Stomata Density Research Articles

VvEPFL9-1 Knock-Out via CRISPR/Cas9 Reduces Stomatal Density in Grapevine.

Epidermal Patterning Factor Like 9 (EPFL9), also known as STOMAGEN, is a cysteine-rich peptide that induces stomata formation in vascular plants, acting antagonistically to other epidermal patterning factors (EPF1, EPF2). In grapevine there are two EPFL9 genes, EPFL9-1 and EPFL9-2 sharing 82% identity at protein level in the mature functional C-terminal domain. In this study, CRISPR/Cas9 system was applied to functionally characterize VvEPFL9-1 in ‘Sugraone’, a highly transformable genotype. A set of plants, regenerated after gene transfer in embryogenic calli via Agrobacterium tumefaciens, were selected for evaluation. For many lines, the editing profile in the target site displayed a range of mutations mainly causing frameshift in the coding sequence or affecting the second cysteine residue. The analysis of stomata density revealed that in edited plants the number of stomata was significantly reduced compared to control, demonstrating for the first time the role of EPFL9 in a perennial fruit crop. Three edited lines were then assessed for growth, photosynthesis, stomatal conductance, and water use efficiency in experiments carried out at different environmental conditions. Intrinsic water-use efficiency was improved in edited lines compared to control, indicating possible advantages in reducing stomatal density under future environmental drier scenarios. Our results show the potential of manipulating stomatal density for optimizing grapevine adaptation under changing climate conditions.

Physiological and biochemical adaptive traits support the specific breeding of alfalfa (Medicago sativa) for severely drought‐stressed or moisture‐favourable environments

AbstractThe adaptation of alfalfa to moisture‐favourable and drought‐prone environments and its underlying mechanisms have not been thoroughly investigated despite their crucial importance to maximize the crop breeding progress. The main aim of this study was to support breeding strategies by exploring the relationship of leaf morphophysiological traits assessed in three growth chamber experiments with the adaptive response of five cultivars (Mamuntanas; Demnat 203; Erfoud 1; Prosementi; SARDI 10) that showed large genotype × environment interaction (GEI) across 10 drought‐prone to moisture‐favourable Mediterranean environments. Changes in shoot and root metabolite profiles across moisture‐contrasting conditions were assessed for two cultivars with contrasting adaptation pattern. The cultivar specifically adapted to drought‐prone environments (Mamuntanas), compared with that specifically adapted to moisture‐favourable environments (Demnat 203), displayed: (i) lower leaf wilting under drought stress; (ii) delayed leaf senescence under stress, assessed as limited chlorophyll reduction either in vivo from upper to central leaves or in vitro from control to polyethylene glycol‐treated leaflets, (iii) greater leaf tolerance to desiccation, measured in vitro as less pronounced reduction of leaf dry weight from control to polyethylene glycol‐treated leaflets, (iv) smaller leaves, (v) lower early root and shoot growth and (vi) lower leaf stomata density. The other cultivars exhibited different combinations and/or intermediate values of these traits. The metabolite profiles of Mamuntanas and Demnat 203 differed more in shoots than in roots. Mamuntanas accumulated more amino acids than Demnat 203 under moisture‐favourable and drought conditions. The distinct and partly incompatible combination of traits featuring the cultivars that maximized the crop yield in favourable or drought‐prone conditions (Mamuntanas and Demnat 203) improves our understanding of traits contributing to large GEI across moisture‐contrasting environments and support the breeding for specific adaptation to either condition. We identified a few inexpensive morphophysiological traits that could be used for early selection targeting drought‐prone environments.

Interactive effect of soil moisture content and phosphorus fertilizer form on chickpea growth, photosynthesis, and nutrient uptake

Water shortage and soil nutrient depletion are considered the main factors limiting crops productivity in the Mediterranean region characterized by longer and frequent drought episodes. In this study, we investigated the interactive effects of P fertilizer form and soil moisture conditions on chickpea photosynthetic activity, water and nutrient uptake, and their consequent effects on biomass accumulation and nutrient use efficiency. Two P fertilizer formulas based on orthophosphates (Ortho-P) and polyphosphates (Poly-P) were evaluated under three irrigation regimes (I1: 75% of field capacity, I2: 50% FC and I3: 25% FC), simulating three probable scenarios of soil water content in the Mediterranean climate (adequate water supply, medium, and severe drought stress), and compared to an unfertilized treatment. The experiment was conducted in a spilt-plot design under a drip fertigation system. The results showed significant changes in chickpea phenotypic and physiological traits in response to different P and water supply regimes. Compared with the unfertilized treatment, the stomata density and conductance, chlorophyll content, photosynthesis efficiency, biomass accumulation, and plant nutrient uptake were significantly improved under P drip fertigation. The obtained results suggested that the P fertilizer form and irrigation regime providing chickpea plants with enough P and water, at the early growth stage, increased the stomatal density and conductance, which significantly improved the photosynthetic performance index (PIABS) and P use efficiency (PUE), and consequently biomass accumulation and nutrient uptake. The significant correlations established between leaf stomatal density, PIABS, and PUE supported the above hypothesis. We concluded that the Poly-P fertilizers applied in well-watered conditions (I1) performed the best in terms of chickpea growth improvement, nutrient uptake and use efficiency. However, their effectiveness was greatly reduced under water stress conditions, unlike the Ortho-P form which kept stable positive effects on the studied parameters.

Plantlet Anatomy of Silver Birch (Betula pendula Roth.) and Hybrid Aspen (Populus tremuloides Michx. × Populus tremula L.) Shows Intraspecific Reactions to Illumination In Vitro

Micropropagation of forest reproductive material is becoming an increasingly important tool of climate-smart forest management, whose efficiency is depending on artificial illumination, which in turn can have species-specific effects. To improve the energy-efficiency of micropropagation, light emitting diodes (LED) are becoming more popular; however, they emit light of narrow spectral composition, synergic effects of which can alter plantlet development. Regarding the in vitro cultures of trees, such effects have been scarcely studied. In this study, three clones of silver birch (Betula pendula Roth.) and three clones of hybrid aspen (Populus tremuloides Michx. × Populus tremula L.) from the eastern Baltic region were tested. The responses of leaf and stem anatomy of in vitro cultures to three LED light illumination treatments differing by spectral composition and to illumination by fluorescent tubes were estimated by linear (mixed) models. The studied light treatments had non-interacted effects on stomata density and on the secondary xylem cell wall in the stem of silver birch and in the stomata length, stem radius, and phloem width of hybrid aspen. Furthermore, clone-specific responses to illumination were observed for number of chloroplasts and phloem width of silver birch and for leaf thickness and xylem cell wall thickness of hybrid aspen, implying different mechanisms of shade avoidance. In general, the responses of plantlet anatomy differed according to the width of the light spectrum in case of LED, as well as for fluorescent tubes. Considering the legacy effects of early development of plantlets, adaptability of illumination in terms of spectral composition according to the requirements of genotypes appear highly beneficial for micropropagation of sustainable forest reproductive material.

Phenotype and mechanism analysis of plant dwarfing in pear regulated by abscisic acid

Close planting of dwarf varieties is currently the main cultivation direction for pear trees, and the screening of excellent dwarf varieties is an important goal for breeders. In this study, the dwarfing pear variety ‘601D’ and its vigorous mutant ‘601T’ were used to show their biological characteristics and further explore the dwarfing mechanism in ‘601D’. The biological characteristics showed that ‘601D’ had a shorter internode length, a shorter and more compact tree body, thicker and broader leaves, lower stomata density, larger stomata size (dimension), and higher photosynthetic capacity. The biological characteristics of ‘601T’ showed notable contrasts. The results of endogenous hormone tests indicated that the contents of abscisic acid (ABA), ABA-glucosyl ester, and GA4 were higher in ‘601D’, but the trans-zeatin content was lower. By transcriptomic analysis, significant differences were found in the biosynthetic and metabolic pathways of ABA. Related transcription factors such as bHLH, WRKY, and homeobox also participated in the regulation of plant dwarfing. We therefore examined three hormones with obvious differences with ‘601T’, and found that only ABA could induce ‘601T’ to return to a dwarfing plant phenotype. Therefore, we conclude that the dwarfing of ‘601D’ is caused by an excessive accumulation of ABA. This study provides a new theoretical basis for breeding dwarf varieties.

Variability in leaf morphological traits of an endemic Mexican oak ( Quercus mexicana Bonpl.) along an environmental gradient

Background: Phenotypic and functional traits of plant populations vary with environmental conditions at local and regional scales. The analysis of these traits along environmental gradients provides information on the differential response of populations to climate changes.
 Objective: We analyzed the leaf morphological variation of an endemic oak to identify the degree of population differentiation along an environmental gradient.
 Study species: Quercus mexicana Bonpl. (Fagaceae).
 Study site and dates: Samples were collected from 39 populations in the Sierra Madre Oriental and east of the Trans-Mexican Volcanic Belt from 2014 to 2016.
 Methods: We measured eight macromorphological traits in 5,507 leaves and three micromorphological traits in 228 leaves. We performed univariate and multivariate statistical analyses to assess the morphological differentiation among populations, and the relationship between variation in leaf traits and environmental variables related to temperature and water availability.
 Results: Populations of Q. mexicana showed leaf morphological differentiation along its distribution. Significant linear correlations were found between leaf traits and environmental variables. Smaller and thicker leaves with lower density of trichomes and smaller stomata were found in populations located in more arid regions. In contrast, larger and thinner leaves with higher trichome density and larger stomata occurred in more humid places.
 Conclusions: Populations of Q . mexicana are adapted to a wide range of climatic conditions. Considering the predictive future climatic changes for the region ( i.e ., warmer and drier conditions), Q . mexicana populations with traits better adapted to a more humid and cooler environments could be negatively affected.

Comparative micro-anatomical features of endemic Fritillaria taxa growing in the Mediterranean region (Turkey)

The micro-morphological features (anatomical) of the endemic Fritillaria taxa, i.e., F. melananthera, F. asumaniae, F. byfieldii, F. carica, F. elwesii, F. forbesii, F. milasense, F. mughlae, F. ozdemir-elmasii distributed in the Mediterranean region were investigated, and their valuable features were identified taxonomically. Anatomical investigations of taxa were made using a light microscope (LM). The cross-sections of stem and leaf of the studied taxa and the surface sections of leaf were examined. Stomata were observed on both the upper and lower surface of the foliar epiderma of the studied taxa. The taxa were distinguished according to similarities and differences of characters in their micro-morphological features, and relationship degrees were investigated. In stem cross sections of taxa, the number of layers of sclerenchyma, the size and shape of epidermis cell, the presence of papillae in the epiderma, the presence of micropapillae on the cuticle, density or sparseness of both papillae and micropapillae, the number of layers of the parenchyma under the epiderma and whether it has chloroplasts, whether the vascular bundles were regular or irregular, number and presence of vascular bundle in the middle, presence or absence of crystals were determined as important distinguishing anatomical features in the stem of the taxa. In leaf cross sections of the studied taxa, stomata index, margins of ordinary irregular shaped cells, the width and length of the stomata, the density or sparseness of stomata, the number of parenchyma layer in the mesophyll, the shape of mesophyll parenchyma, presence or absence of palisade-like parenchyma cells in the mesophyll, the density of micropapillae and papillae were also found as valuable distinguishing anatomical features in the foliar epiderma morphology of these taxa.

Foliar stomata characteristics of tree species in a university green open space

Abstract. Susilowati A, Novriyanti E, Rachmat HH, Rangkuti AB, Harahap MM, Ginting IM, Kaban NS, Iswanto AH. 2022. Foliar stomata characteristics of tree species in a university green open space. Biodiversitas 23: 1482-1489. Stomata, a gas regulatory system of leaves, provide a great chance to investigate the interaction between plants and their environment. Stomata consist of surrounded by two guard cells. Stomata are found in all parts of the plant that are exposed to the air, especially the leaves. In identifying a plant species, it is necessary to have epidermal characteristics such as stomata to complete the taxonomic data. Several studies have been conducted on the type of stomata on the leaves of some dicotyledonous and monocot plants, but not many have reported similar studies on green space. Universitas Sumatera Utara (USU) campus also plays an important function as green space (GS) in Medan City due to its richness in tree collection number and species. In line with the effort in o maximizing the role of trees as the core element of green space, exploring the characteristics of stomata is important to conduct. Therefore, this study aimed to analyze the leaf stomata characteristics of several tree species in the green open space of the USU campus. A total of 83 tree species were taken for their leaves to investigate the stomata characters. Three healthy mature leaves on the lower part of newly grown branches were collected from each plant. The replica and the nail polish method were employed for stomata slice making. The stomata type, length, wide, density and distribution were observed. The result showed that 83 tree species in the USU campus have varied stomata types, with the percentage were highest characteristic found in paracytic (91.46%), followed by anomocytic (6.02%), anisocytic (1.20%), and diacytic (1.20%). The longest stomata were observed in Antidesma bunius (32.04 ????????). The widest stomata were noticed in Garcinia mangostana (37.62 ????????). Meanwhile, the shortest and narrowest stomata were found in Shorea laevis, which were 5.43 ???????? and 3.72 ????????, respectively. The species with the highest stomatal density was Schleichera oleosa (4294 mm-2). According to the study, the tree species at USU generally have high stomata density, length, and width, making them more suitable for green space. Species with a high number and density of stomata and a large size are much more likely to adsorb pollutants such as carbon monoxide.

Vegetative cycle, ant mutualism and leaf characteristics of Coccoloba gigantifolia trees at a new site in central Amazonia

Basic features and inflorescences of Coccoloba gigantifolia were described in 2019 only, after first documentation by academia 1982 at Borba, Madeira river basin, one of two main sites so far. Here we report about vegetative life cycle, leaf and other characteristics of more than 10 trees from a new site, east of the Mamori Lake, at 70 km distance and not directly influenced by the inundation of the Madeira basin. The tree was known there and named by local Mura indigenes and caboclos, but no use is known. All trees, from juvenile saplings to subadult and mature trees, showed an extreme growth form of sympodial monochasium. Also, all trees grew on hillocks in more fertile soil than the surroundings as indicated by high soil conductivity. The habitat suggests previous termite nests on or independent of stubs. The tree is facultatively associated with ants, very convergent to Cecropia species. There were pronounced heterophyllous differences regarding trichomes and stomata density, chlorophyll contents per area, dimensional and anatomical features. The general leaf phenotypes and chlorophyll contents indicated Mg-deficiency and a huge shade leaf responded overnight to magnesium addition with a 3-fold increased, more uniform leaf chlorophyll content. The chlorophyll contents per area and maximum potential photochemical quantum efficiency of PS II of three leaves of a young tree were low but constant. Retention of water by trichomes and anatomical features were compared to glabrous Coccoloba uvifera. With exceptionally huge leaves of C. gigantifolia growing in the understory, the tree is ecologically challenged in an environment low in nutrients which is indicated by the rare existence, ant mutualism and other adaptations.

Effect of stomatal morphology on leaf photosynthetic induction under fluctuating light across diploid and tetraploid rice

Polyploid plants are widely used in crop breeding for their superior performance in anatomical size and nutrient content. Photosynthesis is often affected by highly variable light conditions in the field. So far, few studies have been focused on the comparison of photosynthetic induction between tetraploid and diploid rice. Here, we for the first time compared the leaf photosynthetic induction and the underlying mechanism between tetraploid and diploid rice. After polyploidization, the plants displayed a larger size and lower density of stomata, which resulted in slower stomatal opening in response to a stepwise increase in light intensity. Further analysis indicated that stomatal opening, instead of biochemical processes, is the most important factor that contributes to the difference in photosynthetic induction between tetraploid and diploid rice. With lower stomatal conductance (gs), tetraploid rice displayed a lower intercellular CO2 concentration (Ci), and therefore lower photosynthetic efficiency during light induction. However, we observed a higher intrinsic water use efficiency (WUEi) in tetraploid rice than in diploid rice, which may contribute to the survival and growth of plants under water-limiting conditions. This study highlights the function of stomata in regulating photosynthetic induction and water use efficiency under fluctuating light, which will help the improvement of crop photosynthetic efficiency in the future.

Stomata Density Analysis of Red Chili (Capsicum annuum L.) at Different Location

Red chili (Capsicum annuum L.) is a commodity of vegetable that has high economic value. Stomata are an important part of plant organs, it a gap that role in the process of photosynthesis and plant transpiration. The purpose of this study to determine differences in the stomata density of red chili (Capsicum annuum L.) leaves at different locations, namely locations exposed and shaded from sunlight. This study used a quantitative approach with the type of research used is experiment as by one factor is that sunlight intensity, used two paired treatments and respective of three repetition. The data collection method in this study used direct observation and used analytic method to analyze the stomata density of chili (Capsicum annuum L) leaves. The result of his study showed that the stomata density of red chili (Capsicum annuum L.) leaves differed according to the planting location in the form of locations exposed to sunlight and locations that were shaded. The stomata density planted in a location exposed to full sun had a higher stomata density at 409.9 cells/mm2, while the stomata density of red chili (Capsicum annuum L.) leaves planted in a shaded location had a lower stomata density at 96.9 cells/mm2

Unravelling the anisotropic wetting properties of banana leaves with water and human urine

We report the heterogeneous and anisotropic wetting behaviors of Banana (Musa) leaves on adaxial (top) and abaxial (bottom) surfaces with water and human urine. Both surfaces comprise of varying number densities of micro ridges, micro stomata, micro flakes and nano hairs while the adaxial surface also constitutes discrete visible crest lines. The Wenzel roughness on abaxial and non-crest adaxial are 1.5 ± 0.05 and 1.18 ± 0.008, respectively as measured by combining optical profilometry and atomic force microscopy. A key scientific development in this work is to incorporate the measured Wenzel roughness in the surface energy estimations using Neumann's, Owens-Wendt-Rabel-Kaelble (OWRK) and Wu's models. The surface energy is 29 ± 2 mJ/m2 (OWRK) and 26 ± 1 mJ/m2 (Wu) on the adaxial surface. Nevertheless, the abaxial surfaces are characterized by smaller surface energy values of 20 ± 4 mJ/m2 (OWRK) and 24 ± 3 mJ/m2 (Wu). The measured static contact angles with water and urine are 110 ± 4° and 88 ± 4° (crest line), 130 ± 4° and 107 ± 5° (non-crest adaxial), 121 ± 4° and 120 ± 2° (abaxial) indicating hydrophobicity and urine-phobicity. The water droplets (2.5 to 10 µl) exhibited anisotropic dynamic wettability as they only rolled off parallel to the micro-ridges but stuck when slid perpendicular to the ridges even for specimen tilts up to 90°. Thus, this study unravels the anisotropic wettability of banana leaves due to the presence of micro-ridges which can be biomimicked for providing anisotropic liquid gliding. Also, this can aid in designing the spraying conditions of urine as a natural pesticide/fertilizer in the banana orchards.

Syrah and Grenache (Vitis vinifera) revealed different strategies to cope with high temperature

Background and Aims Global warming will threaten vineyard sustainability in warm and arid regions. Therefore, increasing water use efficiency (WUE) is essential for long-term viticulture sustainability. Nevertheless, studies concerning the response of stomata and WUE to temperature are scarce. We evaluated the effect of sustained warming on WUE and its components in cultivars with contrasting stomatal behaviour. Methods and Results We applied a 1.1°C increase in field-grown, well-watered plants, during the growing season and compared them to Control plants. We measured net assimilation (An), transpiration rate (E), stomatal conductance (gs), stomata density and length, intrinsic and yield WUE (WUEint and WUEyield). Gas exchange and WUEint in response to heating were cultivar-dependent. Heated Grenache plants increased An, gs, E and stomatal length but decreased WUEint. In contrast, gas exchange and WUEint were similar between heated Syrah and Control plants. Both cultivars decreased WUEyield in response to heating. Conclusions An increase in air temperature decreased WUEint in Grenache, whereas Syrah could tolerate heating without modifying leaf functioning. We proposed these strategies to cope with heating as ‘avoiding’ for Grenache and ‘tolerant’ for Syrah in well-watered conditions. Significance of the Study This research contributes to an understanding of the strategies to cope with high temperature of different cultivars, which should be considered to select better-adapted genotypes for the expected warmer conditions.

Stomatal Characteristics of 5 Citrus L. Species (Rutaceae) From Pekanbaru, Riau Province

Stomata of leaf is one of the important trait in plant taxonomic study. This trait can be used to characterisize the members of a plant group including Citrus.This genus is one of fruit plant that commonly known in Pekanbaru, Riau. The aim of this study was to examine the characteristic of stomata of 5 Citrus species from Pekanbaru, Riau Province, Indonesia. Leaves were collected from the field. The stomatal preparations were conducted using replica method. Stomata were then observed and photographed using Mikroskop Binokuler Olympus CX23 and Mikroskop LCD Digital Celestron Model 44340. The results show that stomata of all Citrus species examined in this study shows the similar type, hypostomatic with reniform-shaped stomata. However, the variations are found in stomata density and index, as well as the length and length of stomata. C. hystrix and C. aurantifolia have the lowest (419.89/1 mm²).), and the highest stomatal density (685.89/1 mm²).), respectively. The size of stomata varies within the species. C. microcarpa has the biggest stomata size (20.5 x 18.5 µm).  Stomatal density of Citrus examined in this study are high (> 500 / mm2) in C. aurantifolia and C. limon) and medium (300 - 500 / mm2) in C. amblicarpa, C. hystrix and C. microcarpa. The density, index and size of stomata can be used to characterize each Citrus members that examined in this study.

Contamination of microgreens by Salmonella enterica and Escherichia coli is influenced by selection breeding in chicory (Cichorium intybus L.)

Abstract The aim of this study was to assess whether selection breeding in chicory (Cichorium intybus L.) led changes in the susceptibility to Salmonella enterica and Escherichia coli contamination and whether the anatomical traits of the leaves are involved in the possible changes. Five chicory genotypes subjected to different intensities of selection were compared at the microgreen stage. Bacterial retention was evaluated after leaf incubation for 1.5 h on the surface of the bacterial suspension, followed by rinsing, grinding, plating on selective media, and colony forming unit (CFU) counting. The density of stomata and trichomes, total stomatal length and width, stomatal pit width, surface roughness and sharpness were evaluated. The intensively selected genotype (Witloof) was significantly more prone to contamination (2.9±0.3 lg CFU/cm2) as the average of the two bacterial types than the wild accession (Wild; 2.3±0.4 lg CFU/cm2) and the moderately selected genotypes (two leaf chicories, Catalogna type, and root chicory ‘Magdeburg’; on average, 1.9±0.3 lg CFU/cm2). Witloof microgreens also showed larger stomata (on average +34% for stoma width and +44% for pit width), which could justify, at least in part, the higher susceptibility to enterobacterial contamination. In fact, when contamination was performed in the dark (closed stomata), the bacterial retention in Witloof was significantly reduced in comparison with the opened stomata (–44%) and in Wild (–26%). Differences in retention between Witloof and Wild were still observed after UV treatment. The hierarchical clustering performed by grouping the leaf anatomical features was consistent with the chicory genetic groups. Our results suggest that the domestication process can affect the safety of produce and that the micromorphological traits of the leaves may be involved.

Three Research-Based Quantitative Reasoning Modules for Introductory Organismal Biology Laboratories

We have designed three laboratory modules for an introductory organismal biology course with an emphasis on quantitative reasoning and data analysis skills. Module 1 tests for dimorphism in crayfish chelae using a paired statistical design. Module 2 tests for allometric growth of tapeworm hook structures using a regression model. Module 3 tests for differences in stomatal densities between two groups of plants using a two-sample statistical approach. For all three modules, we emphasize the use of confidence intervals to draw statistical conclusions about hypotheses. Knowledge about the basic biology of animals and plants is required, including arthropods, platyhelminths, and vascular plants. Background reading on dimorphism, allometry, and transpiration provides the necessary foundation to develop questions and hypotheses. Some familiarity with R is necessary for both students and instructors, although the activities can be modified for analysis with Excel or another statistical package. These modules can be taught independently or together as a unit within a course. As stated in the AAAS document, <em>Vision and Change: A Call to Action</em>, the ability to use quantitative reasoning is a core competency that must be developed by all biology students. These modules address the call for instruction in quantitative reasoning and provide a hands-on active introduction to key tools that will be required to build students&rsquo; statistical repertoire in more advanced courses. <em>Primary Image:</em>&nbsp;A highlight of the three modules used in our introductory organismal biology course, including the use of calipers to test for dimorphism in the size of crayfish chelae (upper right), a leaf impression (lower right) from a hydrangea plant (lower left) used to test hypotheses about stomata densities, and the image of an <em>Echinococcus </em>tapeworm (upper left) to test hypotheses about allometry.&nbsp;&nbsp;

Stomatal size and density trade-off varies with leaf phenology and species shade tolerance in a South Asian moist tropical forest

The density and guard cell length of stomata regulate the physiological processes in plants. Yet, the variation of stomatal characteristics among different functional groups of trees is not been well understood. Particularly, a comprehensive understanding of stomatal behaviour in Bangladeshi moist forest trees is lacking. The study investigated how abaxial stomatal density (SD) and guard cell length (GCL) vary among tree functional types and leaf phenological groups in a moist tropical forest of Bangladesh. Cluster dendrogram revealed three groups of species based on SD and GCL. The independent sample t -test showed that there was a significant difference in SD between evergreen and deciduous tree species (t =4.18, P <0.001) but no significant difference in GCL between the two phenological groups. ANOVA revealed no significant difference in SD among the light demanding, intermediate shade tolerant and shade tolerant species (F =0.76, P =0.47). However, GCL significantly differed among the three functional groups (F =3.3, P <0.05). Maximum theoretical stomatal conductance (g max ) varied between evergreen and deciduous species but did not vary with species shade tolerance. In general, there was a significant trade-off between SD and GCL. However, the inverse relationship was stronger in deciduous and shade tolerant species than in evergreen and shade intolerant species. Leaf dry matter content was positively related with SD and negatively related with GCL. Specific leaf area and leaf thickness were not related to the stomatal traits. Our analyses suggest that leaf phenology and species shade tolerance need to be considered while estimating gas exchange through the stomata in tropical moist forests.

Hexaploidy induction improves morphological, physiological and phytochemical characteristics of mojito mint (Mentha × villosa)

Mints are cultivated worldwide as annual herbs or perennial garden plants for their aromatic and therapeutic characteristics and they are sought after by a vast number of food, confectionery, pharmaceutical, and sanitation industries. The aim of this study was to investigate the possibility of polyploidizaion in the Iranian mint genotypes to improve the morpho-physiological traits and enhance the essential oil content. Different concentrations of colchicine (0, 0.0125, 0.025 and 0.05%) and soaking times of rhizomes (3, 6 and 9 h) and three mint genotypes including peppermint (M. × piperita ‘BLACK’, 2n = 6x = 72), mojito mint (M. × villosa, 2n = 3x = 36) and pineapple (M. suaveolens, 2n = 2x = 24) were studied in a factorial experiment design with three replications. The survival rate, mixoploidy and chromosome doubling percentage of plants were checked 2 months and 24 months after induction of treatments. The highest survival rate (90.90%) and mixoploidy (11.11%) were found after two months in M. × piperita ‘Black’ and M. × villosa accessions, respectively. The only and highest rate of polyploidization (15.27%) was observed after two months in M. × villosa (2n = 6x = 72) using 0.05% colchicine for 9 h, which after 24 months some mixoploidy conversion to higher ploidy level increased it to 18.05%. It demonstrated sturdy, thick, dark green leaves with greater stomata size and guard cells’ chloroplast number and lower stomata density. Essential oil yield of hexaploid mojito mint showed 64% increase, from 0.87% (w/w) up to 1.43%. The phytochemicals, α-pinene, sabinene, limonene, menthofuran, and borneol were newly synthesized in the induced hexaploid mojito mint, while 1,8-cineole and pulegone production indicated 53% and 84% increase, respectively. Comparison of the main essential oil constituents of triploid and hexaploid M. × villosa showed a great variation in 1,8-cineole (18.5–28.4%), menthofuran (0–28.51%), neomenthol (22.7–0%), and pulegone (10.8- 20.1%), respectively. These improved characteristics suggest a valuable variety of mojito mint for commercial production.

IMPACT OF REGIONAL DISTRIBUTION AND AIR POLLUTION ON INTERNAL STRUCTURE OF MELIA AZEDARACH L. LEAVES

This study was performed to investigate the impact of air pollution on leaf area and anatomical features of Melia azedarach L. trees, in urban areas with three demographical classes: location (I) industrial area, location (II) roadside area and free parts (control area) as a location (III) of Duhok city/Kurdistan Region-Iraq, during July 2021. The results demonstrated that the leaf area of selected plants' leaves in location I had reduced with no noticeable change in the average stomata density in the three locations I, II and Ⅲ. Meanwhile, the results of the most anatomical features of the blade (blade, lower cuticle, epidermis (both upper and lower) thickness, palisade layer height and spongy parenchyma width) in addition to midrib parameters (epidermis thickness (upper and lower), collenchyma and parenchyma layer width, phloem and xylem width and pith diameter) were decreased in both locations I, II, and with well-developed anatomical features in location III.

Effect of two organic fertilizers on some anatomical features of Pinus pinea L. seedlings grown in field and lathe house

Effect of two organic fertilizers on some anatomical features of Pinus pinea L. seedlings grown in field and lathe house