Guard Cell Length Research Articles

The sensitivity of reconstructed carbon dioxide concentrations to stomatal preparation methods using a leaf gas exchange model.

Mechanistic models using stomatal traits and leaf carbon isotope ratios to reconstruct atmospheric carbon dioxide (CO2) concentrations (c a ) are important to understand the Phanerozoic paleoclimate. However, methods for preparing leaf cuticles to measure stomatal traits have not been standardized. Three people measured the stomatal density and index, guard cell length, guard cell pair width, and pore length of leaves from the same Ginkgo biloba, Quercus alba, and Zingiber mioga leaves growing at known CO2 levels using four preparation methods: fluorescence on cleared leaves, nail polish, dental putty on fresh leaves, and dental putty on dried leaves. There are significant differences between trait measurements from each method. Modeled c a calculations are less sensitive to method than individual traits; however, the choice of assumed carbon isotope fractionation also impacted the accuracy of the results. We show that there is not a significant difference between c a estimates made using any of the four methods. Further study is needed on the fractionation due to carboxylation of ribulose bisphosphate (RuBP) in individual plant species before use as a paleo-CO2 barometer and to refine estimates based upon widely applied taxa (e.g., Ginkgo). Finally, we recommend that morphological measurements be made by multiple observers to reduce the effect of individual observational biases.

Contrasting strategies in morphological and physiological response to drought stress among temperate forest understory forbs and graminoids.

Drought stress can profoundly affect plant growth and physiological vitality, yet there is a notable scarcity of controlled drought experiments focused on herbaceous species of the forest understorey. In this study, we collected seeds from five forb and four graminoid species common in European temperate forests. Seeds were germinated under controlled glasshouse conditions and subjected to moderate drought stress for 5 weeks. We assessed biomass partitioning, stomatal and leaf morphology, leaf gas exchange, minimum leaf conductance (gmin), and chlorophyll fluorescence parameters. Comparison of the two ecological guilds revealed that graminoids had a higher R/S, improved WUE, greater carboxylation efficiency, and enhanced non-photochemical quenching under drought conditions compared to forbs. In contrast, forbs had significantly lower gmin, with higher total biomass and total leaf area. Despite these differences in morpho-physiological functional traits, both groups experienced a similar relative reduction in biomass after drought stress. Key predictors of biomass accumulation under drought included photochemical quenching, stomatal traits, total leaf area and gmin. A negative correlation between biomass and gmin suggests that plants with lower residual water loss after stomatal closure can accumulate more biomass under drought stress. Additionally, gmin was positively correlated with guard cell length, suggesting that larger stomata contribute to higher residual water loss. Contrasting strategies in morpho-physiological responses to drought define the differences between the two groups. In graminoids, drought resistance suggests greater emphasis on stress tolerance as a survival strategy. In contrast, forbs were able to maintain higher biomass and total leaf area, indicating a competitive strategy for maximizing resource acquisition.

Effects of ploidy level on leaf morphology, stomata, and anatomical structure of Hibiscus syriacus L.

BackgroundHibiscus syriacus L. is a deciduous shrub with a strong environmental resistance and wide application prospects. The genetic background and ploidy levels of Hibiscus cultivars are complex, and polyploid breeding has long been an important method for developing new Hibiscus cultivars. However, the relationship of ploidy levels with leaf morphology, stomatal characteristics, and leaf anatomy remains unclear.ResultsThis study analyzed three ploidy levels (triploid, tetraploid, and hexaploid) of Hibiscus syriacus. Flow cytometry confirmed the ploidy levels, and morphological traits were evaluated. Leaf length, leaf width, and petiole length decreased with increasing ploidy. Stomatal length, stomatal width, guard cell length, and guard cell width increased and stomatal number and density decreased with increasing ploidy. The hexaploids exhibited the highest midrib diameter and palisade tissue thickness values. Correlation analyses revealed that stomatal morphology served as a reliable marker for determining ploidy levels.ConclusionThis study highlights the impact of varying ploidy levels on the leaf and stomatal morphologies and leaf anatomy of Hibiscus syriacus. These findings can provide theoretical guidance for improving Hibiscus cultivars in terms of stress resistance, adaptability, and ornamental traits, and for developing new cultivars with enhanced characteristics. Future research should focus on utilizing these morphological markers to optimize breeding strategies for Hibiscus cultivars.

Linking stomatal size and density to water use efficiency and leaf carbon isotope ratio in juvenile and mature trees.

Water-use efficiency (WUE) is affected by multiple leaf traits, including stomatal morphology. However, the impact of stomatal morphology on WUE across different ontogenetic stages of tree species is not well-documented. Here, we investigated the relationship between stomatal morphology, intrinsic water-use efficiency (iWUE) and leaf carbon isotope ratio (δ13C). We sampled 190 individuals, including juvenile and mature trees belonging to 18 temperate broadleaved tree species and 9 genera. We measured guard cell length (GCL), stomatal density (SD), specific leaf area (SLA), iWUE and bulk leaf δ13C as a proxy for long-term WUE. Leaf δ13C correlated positively with iWUE across species in both juvenile and mature trees, while GCL showed a negative and SD a positive effect on iWUE and leaf δ13C. Within species, however, only GCL was significantly associated with iWUE and leaf δ13C. SLA had a minor negative influence on iWUE and leaf δ13C, but this effect was inconsistent between juvenile and mature trees. We conclude that GCL and SD can be considered functional morphological traits related to the iWUE and leaf δ13C of trees, highlighting their potential for rapid phenotyping approaches in ecological studies.

Foliar epidermal micro-morphology of selected brinjal varieties: A study on leaf surface characteristics

Studies on the leaf epidermal morphological characteristics were conducted on the three varieties of brinjal (Solanum melongena L.) belonging to the family Solanaceae. The varieties used in the study were Bhavani Gold, Purple Round and Haritha. Fresh mature brinjal leaves were randomly selected from the three experimental genotypes, and the foliar epidermal features were studied by using light microscopy and SEM imaging. Measurements were taken with an ocular and stage micrometer using 10X and 40X magnifications. The photographs were taken from mounted slides. The stomatal count and each measurement represent the average of ten readings. The upper and lower epidermal surfaces of leaf were studied for stomatal features including, stomatal distribution, stomatal type, stomatal index, stomatal pore length, stomatal pore width, guard cell length, guard cell width, subsidiary cell length and width, epidermal cell type, epidermal cell length and width, trichome type, trichome length and width. Amphistomatous, anisocytic, and with more stomata on the lower epidermal surface than the upper epidermal surface were present in all leaf varieties. On the leaves, the abaxial stomatal index ranged from 68.19 mm-2 (Bhavani Gold) to 56.67 mm-2 (Purple Round) to 58.8 mm-2 (Haritha). While on the adaxial surface, it varied from 59.67 mm-2 (Bhavani Gold), 53.46 mm-2 (Purple Round) and 56.67 mm-2 (Haritha). The three varieties of this study exhibited similarities in the pattern of epidermal cell on the adaxial and abaxial surfaces and were irregular in shape. Among the three varieties epidermal cell become irregular in outline and trichomes were present on both leaf surfaces. It becomes stellate, non-glandular, glandular and 8-12 in number. The highest trichome length was obtained in Bhavani Gold (63 μm) followed by Haritha (57.5 μm) and Purple Round (43 μm) on the upper epidermis. On the lower epidermal region maximum length was obtained in Bhavani Gold (65.5 μm) followed by Haritha (53 μm) and Purple Round (44 μm).

Efficient gene editing of a model fern species through gametophyte-based transformation.

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease (Cas) system allows precise and easy editing of genes in many plant species. However, this system has not yet been applied to any fern species through gametophytes due to the complex characteristics of fern genomes, genetics, and physiology. Here, we established a protocol for gametophyte-based screening of single-guide RNAs (sgRNAs) with high efficiency for CRISPR/Cas9-mediated gene knockout in a model fern species, Ceratopteris richardii. We utilized the C. richardii ACTIN promoter to drive sgRNA expression and the enhanced CaMV 35S promoter to drive the expression of Streptococcus pyogenes Cas9 in this CRISPR-mediated editing system, which was employed to successfully edit a few genes, such as Nucleotidase/phosphatase 1 (CrSAL1) and Phytoene Desaturase (CrPDS), which resulted in an albino phenotype in C. richardii. Knockout of CrSAL1 resulted in significantly (P < 0.05) reduced stomatal conductance (gs), leaf transpiration rate (E), guard cell length, and abscisic acid (ABA)-induced reactive oxygen species (ROS) accumulation in guard cells. Moreover, CrSAL1 overexpressing plants showed significantly increased net photosynthetic rate (A), gs, and E as well as most of the stomatal traits and ABA-induced ROS production in guard cells compared to the wild-type (WT) plants. Taken together, our optimized CRISPR/Cas9 system provides a useful tool for functional genomics in a model fern species, allowing the exploration of fern gene functions for evolutionary biology, herbal medicine discovery, and agricultural applications.

Lamiales epidermal dynamics: Unveiling antimicrobial resilience in a structural symphony.

This research on Lamiales epidermal anatomy not only provides in-depth understanding of their structural traits but also highlights the significance of uncovering the inherent antimicrobial resilience embedded within these plants. Such insights hold promise for advancing natural product-based approaches in medicine, potentially contributing to the development of novel antimicrobial agents inspired by Lamiales unique biological defense mechanisms. Scanning microscopic tools were utilized to conduct foliar epidermal anatomy of nine species that belong to seven genera and four families within the Lamiales order, Plantaginaceae, Scrophulariaceae, Verbenaceae, and Lamiaceae. This approach aimed to gather both qualitative and quantitative data, facilitating the assessment of taxonomic microanatomical significance. The shape of epidermal cells and their anticlinal walls; number of epidermal cells, stomata, and trichomes; type of stomata and trichomes; length and width of epidermal cells, trichomes, stomatal pore, guard cells, and subsidiary cells; and stomatal index were determined statistically. Most of the species examined were amphistomatous and showed extensive array of trichomes diversity. The exploration of Lamiales epidermal micromorphology and their antimicrobial potential were significant for their implications in multidisciplinary fields. The pharmacological research to utilize sustainable agricultural practices prompts avenues to strengths of Lamiales order for the development of novel antimicrobial solutions and ecological benefits. RESEARCH HIGHLIGHTS: Diverse trichome morphometry reveals a wide array of trichome structures across Lamiales species. Epidermal microscopic architecture variability of epidermal cell shapes and sizes signifies the interspecies variability. Secondary metabolite localization within microanatomical structures elucidates potential hotspots for antimicrobial compound production.

Efficient induction and rapid identification of haploid grains in tetraploid wheat by editing genes TtMTL and pyramiding anthocyanin markers.

Doubled haploid (DH) technology provides an effective way to generate homozygous genetic and breeding materials over a short period of time. We produced three types of homozygous TtMTL gene-edited mutants (mtl-a, mtl-b, and mtl-ab) by CRISPR/Cas9 in durum wheat. PCR restriction enzymes and sequencing confirmed that the editing efficiency was up to 53.5%. The seed-setting rates of the three types of mutants ranged from 20% to 60%. Abnormal grain phenotypes of kernel, embryo, and both embryo and endosperm abortions were observed in the progenies of the mutants. The average frequency of embryo-less grains was 25.3%. Chromosome counting, guard cell length, and flow cytometry confirmed that the haploid induction rate was in the range of 3%-21% in the cross- and self-pollinated progenies of the mtl mutants (mtl-a and mtl-ab). Furthermore, we co-transformed two vectors, pCRISPR/Cas9-MTL and pBD68-(ZmR + ZmC1), into durum wheat, to pyramide Ttmtl-edited mutations and embryo-specifically expressed anthocyanin markers, and developed a homozygous durum haploid inducer with purple embryo (DHIPE). Using DHIPE as the male parent to be crossed with the wild-type Kronos, the grains with white embryos were identified as haploid, while the grains with purple embryos were diploid. These findings will promote the breeding of new tetraploid wheat varieties.

Biochar addition and reduced irrigation modulates leaf morpho-physiology and biological nitrogen fixation in faba bean-ryegrass intercropping

Intercropping legume with grass has potential to increase biomass and protein yield via biological N2-fixation (BNF) benefits, whereas the joint effects of biochar (BC) coupled with deficit irrigation on intercropping systems remain elusive. A 15N isotope-labelled experiment was implemented to investigate morpho-physiological responses of faba bean-ryegrass intercrops on low- (550 °C, LTBC) or high-temperature BC (800 °C, HTBC) amended sandy-loam soil under full (FI), deficit (DI) and partial root-zone drying irrigation (PRD). LTBC and HTBC significantly reduced intrinsic water-use efficiency (WUE) by 12 and 14 %, and instantaneous WUE by 8 and 16 %, respectively, in faba bean leaves, despite improved photosynthetic (An) and transpiration rate (Tr), and stomatal conductance (gs). Compared to FI, DI and PRD lowered faba bean An, gs and Tr, but enhanced leaf-scale and time-integrated WUE as proxied by the diminished shoots Δ13C. PRD enhanced WUE as lower gs, Tr and guard cell length than DI-plants. Despite higher carbon ([C]) and N concentration ([N]) in faba bean shoots amended by BC, the aboveground C- and N-pool of faba bean were reduced, while these pools increased for ryegrass. The N-use efficiency (NUE) in faba bean shoots was reduced by 9 and 14 % for LTBC and HTBC, respectively, but not for ryegrass. Interestingly, ryegrass shoots had 52 % higher NUE than faba bean shoots. The N derived from atmosphere (% Ndfa) was increased by 2 and 9 % under LTBC and HTBC, respectively, while it decreased slightly by reduced irrigation. Quantity of BNF in faba bean aboveground biomass decreased with HTBC coupled with reduced irrigation, mainly towards decreased biomass and soil N uptake by faba bean. Therefore, HTBC might not be a feasible option to improve WUE and BNF in faba bean-ryegrass intercropping, but PRD is permissible as the clear trade-off between BC and PRD.

Determining Formaldehyde Phytoremediation Efficacy of Selected Ornamental Plants

In the recent past, deterioration of indoor air quality has become a serious concern due to the increased energy efficiency and reduced air exchange rate inside urban buildings. Volatile organic compounds (VOCs) are a major category of indoor air pollutants that can lead to adverse health outcomes such as headaches, allergies and asthma in those exposed for prolonged periods. Formaldehyde, the VOC used in the present study is a common contaminant of indoor air which originates from particle board, plywood, paper products, certain adhesives, tobacco smoke and other sources. The use of plants for the mitigation of indoor air pollution is viewed as a cost effective and eco-friendly method with untapped potential. The main objective of the present study was to determine the formaldehyde removal efficacy of selected plant species while investigating the mechanisms used by these plants in the removal process. The selected plant species were Zamioculcas zamiifolia, Hedera helix, Dracaena sanderiana and Ficus sp. Plants of the same age were used with three replicates from each species. Phytoremediation potential was assessed by exposing the plants for 24 hours to gaseous formaldehyde (2.0 μL L-1) in air tight chambers made of Plexiglass (an inert material for VOCs) with dimensions of 0.9 m height×0.58 m length×0.55 m width. Formaldehyde removal was measured using GC-MS and the result was expressed as removal percentages. Several leaf anatomical characters (cuticle thickness, epidermal thickness and mesophyll layer thickness), stomatal characters (stomatal density, stomatal index, guard cell length and potential conductance index) and physiological characters (stomatal conductance and photosynthetic rate) were measured to study the possible mechanisms involved in the formaldehyde removal process. The data were subjected to ANOVA and Pearson correlation test. According to the results obtained, Ficus sp. had the highest formaldehyde removal percentage (92.80%) while Hedera helix had the lowest (56.86%). The study further showed that stomatal density and stomatal conductance play a major role in formaldehyde removal by these plants while cuticle and epidermal thickness act as hindrances to this process. This conclusion was further confirmed by Pearson‘s correlation values in correlation analysis. The current study was carried out for 24 hours of exposure and it would be of interest to explore, the long term behavior of the plants through further studies. Overall, the results justify future studies on a cross-section of diverse plant species for formaldehyde removal efficiency to determine species with superior removal efficiencies for a better phytoremediation process. &#x0D; Keywords: Phytoremediation, VOCs, Formaldehyde, GC-MS technology

Stomatal dimensions of Laguncularia racemosa leaves in restored and degraded mangrove ecosystems

ABSTRACT Mangrove leaves have adapted to effectively manage water conservation and regulate toxic saline conditions through the morphological characteristics of stomatal dimensions. The present study examines the stomatal dimensions of 120 Laguncularia racemosa leaves from both a degraded mangrove ecosystem and a restored mangrove ecosystem located along the Guyana coastline. Datasets were obtained during the wet and dry seasons using the nearest individual sampling method. The nail polish blotting technique, microscopy, and digital photography were used to obtain measurements of various stomatal dimensions, including guard cell length and width, pore length and width, circumference, surface area, stomatal frequency, density, index, and epidermal cell frequency. Our hypothesis is that there is significant variation in the stomatal dimensions of Laguncularia racemosa leaves as a function of mangrove ecosystem type and seasonal change. The results of this study confirmed this hypothesis as significant variations were observed in stomatal dimensions as a function of seasonal changes and mangrove ecosystem type. Statistically significant differences (p < 0.05, R > 0.70) were observed between the degraded ecosystem during the dry season and the restored ecosystem during the wet season, specifically regarding guard cell length and width, pore length and width, area, and circumference. Multiple regression analysis and PCA provide compelling evidence to support the existence of robust correlations between ecosystem types and stomatal dimensions. The results of our study indicate that the leaves of Laguncularia racemosa display certain small-scale adjustments that enable them to manage the stress factors present in different ecosystems and seasons.

Early haploid identification by stomatal guard cell length in tropical supersweet corn using different inducers

Early haploid identification by stomatal guard cell length in tropical supersweet corn using different inducers

Genome size and guard cell length are associated in four species of Miconia (Miconieae, Melastomataceae)

Genome size and guard cell length are associated in four species of Miconia (Miconieae, Melastomataceae)

Ecological implications of stomatal density and stomatal index in the adult stage of Mimosa L. (Leguminosae, Caesalpinioideae).

Differences in stomatal density (SD) and stomatal index (SI) are associated with the conditions of the environment in which they are distributed. Mimosa species are important elements in different plant communities, yet knowledge of the ecological implications of its stomatal characteristics is scarce. For this reason, SD and SI were determined in seven Mimosa species from different environments in this study. Five individuals per species were selected, and a sample of leaflets was obtained from each. Fifteen mature leaflets per individual were then extracted and observed by optical microscopy. SD, SI, epidermal cell density (ECD), and guard cell length (GCL) values were obtained. Differences between species were analyzed through a balanced analysis of variance test, and the correspondence between the stomatal characteristics and 21 climate variables was determined by canonical correspondence analysis. The species differed in all evaluated characteristics. It should be noted that only M. affinis showed differences between the leaflet surfaces. Both DE and ECD were negatively associated with altitude and solar radiation and positively with temperature and precipitation. SI was explained by temperature and seasonality of precipitation, and GCL by temperature oscillation and seasonality of precipitation. The results suggest that the stomatal characteristics of the leaflets confer resistance in the species to alterations in environmental conditions.

Stomata variation in the process of polyploidization in Chinese chive (Allium tuberosum).

Stomatal variation, including guard cell (GC) density, size and chloroplast number, is often used to differentiate polyploids from diploids. However, few works have focused on stomatal variation with respect to polyploidization, especially for consecutively different ploidy levels within a plant species. For example, Allium tuberosum, which is mainly a tetraploid (2n = 4x = 32), is also found at other ploidy levels which have not been widely studied yet. We recently found cultivars with different ploidy levels, including those that are diploid (2n = 2x = 16), triploid (2n = 3x = 24), pseudopentaploid (2n = 34-42, mostly 40) and pseudohexaploid (2n = 44-50, mostly 48). GCs were evaluated for their density, size (length and width) and chloroplast number. There was no correspondence between ploidy level and stomatal density, in which anisopolyploids (approximately 57 and 53 stomata/mm2 in triploid and pseudopentaploid, respectively) had a higher stomatal density than isopolyploids (approximately 36, 43, and 44 stomata/mm2 in diploid, tetraploid and pseudohexaploid, respectively). There was a positive relationship between ploidy level and GC chloroplast number (approximately 44, 45, 51, 72 and 90 in diploid to pseudohexaploid, respectively). GC length and width also increased with ploidy level. However, the length increased approximately 1.22 times faster than the width during polyploidization. This study shows that GC size increased with increasing DNA content, but the rate of increase differed between length and width. In the process of polyploidization, plants evolved longer and narrower stomata with more chloroplasts in the GCs.

Comparative taxonomical, biological and pharmacological potential of healthy and geminivirus infected leaves of Hibiscus rosa-sinensis L.: First report

In the present research project, the first report on comparative analysis of the taxonomical, biological and pharmacological potential of healthy and geminivirus infected Hibiscus rosa sinensis (L.) leaves of the family Malvaceae was done by using different micro and macroscopic techniques. First of all, leaves were characterized for Cotton leaf curl Multan virus (CLCuMuV) and its associated betasatellite (Cotton leaf curl Multan Betasatellite; CLCuMB). Different morphological parameters like shape and size of stem, leaves, seeds and roots, presence and absence of ligule, distance between nodes and internodes and type of inflorescence etc. were analyzed. CLCuMuV infected H. rosa-sinensis revealed systematic symptoms of infection like chlorosis of leaves, stunted growth, decrease in size of roots, shoots and distortion etc. Anatomical investigation was performed under light ad scanning electron microscope. Different anatomical features like length and shape of guard cells, subsidiary cells, presence or absence of stomata, secretory ducts and trichomes were examined. In both plant samples anomocytic types of stomata and elongated, non-glandular and pointed tip trichomes were present, but the size (especially length and width) of trichomes and other cells like epidermal, subsidiary, and guard cells were highest in virus infected plants likened to healthy one. In the antibacterial activity, the maximum antibacterial potentail was seen in methanolic extract of K. pneumonea while antifungal activity was shown by methanolic extract of A. solani. Plants interact with different biological entities according to environmental conditions continuously and evolved. These types of interactions induce changes positively and negatively on plant metabolism and metabolites production. Many plant viruses also attacked various host plants consequently alter their secondary metabolism. To overcome such virus infected plants produces many important and different types of secondary plant metabolites as a defense response. Subsequent analysis of this n-hexane plant extract using Gas chromatography mass spectroscopy technique revealed that Hibiscus eluted contained 10 main compounds in Healthy sample and 13 compounds in infected one. Presence of essential secondary metabolites were also analyzed by FTIR analysis. The present study provides a comprehensive and novel review on taxonomy (morphology, anatomy) and antimicrobial potential of both healthy and geminivirus infected H. rosa-sinensis.

Comparative microscopic investigations of leaf epidermis in four Ajuga species from Korea.

The genus Ajuga is widely distributed in temperate to subtropical regions, and four species are currently recognized in Korea (A. decumbens, A. multiflora, A. nipponensis, and A. spectabilis), but epidermal anatomical differences across these species have never been described. A comparative study of the leaf micromorphological characteristics of Korean Ajuga species was performed using light microscopy (LM) and scanning electron microscopy (SEM) to elucidate their taxonomic usefulness and to assess leaf micromorphological diversity. Considerable diversity in epidermal and stomatal anatomy was observed across Korean Ajuga species. Species had both hypostomatic or amphistomatic leaves, with anomocytic, anisocytic, diactyic, or actinocytic stomatal complexes. Guard cell length across species ranged from 17.66 ± 0.57 μm to 32.50 ± 2.38 μm and correlated with genome size. Abnormal stomata were frequently observed in three species (A. decumbens, A. multiflora, and A. nipponensis) but not in A. spectabilis. Three types of glandular trichomes were found: peltate in all species, short-stalked in all species, and long-stalked glandular trichomes in A. multiflora. Among the investigated leaf micromophological characters, trichome type, epidermal cell shape, and stomatal morphology were all taxonomically informative traits at a species level. RESEARCH HIGHLIGHTS: A comprehensive micromorphological description of the leaf surface is provided for Korean Ajuga species using scanning electron microscopic (SEM) and light microscopic (LM) analyses. The diverse range of stomatal development and the occurrence of polymorphic stomatal types are documented for the first time in Korean Ajuga species. The great diversity in stomatal and trichome morphology in Korean Ajuga species are taxonomically useful traits for species identification.

Elucidating growth and biochemical characteristics of rice seedlings under stress from chromium VI salt and nanoparticles.

Plants are usually provoked by a variety of heavy metal (HM) stressors that have adverse effects on their growth and other biochemical characterizations. Among the HMs, chromium has been considered the most toxic for both plants and animals. The present study was conducted to compare the phytotoxic effects of increasing chromium (VI) salt and nanoparticles (NPs) concentrations on various growth indexes of rice (Oryza sativa L. var. swat 1) seedlings grown in a hydroponic system. The 7-day rice seedlings were exposed to Cr (VI) salt and NPs hydroponic suspensions which were adjusted to the concentration of 0, 50, 100, 150, 200 and 250 mg/L. Both the Cr (VI) salt and NPs with lower concentrations (up to 100mg/L) exerted minimum inhibitory effects on the growth performance of rice seedlings. However, a significant decrease in shoot and root length and their fresh and dry weight was recorded at higher doses of Cr (VI) salt (200 mg/L) and NPs (250 mg/L). The stress induced by Cr (VI) salt has drastically affected the roots, whereas, Cr (VI) NPs significantly affected the shoot tissues. Photosynthetic pigments decreased significantly in a dose-dependent manner, and the reduction was more pronounced in rice seedlings exposed to Cr (VI) NPs compared to Cr (VI) salt. Cr (VI) NPs enhanced the membrane permeability in shoots and roots as compared to that of Cr (VI) salt, which resulted in higher concentration of reactive oxygen species (ROS) and increased lipid peroxidation. The activities of antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) increased significantly in shoot/root tissue following exposure to higher doses of Cr (VI) salt (200 mg/L) and NPs stress (250 mg/L), while minor changes in CAT and APX activities were observed in root and shoot tissues after exposure to higher concentration of Cr (VI) NP. Furthermore, the increasing concentrations of Cr (VI) NPs increased the length of stomatal guard cells. Conclusively, Cr (VI) salt and NPs in higher concentrations have higher potential to damage the growth and induce oxidative stress in rice plants.

Growth and Morpho-Stomatal Response of Kenaf (Hibiscus cannabinus) to Varying Water, Light, and Soil Conditions

This study investigated the stomatal responses of kenaf (Hibiscus cannabinus) to varying water, light, and soil conditions to explain how the species acclimatize to the changes in growing conditions. Seedlings were subjected to different watering regimes (daily – CON, 2 days interval – W2, 3 days interval – W3), light intensities (high, moderate, low), and soil conditions (garden soil – GS, Mt Makiling soil – MAK, UP Land Grant soil – UPL). The biomass, stomatal density (SD), epidermal cell density (ECD), stomatal index (SI), stomatal aperture length (SAL), guard cell length (GCL), stomatal area (SA), and potential conductance index (PCI) were measured across treatments. Water and light treatments had significant effects, but soil treatment did not affect most of the parameters measured. CON and/or W2 and high light intensity resulted in a higher SD, SI, SAL, and GCL, which resulted in a higher PCI, compared with the other water and light treatments. Contrarily, W3-treated seedlings had lower SD but significantly lower SAL, GCL, PCI, and aboveground biomass, compared to CON and W2-treated ones. Biomass allocation to root was also significantly higher in W3-treated seedlings. Therefore, kenaf seedlings exhibited a degree of stomatal plasticity in response to contrasting water, light, and soil conditions. Keywords: biomass allocation, potential conductance index, shade tolerance, stomatal index, water stress

Comprehensive leaf and pistil micromorphology and its taxonomic value in the Korean Luzula species

Micromorphological characteristics provide important diagnostic criteria for differentiating plant groups and have thus been widely used to better understand the taxonomic significance of morphologically complex species. A comprehensive leaf and pistil micromorphological study of the Korean woodrush was performed using light and scanning electron microscopy to determine whether comparisons of these provide systematically informative traits. All six examined Korean Luzula species belonged to two subgenera, Luzula (L. capitata, L. multiflora and L. pallescens) and Pterodes (L. odaesanensis, L. rufescens and L. plumosa), and had hypostomatic leaves, with paracytic stomatal complexes found only on the abaxial surface. The epidermal surface could be divided into two types: verrcuate or scabrate on both abaxial and adaxial leaves. Guard cell length was an important trait for subgeneric identification in Korean Luzula, but highly variable among species, ranging from 23.02 μm in L. capitata to 63.75 μm in L. odaesanensis, in which the size variations might be influenced by different environmental conditions. The occurrence of abnormal stomatal complexes in the Korean Luzula species was reported here for the first time, which could be an adaptation to various environmental factors. We also report a detailed description of the pistil microstructure of Korean woodrush. Despite similar pistil surface ornamentation, the micromorphological features described in this study provide valuable information for developing further systematic context in the Korean Luzula species.