Stomatal Size Research Articles

Relationship between Leaf Traits and PM-Capturing Capacity of Major Urban-Greening Species

High concentrations of airborne particulate matter (PM) in urban areas are of great concern to human health. Urban greening has been shown to be an effective and eco-friendly way to alleviate particle pollution, and attention to its role in mitigating particle pollution has increased worldwide. The species-specific PM-capturing capacity of ten urban-greening species in Seoul was evaluated by leaf functional traits (average leaf area (ALA), specific leaf area (SLA), and leaf width-to-length ratio (W/L)), microstructures (roughness, stomata, and trichomes), and physicochemical traits (contact angle (θw), surface free energy (rs), the work of adhesion for water (Wa), and epicuticular wax loads (EWL)). The relationships between leaf traits and PM adsorption by leaves were revealed by Pearson’s correlations and principal component analysis (PCA). A gravimetric method was used to quantify, by particle size, the PM adsorbed on leaf surfaces or embedded in leaf epicuticular wax layers. The key factors for PM adsorption on leaf surfaces were the SLA, the mean roughness value (Ra), and stomatal size. The SLA and Ra of adaxial leaf surfaces were negatively correlated with PM accumulation on leaf surfaces, while stomatal length and width were positively correlated with surface PM load. The rs and EWL positively affected the in-wax PM load. Species-specific PM deposition was the result of complicated mechanisms of various leaf traits. Three evergreen shrub species, Buxus sinica (Rehder & E.H. Wilson) M.Cheng var. insularis (Nakai) M.Cheng, Taxus cuspidata Siebold & Zucc., and Euonymus japonicus Thunb., were efficient in capturing both surface PM and in-wax PM. The PCA revealed that the high PM accumulation efficiency of these three species might be attributable to the interaction between stomatal size and EWL. Aesculus turbinata Blume, Chionanthus retusus Lindl. & Paxton, and Rhododendron schlippenbachii Maxim. had intermediate PM adsorption ability, which might be a result of interactions among stomatal density, the Wa of adaxial surfaces, and ALA. Magnolia denudata Desr., Styphnolobium japonicum (L.) Schott, Liriodendron tulipifera L., and Ginkgo biloba L. had low PM accumulation efficiency. These four species exhibited correlations among SLA, the Ra of adaxial leaf surfaces, and W/L, which had negative effects on PM adsorption.

Physio-biochemical analysis and molecular characterization of induced lentil mutant lines.

Lens culinaris is a proteinaceous food crop that is consumed worldwide for protein requirements. Mutation breeding has been used to improve protein content, yield, and related traits, as well as to select highly desirable mutants that are economically significant. An investigation of genotypic variation in lentil germplasm was carried out using induced mutagenesis, with caffeine, ethyl methane sulfonate (EMS), lead nitrate, and cadmium nitrate as mutagens that resulted in 18 mutant lines in the M3 generation. For the present study, we analyzed the genetic diversity of lentil mutant lines using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and random amplified polymorphic DNA markers (RAPD). The heterozygosity of RAPD markers per primer ranged from 50.00–90.90% with an average of 71.04%. The genetic divergent analysis was performed using hierarchical clustering (UPGMA), exhibited that these mutant lines were classified mainly into five subpopulation or clusters. A close resemblance with highest genetic coefficient similarity (1.00) were observed between control and mutant H; between mutant M and E; between mutant Q and J2, while more divergent mutants were N2 with mutant B; and mutant R with mutant J1with least genetic coefficient similarity (0.22). Protein and mineral content (Fe, Zn and Cu) were increased significantly in some high yielding mutant lines concerning to the control plant, and showed polymorphic variations in polypeptide chains in terms of banding pattern. Stomatal morphology in high yielding mutants were perceived utilizing scanning electron microscopy (SEM), exhibiting variations in stomatal size, stomatal opening and number of stomata. The present study’s promising mutant lines’ biological, physiological, and molecular profiles provide a foundation for forthcoming preservation and consumption strategies to broaden the genetic diversity of the breeding population of lentil.

Leaf Adaptation of Eurya japonica Thunb. (Pentaphylacaceae) in Coastal Area

To clarify the process of plant adaptation to coastal areas, we conducted morphological and anatomical analyses of Eurya japonica Thunb. (Pentaphylacaceae). There was no significant difference in leaf shape between the inland and coastal populations, although the leaves in coastal populations tended to be thicker. However, our anatomical analysis revealed significant differences in stomatal size and adaxial and abaxial epidermal cell sizes. The smaller stomata of the coastal population of this species were effective in reducing transpiration during gas exchange. Furthermore, the expansion of epidermal cells could be an adaptive strategy to retain water in leaves in coastal environments.

Maize stomatal responses against the climate change.

Drought and heat, in the context of climate change, are expected to increase in many agricultural areas across the globe. Among current abiotic stresses, they are the most limiting factors that influence crop growth and productivity. Maize is one of most widely produced crops of the world, being the first in grain production with a yield that exceeded 1.1 billion tons in 2021. Despite its wide distribution in semi-arid regions, it is highly vulnerable to climate change, which triggers important losses in its productivity. This article explores how maize yield may persevere through climate change by focusing on the stomatal regulation of gas exchange. The emerging picture unravels that maize copes with drought stress by reducing stomatal size and stomatal pore area, and increasing stomatal density, which, in turn, reduces transpiration and photosynthetic rate. When drought and heat co-occur, heat enhances stomatal response to drought stress. To avoid plant heat damage, the decline in stomatal aperture could trigger the expansion of the distance of action, from the longitudinal leaf veins, of ZmSHR1, which might act to positively regulate ZmSPCHs/ZmICE1 heterodimers, increasing the stomatal density. Only when drought is not very severe, elevated CO2 levels reduce yield losses. The knowledge of the upcoming climate changes together with the prediction of the developmental and physiological stomatal responses will allow not only to anticipate maize yield in the next years, but also to contribute to the correct decision-making in the management of this important crop.

Morphological and anatomical parameters of Forsythia suspensa (Thunb.) Vahl leaves in the urban environment

The anatomical and morphological parameters of the leaf blade of Forsythia suspensa were investigated to determine the species’ stability in the Kyiv metropolis (Ukraine) conditions and monitor environmental pollution. The leaves of F. suspensa were selected at four monitoring sites in Kyiv, which differed in their distance to highways and the intensity of traffic. The histological structure of F. suspensa leaves changed toward xeromorphism in the variants where plants were exposed to increased vehicles’ emissions. In particular, the thickness of the cuticle and adaxial epidermis increased, the stomatal size decreased, the degree of stomata opening decreased and their density increased, and the stomatal index and xeromorphism index increased. In general, such changes in the structure of F. suspensa leaves increased the plants’ resistance to pollution. This indicates the plasticity of F. suspensa plants and a sufficient level of their adaptation to the urban environment. Hence, the parameters of the stomatal apparatus of F. suspensa leaves can be applied as test indicators for biomonitoring of urban pollution. This species can be recommended for creating stable culturphytocoenoses in conditions of a high level of technogenic influence.

In Vitro Polyploid Induction of Highbush Blueberry through De Novo Shoot Organogenesis.

Polyploid induction is of utmost importance in horticultural plants for the development of new varieties with desirable morphological and physiological traits. Polyploidy may occur naturally due to the formation of unreduced gametes or can be artificially induced by doubling the number of chromosomes in somatic cells. In this experiment, a protocol for in vitro polyploid induction of highbush blueberry (Vaccinium corymbosum L.) leaf tissues was studied by using different concentrations of colchicine and oryzalin. Oryzalin was found to be highly toxic to this species, while the adventitious shoot organogenesis media enriched with 25 and 250 µM colchicine was able to induce polyploidization, with significant differences among the treatments used. Higher concentrations of both antimitotic agents led to the browning and death of the leaf tissues. The polyploids obtained showed several morphological differences when compared with the diploid shoots. Flow cytometry analysis was used to confirm the ploidy level of the regenerated shoots, demonstrating that a total of 15 tetraploids and 34 mixoploids were obtained. The stomatal sizes (length and width) of the tetraploids were larger than those of the diploids, but a reduced stomatal density was observed as compared to the controls. These shoots will be acclimatized and grown until they reach the reproductive phase in order to test their potential appeal as new varieties or their use for breeding and genetic improvement.

Response of Bletilla striata to Drought: Effects on Biochemical and Physiological Parameter Also with Electric Measurements.

In heterogeneous landscapes with temporary water deficit characteristics in southwestern China, understanding the electrophysiological and morphological characteristics of Bletilla striata under different water conditions can help to better evaluate its suitability for planting plants in specific locations and guide planting and production. Using B. striata seedlings as experimental materials, the maximum field capacity (FC) was 75–80% (CK: control group), 50–60% FC (LS: light drought stress), 40–45% FC (MS: moderate drought stress), and 30–35% FC (SS: severe drought stress). In terms of physiological response, the activities of peroxidase (POD) and catalase (CAT) decreased under drought conditions, but the activity was well under the LS treatment, and the contents of proline (Pro) and malondialdehyde (MDA) increased. In terms of morphological responses, under drought conditions, root lengths of the rhizomes (except the LS treatment) were significantly reduced, the leaf lengths were reduced, and the biomass was significantly reduced. The stomatal size reached the maximum under the LS treatment, and the stomatal density gradually decreased with the increase in drought degree. In terms of electrophysiological responses, drought significantly decreased the net photosynthetic rate (PN) of B. striata, stomatal conductance (gs), and transpiration rate (Tr), but effectively increased the water use efficiency (WUE). The effective thickness of leaves of B. striata increased under drought conditions, and drought promoted the formation of leaf morphological diversity. Our results showed that drought stress changed the physiological and morphological characteristics of B. striata, and under light drought conditions had higher physiological activity, good morphological characteristics, higher cellular metabolic energy and ecological adaptability. Appropriate drought can promote the improvement of the quality of B. striata, and it can be widely planted in mildly arid areas.

Exogenous silicon alleviates drought stress in maize by improving growth, photosynthetic and antioxidant metabolism

Extreme dry weather caused by global climate change will reduce the growth and yield of plant crops. Silicon (Si) can improve plant growth and the resistance to various stresses. However, its effects on maize drought stress of the jointing and tasseling stages are unclear in the field. Therefore, the present study was carried out to investigate the effect of growth, photosynthetic and antioxidant metabolism on maize under moderate and severe drought stress with or without Si application (5, 15, 25 g·L−1) in the large farmland moisture control test field. Drought stress down-regulated plant height growth rate (25.80% ~ 39.11%), shoot dry weight (40.42%~68.97%), root dry weight (31.34% ~ 57.96%) and yield (14.51% ~ 36.52%) in the both stages, respectively. With the increase of drought stress, actual photochemical efficiency of PSⅡ (ΦPSⅡ), maximum photochemical efficiency of PSⅡ (Fv/Fm) and photochemical quenching (qP) decreased at different degrees while the non-photochemical quenching (NPQ) increased. One-to-twofold increase was observed in the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) in the drought-stressed conditions. Exogenous Si alleviated drought stress to a certain extent of damage, enhanced plant growth, photosynthetic pigment contents, chlorophyll fluorescence parameters, gas exchange parameters, photosynthetic enzymes activity, the stomatal size and stomatal aperture, inhibited the increase in the superoxide free radical ion (O2·−) production rate, hydrogen peroxide (H2O2), malondialdehyde (MDA) and electrolyte leakage (EL), and further increased the key antioxidant enzymes activities and the osmotic regulatory substance contents. The activities of monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR), and the contents of ascorbate (AsA) and glutathione (GSH) increased, and the contents of dehydroascorbate (DHA) and oxidized glutathione (GSSG) declined by Si application in both stages. Therefore, exogenous Si could decrease maize oxidative stress response in drought-stressed by strengthening the antioxidant defense system and photosynthetic metabolism, improving the AsA-GSH cycle, increasing osmotic substance contents, as well as playing a vital role in improving the drought resistance of maize. Overall, the external use of Si ameliorated growth, photosynthetic and antioxidant metabolism under drought stress.

Tetraploid induction through somatic embryogenesis in Panax vietnamensis Ha et Grushv. by colchicine treatment

• Somatic embryos regenerated from AgNPs-sterilized leaf explants of Ngoc Linh ginseng. • Tetraploid induction by colchicine in Panax vietnamensis Ha et Grushv. from somatic embryo. • Tetraploid plantlets had vigorous growth compared to the diploid plantlets. In the present study, the protocol of polyploid induction via somatic embryogenesis of the Ngoc Linh ginseng (Panax vietnamensis Ha et Grushv.) (2n = 2x = 24) was developed. Ex vitro leaf explants were disinfected with AgNPs at concentrations of 0.05, 0.1, 0.2 and 0.5 g/L for 5, 10, 15, 20 and 30 min and cultured on MS medium supplemented with 1.0 mg/L 2,4-D, 0.5 mg/L NAA and 0.2 mg/L Kin for somatic embryogenesis. Globular embryos induced from the leaf explants were treated with colchicine by immersed method at different concentrations of 0, 0.1, 0.2, 0.3, 0.5 and 0.7% for 24, 36, 48 and 72 h. Then, these embryos were cultured on medium supplemented with 1.0 mg/L 2,4-D, 0.5 mg/L NAA and 0.2 mg/L Kin for secondary embryos induction. The ploidy level was identified by counting chromosomes of the root tip of plantlets derived from these secondary embryos. The results showed that the survival rate and somatic embryo induction the highest (65.56% and 29.89%, respectively) at 0.2 g/L AgNPs for 20 min. For colchicine treatment, the increase in the concentration and exposure time of colchicine decreased the survival rate of explants and the number of secondary embryos but increased the abnormal secondary embryo formation. Identifying the ploidy level showed that the treatments with colchicine concentrations from 0.3% to 0.5% for 48 h lead to tetraploid induction rates from 22.22% to 25.92%. The results also revealed that the tetraploids (2n = 4x = 48) had larger stomatal size, lower stomatal density, denser stomatal chloroplast density, and better growth than did the diploids.

Impact of white mistletoe (Viscum album ssp. abietis) infection severity on morphology, anatomy and photosynthetic pigment content of the needles of cilicican fir (Abies cilicica)

White mistletoe (Viscum album ssp. abietis, Santalaceae) is a hemi-parasitic plant and is regarded as one of the most significant biotic factors affecting fir forests. Mistletoe affects its host in many ways, including changes in leaf development. This paper studies and quantifies the effect of white mistletoe on morphological, anatomical traits and photosynthetic pigment content of cilicican fir (Abies cilicica (Antoine & Kotschy) Carrière, Pinaceae) needles growing on uninfected branches of infected and uninfected trees in relation to varying mistletoe infection severity. Morphological (needle length and width, area and weight, and specific leaf area), anatomical (needle width and thickness, epidermis and central vein thickness, needle cross sectional and mesophyll area, epidermis plus hypodermis and central vein area, xylem and phloem area, transfusion and resin duct area), stomatal (number of stomata rows, stomatal band width, stomata length and density) traits and photosynthetic pigment content (chlorophyll a and b, total chlorophyll (a+b), total carotenoid) were measured in one-year-old needles growing on uninfected branches from a total of 48 cilicican fir trees. Of the trees, 10 were uninfected, 13 lightly infected, 14 moderately infected and 11 severely infected. The results indicated that morphological dimension of needles decreased steadily with increasing infection severity. Stomatal size of needles decreased gradually while stomatal density increased gradually with increasing infection severity. Reduced anatomical dimension were only evident in needles from moderate and severe infection classes, while chlorophyll content decreased in only severely infected trees.

Reactions of Some Grapevine Rootstock Cuttings to Mutagenic Applications

Grapevine (Vitis spp.) is one of the most important socio-economically important plants in the global scale, and the need for its breeding is increasing. In viticulture, mutation is more promising than crossbreeding in breeding new genotypes from natural genetic diversity. Polyploid plants outperform their diploid relatives in several respects. In this study, the efficacy of oryzalin and N2O mutagens in the induction of polyploidy was investigated by applying different doses and durations to the forced cuttings of 41B [Chasselas (Vitis vinifera L.) × Vitis berlandieri Planch)] and Fercal [(Vitis vinifera x Vitis berlandieri) × 333 EM] rootstocks. LD50 values of mutagen applications were determined, morphological and cytological effects were examined by macroscopic, microscopic, and cytological methods. Application time and dose increase of mutagens decreased LD50 values. As a result of mutagen applications, leaf thickness and chlorophyll content of the surviving plants increased. Applications increased stomatal sizes, decreased their density, increased chloroplast numbers, increased leaf thicknesses and partially SPAD values. It was determined that they were not polyploid in the confirmation test performed with flow cytometry (FC) analyses in 4 Fercal and 1 41B samples that were assumed to be mutant by stoma and chloroplast examinations. After that, it was thought that it would be appropriate to try vegetative material with actively dividing cells, such as nodal cuttings, in the studies of obtaining polyploid individuals on grapevine rootstocks

Comparative leaf epidermis study in Habenaria spp. (Orchidaceae) from Thailand

Abstract. Muangsan N, Saensouk P, Chanokkhun T, Watthana S. 2022. Comparative leaf epidermis study in Habenaria spp. (Orchidaceae) from Thailand. Biodiversitas 23: 4159-4168. The variation of epidermal and stomatal characteristics could be used for plant classification, including orchids. This study aimed to investigate leaf epidermis characters of Habenaria from Thailand and focused on the H. rhodocheila group and related species. Fourteen accessions belonging to 10 species were studied and compared. Epidermal peels were taken from the upper and lower surfaces of the leaves and were observed under a light microscope. The stomata of all accessions studied were distributed only in the lower epidermis, where they were hypostomatic and anomocytic. The epidermal cell density showed significant differences between the two surface sides. The stomatal size is significantly different among all samples. The highest stomatal index was presented in H. rostrata and the lowest on H. rhodocheila (red). There is no gap variation of epidermis characteristics in H. rhodocheila and its closely related species. It is indicated that the leaf epidermal characters are the shared characters of the genus Habenaria from Thailand. H. rostrata has tentatively separated from other species based on epidermal anatomical characteristics.

An extremely low stomatal density mutant overcomes cooling limitations at supra-optimal temperature by adjusting stomatal size and leaf thickness.

The impact of global warming on transpiration and photosynthesis would compromise plant fitness, impacting on crop yields and ecosystem functioning. In this frame, we explored the performance of a set of Arabidopsis mutants carrying partial or total loss-of-function alleles of stomatal development genes and displaying distinct stomatal abundances. Using microscopy and non-invasive imaging techniques on this genotype collection, we examined anatomical leaf and stomatal traits, plant growth and development, and physiological performance at optimal (22°C) and supra-optimal (30°C) temperatures. All genotypes showed thermomorphogenetic responses but no signs of heat stress. Data analysis singled out an extremely low stomatal abundance mutant, spch-5. At 22°C, spch-5 had lower transpiration and warmer leaves than the wild type. However, at 30°C, this mutant developed larger stomata and thinner leaves, paralleled by a notable cooling capacity, similar to that of the wild type. Despite their low stomatal density (SD), spch-5 plants grown at 30°C showed no photosynthesis or growth penalties. The behavior of spch-5 at supra-optimal temperature exemplifies how the effect of very low stomatal numbers can be counteracted by a combination of larger stomata and thinner leaves. Furthermore, it provides a novel strategy for coping with high growth temperatures.

Response of Phaius tankervilleae Bl. to Various Nutrient Concentration Levels

To ensure the healthy growth and development of vegetative and reproductive tissues, all plants must obtain a specific amount of inorganic mineral elements from their surroundings.One of the most crucial elements that regulates the growth and development of floral crops is the availability of mineral nutrients in sufficient quantities. The current study was carried out at the Assam Agricultural University's Horticulture Experimental Farm in Jorhat, Assam, during the 2020–2021 academic year utilising a completely randomised design with seven different treatment combinations and three replications. The findings showed that mineral nutrients had a substantial impact on all growth features. The treatment T5 (RDF+ Ca 500 ppm) was the most effective in boosting all growth characteristics, including plant height (56.27 cm) ,leaf count (12.33, leaf length (53.07cm), leaf width (9.67cm), leaf area (469.23cm2), stem diameter (7.07cm), and number of pseudobulbs (2.80).T2 (RDF+ Zn 750ppm) exhibited the shortest days for inflorescence visibility (50.87), bud development (142.80), days to half bloom (146.30), and days to full bloom (148.77), as well as the greatest value for spike length (66.73cm), floret diameter (9.67cm), stalk girth (3.67cm), number of florets per spike (12.93), number of spikes per plant (2. (22.80g). For Physiological characters, treatment T2 (RDF+Zn(750ppm) was best for increasing total chlorophyll content (1.55 mg g-1 fw,), stomatal number (37.13), and stomatal size (5.80 \(\mu\) m2).

The structural correlations and the physiological functions of stomatal morphology and leaf structures in C3 annual crops

This study suggests that stomatal and leaf structures are highly correlated, and mesophyll cell size is an important anatomical trait determining the coordination between stomatal size and mesophyll porosity. A comprehensive study of the correlations between the structural traits and on their relationships with gas exchange parameters may provide some useful information into leaf development and improvement in efficiencies of photosynthetic CO2 fixation and transpirational water loss. In the present study, nine plant materials from eight crop species were pot grown in a growth chamber. Leaf structural traits, gas exchange, and leaf nitrogen content were measured. We found that stomatal size, mesophyll cell size (MCS), and mesophyll porosity were positively correlated and that the surface areas of mesophyll cells and chloroplasts facing intercellular air spaces were positively correlated with both stomatal density and stomatal area per leaf area (SA). These results suggested that the developments of stomata and mesophyll cells are highly correlated among different crop species. Additionally, MCS was positively correlated with leaf thickness and negatively correlated with leaf density and leaf mass per area, which indicated that MCS might play an important role in leaf structural investments and physiological functions among species. In summary, this study illustrates the correlations between stomatal and mesophyll structures, and it highlights the importance of considering the covariations among leaf traits with the intent of improving photosynthesis and iWUE.

Vapour pressure deficit and endogenous ABA level modulate stomatal responses of tomato plants to soil water deficit

High vapour pressure deficit (VPD) in the air and water deficits in the soil are considered two key stress factors limiting crop growth and production. To explore their interactive effects on stomatal behaviour and plant water use and the role of abscisic acid (ABA) in mediating these responses, two tomato (Solanum lycopersicum) genotypes, Ailsa Craig (AC) and its ABA-deficient mutant (flacca), were grown at two VPD levels (VPD1, 0.71 kPa and VPD2, 1.25 kPa) and were exposed to progressive soil drying. The results showed that the relatively higher VPD, i.e. VPD2, decreased stomatal conductance only in AC, and increased transpiration rate and water consumption in both genotypes, which was associated with altered stomatal morphological traits, including lowered stomatal density, reduced stomatal size and pore aperture. During progressive soil drying, both AC and flacca grown at VPD2 closed stomata earlier than VPD1-plants with a low leaf ABA concentration, indicating that rising VPD advanced stomatal drought response in an ABA-independent way. At the end of soil drying, the stomata of VPD1-AC plants remained widely opened resulting in fast desiccation of the leaves excised from the plants upon exposure to VPD2, which implied an interaction of VPD and ABA in mediating short-term stomatal response. VPD2 increased the intrinsic water use efficiency (WUE) in AC plants but decreased the whole-leaf and plant WUE in both genotypes, as affirmed by the corresponding changes in leaf δ13C and δ 18O. Compared to δ 18O, δ13C was a more robust indicator of stomatal movement when plants were exposed to combined atmospheric and soil droughts. Collectively, these findings provide some novel insights into the stomatal regulation of tomato plants confronting combined atmospheric and edaphic droughts.

Banana leaf anatomy characteristics related to ploidy levels

Many important crops have cultivars with different ploidy and provide a diverse choice of materials for breeding programs. Therefore, it is essential to accurately assess the ploidy of all breeding materials. Increased DNA content is known to have various effects on external and internal morphology, an effect known as the “nucleotypic effect”. Thus, anatomical assessment can be used as a tool for determining ploidy in plants, making the chromosome counting technique or flow cytometry unnecessary. This study aimed to evaluate the leaf anatomical characteristics of banana cultivars and understand the relationship between these features and ploidy levels. Thirteen accessions were evaluated, including diploid, triploid, and tetraploid genotypes, and cultivars, resulting from in vitro propagation after 90 days of acclimatization. Five fully expanded young leaves were collected from each cultivar, fixed in FAA70 (formaldehyde–acetic acid–ethanol) and preserved in 70% alcohol. Transverse and paradermal sections of the abaxial and adaxial regions were taken, and variables such as size and stomatal density, leaf thickness in the midrib and fourth vascular bundle region, and thickness of the epidermis, hypodermis, and parenchyma were measured. Results for leaf thickness, stomatal size, and density proved to be appropriate parameters for characterizing banana ploidy levels.

Identification of Vehicular Emission Hyper Accumulator And Its Subsequent Use as Phytoremediation

Effects of vehicular emission on two plants Amaranthus spinosus Linn. and Croton bonplandianum Baill, collected from polluted site and from relatively less polluted site/control site of Kolkata city of West Bengal, India was studied. Photosynthetic pigment content, proline content, phosphatase activity and Hill activity, heavy metal contents and their relevance to be used as phytoremediators was investigated. Decrease in pigment content and increase in proline content and phosphatase activity was observed in the plants from polluted areas. Micromorphological studies revealed the effect of automobile emission on epidermal cells and stomatal size on both the experimental plants. Data indicated that between the two plants, A. spinosus was more susceptible and C. bonplandianum was more tolerant to vehicular pollution. Bangladesh J. Bot. 51(2): 207-216, 2022 (June)

Elevated light intensity compensates for nitrogen deficiency during chrysanthemum growth by improving water and nitrogen use efficiency

Identifying environmental factors that improve plant growth and development under nitrogen (N) constraint is essential for sustainable greenhouse production. In the present study, the role of light intensity and N concentrations on the biomass partitioning and physiology of chrysanthemum was investigated. Four light intensities [75, 150, 300, and 600 µmol m−2 s−1 photosynthetic photon flux density (PPFD)] and three N concentrations (5, 10, and 15 mM N L−1) were used. Vegetative and generative growth traits were improved by increase in PPFD and N concentration. High N supply reduced stomatal size and gs in plants under lowest PPFD. Under low PPFD, the share of biomass allocated to leaves and stem was higher than that of flower and roots while in plants grown under high PPFD, the share of biomass allocated to flower and root outweighed that of allocated to leaves and stem. As well, positive effects of high PPFD on chlorophyll content, photosynthesis, water use efficiency (WUE), Nitrogen use efficiency (NUE) were observed in N-deficient plants. Furthermore, photosynthetic functionality improved by raise in PPFD. In conclusion, high PPFD reduced the adverse effects of N deficiency by improving photosynthesis and stomatal functionality, NUE, WUE, and directing biomass partitioning toward the floral organs.

Contrasting Phaseolus Crop Water Use Patterns and Stomatal Dynamics in Response to Terminal Drought.

Terminal drought stress affects more than half of the areas planted with common bean (Phaseolus vulgaris), the main food legume globally, generating severe yield losses. Phenotyping water deficit responses and water use are central strategies to develop improved terminal drought resilience. The exploration and exploitation of genetic diversity in breeding programs are gaining importance, with a particular interest in related species with great adaptation to biotic and abiotic factors. This is the case with tepary beans (Phaseolus acutifolius), a bean that evolved and was domesticated in arid conditions and is considered well adapted to drought and heat stress. Under greenhouse conditions, using one genotype of tepary beans (resistant to drought) and two of common beans (one resistant and one susceptible to terminal drought), we evaluated phenotypic differences in traits such as water use efficiency (WUE), transpiration efficiency, rate of photosynthesis, photosynthetic efficiency, stomatal density, stomatal index, stomatal size, and the threshold for transpiration decline under well-watered and terminal drought conditions. Our results indicate two different water use strategies in drought-resistant genotypes: one observed in common bean aimed at conserving soil water by closing stomata early, inhibiting stomatal development, and limiting growth; and the other observed in tepary bean, where prolonged stomatal opening and higher carbon fixation, combined with no changes in stomata distribution, lead to higher biomass accumulation. Strategies that contribute to drought adaptation combined with other traits, such as greater mobilization of photoassimilates to the formation of reproductive structures, confer bean drought resistance and are useful targets in breeding programs.