in Indonesia. The leaf is rich in vitamins, minerals, nutrients, and dietary fiber. The study aimed to investigate the leaf growth pattern and morphological characteristics of the chikurmanis cultivated in the tropical lowland ecosystem. The research was conducted on local farmland in Marga Sakti Sebelat, Bengkulu, Indonesia on December 2023 by survey method. The results showed that the leaf of chikurmanis grew in the daytime and continued to grow at nighttime as indicated in midrib length, leaf width, and foliole number. It is likely that nighttime growth become predominant in chikurmanis. The plant was a type of shrub with complete organs of stem, branch, root, flower, and leaf. The leaf was arranged as a compound leaf with many folioles in opposite positions. Midrib length (M) x leaf width (W) with a zero intercept of linear regression was the most reliable predictor of leaf area with the formula Y = 0.4964MxW (R2 = 0.9677). Keywords: chikurmanis plant; katuk; leaf area estimation; morphological trait; traditional leafy vegetable

An unmanned ground vehicle phenotyping-based method to generate three-dimensional multispectral point clouds for deciphering spatial heterogeneity in plant traits

Fusing three-dimensional (3D) and multispectral (MS) imaging data holds promise for high-throughput and comprehensive plant phenotyping to decipher genome-to-phenome knowledge. Acquiring high-quality 3D MS point clouds (3DMPCs) of plants remains challenging because of poor 3D data quality and limited radiometric calibration methods for plants with a complex canopy structure. Here, we present a novel 3D spatial–spectral data fusion approach to collect high-quality 3DMPCs of plants by integrating the next-best-view planning for adaptive data acquisition and neural reference field (NeREF) for radiometric calibration. This approach was used to acquire 3DMPCs of perilla, tomato, and rapeseed plants with diverse plant architecture and leaf morphological features evaluated by the accuracy of chlorophyll content and equivalent water thickness (EWT) estimation. The results showed that the completeness of plant point clouds collected by this approach was improved by an average of 23.6% compared with the fixed viewpoints alone. The NeREF-based radiometric calibration with the hemispherical reference outperformed the conventional calibration method by reducing the root mean square error (RMSE) of 58.93% for extracted reflectance spectra. The RMSE for chlorophyll content and EWT predictions decreased by 21.25% and 14.13% using partial least squares regression with the generated 3DMPCs. Collectively, our study provides an effective and efficient way to collect high-quality 3DMPCs of plants under natural light conditions, which improves the accuracy and comprehensiveness of phenotyping plant morphological and physiological traits, and thus will facilitate plant biology and genetic studies as well as crop breeding.

Morphological Traits and Biomass Allocation of Leymus secalinus along Habitat Gradient in a Floodplain Wetland of the Heihe River, China

Plant organ biomass allocation and morphological characteristics are important functional traits. The responses of plant root, stem, and leaf traits to heterogeneous habitats in floodplain wetlands are highly important for understanding the ecological adaptation strategies of riparian plants. However, the patterns of these responses remain unclear. In a floodplain wetland in the middle reaches of the Heihe River, we studied the responses of the root, stem, and leaf morphological traits and biomass allocation of Leymus secalinus to varying habitat conditions. We measured these traits in three sample plots, delineated based on distance from the riverbank: plot I (near the riparian zone, 50–150 m from the riverbank), plot II (middle riparian zone, 200–300 m from the riverbank), and plot III (far riparian zone, 350–450 m from the riverbank). The results showed that in plot I, L. secalinus tended to have slender roots and stems and small leaves, with a biomass allocation strategy that maximized the root–shoot ratio (RSR). In plot II, L. secalinus had thick stems and moderate leaf and root patterns, and the RSR values were between those of plot I and plot III. In plot III, L. secalinus had thin and short stems and large leaves; furthermore, among the root morphological structures, plot III had the shortest Rhizome length (RL) and longest Rhizome diameter (RD), and the RSR was the lowest. Moreover, there was a significant correlation between organ biomass and leaf thickness, stem length, RD, and RL in the three habitats (p < 0.05). By balancing the biomass allocation among organs, wetland plants in floodplains balance changes in root, stem, and leaf morphological characteristics to improve their environmental adaptation.

Cuticular analysis of Late Pleistocene, Middle Holocene, and modern Nothofagus dombeyi leaves from Chile: Implications for understanding changes in plant function at different atmospheric CO2 concentrations

How will forests respond to increases in atmospheric CO2 concentrations over the next century? This question is the subject of intensive research, and is based mostly on the results of greenhouse experiments, landscape-level experiments and modeling. In this paper, we examined leaf morphological and physiological characteristics of Nothofagus dombeyi populations exposed to different atmospheric CO2 levels by analyzing leaf cuticle from a Late Pleistocene (∼15,500–13,200 cal yr BP) fossil site, a Middle Holocene (∼6700–4900 cal yr BP) fossil site, and a modern (2016) collection in mid-latitude Chile. Atmospheric CO2 concentrations were inferred as ∼230 ppm, ∼270 ppm and ∼ 400 ppm based on a comparison with icecore and instrumental records. Our findings show that as atmospheric CO2 concentrations increased by 74% during the transition from late glacial to modern conditions, stomatal density decreased by 24% and maximum stomatal conductance decreased by 42%. In contrast, we observed a 10% increase in stomatal size, a 195% increase in intrinsic water use efficiency, and an increase in leaf nitrogen content. Carbon discrimination decreased as CO2 levels increased contrary to our expectations underscoring that additional factors such as water availability and nutrients can affect carbon discrimination. We also tested the paleo-CO2 method of Franks that performed well under high CO2 conditions (∼400 ppm) but failed under low levels (∼230 ppm) of atmospheric CO2 indicating the need for a better understanding of photosynthesis during glacial times.

GWAS combined with QTL mapping reveals the genetic loci of leaf morphological characters in Nicotiana tabacum

BackgroundLeaf morphology plays a crucial role in photosynthetic efficiency and yield potential in crops. Cigar tobacco plants, which are derived from common tobacco (Nicotiana tabacum L.), possess special leaf characteristics including thin and delicate leaves with few visible veins, making it a good system for studying the genetic basis of leaf morphological characters.ResultsIn this study, GWAS and QTL mapping were simultaneously performed using a natural population containing 185 accessions collected worldwide and an F2 population consisting of 240 individuals, respectively. A total of 26 QTLs related to leaf morphological traits were mapped in the F2 population at three different developmental stages, and some QTL intervals were repeatedly detected for different traits and at different developmental stages. Among the 206 significant SNPs identified in the natural population using GWAS, several associated with the leaf thickness phenotype were co-mapped via QTL mapping. By analyzing linkage disequilibrium and transcriptome data from different tissues combined with gene functional annotations, 7 candidate genes from the co-mapped region were identified as the potential causative genes associated with leaf thickness.ConclusionsThese results presented a valuable cigar tobacco resource showing the genetic diversity regarding its leaf morphological traits at different developmental stages. It also provides valuable information for novel genes and molecular markers that will be useful for further functional verification and for molecular breeding of leaf morphological traits in crops in the future.

Leaf morphological variation in Betula medwediewii Regel populations from Türkiye

Leaf variations of Betula medwediewii in Türkiye with respect to its distribution pattern were studied because this plant taxon is a Euxine element and a distinct relict species in Türkiye. In this context, the aim of this study is to investigate variations in leaf morphological characteristics within and among B. medwediewii populations in natural distribution areas in Türkiye. Thus, the morphological leaf characteristics of four populations of B. medwediewii growing at different elevations spanning from 1472 to 2065 m.a.s.l in two cities (Artvin and Rize) and four boroughs (Arhavi, Borçka, Murgul, and Çamlıhemşin) of Türkiye were analyzed. The four populations were selected based on their natural distribution and 1,200 leaf samples belonging to 40 individuals were measured with ImageJ. According to the results of correlation analysis, statistically significant relationships were determined among morphological leaf characteristics. Mean values for petiole length (1.16 cm), leaf width (5.11 cm), leaf length (7.96 cm), length of lamina (6.79 cm), leaf area (26.62 cm²), leaf vein angle (54.21°), and number of primary leaf veins (20.03) were determined in all populations. Because B. medwediewii contributes to biodiversity and can preserve the ecological stability of the Turkish forest area, its conservation is crucial.

Evaluation of a low-cost staining method for improved visualization of sweet potato whitefly (Bemisia tabaci) eggs on multiple crop plant species

BackgroundThe sweet potato whitefly (Bemisia tabaci) is a globally important insect pest that damages crops through direct feeding and by transmitting viruses. Current B. tabaci management revolves around the use of insecticides, which are economically and environmentally costly. Host plant resistance is a sustainable option to reduce the impact of whiteflies, but progress in deploying resistance in crops has been slow. A major obstacle is the high cost and low throughput of screening plants for B. tabaci resistance. Oviposition rate is a popular metric for host plant resistance to B. tabaci because it does not require tracking insect development through the entire life cycle, but accurate quantification is still limited by difficulties in observing B. tabaci eggs, which are microscopic and translucent. The goal of our study was to improve quantification of B. tabaci eggs on several important crop species: cassava, cowpea, melon, sweet potato and tomato.ResultsWe tested a selective staining process originally developed for leafhopper eggs: submerging the leaves in McBryde’s stain (acetic acid, ethanol, 0.2% aqueous acid Fuchsin, water; 20:19:2:1) for three days, followed by clearing under heat and pressure for 15 min in clearing solution (LGW; lactic acid, glycerol, water; 17:20:23). With a less experienced individual counting the eggs, B. tabaci egg counts increased after staining across all five crops. With a more experienced counter, egg counts increased after staining on melons, tomatoes, and cowpeas. For all five crops, there was significantly greater agreement on egg counts across the two counting individuals after the staining process. The staining method worked particularly well on melon, where egg counts universally increased after staining for both counting individuals.ConclusionsSelective staining aids visualization of B. tabaci eggs across multiple crop plants, particularly species where leaf morphological features obscure eggs, such as melons and tomatoes. This method is broadly applicable to research questions requiring accurate quantification of B. tabaci eggs, including phenotyping for B. tabaci resistance.

Reponses of morphological and biochemical traits of bamboo trees under elevated atmospheric O3 enrichment

Dwarf bamboo (Indocalamus decorus) is an O3-tolerant plant species. To identify the possible mechanism and response of leaf morphological, antioxidant, and anatomical characteristics to elevated atmospheric O3 (EO3) concentrations, we exposed three-year-old I. decorus seedlings to three O3 levels (low O3-LO: ambient air; medium O3-MO: Ambient air+70 ppb high O3–HO: Ambient air+140 ppb O3) over a growing season using open-top chambers. Leaf shape and stomatal characteristics, and leaf microscopic structure of I. decorus were examined. The results indicated that 1) the stomata O3 flux (Fst) of HO decreased more rapidly under EO3 as the exposure time increased. The foliar O3 injury of HO and MO occurred when AOT40 was 26.62 ppm h and 33.20 ppm h, respectively, 2) under EO3, leaf number, leaf mass per area, leaf area, and stomata length/width all decreased, while leaf thickness, stomatal density, width, and area increased compared to the control, 3) MDA and total soluble protein contents all showed significantly increase under HO (36.57% and 32.77%) and MO(31.91% and 19.52%) while proline contents only increased under HO(33.27%). 4) MO and HO increased bulliform cells numbers in the leaves by 6.28% and 23.01%, respectively. HO reduced the transverse area of bulliform cells by 13.73%, while MO treatments had no effect, and 5) the number of fusoid cells interspace, the transverse area of fusoid cells interspace, and mesophyll thickness of HO significantly increased by 11.16%, 28.58%, and 13.42%, respectively. In conclusion, I. decorus exhibits strong O3 tolerance characteristics, which stem from adaptions in the leaf's morphological, structural, antioxidant, and anatomical features. One critical attribute was the enlargement of the bulliform cell transverse area and the transverse area of fusoid cells interspace that drove this resistance to O3. Local bamboo species with high resistance to O3 pollution thus need to be promoted for sustained productivity and ecosystem services in areas with high O3 pollution.

Evaluation of cotton varieties resistant to Amrasca biguttula (Hemiptera: Ciccadelidae) in the Indonesian agroecosystem to mitigate climate change impacts

Climate change employs substantial effects on agroecosystems, particularly the dynamics between plants and herbivores. In response, the adoption of pest-resistant varieties has emerged as a critical strategy within agroecosystems, notably in Indonesia’s cotton Integrated Pest Management (IPM). This research focused on evaluating the response of five cotton lines, which adapted to the Indonesian agroecosystem, to the cotton leafhopper (Amrasca biguttula) as a mitigating measure to climate change. Two upland cotton varieties, Tamcot SP 37 (susceptible) and LRA 5166 (resistant), served as standards for susceptibility and resistance to leafhoppers. The study examined leaf morphological characters, specifically trichome density, known to act as oviposition deterrents for leafhopper females, indicative of non-preference resistance. Low damage scores and high leaf trichome density comparable to the resistant variety (LRA 5166) were indicators of notable field resistance in lines 06062/3/3 and 06062/3/4 against A. biguttula during observations that spanned 35 to 105 days post-planting. These findings highlight the potential of these lines as promising cotton varieties, marked by their resilience to A. biguttula, fostering sustainable cultivation practices that address climate change impacts. This study underscores the intricate dynamics between plant-insect interactions and resilience strategies within agroecosystems.

Physiological and Structural Changes in Leaves of Platycrater arguta Seedlings Exposed to Increasing Light Intensities.

Understanding the light adaptation of plants is critical for conservation. Platycrater arguta, an endangered deciduous shrub endemic to East Asia, possesses high ornamental and phylogeographic value. However, the weak environmental adaptability of P. arguta species has limited its general growth and conservation. To obtain a deeper understanding of the P. arguta growth conditions, we examined the leaf morphology and physiology via anatomical and chloroplast ultrastructural analyses following exposure to different natural light intensities (full light, 40%, and 10%). The findings indicated that P. arguta seedings in the 10% light intensity had significantly improved leaf morphological characteristics and specific leaf area compared to those exposed to other intensities. The net photosynthetic rate, chlorophyll (Chl) content, photosynthetic nitrogen use efficiency (PNUE), and photosynthetic phosphorus use efficiency (PPUE) exhibited marked increases at a 10% light intensity compared to both 40% light and full light intensities, whereas the light compensation point and dark respiration levels reached their lowest values under the 10% light condition. With reduced light, leaf thickness, palisade tissue, spongy tissue, and stomatal density significantly decreased, whereas the stomatal length, stomatal width, and stomatal aperture were significantly elevated. When exposed to 10% light intensity, the ultrastructure of chloroplasts was well developed, chloroplasts and starch grain size, the number of grana, and thylakoids all increased significantly, while the number of plastoglobules was significantly reduced. Relative distance phenotypic plasticity index analysis exhibited that P. arguta adapts to varying light environments predominantly by adjusting PPUE, Chl b, PNUE, chloroplast area, and the activity of PSII reaction centers. We proposed that P. arguta efficiently utilizes low light to reconfigure its energy metabolism by regulating its leaf structure, photosynthetic capacity, nutrient use efficiency, and chloroplast development.

Leaf-based characterization of intermediate forms between Cuban and Honduran mahogany

The genus Swietenia includes two mahogany species, Swietenia macrophylla (King.), commonly known as Honduran mahogany, and Swietenia mahagoni (L.) Jacq, commonly known as Cuban mahogany. There are reports of morphologically intermediate forms between Cuban and Honduran mahogany that have been localized in some Caribbean islands. The main objective of this research is to distinguish morphologically intermediate forms between the parental species S. mahagoni and S. macrophylla based on leaf morphological characters. Phenotypic data from a total of 357 mahogany trees were collected in the province of Sancti Spiritus, Cuba. Rachis length, petiole length, leaflet length, leaflet width, number of leaflets and number of nerves were evaluated. Morphological descriptor analysis revealed significant differences in the morphometric variables of the evaluated leaves, with rachis length, number of leaflets, leaflet length, petiole length, leaflet width, and number of nerves being significantly higher in S. macrophylla than in S. mahagoni. ANOVA reflected the variance between all leaf morphological parameters evaluated between the two pure species with statistically significant difference. Using the function obtained in the first DC of the two species, the individuals in the mixed stands were classified into 71 morphologically intermediate forms, 45 S. macrophylla and 64 S. mahagoni. In the second DC with the two species and the morphologically intermediate forms, Wilks’ partial lambda indicates that the variable "leaflet length" with 0.67 contributed most to the overall discrimination.

Examining preharvest genetic and morphological factors contributing to lettuce (Lactuca sativa L.) shelf-life

Lettuce is a highly perishable horticultural crop with a relatively short shelf-life that limits its commercial value and contributes to food waste. Postharvest senescence varies with influences of both environmental and genetic factors. From a larger pool of romaine lettuce genotypes, we identified three genotypes with variable shelf lives and evaluated their leaf morphology characteristics and transcriptomic profiles at preharvest to predict postharvest quality. Breeding line 60184 had the shortest shelf-life (SSL), cultivar ‘Manatee’ had an intermediate shelf-life (ISL), and ‘Okeechobee’ had the longest shelf-life (LSL). We observed significantly larger leaf lamina thickness and higher stomatal index in the SSL genotypes relative to the LSL cultivar. To identify molecular indicators of shelf-life, we used a transcriptional approach between two of the contrasting genotypes, breeding line 60184 and cultivar ‘Okeechobee’ at preharvest. We identified 552 upregulated and 315 downregulated differentially expressed genes between the genotypes, from which 27% of them had an Arabidopsis thaliana ortholog previously characterized as senescence associated genes (SAGs). Notably, we identified several SAGs including several related to jasmonate ZIM-domain jasmonic acid signaling, chlorophyll a–b binding, and cell wall modification including pectate lyases and expansins. This study presented an innovative approach for identifying preharvest molecular factors linked to postharvest traits for prolonged shelf.

Morpho-Anatomical Variations of Leaves Several Types of Betel Piperaceae in Durenan District, Trenggalek Regency

The Piperaceae family is a plant species that has 3,700 species. In Durenan District, Trenggalek Regency, there are several species of Piperaceae family plants which have different leaf shapes. This study aimed to describe the morpho-anatomical variations of betel leaves in Durenan District, Trenggalek Regency. This study was a descriptive study to describe three types of betel; green betel, red betel, and china betel. Parameters measured were leaf morphology and leaf anatomy. Variations in betel leaf morphological characters from the Piperaceae family can be seen from leaf shape, leaf color, leaf base, petiole color, leaf length, leaf width, petiole length, and leaf area. Anatomical variations of betel leaf from the Piperaceae family included variations in the number of epidermal layers, the number of hypodermic layers, the number of palisade parenchyma layers, the number of spongy parenchyma layers, stomata shape, stomatal density, and stomata index.

Leaf Architecture and Genome Size Variation of Durio zibethinus L. from Jelebu, Negeri Sembilan, Malaysia.

Durio zibethinus L. is known as the "king of fruit" in Malaysia. Meanwhile, Jelebu, Negeri Sembilan has always become the top choice district to visit for durian lover for its Durian Kampung Jelebu, which possessed good quality on par with top D. zibethinus clones such as D197 Musang King and D24. However, there is still lacking in taxonomic data of D. zibethinus especially from Jelebu. This study aimed to analyse the leaf architecture and genome size variations of selected D. zibethinus accessions from Jelebu. Five D. zibethinus accessions from Jelebu were examined. Thirty-seven parameters of gross leaf morphological characteristics and leaf venation pattern were observed and recorded for identification and classification of D. zibethinus accessions from Jelebu. Seven parameters have been recorded which are petiole length, petiole features, leaf size, leaf shape, leaf base shape, lower leaf surface colour and areolation could be used in differentiating between accessions. Results of this study showed the intraspecific variations existed among D. zibethinus accessions from Jelebu with a genome size varying between 1.7433 pg and 1.800 pg. In conclusion, data on leaf architecture and genome size variations from D. zibethinus accessions are beneficial for early plant identification and classification.

Increased nutritional quality of rice grains and migration mechanisms of selenium by spraying a foliar selenium-rich nutrient solution

Foliar application of selenium (Se) is an effective method for biofortification in rice, to ensure that sufficient Se is supplied by the crop to maintain human health. In order to improve Se concentration in rice and meet the daily recommended intake for humans, a foliar Se fertilizer was applied in five regions of Liaoning and Jilin provinces, China, and its effects on rice quality, leaf morphology, and wax characteristics were assessed in field tests. The effects of alkyl polyglycosides (APG) in the Se fertilizer were evaluated, and epicuticular waxes were measured to analyze the effects of the fertilizer on plant water status. The Se fertilizer effectively enhanced organic Se levels in rice (p < 0.05), ranging from 599.8 to 2002.0 µg kg−1. An intake of 50 g d−1 of Se-enriched rice can meet nutritional requirements, with total Se intake ranging from 30.0 to 100.1 µg d−1. The Se fertilizer increased the protein content and decreased the proportion of chalky rice (p < 0.05). APG increased the wettability of Se fertilizer on the surface of leaves, so Se could be better absorbed into the leaves and accumulate in rice. The Se fertilizer increased the epicuticular wax so that moisture loss from leaves was reduced. Mean cuticular wax thicknesses were 2.36 and 2.25 µg cm2 in Daohuaxiang and Wuyou 4, respectively. These results suggest a link between the quality of rice and epicuticular wax thickness, and the foliar application of Se fertilizer shows promise for increasing Se content in rice grown in Se deficient soils.

Anatomical Mechanisms of Leaf Blade Morphogenesis in Sasaella kogasensis 'Aureostriatus'.

There are limited studies on the cytology of bamboo leaf development from primordium to maturity. This study delves into the leaf morphological characteristics and growth patterns of Sasaella kogasensis 'Aureostriatus' and provides a three-dimensional anatomical analysis of cell division, expansion, and degradation. Leaves on the same branch develop bottom-up, while individual leaves develop the other way around. Like bamboo shoots and culms, the leaves follow a "slow-fast-slow" growth pattern, with longitudinal growth being predominant during their development. The growth zones of individual leaves included division, elongation, and maturation zones based on the distribution of growth space. By measuring 13,303 epidermal long cells and 3293 mesophyll cells in longitudinal sections of rapidly elongating leaves, we observed that in the rapid elongation phase (S4-S5), the division zone was located in the 1-2 cm segment at the bottom of the leaf blade and maintained a constant size, continuously providing new cells for leaf elongation, whereas in the late rapid elongation phase (S6), when the length of the leaf blade was approaching that of a mature leaf, its cells at the bottom of the blade no longer divided and were replaced by the ability to elongate. Furthermore, to gain an insight into the dynamic changes in the growth of the S. kogasensis 'Aureostriatus' leaves in the lateral and periclinal directions, the width and thickness of 1459 epidermal and 2719 mesophyll cells were counted in the mid-cross section of leaves at different developmental stages. The results showed that during the early stages of development (S1-S3), young leaves maintained vigorous division in the lateral direction, while periplasmic division gradually expanded from the bottom to the top of the leaf blade and the number of cell layers stabilized at S4. The meristematic tissues on both sides of the leaf were still able to divide at S4 but the frequency of the division gradually decreased, while cell division and expansion occurred simultaneously between the veins. At S6, the cells at the leaf margins and between the veins were completely differentiated and the width of the leaf blade no longer expanded. These findings revealed changes in cell growth anisotropically during the leaf development of S. kogasensis 'Aureostriatus' and demonstrated that leaf elongation was closely related to the longitudinal expansion of epidermal cells and proliferative growth of mesophyll cells, whereas the cell division of meristematic tissues and expansion of post-divisional cells contributed to the increases in blade width and thickness. The presented framework will facilitate a further exploration of the molecular regulatory mechanisms of leaf development in S. kogasensis 'Aureostriatus' and provide relevant information for developmental and taxonomic studies of bamboo plants.

VARIATION IN THE MACRO-MORPHOLOGICAL TRAITS OF LEAVES IN RESPONSE TO AUTOMOBILE POLLUTION IN SELECTED URBAN TREE SPECIES IN THE CITY OF DHAKA

The present study was carried out at National Botanical Garden, Dhaka, considered as control site and Motijheel- Sayedabad roadside areas as polluted site to compare the impact of automobile pollution on leaves macro- morphological traits of selected ten plants growingin the polluted areas with those growingin control sites. Leaf morphological characteristics including leaf abnormalities of both young and mature leaves were assessed. Variations in leaf color such as light green, dark green, browning, yellowing and change in the leaf’s shape either normal or deformed were also assessed for both the sites. All the selected plant species showed highly significant (p&lt;0.0001) reduction at polluted site in theirall leaf macro-morphological traits(leaf length, leaf breadth, leaf area, leaf perimeter, specific leaf area and petiole length) when compared with control site. The findings of this study revealed that the automobile pollution stress influenced tree morphological features in the Dhaka city. This study also indicated that plants go through adaptive processes in order to survive in automobile polluted environments.