Stomatal Characteristics Research Articles

Influence of stomatal characteristics on yield and yield attributes of rice

Stomatal distribution is found to be an important trait of rice cultivars for increasing yield. A total of six rice cultivars, three from each of inbred and hybrid cultivars, were used to study stomatal distribution on the leaf epidermis and its influence on yield and yield attributing characters of rice during the Boro season. The hybrid cultivars exhibited superiority in respect of number of stomata, length and breadth of stomatal apparatus. They also produced longer panicle, higher number of filled grains panicle–1, heavier grains and finally, higher grain yield ha–1 than inbreds. The higher grain yield of the hybrid cultivars might be due to higher number of large sized stomata causing higher photosynthetic efficacy, although, they produced relatively lower number of effective tillers hill–1. DOI: http://dx.doi.org/10.3329/jbau.v11i1.18207 J. Bangladesh Agril. Univ. 11(1): 47-52, 2013

Interactive Effects of Elevated [CO<sub>2</sub>] and Soil Water Stress on Leaf Morphological and Anatomical Characteristic of Paper Birch Populations

The leaf morphological and stomatal characteristics of four paper birch (Betula papyrifera Marsh) populations, grown at four treatment conditions of carbon dioxide [CO2] and soil water levels were investigated to determine whether future increases in atmospheric [CO2] and water deficit affected the leaf characteristics. The populations from Cussion Lake, Little Oliver, Skimikin and Wayerton were grown for 12 weeks under ambient (360 ppm) and elevated (720 ppm) [CO2] at both high and low water levels. The populations significantly differed in leaf area and stomatal characteristics due to the interaction effects of [CO2], water levels and population differences. Most leaf morphological characteristics and stomatal density varied due to the effects of [CO2] and/or populations, but not due to the effect of water levels. Although elevated [CO2] alone barely affected stomatal area of the birch populations, simultaneous elevated [CO2] at both water levels had stimulated stomatal characteristics within and among the populations. Overall, elevated [CO2] reduced leaf area and increased stomatal density; and low water level resulted in smaller stomatal area, pore area and guard cell width. However, the populations responded differently to an increase in [CO2] and water levels. All populations showed plastic responses with respect to [CO2] and water levels either by decreasing stomatal area under low water level or by increasing stomatal density under elevated [CO2]. Hence, integration between and within leaf characteristics had helped paper birch populations maintain balance between [CO2] gain and water loss.

Effects of a nitrogen fixing plant Vigna radiata on growth, leaf stomatal gas exchange and hydraulic characteristics of the intercropping Juglans regia seedlings

Aims Our main purposes were to determine the effects of Vigna radiata, a nitrogen fixing plant, on growth, water balance and gas exchange of the intercropping Juglans regia seedlings and to investigate the hydraulic mechanism involved in photosynthesis and growth. Methods We measured growth, hydraulic characteristics, and rate of gas exchange in J. regia seedlings, and analyzed the effects of the intercropping nitrogen fixing V. radiata on xylem anatomic structure, water balance and photosynthetic characteristics of J. regia seedlings under conditions of nitrogen deprivation and enrichment. Important findings Under conditions of nitrogen deficiency, the nitrogen fixing V. radiata facilitated the growth of the intercropping J. regia seedlings by improving xylem development, water transport and hydraulic characteristics in high transpiration demand. However, with nitrogen addition, the occurrence of V. radiata inhibited the growth of J. regia seedlings, likely by competing for water and other elements.

Stomatal characteristics of ferns and angiosperms and their responses to changing light intensity at different habitats

Stomatal characteristics of ferns and angiosperms and their responses to changing light intensity at different habitats

Leaf Morphological and Stomatal Variations in Paper Birch Populations along Environmental Gradients in Canada

Variations in leaf morphology and stomatal characteristics have been extensively studied at both inter- and intraspecific levels although not explicitly in the context of paper birch (Betula papyrifera Marsh) populations. The birch populations might have developed the leaf variations that allowed them to adapt to a wide climatic gradient. Therefore, in this study we examined variations in the leaf morphological and stomatal characteristics of sixteen paper birch populations collected across Canada and grown in a common garden. We also examined the relationship between these leaf characteristics and the climate of the population’s origin. Significant genotypic differences were found in the leaf characteristics measured among the birch populations. Thus, we expected that the observed leaf variations may be partly explained as natural diversity in the birch due to differences in environment of origin. We noticed that along mean annual precipitation and aridity gradients, hair density on leaf adaxial surface had decreased whereas stomatal density increased significantly. Our results showed that the populations with larger leaf area and specific leaf area had higher hair density but low stomatal density. These leaf characteristics provided a structural basis in reducing water loss through leaves and increasing water use efficiency. A trade-off between stomatal area and density resulted in this study might be a strategy of the birch to balance stomatal conductance in decreased precipitation.

Ploidy levels in Citrus clementine affects leaf morphology, stomatal density and water content

The objective of the present study was to understand the relationship among leaf morphology, stomatal characteristics and water relations in triploids generated through anther culture and their counterpart diploid plant of C. clementina. Triploid plants possessed small and narrow leaves as compared to diploid plant as evident by less leaf length, leaf width and leaf area. By contrast, the leaf index was observed to be more in triploids than haploid ones. Flow cytometric analysis re-confirmed the ploidy levels of heterozygous plant Hd as diploid and the ploidy of Th1, Th2, Th3 and Th4 plants as triploids. A positive relation was found between ploidy level and stomatal guard cell length and width, whereas a negative relation was observed between the stomata density and ploidy level. The stomatal density was reported to be 6.2±0.2 stomata per µm2 in diploid plant, while stomatal density varied between 3.0 and 3.6 stomata per µm2 in triploids. Leaf relative water content (RWC) was slightly higher in triploids (90.8 to 93.1%) than diploid (89.5%). The leaf water loss was found to be marginally higher in diploid than in triploid plants. Our results show that increase in ploidy level from diploids to triploids caused an effect on leaf morphology and stomatal characteristics with probable consequences to water relations of leaves. This research will serve as an important basis for future work on complete analysis of both morphological and behavioural traits of the leaf stomata and transpiration rates in relation to diploid versus triploid plants.

The physiological importance of developmental mechanisms that enforce proper stomatal spacing in Arabidopsis thaliana

• Genetic and cell biological mechanisms that regulate stomatal development are necessary to generate an appropriate number of stomata and enforce a minimum spacing of one epidermal cell between stomata. The ability to manipulate these processes in a model plant system allows us to investigate the physiological importance of stomatal patterning and changes in density, therein testing underlying theories about stomatal biology. • Twelve Arabidopsis thaliana genotypes that have varied stomatal characteristics as a result of mutations or transgenes were analyzed in this study. Stomatal traits were used to categorize the genotypes and predict maximum stomatal conductance to water vapor (Anatomical g(smax)) for individuals. Leaf-level gas-exchange measurements determined Diffusive g(smax), net carbon assimilation (A), water-use efficiency (WUE), and stomatal responses to increasing CO₂ concentration. Genotypes with proper spacing (< 5% of stomata in clusters) achieved Diffusive g(smax) values comparable to Anatomical g(smax) across a 10-fold increase in stomatal density, while lines with patterning defects (> 19% clustering) did not. • Genotypes with clustering also had reduced A and impaired stomatal responses, while WUE was generally unaffected by patterning. • Consequently, optimal function per stoma was dependent on maintaining one epidermal cell spacing and the physiological parameters controlled by stomata were strongly correlated with Anatomical g(smax).

Stomatal characteristics of Eucalyptus grandis clonal hybrids in response to water stress

This study describes the stomatal response occurring during water stress and subsequent recovery of three Eucalyptus grandis clonal hybrids. The aim was to investigate the degree to which stomatal conductance (g s) and stomatal density differ between the clonal hybrids across seasons and in response to water stress. Plants from one E. grandis × E. camaldulensis (GC) and two E. grandis × E. urophylla (GU1 and GU2) clones were grown for 18 months in 80 l planting bags. Plants were subjected to three watering treatments: control (100% field capacity), chronic water stress (maintained at 15% of field capacity) and acute water stress (cyclic water stress, where water was withheld until leaf wilting point, and a subsequent period of recovery followed). Stomatal conductance was measured after 6, 12 and 18 months growth. At 12 months of age, the recovery of g s 1, 2 and 7 d after rewatering (following acute water stress) was further investigated. The GC hybrid showed consistently higher g s than the GU clones at each measurement period. Stomatal conductance was 24–66% higher during winter (after 12 months growth) than during summer. The recovery of stomatal conductance from acute water stress was more rapid in the GC clone than the GU clones. Chronic water stress was shown to decrease g s in GU clones by up to 70%, but not in the GC clone. Water stress did not affect stomatal density or size. Remarkably, stomata were absent from the adaxial leaf surface of clone GU1 leaves, but not from the leaves of the other E. urophylla hybrid cross (GU2). Total biomass of the GC clone was significantly greater at 9 months growth, but after 18 months growth the GU1 clone had attained greater biomass accumulation (although not significantly). Measurement of g s, transpiration, stomatal density and total biomass in the GU1 clone indicated stomatal sensitivity to water stress, a favourable trait during periods of drought. The differing growth strategies of the GU and GC clones could be partially explained by their differences in stomatal sensitivity in response to water stress.

Do faba bean (Vicia faba L.) accessions from environments with contrasting seasonal moisture availabilities differ in stomatal characteristics and related traits?

Drought is a major constraint to faba bean (Vicia faba L.) production, and there are many mechanisms by which leaves can regulate water loss. Our primary objective was to test if the origin of the faba bean accessions, from drought-prone and non-drought-prone environments, was associated with differences in measurable aspects of stomatal morphology and physiology related to water use. Two sets, each consisting of 201 faba bean accessions, were chosen from environments with contrasting seasonal moisture profiles following the focused identification of germplasm strategy (FIGS), and then screened under well watered conditions. From these, two subsets of 10 accessions each were chosen to test for differences in response to drought. Parameters related to stomatal function and water status were measured. The dry-adapted set had bigger stomata, higher leaf relative water content (LRWC) and cooler leaves under well watered conditions. Stomatal density and stomatal area per unit area of leaflet were negatively correlated with gas exchange parameters and positively correlated with intrinsic water use efficiency. Drought caused stomatal densities to increase in the dry set while stomatal length decreased in both sets. The moisture deficit was sufficient to decrease gas exchange in both sets to similar levels, but the dry-adapted set maintained warmer leaves and a higher LRWC that showed no significant correlations with leaf morphology or gas exchange, demonstrating more effective stomatal regulation. The results also support that collection site data from the environment where genetic resources are collected can be used as indicators of adaptive traits in an herbaceous annual species.

Adaptive Phenotypic Plasticity of Siberian Elm in Response to Drought Stress: Increased Stomatal Pore Depth

Leaf stomatal characteristics of Siberian elm (Ulmus pumila) were investigated by electron microscopy and white light scanning interferometry. On the basis of average annual precipitations, two types of tree specimens were collected from Korea, China, and Mongolia: (1) trees under normal environmental conditions and (2) trees under arid conditions. Field emission scanning electron microscopy revealed oval-shaped stomata on the lower surface, and they were ca. 20 μm in width. In-lens secondary electron imaging showed differences in electron density and stomatal pore depth between the two types. According to the line profile analysis by white light scanning interferometry, stomata under arid conditions appeared to have higher levels of the stomatal pore depth than ones under normal conditions. Focused ion beam-field emission electron microscopy supported the increased stomatal pore depth with the increasing drought stress gradient. These results suggest that complementary microscopy can be employed to unravel the adaptive phenotypic plasticity of Siberian elm in response to drought stress.

Effects of artificial warming on the structural, physiological, and biochemical changes of maize (Zea mays L.) leaves in northern China

We examined the effects of artificial warming on physiological, biochemical, and structural changes in leaves of maize plants (Zea mays L.) with a field warming experiment in the North China Plain. Stomatal characters, leaf anatomy and ultrastructure, gas exchange, and carbohydrate and mineral nutrition concentrations were examined using light microscopy, electron microscopy, portable photosynthesis system (Licor-6400), and inductively coupled plasma atomic emission spectroscopy. We found that artificial warming (about 2 °C) increased both the stomatal index and stomatal size, and thus increased net photosynthesis rate (A), stomatal conductance (gs), and transpiration rate (E). Artificial warming also significantly increased the profile area of chloroplast and mitochondria, but decreased leaf width and thickness, mesophyll thickness, and mesophyll cell size (mainly palisade cell size). In addition, artificial warming also significantly increased the foliar C:N ratio and soluble sugar contents (glucose, fructose, and sucrose), but not the mineral nutrients and starch contents. Our findings suggest that future global warming may affect the maize growth and production in northern China due to the direct warming effects on the structures (anatomy and ultrastructure), biochemical properties and gas exchanges of the maize leaves.

Viabilidad de polen, densidad y tamaño de estomas en autotetraploides y diploidesde Physalis ixocarpa

Con el objetivo de estudiar el impacto de la autopoliploidía en la viabilidad de polen y el tamaño y frecuencia estomática del tomate de cáscara ( Physalis ixocarpa ) se analizó el polen, tamaño y número de estomas de cinco poblaciones diploides y cinco autotetraploides formadas con colchicina. Las diez poblaciones se establecieron en campo, bajo un diseño de bloques al azar con cuatro repeticiones. Para el estudio de viabilidad de polen, éste fue colectado y coloreado con acetocarmín al 1%. Los granos de polen redondeados y coloreados de rojo se consideraron viables y los constreñidos y sin teñir, no viables. Además, se estimó la densidad e índice estomático, largo y ancho de células oclusivas de estomas de la superfi cie adaxial y abaxial de la hoja. Los diploides tuvieron valores de viabilidad de polen y densidad estomática, signifi cativamente mayores que los autotetraploides (P ≤ 0.05); sin embargo, los diploides tuvieron granos de polen y estomas signifi cativamente más pequeños que los autotetraploides. Por lo tanto, la poliploidía si afectó la viabilidad del polen, ocasionado pérdida de fertilidad. Sin embargo, esta característica se puede evitar por selección de plantas con estabilidad meiótica, para incrementar la fertilidad de los autotetraploides. El aumento del tamaño celular muestra que los autopoliploides tienen el potencial de generar plantas más vigorosas, pero con una disminución en la fertilidad, aunque esta característica puede mejorarse al paso de varias generaciones, por lo que este tipo de estudios abre la posibilidad de iniciar nuevas estrategias para el mejoramiento del tomate de cáscara.

A comprehensive analysis of the physiological and anatomical components involved in higher water loss rates after leaf development at high humidity

To better understand the poor regulation of water loss after leaf development at high relative air humidity (RH), the relative importance of the physiological and anatomical components was analyzed focusing on cultivars with a contrasting sensitivity to elevated RH. The stomatal responsiveness to three closing stimuli (desiccation, abscisic acid feeding, light/dark transition), as well as several stomatal features (density, index, size and pore dimensions) and the cuticular transpiration rate (CTR) were determined in four rose cultivars, grown under moderate (60%) and high (95%) RH. Moreover, the effects of changes in stomatal density and pore dimensions on the stomatal conductance (gs) were quantified using a modified version of the Brown and Escombe equation. Higher water loss, as a result of plant growth at high RH, was primarily caused by an increase in residual gs, and to a lesser extent due to higher CTR. It was estimated that in leaflets subjected to desiccation the enhanced gs in high RH- as compared to moderate RH-grown plants was mostly due to poor stomatal functionality and to a lesser extent the combined result of higher stomatal density and longer pore length. It is concluded that the reduced degree and, specially, the reduced rate of stomatal closure are the primary causes of the large genotypic variation in the control of water loss in high RH-grown plants. Furthermore, it was found that although changes in stomatal length have no influence on stomatal functionality, changed anatomical features per se represent a significant and direct contribution to the increased water loss.

Evaporation from multi-component canopies: Generalized formulations

Summary A general formulation is derived for expressing the evaporation from multi-component canopies representing mixed-plant communities. It generalizes to n components the formulations introduced by Lhomme et al. (Bound-Layer Meteorol. 144, 243–262, 2012) for two and three components models. The new formulation is an alternative and simpler form of the equations previously developed by Wallace (Q. J. R. Meteorol. Soc. 123, 1885–1905, 1997). It is sounder, in the sense that: (i) it accounts for the impact of stomatal characteristics (hypostomatous or amphistomatous) on evaporation expression; (ii) it allows one to eliminate the confusing “Penman–Monteith” type terms of Wallace’s formulation (which do no not represent the individual component evaporations). Additionally, the steps of the mathematical demonstration are clearly specified, which was not the case for Wallace’s formulation. In this way, a general conceptual framework is defined for evaporation from complex vegetation, from which simpler representations (1, 2 or 3 components models) and asymptotic limits (infinite identical components) can be inferred.

Comparative morphological, epidermal, and anatomical studies of Pinus roxburghii needles at different altitudes in the North-West Indian Himalayas

The aim of the present study was to understand the ecological adaptation of Pinus roxburghii Sarg. in the North-West Himalayan region. P. roxburghii needles showed morphological, epidermal, and anatomical variation at different altitudes. Needle length was negatively correlated with altitude. Stomatal characters like stomatal density, stomatal index, and guard cell lengths were found to be affected by environmental factors and showed a direct correlation with altitude. The results showed that potential conductance index was dependent on the climatic conditions of the habitat. The anatomical properties of needles exhibited variation from lower to higher elevation, especially in the number and position of resin ducts.

Delayed water loss and temperature rise in floral buds compared with leaves of Brassica rapa subjected to a transient water stress during reproductive development.

Leaf canopy temperature has been proposed as a rapid selection tool for drought tolerance among crop genotypes. However, floral bud temperature may be a better indicator of drought tolerance than leaf temperature in grain crops. In this study, we examined whether the floral bud and leaves of Brassica rapa L. had similar stomatal characteristics and showed similar water loss during a drying cycle. We also compared the leaf and bud temperatures when the plants were exposed to a 10-day transient water stress during reproductive development that affected flower development, increased flower abortion, increased pod abortion and reduced yield by an average of 85%. The water loss of detached leaves and floral buds showed that the stomata on the leaves closed before those of the floral buds as the leaf water potential decreased. Consistent with the water loss studies, the temperature of the intact bud showed a delayed increase during the drying process compared with the leaves. This suggested that floral bud temperature could be a useful indicator of the water status of the reproductive organs of B. rapa.

Resistance Mechanisms inPierisTaxa (Ericaceae) toStephanitis takeyai(Hemiptera: Tingidae)

This study examines some of the potential mechanisms of resistance in selected Pieris (Ericaceae) taxa to the Andromeda lace bug, Stephanitis takeyai Drake and Maa, based on differences in resistance to lace bug feeding, and the possible role of leaf parameters such as leaf wax, toughness, nutrient composition, and stomatal characters in plant resistance. Experiments with extracts of leaf-surface lipids revealed that Pieris leaf wax did not have a role in resistance to lace bug feeding. Leaf wax extracts from a resistant species P. phillyreifolia (Hook.) DC. applied to leaves of a susceptible cultivar P. japonica (Thunb.) D.Don ex G.Don 'Temple Bells' did not affect feeding, oviposition, or survival of S. takeyai; and neither the extracts from Temple Bells induce susceptibility in P. phillyreifolia. Leaf penetrometer measurements indicated that significantly higher force was required to puncture P. phillyreifolia leaves, which also had higher fiber, lignin, and cellulose, and lower leaf moisture contents. Ultrastructural examination of leaves of Pieris taxa revealed significant differences in the number and size of stomata. P. phillyreifolia leaves had the highest number of stomata per unit area but these were the smallest in size, whereas P. japonica (Thunb.) D.Don ex G.Don Temple Bells leaves had the fewest and largest stomata. Resistance in Pieris taxa to S. takeyai may be attributed to a combination of different factors including leaf toughness, moisture, and stomatal characters. The type of resistance may be described as antixenosis combined with antibiosis, because reduced adult survival and reproduction were observed on the taxa resistant to lace bug feeding.

Canopy Uptake of 15NH3 by Four Temperate Tree Species and the Interaction with Leaf Properties

Tree canopies are believed to act as a sink of atmospheric ammonia (NH3). However, few studies have compared the uptake efficiency of different tree species. This study assessed the uptake of 15N-labelled NH3 at 5, 20, 50 and 100 ppbv by leaves and twigs of potted silver birch, European beech, pedunculate oak and Scots pine saplings in June, August and September 2008. Additionally, foliar uptake of 13C-labelled carbon dioxide (13CO2) and leaf stomatal characteristics were determined per species and treatment date and the relation with 15NH3 uptake and estimated stomatal 15NH3 uptake were assessed. Both 15NH3 and 13CO2 uptake were affected by tree species and treatment date, but only 15NH3 uptake was influenced by the applied NH3 concentration. Depending on the treatment date, 15NH3 uptake by leaves and twigs was highest at 5 (September), 20 (June) or 50 (August) ppbv. Birch, beech and oak leaves showed the highest uptake in August, while for pine needles this was in June and, except at 5 ppbv in June, the 15NH3 uptake was always higher for the deciduous species than for pine. For all species except beech 13CO2 uptake was highest in August and on every treatment date the 13CO2 uptake by leaves of deciduous species was significantly higher than by pine needles. Leaf characteristics and 13CO2 uptake did not provide a strong explanation for the observed differences in 15NH3 uptake. This study shows that on the short-term a high interspecific variability exists in NH3 uptake, which depends on the time in the growing season.

Changes in stomatal characteristics and photochemical efficiency during leaf development in six species of Sorbus

Measurements of Sorbus stomata size and density, maximal photochemical efficiency of photosystem II (Fv/Fm), variable-to-initial fluorescence ratio (Fv/F0) and potential electron acceptor capacity ('area') were performed during leaf development in four parental diploid species, S. aria, S. aucuparia, S. chamaemespilus, S. torminalis, and two hybrid species, S. hazslinszkyana and S. intermedia. In fully expanded mature leaves, stomata lengths and densities were significantly larger in the shrub S. chamaemespilus than in the five tree species. The best performance of both the Fv/Fm and the Fv/F0 ratio was recorded in S. intermedia, whereas S. chamaemespilus had the highest value of 'area'. From a physiological point of view, the results of this study showed that the photosystem II reaction centers remained intact functionally through all phenological stages of leaf expansion for all examined species of Sorbus.

Clinal variation in stomatal characteristics of an Arctic sedge, Eriophorum vaginatum (Cyperaceae)

In a large reciprocal transplant experiment, Eriophorum vaginatum tussocks transplanted along a latitudinal gradient in Alaska's interior exhibited genetic differentiation and phenotypic plasticity for vegetative traits. Using the same tussocks 30 yr later, we used estimates of growing season temperature at each site to ask whether there was a climatic cline for stomatal density, size, and conductance. We created impressions of the abaxial leaf surfaces of the transplanted individuals for viewing under a microscope and measured stomatal density (SD) and length (SL) for 224 individuals. We used SD and SL to estimate stomatal conductance (C). Separate one-way analyses of variance were performed to quantify the effect of population genetic differences and latitudinal environmental variation on stomatal characteristics. Our data suggest that stomatal size was influenced by both genetics and environment and that plasticity for stomatal density produced highest densities at the coolest sites. Stomatal conductance increased with decreasing temperature of site from which the populations originated. Our results demonstrate a cline in stomatal conductance in E. vaginatum, with some ability of populations to plastically produce an appropriate phenotypic response in a new environment. Because the species is a dominant species in many arctic plant communities, its ability to produce an appropriate stomatal phenotype and to optimize water use efficiency by decreasing stomatal conductance in warmer environments could affect both community composition and total primary productivity in future, warmer climates.