Leaf Structural Characteristics Research Articles

Leaf functional traits of Daphniphyllum macropodum across different altitudes in Mao’er Mountain in Southern China

Investigating functional traits among mountain species with differing altitude requirements is integral to effective conservation practices. Our study aims to investigate the structural and chemical characteristics of Daphniphyllum macropodum leaves at three altitudes (1100 m, 1300 m, and 1500 m) across southern China to provide insight into changes in leaf functional traits (LFT) as well as plant adaptations in response to changing environmental conditions. Leaf structural characteristics include leaf thickness (LT), leaf area (LA), specific leaf area (SLA), and leaf tissue density (LD), respectively, while chemical properties include carbon-nitrogen-phosphorus (C:N:P) contents and ratios, such as C/N, C/P, and N/P. Our findings demonstrated the significant effect of altitude on both structural (LT, SLA, LD) and chemical aspects (N, C/N, N/P) of LFT. In particular, leaves at 1100 and 1300 m differed greatly, with 1300 m having lower SLA values than 1100 m. Observable trends included an initial increase followed by a decline as the altitude rose. Notable among them were the LT, LD, N, and N/P values at both locations. Traits at 1300 m were significantly higher than at 1100 m; SLA and C/N values displayed an inverse trend, with their lowest values occurring at 1300 m. Furthermore, this research demonstrated various degrees of variation among LFT, with structural traits exhibiting greater fluctuation than chemical traits. Robust correlations were observed among certain traits, such as LT, LD, and SLA. Furthermore, the interdependency relationships between N and C/N, as well as P and C/P, demonstrated interconnectedness. Redundancy analysis indicated that soil factors, specifically P content, exerted the strongest impact on LFT. At 1100 m, D. macropodum employed acquisition strategies; however, at 1300 m, conservation strategies emerged, showing a shift from acquisition strategies at lower altitudes to conservative strategies at higher ones.

Effects of silicon application on leaf structure and physiological characteristics of Glycyrrhiza uralensis Fisch. and Glycyrrhiza inflata Bat. under salt treatment

BackgroundSoil salinization leads to a significant decline in crop yield and quality, including licorice, an important medicinal cash crop. Studies have proofed that the application of exogenous silicon can significantly improve the ability of licorice to resist salt stress, however, few studies concentrated on the effects of foliar silicon application on the morphology, physiological characteristics, and anatomical structure of licorice leaves under salt stress. In this study, the effects of Si (K2SiO3) on the structural and physiological characteristics of Glycyrrhiza uralensis Fisch. and G. inflata Bat. leaves under different salt concentrations (medium- and high-salt) were studied.ResultsCompared with the control (without salt), the plant height, total dry weight, leaf area, leaf number, relative water content, xylem area, phloem area, ratio of palisade to spongy tissue, gas exchange parameters, and photosynthetic pigment content of both licorice varieties were significantly reduced under high-salt (12S) conditions. However, the thickness of the leaf, palisade tissue, and spongy tissue increased significantly. Applying Si to the leaf surface increased the area of the vascular bundle, xylem, and parenchyma of the leaf’s main vein, promoted water transportation, enhanced the relative leaf water content, and reduced the decomposition of photosynthetic pigments. These changes extended the area of photosynthesis and promoted the production and transportation of organic matter. G. uralensis had a better response to Si application than did G. inflata.ConclusionsIn conclusion, foliar application of Si can improve water absorption, enhance photosynthesis, improve photosynthetic capacity and transpiration efficiency, promote growth and yield, and alleviate the adverse effects of salt stress on the leaf structure of the two kinds of licorice investigated.

Capture of fire smoke particles by leaves of Cunninghamia lanceolata and Schima superba, and importance of leaf characteristics

Emission of particulate matter (PM) during forest fires is a major source of air pollution and hence purification of atmospheric pollution has gained increasing importance. Trees can absorb polluting gases and fine particles by their leaves from the atmosphere and act as a sustainable air purification filter. However, the capture efficiency varies among tree species; thus exploring the ability of forest trees to capture smoke PM released during forest fires provides a basis for assessing net emissions from forest fires and the impact of smoke on forest ecosystems. In this study, the main afforestation tree species, Cunninghamia lanceolata (Lamb.) Hook, and a fire-resistant tree species, Schima superba Gardn.et Champ, in southern China were exposed to different smoke concentrations by simulating forest fire. The amount of PM per unit leaf area, absorption of nutrient element, leaf surface characteristics and antioxidant enzyme activities were determined. The main findings were: (1) The total quantity of PM captured by unit leaf area (μg·cm−2) of C. lanceolata was 28.25 ± 1.12, 30.52 ± 3.43 and 33.14 ± 3.00 in low, intermediate and high smoke concentrations, respectively. The corresponding values for S. superba was 5.96 ± 0.56, 10.09 ± 1.13 and 12.27 ± 0.39, respectively. (2) Both species had weak absorption capacity for inorganic ions in the PM. (3) The purification of smoke PM by leaves was mainly related to leaf surface roughness, where it was higher for C. lanceolata than S. superba leaves. (4) Smoke treatment positively affected the contents of chlorophyll and soluble protein as well as increased antioxidant enzyme activities. In conclusion, the findings highlight the importance of leaf structural characteristics in capturing smoke particles and C. lanceolata is better suited for purification of atmospheric smoke particles following forest fire than S. superba.

Artificial Regulation Effect of Plant Retardants on Leaf Anatomical Characteristics of Elaeagnus Angustifolia

Aims: In order to explore the adaptation mechanisms of Elaeagnus angustifolia to the arid environment in desert areas under the treatment of artificial plant retardants, we used to investigate artificial regulation by using retardants of paclobutrazol (PP333), paclobutrazol+adhesive (NPP333), and chlormequat (CCC) based on multiple factors and multiple levels.Methods: Orthogonal experimental design of L9 (34) was used to design the experimental treatment combinations. Leaf morphological and structural characteristics determined by the paraffin section method were used to explain the effect of different treatments and their combinations.Results: The leaves of Elaeagnus angustifolia were iso-petalous with obvious stellate epidermal fuzzy borders on the upper epidermis. The palisade tissue was well developed and tightly arranged. The T1-T9 treatment significantly increased leaf thickness. Conversely, leaf length and width showed a delayed growth effect, while leaf growth developed as an elongated type after application. After plant retardant control, the upper epidermal, palisade tissue, and spongy tissue thickness of the leaves showed a significant trend to increase, at the same time, the number of xylem rows increased and the number of cells per row increased and were arranged closely. Meanwhile, there was a synergistic evolution phenomenon among the indexes. The best treatment combination of plant retardants to regulate the leaf configuration of plants was selecting the concentration of 600 mg/L of PP333, using the root application + leaf application method for two applications.Conclusions: The study showed that plant retardants improved the ability of plants to resist external environmental stress by reducing leaf area, increasing leaf and epidermal thickness, and promoting the development of mesophyll and vein structures in order to improve water retention capacity and prevent transitional transpiration.

Analysis of Photosynthetic Pigment Content and Leaf Structure of Pteroceltis Tatarinowii Mutant with Yellow Leaf

The relationship betweenleaf variation characteristics and leaf structure characteristics of Pteroceltistatarinowii with yellow leaf was explored to provide a theoretical basisfor the breeding of other ornamental plants. In this study, the differences inpigment content, leaf structure, and chloroplast ultrastructure in leaves of Pteroceltistatarinowii mutant with yellow leaf 'Huiguang' and its original species'Lingyansi No. 1’ were studied. The results showed that the chlorophyll in'Huiguang' leaves decreased significantly, and the carotenoids-totalchlorophyll ratio increased greatly. The palisade tissue cells in 'Huiguang'leaves are short, thick, and loosely structured, while the sponge tissue cellsare irregular in shape and loosely arranged. In addition, the chloroplasts of'Huiguang' leaves were irregular in shape and the grana lamellae were looselyarranged, broken, and missing, with more osmiophilic granules and fewer starchgranules. These anomalies in leaf pigment content and chloroplast structureaffect leaf photosynthesis and chlorophyll accumulation, thereby affecting leaf color changes.

Preservation of Features of Anatomical Polymorphism of Deschampsia antarctica É. Desv. (Poaceae) During In Vitro Clonal Reproduction

Abstract We studied the anatomical features of the leaf structure of Deschampsia antarctica É. Desv. (Poaceae) obtained from seeds collected from different habitats of the maritime Antarctic. These plants have been maintained in culture in vitro for more than 7 years. The plants include stable chromosome forms comprising diploids (2 n = 26), a diploid plant with B-chromosomes (2 n = 26 + 0–3B), a triploid with rearranged chromosome morphology, and myxoploids with different ratios of diploid and nondiploid cells in the root meristem. The D. antarctica plants that were studied generally had a similar anatomical structure in culture in vitro and in nature. At the same time, plants of different cultivated genotypes also displayed their own leaf structure features. In particular, qualitative features included asymmetric four-ribs and five-rib leaves instead of typical three-rib leaves for some genotypes, some individuals characterized by the presence of unicellular nonglandular pointed trichomes on an adaxial side, differences in vascular bundle sheath, and other features. No clear dependence of the anatomical structural features on the chromosomal status of the studied genotypes was evident. At the same time, differences were evident in traits that included the number of stomata, thickness of the outer cell walls of the epidermis, bundles sheath state, number of leaf ribs, and the persistent presence of trichomes under prolonged in vitro cloning. The findings indicate that D. antarctica plants collected from different locations of the maritime Antarctic for long-term cultivation in vitro under standard cultivation conditions retain the anatomical characteristics of the wild plants. The polymorphism of in vitro-cultivated plants is not related to the polymorphism of their karyotype, but is apparently due to the heterogeneity of the original plants and possibly the epigenetic fixation of a number of anatomical features produced in the natural microhabitats of D. antarctica populations.

Influence of Green Light Added with Red and Blue LEDs on the Growth, Leaf Microstructure and Quality of Spinach (Spinacia oleracea L.)

The aim of this study was to investigate the effects of green light, added with red and blue LEDs, on the growth, leaf microstructure and quality of spinach plants. Plants were transplanted and grown hydroponically for 30 days under different combinations of red:blue with a 4:1 ratio (R4B1), red:blue:green with a 5:2:3 ratio (R5B2G3) and red:blue:green with a 1:1:1 ratio (R1B1G1), at a 190 µmoL m−2·s−1 photosynthetic photon flux density (PPFD). The results showed that green light, added to red and blue LEDs at a reasonable ratio, could reduce the growth, leaf microstructure and quality of spinach plants, but not the organic acid content. The highest values for the growth parameters, photosynthetic pigments, leaf structure characteristics and quality of the spinach plant were observed for the R4B1 treatment, but not for the organic acid content. Therefore, our results suggest that green light added to red and blue LEDs at a reasonable ratio is not suitable for the growth of spinach.

Wounding-Induced VOC Emissions in Five Tropical Agricultural Species.

Leaf mechanical wounding triggers a rapid release—within minutes—of a blend of volatile organic compounds. A wounding-induced VOC blend is mainly composed of oxygenated ubiquitous stress volatiles such as methanol and volatile products of lipoxygenase (LOX) pathway (mainly C5 and C6 alcohols and aldehydes and their derivatives), but also includes multiple minor VOCs that collectively act as infochemicals, inducing defences in non-damaged plant leaves and neighbouring plants and attracting herbivore enemies. At present, the interspecific variability of the rate of induction and magnitude of wounding-induced emissions and the extent to which plant structural traits and physiological activity alter these emissions are poorly known. Particularly scarce is information on the induced emissions in tropical agricultural plant species, despite their economic importance and large area of cultivation at regional and global scales. We chose five tropical crops with varying photosynthetic activity and leaf structural characteristics—Abelmoschus esculentus, Amaranthus cruentus, Amaranthus hybridus, Solanum aethiopicum, and Telfairia occidentalis—to characterize the kinetics and magnitude of wounding-induced emissions, hypothesizing that the induced emission response is greater and faster in physiologically more active species with greater photosynthetic activity than in less active species. Rapid highly repeatable leaf wounds (12 mm cuts) were generated by a within-leaf-chamber cutting knife. Wounding-induced VOC emissions were measured continuously with a proton-transfer reaction time-of-flight mass spectrometer and gas-chromatography mass spectrometry was used to separate isomers. Twenty-three ion VOCs and twelve terpenoid molecule structures were identified, whereas ubiquitous stress volatiles methanol (on average 40% of total emissions), hexenal (24%), and acetaldehyde (11%) were the main compounds across the species. Emissions of low-weight oxygenated compounds (LOC, 70% of total) and LOX products (29%) were positively correlated across species, but minor VOC components, monoterpenoids and benzenoids, were negatively correlated with LOC and LOX, indicating a reverse relationship between signal specificity and strength. There was a large interspecific variability in the rate of induction and emission magnitude, but the hypothesis of a stronger emission response in physiologically more active species was only partly supported. In addition, the overall emission levels were somewhat lower with different emission blend compared to the data reported for wild species, as well as different shares for the VOCs in the blend. The study demonstrates that wounding-dependent emissions from tropical agricultural crops can significantly contribute to atmospheric volatiles, and these emissions cannot be predicted based on current evidence of wild plant model systems.

Tolerance Mechanisms of the Aromatic and Medicinal Plant Salvia sclarea L. to Excess Zinc.

In recent years, due to the development of industrial and agricultural production, heavy metal contamination has attracted increasing attention. Aromatic and medicinal plant Salvia sclarea L. (clary sage) is classified to zinc (Zn) accumulators and considered as a potential plant for the phytoremediation of heavy metal polluted soils. In this study, an adaptation of clary sage to 900 µM (excess) Zn exposure for eight days in a hydroponic culture was investigated. The tolerance mechanisms under excess Zn exposure were assessed by evaluating changes in the nutrient uptake, leaf pigment and phenolic content, photosynthetic activity and leaf structural characteristics. The uptake and the distribution of Zn, as well as some essential elements such as: Ca, Mg, Fe, Mn and Cu, were examined by inductively coupled plasma mass spectrometry. The results revealed that Salvia sclarea is a Zn-accumulator plant that tolerates significantly high toxic levels of Zn in the leaves by increasing the leaf contents of Fe, Ca and Mn ions to protect the photosynthetic function and to stimulate the photosystem I (PSI) and photosystem II (PSII) activities. The exposure of clary sage to excess Zn significantly increased the synthesis of total phenolics and anthocyanins in the leaves; these play an important role in Zn detoxification and protection against oxidative stress. The lipid peroxidation and electrolyte leakage in leaves, used as clear indicators for heavy metal damage, were slightly increased. All these data highlight that Salvia sclarea is an economically interesting plant for the phytoextraction and/or phytostabilization of Zn-contaminated soils.

Variation and potential influence factors of foliar pH in land-water ecozones of three small plateau lakes

Abstract Aims Foliar pH of terrestrial plants, a trait tightly associated with plant physiology and nutrient utilization, varies with plant functional types (PFTs) and environmental changes. However, it is yet unclear about the variation in foliar pH of aquatic plants, and the difference between aquatic and terrestrial plants. Methods Foliar pH, leaf carbon, nitrogen content of plants along the lakeshore zones and the environmental conditions (water or soil pH, water status) of the corresponding vegetation of three small plateau lakes were investigated, to determine the variation and potential influence factors of foliar pH at both PFT and community levels. Important Findings Foliar pH varied largely among aquatic plants, and across aquatic, helophytic and terrestrial plants. Floating-leaved macrophytes had more acidic foliage (pH = 4.21 ± 0.05) than emergent (5.71 ± 0.07) and submerged macrophytes (5.82 ± 0.06). Foliar pH of aquatic herbs (5.43 ± 0.10) was lower than that of helophytic (6.12 ± 0.07) and terrestrial herbs (5.74 ± 0.05). Terrestrial herbs had significantly higher foliar pH than woody plants. The variation in foliar pH across PFTs may be mainly ascribed to leaf structure, light utilization and nutrient characteristics. Consistent with the pattern on PFT level, aquatic communities had more acidic foliage than terrestrial communities, which was mainly shaped by species composition, water status and environmental pH. This study documented the first-time foliar pH of aquatic plants, and comparison of foliar pH among various plant types at a landscape scale. Our results provide bases for further exploration of the underlying mechanism and its ecological significance for wetland ecosystems.

Leaf Morpho-anatomical Structure Determines Differential Response Among Restinga Species Exposed to Emissions from an Iron Ore Pelletizing Plant

An iron ore pelletizing plant in southeastern Brazil exposes the tropical coastal ecosystems known as restinga to emissions of dust, iron solid particulate matter, and sulfur dioxide (SO2). We aimed to assess the effects of those emissions on the leaf morphology and anatomy of the restinga species Byrsonima sericea, Cordia verbenacea, and Psidium guineense by evaluating visual symptomatology and analyzing the anatomical and micromorphological alterations resulting from exposure. Leaves were collected from individuals growing at two sites: a restinga forest fragment located 800 m away from the pelletizing plant and a restinga conservation unit 20 km away, which served as reference site. In all three species, individuals growing near the pelletizing plant showed necrotic regions on the leaf and foliar micromorphological alterations like turgor loss of epidermal cells, cuticle and epicuticular wax erosion, stomatal obliteration, and rupture and plasmolysis of trichomes. Anatomically, we found cell collapse, cell hypertrophy, and formation of a wound tissue. C. verbenacea showed the most severe visual and anatomical damage, being thus considered the most sensitive species to emissions. Leaf structural features such as uniseriate epidermis, lack of hypodermis, and presence of trichomes contributed to the highest sensitivity of C. verbenacea. Our findings reinforce the importance of performing morpho-anatomical studies to elucidate how leaf structure determines differential sensitivity to airborne pollutants in native species.

High Nitrate or Ammonium Applications Alleviated Photosynthetic Decline of Phoebe bournei Seedlings under Elevated Carbon Dioxide

Phoebe bournei is a precioustimber species and is listed as a national secondary protection plant in China. However, seedlings show obvious photosynthetic declinewhen grown long-term under an elevated CO2 concentration (eCO2). The global CO2 concentration is predicted to reach 700 μmol·mol−1 by the end of this century; however, little is known about what causes the photosynthetic decline of P. bournei seedlings under eCO2 or whether this photosynthetic decline could be controlled by fertilization measures. To explore this problem, one-year-old P. bournei seedlings were grown in an open-top air chamber under either an ambient CO2 (aCO2) concentration (350 ± 70 μmol·mol−1) or an eCO2 concentration (700 ± 10 μmol·mol−1) from June 12th to September 8th and cultivated in soil treated with either moderate (0.8 g per seedling) or high applications (1.2 g per seedling) of nitrate or ammonium. Under eCO2, the net photosynthetic rate (Pn) of P. bournei seedlings treated with a moderate nitrate application was 27.0% lower than that of seedlings grown under an aCO2 concentration (p < 0.05), and photosynthetic declineappeared to be accompanied by a reduction of the electron transport rate (ETR), actual photochemical efficiency, chlorophyll content, ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco), rubisco activase (RCA) content, leaf thickness, and stomatal density. The Pn of seedlings treated with a high application of nitrate under eCO2 was 5.0% lower than that of seedlings grown under aCO2 (p > 0.05), and photosynthetic declineoccurred more slowly, accompanied by a significant increase in rubisco content, RCA content, and stomatal density. The Pn of P. bournei seedlings treated with either a moderate or a high application of ammonium and grown under eCO2 was not significantly differentto that of seedlings grown under aCO2—there was no photosynthetic decline—and the ETR, chlorophyll content, rubisco content, RCA content, and leaf thickness values were all increased. Increasing the application of nitrate or the supply of ammonium could slow down or prevent the photosynthetic declineof P. bournei seedlings under eCO2 by changing the leaf structure and photosynthetic physiological characteristics.

Analysis of mesophyll conductance in five understory herbaceous species.

Mesophyll conductance (g m) has received over time much less attention than stomatal conductance (g s), although it affects leaf photosynthesis to about the same extent as stomatal conductance does. The objective of this study was to analyze the g m trend in five understory herbaceous species growing in a close-canopy forest in the north-west of Italy. In particular, three of analyzed species were monocots: Carex brizoides Lam., Carex pilosa Scop., and Oplismenus undulatifolius P. Beauv and the others dicots species: Circaea lutetiana L., and Pulmonaria officinalis Ced. The results showed, on one hand, the absence of correlation between g m and the considered environmental variables in the forest understory (i.e. air temperature, photosynthetic photon flux density and carbon dioxide concentration). Moreover, we carried out a principal component analysis considering all the analyzed morphological and physiological variables for the five species. The following correlation between the first component, related to the leaf mass per unit of leaf area and the leaf tissue density, and g m seem to suggest a key role of the leaf structural features in determining g m variations across the five species.

Leaf anatomy micromorphometry plasticity and histochemistry of Azadirachta indica during acclimatization

Abstract Environmental conditions of grow can modify leaf structure and metabolite production. Neem plants produce a high amount of medicinal metabolites and contain biopesticide terpenoids with low toxicity. However, the high genetic variation and the low material quality, besides the environmental modifications warn to the need of biotechnological techniques to ensure the production of high quality metabolites. The aim was to investigate leaf structural and histochemical characteristics of Azadirachta indica grown in vitro, in vivo and acclimatized condition. It was found anatomical differences among the environments, with higher leaf thickness associated to in vivo conditions, as well as were more evenly distributed stomata. Those modifications did not qualitatively affect the production of medicinal metabolites and biopesticides. Terpenes and tannins were observed in specialized cells called idioblasts, located in the mesophyll and in the midrib region, respectively. Thus, in a qualitative approach, we can affirm that the different environments do not modify metabolites production. Increased production of these bioactive compounds could be achieved by isolation and in vitro culture of idioblasts as a new source of research in plant biotechnology.

Elevated temperature and ozone modify structural characteristics of silver birch (Betula pendula) leaves.

To study the effects of slightly elevated temperature and ozone (O3) on leaf structural characteristics of silver birch (Betula pendula Roth), saplings of four clonal genotypes of this species were exposed to elevated temperature (ambient air temperature+0.8-1.0 °C) and elevated O3 (1.3-1.4× ambient O3), alone and in combination, in an open-air exposure field over two growing seasons (2007 and 2008). So far, the impacts of moderate elevation of temperature or the combination of elevated temperature and O3 on leaf structure of silver birch have not been intensively studied, thus showing the urgent need for this type of studies. Elevated temperature significantly increased leaf size, reduced non-glandular trichome density, decreased epidermis thickness and increased plastoglobuli size in birch leaves during one or both growing seasons. During the second growing season, O3 elevation reduced leaf size, increased palisade layer thickness and decreased the number of plastoglobuli in spongy cells. Certain leaf structural changes observed under a single treatment of elevated temperature or O3, such as increase in the amount of chloroplasts or vacuole, were no longer detected at the combined treatment. Leaf structural responses to O3 and rising temperature may also depend on timing of the exposure during the plant and leaf development as indicated by the distinct changes in leaf structure along the experiment. Genotype-dependent cellular responses to the treatments were detected particularly in the palisade cells. Overall, this study showed that even a slight but realistic elevation in ambient temperature can notably modify leaf structure of silver birch saplings. Leaf structure, in turn, influences leaf function, thus potentially affecting acclimation capacity under changing climate.

Changes in Leaf Structural and Functional Characteristics when Changing Planting Density at Different Growth Stages Alters Cotton Lint Yield under a New Planting Model

Manipulation of planting density and choice of variety are effective management components in any cropping system that aims to enhance the balance between environmental resource availability and crop requirements. One-time fertilization at first flower with a medium plant stand under late sowing has not yet been attempted. To fill this knowledge gap, changes in leaf structural (stomatal density, stomatal length, stomata width, stomatal pore perimeter, and leaf thickness), leaf gas exchange, and chlorophyll fluorescence attributes of different cotton varieties were made in order to change the planting densities to improve lint yield under a new planting model. A two-year field evaluation was carried out on cotton varieties—V1 (Zhongmian-16) and V2 (J-4B)—to examine the effect of changing the planting density (D1, low, 3 × 104; D2, moderate, 6 × 104; and D3, dense, 9 × 104) on cotton lint yield, leaf structure, chlorophyll fluorescence, and leaf gas exchange attribute responses. Across these varieties, J-4B had higher lint yield compared with Zhongmian-16 in both years. Plants at high density had depressed leaf structural traits, net photosynthetic rate, stomatal conductance, intercellular CO2 uptake, quenching (qP), actual quantum yield of photosystem II (ΦPSII), and maximum quantum yield of PSII (Fv/Fm) in both years. Crops at moderate density had improved leaf gas exchange traits, stomatal density, number of stomata, pore perimeter, length, and width, as well as increased qP, ΦPSII, and Fv/Fm compared with low- and high-density plants. Improvement in leaf structural and functional traits contributed to 15.9%–10.7% and 12.3%–10.5% more boll m−2, with 20.6%–13.4% and 28.9%–24.1% higher lint yield averaged across both years, respectively, under moderate planting density compared with low and high density. In conclusion, the data underscore the importance of proper agronomic methods for cotton production, and that J-4B and Zhongmian-16 varieties, grown under moderate and lower densities, could be a promising option based on improved lint yield in subtropical regions.

Morphophysiology of buffel grass grown under different water supplies in the dry and dry-rainy seasons

ABSTRACT The lack of information on the growth of forage grasses in semi-arid environment, especially from the perspective of irrigation, is one of the obstacles to regular forage supply, as well as to the rational use of irrigation water. The objective with this study was to evaluate the leaf gas exchanges, biomass flow and structural characteristics of buffel grass cultivar Gayndah under different water supplies (30, 60, 90 and 120% of the reference evapotranspiration - ETo) during the dry season and dry-rainy season, in completely randomized design in a split-plot scheme with three repetitions. The experiment was conducted in Sobral, CE, Brazil (3° 45’ 00.77” S and 40° 20’ 38.55” W, altitude of 101 m) from September 2015 to January 2016. A higher photosynthetic rate was verified during the dry season, evidencing the adaptability of buffel grass to environments with water restriction. Overall, the best morphogenic and structural characteristics and the biomass production were observed in the dry season. The 90% ETo regime leads to maximum amount of forage accumulation, whereas the 30% ETo allows the maintenance of the cultivar Gayndah of buffel grass in a state of latency during the dry season.

Correlation between population size of pear Psylla (Cacopsylla chinensis) and leaf structure features in different pear cultivars

Abstract The feeding preference of pear psylla (Cacopsylla chinensis) varies among pear cultivars. To clarify whether leaf structural factors are related to C. chinensis resistance, eleven pear cultivars of three pear species and their hybrids in China were studied. The population size of C. chinensis in plots of different cultivars was investigated, and leaf paraffin sections of each pear cultivar were observed. Correlation analysis results showed that the thickness of palisade tissue (PT) and the thickness ratio (TR) of PT to leaf (L) were the main factors influencing resistance to C. chinensis. The leaves of cultivar Wujiuxiang and those species from France and the USA exhibited the thickest PT and the highest TR; these three cultivars demonstrated much higher resistance to C. chinensis than did the other cultivars. The cultivar Gold Nijisseiki, with a large C. chinensis population size, showed low PT and TR. The findings of this study may provide valuable information to pear growers, experts and scientists regarding plant protection, cultivation and breeding when selecting suitable varieties to culture from the perspective of pest control.

Anchoring of greenhouse whitefly eggs on different rose cultivars

Whiteflies attach their eggs to plants by implanting the egg pedicel into the epidermis of the underside of leaves. This pedicel works like a wall plug embedded in sealing cement, presenting a smart interconnection, which was exemplarily studied in Trialeurodes vaporariorum eggs on two stages of abaxial leaflets of four cut rose cultivars using a combination of microscopic and biomechanical techniques. The penetration force obtained by piercing single epidermal cells with an insect minuten pin did not significantly correlate with the force which was applied to pull off the greenhouse whitefly eggs from abaxial leaves. A maximum pull-off force of 5.4 mN was measured on young leaves of the rose cultivar ‘Schloss Ippenburg®’, corresponding to maximum 941 times the egg weight. Egg pull-off force significantly differed between cut rose cultivars and leaf ages. On greenhouse whitefly-susceptible cultivars ‘Poesie®’ and ‘Reggae®’, eggs detached, applying less force compared to that on resistant cultivars. Leaf structural features had no significant impact on greenhouse whitefly egg pull-off forces. A major effect of leaf turgor pressure and swelling of colleterial gland secretion (cement) surrounding the whitefly egg is assumed to facilitate the firm interconnection between egg and plant epidermis by a combination of form closure, friction locking, and adhesive bond forming a composite material in the contact region. This bond exhibits a maximum adhesive strength of 12.2 MPa, which is much higher than those in beetle and moth eggs glued to oviposition substrates.

Effect of rootstocks on morphological and physiological traits of Sultana grapevine under moisture stress conditions

The effects of two Iranian grape rootstocks namely Kaj Anguor Bojnord (KA) and Qare Gandomeh (QG) with scion Sultana were studied in 2015 for drought stress, leaf structural characteristics and gas exchange parameters. Greenhouse grown, grapevines of cv. Sultana (Vitis vinifera L.) grafted onto two rootstocks and on own roots, were subjected to three drought stress levels (NS: no-stress, MS: moderate stress and SS: severe stress). The results indicated that under SS, relative water content in KA-grafted was similar to that in un-grafted Sultana under MS. Moreover, leaf area decreased under SS compared MS. Furthermore, KA-grafted exhibited the highest value of leaf fresh mass. The leaf dry mass for un-grafted Sultana was significantly lower than grafted vines and, the values of leaf tissue density for the three rootstocks were lower than control. Under MS, the leaf thickness of Sultana on KA exhibited an increase, while the other rootstocks followed a decreasing trend under SS. Also un-grafted Sultana had a higher specific leaf area compared to grafted vines. The amounts of leaf chlorophyll in Sultana on KA and QG were significantly higher than un-grafted vines. KAgrafted improved photosynthesis rate of Sultana scion compared to the own-rooted plants in all experimental drought conditions. Additionally, the transpiration for Sultana scion leaves had declined compared to ungrafted plants. Significant interactions were observed between stress levels and rootstocks on the water use efficiency. Concluding, in his experiment KA rootstock could be better performance compared to QG and un-grafted Sultana to drought stress.