Number Of Stomata Research Articles

Functional leaf anatomy of the invasive weed Solanum rostratum Dunal

AbstractSolanum rostratum Dunal is an aggressive invasive weed invading many countries worldwide. Our previous study indicated differences in herbicide response between young and mature plants. In this study, we explore the functional leaf surface anatomy of S. rostratum. Leaf area surface characterisation was performed by counting stomata, stellate and glandular trichomes on upper and lower leaf sides on scanning electron microscopy (SEM) micrographs. Total cuticular waxes were extracted and weighed in young and mature leaves. Young and mature leaves were tested for water permeability of the epidermal surfaces using the apoplastic tracer Calcofluor. S. rostratum plants were sprayed with luminous trace colour solution with and without 1% surfactant, droplet number and area were calculated. In young S. rostratum leaves, the leaf surface was densely covered with stellate trichomes on both leaf sides; however, in the mature leaf, stellate trichomes density became low, and prickle rigid increased in mature leaves. Wax amount was significantly higher in mature leaves, while number of stomata was higher in young leaves. Young leaves showed high leaf permeability, with the fluorescent dye permeating the leaf staining the vascular bundles. In young and mature leaves treated with a spraying solution with the addition of surfactant, low droplet number alongside higher coverage area was recorded. Our data highlight the notable differences in leaf epidermal structure of young versus mature plants. We conclude that differences in herbicide permeability, water loss and herbivory in young versus mature leaves of S. rostratum are governed by variation in leaf functional anatomy.

MORPHOLOGICAL AND ANATOMICAL FEATURES OF THE STRUCTURE OF VEGETATIVE AND GENERATIVE ORGANS OF LYCIUM CHINENSE MILL. AND LYCIUM BARBARUM L. SOLANACEAE JUSS. IN THE CONDITIONS OF UZBEKISTAN

The characteristics of Lycium chinense Mill and Lycium barbarum L., species, taxonomy, origin and use in medicineare given. The adaptation of these plants in the conditions of the Botanical Garden of Tashkent, as well as in the conditions of the Namangan region, was studied. The morphological and anatomical structures of two species of the genus Lycium have been studied. The morphology and structure of vegetative and generative organs, which differ from each other in leaf shape and venation, are described. Leaf cells are studied in detail: the epidermis of the upper side has a smaller number of stomata, which makes it possible to reduce the evaporation of water in summer drought conditions. The spongy parenchyma is chlorophyllon-bearing. Calcium oxalate was found in palisade and spongy parenchyma cells. Conductive bundles of bicollateral type are numerous, consist of phloem and xylem. The center of the petiole has one vascular bundle with a closed bicollateral type. Parenchymal cells are thin-walled, but some have hydrocytic cells. The petiole of the leaf in a transverse section is of the parenchymal-fascicular type, has numerous parenchymas and vascular bundles. Collenchyma is located under the epidermis, based on osmotic phenomena. The stems are sclerified, helping to resist various environmental influences. It was found that with age, the cambium changes the anatomical structure of the stem, and also annually produces secondary xylem.The fruit of Lyciumchinense is a berry, syncarpous and 2-celled. Nucleoli were found in the epidermis. On a transverse section, the pericarp consists of several parenchymal cells, the walls of the epidermis are thickened and cutinized. The mesocarp consists of multi-row parenchymal cells. They are tangentially elongated in the outer layers, and rounded in the inner ones. Endocarp of irregular shape. The seeds of Lyciumchinense are large, round, and have a beak-shaped rib. The cells of the outer epidermis become lignified over time. The parenchyma of the intigument is enclosed between the epidermis. The perisperm is absent. The endosperm is of a cellular type, the endosperm cells contain oil droplets and aleurone grains. Based on the results, morphological-anatomical-histological features were determined. The data obtained can serve to identify plant materials, in environmental studies, as well as to determine diagnostic features.

Changes of stomatal distribution and leaf thickness in response to transpiration rate in six dicot plant species

Changes in leaf anatomy can be influenced by the surrounding environment and several other factors. Shade plants or ornamental plants themselves also have their characteristics in responding to surrounding conditions through transpiration. This study aimed to measure the rate of transpiration related to changes in the distribution of stomata and leaf thickness of six types of dicot ornamental plants and to describe the leaf anatomy of each type. The experiment used Completely Randomized Design (CRD) with six types of plants as treatment with three replications. Transpiration rate was measured by modified lysimeter method, stomatal distribution was calculated from the ratio of the number of stomata to epidermal cells and leaf anatomy was observed using preserved slide made from paraffin method. Data were analyzed by SAS with CRD model and correlation was performed between transpiration rate and leaf thickness. The results showed that the transpiration rate, leaf thickness, and stomatal distribution were significantly different at α = 0.05 amongst plants. The transpiration rate was inversely proportional to leaf thickness with various correlation coefficients. The leaf anatomy of six plant species showed various thicknesses between tissues. Further research needs to be done to explain the rate of transpiration with changes in leaf anatomy.

Irradiation effect on leaf sclerophylly, gas exchange and stomata in sweet orange (Citrus sinensis)

The study was carried out in mutated population of sweet orange [Citrus sinensis (L.) Osbeck] cv. Mosambi developed from varying dose of gamma rays (10-35 Gy) to determine its effect on leaf sclerophylly, photosynthesis and leaf anatomical characters at the Division of Fruits and Horticultural Technology, ICAR-Indian Agricultural Research Institute, New Delhi during 2017 and 2018. As compared to wild type leaf area, fresh and dry mass was stimulated by 19.53, 18.42 and 20.37% in mutant GS-3 developed from 10 Gy, while in the mutants GS-33 and GS-35 developed from 35 Gy >50% inhibitory effects were noticed. Leaves were however, 82.06% more succulent in the mutant developed from 30 Gy. Mutated population showed dose dependent effect with regard to SLA, SLW and DFT. A significant decline in the photosynthetic rate and stomatal conductance was noticed at 35 Gy in GS-32, whereas mutant GS-34 developed from the same irradiation dose had the minimum transpiration rate. Stomata length and width in the mutants GS-17 and GS-15 as compared to wild type registered an increase of 25.50% and 15.96%. A general reduction in stomata number was observed in the mutated populations. Our result indicated alteration in traits of the mutated population which are of significance and can be used as a selection criterion for improvement of sweet orange.

Identifikasi Stomata Pteridophyta di Kawasan Air Terjun Parangkikis Pagerwojo Tulungagung Jawa Timur

The aim of this study was to identifiy the stomata morphological characters of Pteridophyta in the ​​Parangkikis Pagerwojo Waterfall area, Tulungagung. The first step of stomata observation was preparation of the abaxial leaf slice. The preparation was carried out by the replica method. Stomata character studied include types and size of stomata, the number of stomata and epidermis cells, and value of the stomatal index. The result of this study showed that stomata types of Pteridophyta were polocytic and anomocytic. Of the 15 Pteridophyta species observed, the all of stomata type were polocytic, except Selaginella which had type stomata anomocytic. Stomata oval was found in Selaginella intermedia and Phymatosorus sp., slightly oval (kidney) was found in Asplenium apogamum, Dryopteris sp., Asplenium normale, Nephrolepis bisserata, Nephrolepis davallioides, Asplenium nidus, and Pteris longipinnula sp., spherical was found in Dicranopteris linearis, Cyclosorus arida, Goniophlebium percussom, and Goniophlebium manmiense, and nonconcave was found in Coniogramme fraxinea. Stomata size affected the number of stomata. If the size of the stomata was small, the number of stomata was increasing. The highest number of stomata was found in D. linearis, which was 362, while the least number of stomata was S. intermedia, which was 18. Data on the number of stomata and epidermal cells were used to determine the stomatal index. The highest stomata index was found in D. linearis, which was 22.05% and the lowest was C. fraxinea, which was 5.44 %.
 
 Keywords: Anomocytic, Parangkikis, polocytic, Pteridophyta, stomata

In Vitro Growth Responses of Ornamental Bananas (Musa sp.) as Affected by Light Sources

Light-emitting diodes (LEDs) have become very popular for the production of horticultural crops. LEDs represent an alternative lighting source to regular fluorescent (FL) bulbs, increasing the quality of plants and minimizing production costs. LEDs also provide selective light intensity and quality, suitable for commercial micropropagation. The objective of this study was to evaluate the growth and development of in vitro ornamental bananas under different light sources. Two ornamental banana varieties were selected for this study: Musa ‘Little Prince’ and Musa ‘Truly Tiny’. Light quality and intensity of three different light sources were evaluated: LED-1 (116 μmol m−2 s−1), LED-2 (90 μmol m−2 s−1), and FL (100 μmol m−2 s−1). Length and biomass of plantlets were greater under LED-1 compared to FL but not significantly different from LED-2. The fresh and dry weight of shoots and roots, number of leaves, and number and length of roots were not significantly different between treatments. Chlorophyll content was greater under LEDs. Leaf number and stomata number and size were greater under FL. Our results indicate that shoot length and biomass could be improved by optimizing light quality and intensity. Different responses to light sources between the two banana varieties also indicated a genotype effect.

Características morfológicas, fisiológicas e agronômicas de cruzamentos de cafeeiro 'Icatu' x 'Catimor' submetidos a deficit hídrico

Abstract The objective of this work was to select genotypes of Coffea arabica with good yield and potential tolerance to water deficit, as well as to try to understand the physiological and anatomical mechanisms involved in the adaptability of these genotypes to water stress. The physiological, anatomical, and agronomic traits of 19 genotypes of C. arabica were evaluated under the two following water conditions: regular irrigation and no irrigation (soil water deficit). The 'IPR 100', 2, 5, and 7 genotypes showed agronomic, physiological, and anatomical traits that contributed to a better water status maintenance in the initial development of coffee plants. Based on these results, these genotypes are potentially tolerant to water deficit. The 4, 10, 11, 14, 15, and 'Bourbon Amarelo IAC J10' genotypes show a lower adaptability of the anatomical structures under soil-water deficit conditions. The coffee tree genotypes display leaf plasticity, such as the thickness of palisade and spongy parenchyma, and the number, position, dimensions, and mobility of stomata under water deficit conditions.

Production Improvement of M1 Generation Garut (Maranta arundinacea) Rhizomes through Gamma Radiation Mutation

Garut (Maranta arundinacea L.) is a tuber containing flour with a low Glycemic Index (IG) suitable for diabetics and other degenerative diseases. It needs to be developed to reduce the dependence on imports or to substitute wheat flour. The objective of the study was to obtain superior arrowroot seedlings and observe the effect of gamma-ray irradiation on the density and position of stomata on arrowroot leaves. In this research, the irradiation of five arrowroot accessions of second-generation (MV1) with gamma rays (0, 10, 20, 30, 40, and 50 Gray) was carried out to obtain mutants with superior character so that they could be used as parent plants for arrowroot flour production. The treatments administered were arrowroot accessions (V), gamma-ray radiation dose (R), and their interaction. The qualitative and quantitative characters on plant characteristics, tuber production, and arrowroot leaves' stomata were observed. The research results showed that increased production is primarily for 25-Pandeglang accession (808.33 grams) and 10 Gray (800.00 grams) of gamma ray radiation treatment. It is expected that this accession can be released as a new variety candidate after subsequent selection and evaluation in a further generation. Moreover, the dose of gamma-ray radiation is inversely proportional to the number of stomata, which will increase the photosynthesis, thus increasing the number of tubers produced.

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.

Anatomy of the leaf blades of Waldsteinia ternata (Stephan) Fritsch (Rosaceae) grown under different light conditions

AbstractThe paper reports the results of a comparative study of the anatomical structures of the leaf blades of Waldsteinia ternata grown under different light conditions in the Siberian Botanical Garden of Tomsk State University. Waldsteinia ternata is a tertiary nemoral relict from the mountains of southern Siberia, which is found in a limited number of taiga communities due to narrow environmental tolerance to various factors. The species remains poorly studied; comprehensive studies of the anatomical features of its leaves have not been performed on the territory of Russia. Leaves of W. ternata are dorsoventral and amphistomatous with anomocytic type stomata. The plants are classified as mesophytes. The relationship between the development of the anatomical structure of leaves and light conditions was revealed. The W. ternata plants grown in the sun showed an increased number of stomata and epidermal cells, an increased thickness of the leaf and mesophyll, and an increased number of cells of the upper and lower epidermis, that is, the plants exhibited heliophytic features of plant adaptation to good light conditions. At the same time, the vascular tissues of the plants grown in the sun were less developed, which reflected their adaptation to unfavorable water conditions. A number of relative indicators, such as the stomatal index of the lower epidermis, the ratio of the palisade to spongy mesophyll, and the ratio of xylem to phloem, did not change under different growth conditions. Thus, under different light and water conditions, W. ternata acquires helioxeromorphic or sciomesomorphic features.

Morpho-physiological and phytochemical responses of basil (Ocimum basilicum L.) to toxic heavy metal cadmium

Cadmium (Cd) is a particularly noteworthy metal that may change the secondary metabolism efficacy of pharmaceutical valuable plants. This study aimed to explore the influence of Cd (0, 25, 75, 100, and 150 µM) on the morpho-physiological traits, mineral contents, essential oil composition, and morphology of secretory glands in basil (Ocimum basilicum L.). The exposure to Cd reduced significantly shoot and root dry weight, shoot and root lengths, total chlorophyll, number, and length of secretory gland compared to control plants, while increased peroxidase activity, proline content, and number of stomata. Essential oil compositions were varied in the Cd-treated plants in a dose-dependent manner. The main compounds of the essential oil were Estragole followed by Linalool and Geranial which the highest percentages were observed in the plants treated with Cd 150 µM. The Cd-treated plants exhibited reductions in calcium (Ca) and iron (Fe) concentrations in both leaves and roots. Cd contents in roots and shoots progressively enhanced with increasing Cd concentrations In general, basil showed good tolerance to Cd stress, so that 50% reduction in shoot dry weight occurred in above 100 μm treatments, which can be related to physiological reactions such as increased antioxidant activity, proline content, number of leaves stomata, and changes in other morpho-physiological factors.

Micromorphological evaluation of Daphne mucronata Royle and Myrtus communis L. using scanning electron microscopic techniques.

The present study was undertaken to establish micromorphological standards of Daphne mucronata Royle and Myrtus communis (L.). Daphne mucronata Royle is a xerophytic perennial shrub while, Myrtus communis is an evergreen shrub or small tree. Micromorphological investigation is one of the cheapest methods. It will be helpful in the accurate identification of these plants from other species. Results of macroscopic evaluation showed various organoleptic features. Anatomy of the selected plant parts was carried out. It showed a typical dicot structure as it revealed the presence of epidermal cells, crystals, trichomes, cuticle, mesophyll tissues, xylem, phloem, paracytic, and dicytic stomata. Anatomical study facilitates the detection of adulteration with inferior commercial varieties, exhausted drugs, cheaper natural substances, and chemicals. Stomatal number, types, and size of stomata, and palisade ratio of Myrtus communis were observed. These observations will be helpful in the preparation of taxonomic key for the identification of selected species. Powder drug study [scanning electron microscopy (SEM)] showed characteristics histological differentiation. The methods cited here can be measured as characteristics to identify and validate these drugs.

StomataScorer: a portable and high-throughput leaf stomata trait scorer combined with deep learning and an improved CV model.

To measure stomatal traits automatically and nondestructively, a new method for detecting stomata and extracting stomatal traits was proposed. Two portable microscopes with different resolutions (TipScope with a 40× lens attached to a smartphone and ProScope HR2 with a 400× lens) are used to acquire images of living stomata in maize leaves. FPN model was used to detect stomata in the TipScope images and measure the stomata number and stomatal density. Faster RCNN model was used to detect opening and closing stomata in the ProScope HR2 images, and the number of opening and closing stomata was measured. An improved CV model was used to segment pores of opening stomata, and a total of 6 pore traits were measured. Compared to manual measurements, the square of the correlation coefficient (R 2) of the 6 pore traits was higher than 0.85, and the mean absolute percentage error (MAPE) of these traits was 0.02%–6.34%. The dynamic stomata changes between wild‐type B73 and mutant Zmfab1a were explored under drought and re‐watering condition. The results showed that Zmfab1a had a higher resilience than B73 on leaf stomata. In addition, the proposed method was tested to measure the leaf stomatal traits of other nine species. In conclusion, a portable and low‐cost stomata phenotyping method that could accurately and dynamically measure the characteristic parameters of living stomata was developed. An open‐access and user‐friendly web portal was also developed which has the potential to be used in the stomata phenotyping of large populations in the future.

IMPACT OF CADMIUM TOXICITY ON LEAF AREA AND STOMATAL CHARACTERISTICS IN FABA BEAN

Although changes in stomatal response to elevated doses of cadmium has already been observed in several plants, few studies have focused on this phenomenon in more detail. The effects of different doses of cadmium Cd2+ (50 and 100 mg.kg-1 soil) on leaf area and stomatal characteristics (number of stomata, number of epidermal cells, stomatal index and size of stomata) of faba bean (Vicia faba L. cultivar Aštar) were studied after 15 days of heavy metal treatment. No visual changes on adaxial or abaxial side of leaves of the tested variety of faba bean were found. The leaf area was higher by 14.15 % at lower and by 12.23 % at the higher doses of Cd. The tested doses of Cd did not lead to a change in the number of stomata. The number of epidermal cells was increased on adaxial side by 4.98 % at dose Cd50. Stomatal index was decreased due to the effect of higher dose of cadmium by 11.38 % on adaxial side of leaves. In stomatal widths, decrease by 2.04 % (adaxial side) and 2.26 % (abaxial side) was observed at higher doses of Cd. In stomatal length decrease by 1.85 % was observed at higher dose of Cd on adaxial and decrease by 3.89 % (Cd50) and 4.63 % (Cd100) on abaxial side of leaves respectively. The variations of response could be signals of tolerance or adaptive mechanisms of the leaves of tested bean cultivar under the used concentrations of cadmium.

Hubungan Senyawa Metabolit Pada Tanaman Meliaceae Terhadap Tingkat Serangan Hypsipyla robusta

This study aims to determine the relationship of metabolite compounds in meliaceae plants to the preference of Hypsipyla sp. This research was conducted at the Chemistry Laboratory, Faculty of Mathematics and Natural Sciences, Sam Ratulangi State University, Manado BALITKA Laboratory, Chemistry Laboratory, Faculty of Mathematics and Natural Sciences, State University of Gorontalo and sending samples to the Pharmacy Laboratory of Sendai Japan to see the NMR structure. This study was designed in a Latin square design with 5 treatments and 5 replications. The total number of plants in all treatments was 250 plants. The determination of secondary metabolites was carried out in five stages, namely: 1) sample collection and processing, 2) extraction, 3) purification, 4) phytochemical test, 5) identification of compounds using UV-Vis and IR spectrophotometers. The sample materials used were dry samples of langsat, duku, mindi, and mahogany leaves consisting of large mahogany and small mahogany. The results of phytochemical screening on samples of lansium, duku, chinaberry, large mahogany and small mahogany in the n-hexane, ethyl acetate and water fractions showed positive results for flavonoids and steroids, while for alkaloids, terpenoids and saponins showed negative results. The results of the analysis showed that small mahogany plants contained high starch content of 43.72 g/mL, high fat content of small mahogany plants of 24.15% and high protein content of Langsat plants of 9.01 g/mL. The level of preference Hypsipyla sp prefers small mahogany plants compared to other plants. The number of mahogany stomata compared to other plants regulates the rate of evaporation in which will also release secondary metabolic compounds as attractants to attract insects to plants. The main flavonoid groups in mahogany are Quercetin 3-O-β-D-galactopyranoside, Quercetin 3-O-β-D-glucopyranoside, and quercetin 3-O-α-L-rhamnopyranoside.  Key words: phytochemicals; plant metabolites; quercetin; mahogany; Hypsipyla sp.

Rice histone deacetylase HDA704 positively regulates drought and salt tolerance by controlling stomatal aperture and density.

HDA704 enhances drought and salt tolerance via stomata-regulated mechanism. HDA704 negatively regulates stomatal aperture and density, repressing the transcription of DST and ABIL2 by histone deacetylation modification. Drought and salinity can damage crop growth and reduce yield. Stomata play an important role in abiotic stress tolerance. In this study on rice, we identified the RPD3/HDA1-type histone deacetylase HDA704 as a positive regulatory factor in drought and salt tolerance. HDA704 was induced by drought and salt stresses. Overexpression of HDA704 in transgenic rice promoted stomatal closure, decreased the number of stomata and slowed down the rate of water loss, consequently resulting in increased drought and salt tolerance. By contrast, knockdown of HDA704 in transgenic rice decreased stomatal closure and accelerated the rate of water loss, leading to decrease drought and salt tolerance. We detected the transcript expression of DST (Drought and Salt Tolerance) and ABIL2 (Abscisic Acid-insensitive Like2), which positively regulate stomatal aperture and density in rice. Our results showed that HDA704 directly binds to DST and ABIL2, repressing their expression via histone deacetylation modification. Collectively, these findings reveal that HDA704 positively regulates drought and salt tolerance by repressing the expression of DST and ABIL2. Our findings provide a new insight into the molecular mechanisms of stomata-regulated abiotic stress tolerance of plants.

A Deep Learning-Based Method for Automatic Assessment of Stomatal Index in Wheat Microscopic Images of Leaf Epidermis.

The stomatal index of the leaf is the ratio of the number of stomata to the total number of stomata and epidermal cells. Comparing with the stomatal density, the stomatal index is relatively constant in environmental conditions and the age of the leaf and, therefore, of diagnostic characteristics for a given genotype or species. Traditional assessment methods involve manual counting of the number of stomata and epidermal cells in microphotographs, which is labor-intensive and time-consuming. Although several automatic measurement algorithms of stomatal density have been proposed, no stomatal index pipelines are currently available. The main aim of this research is to develop an automated stomatal index measurement pipeline. The proposed method employed Faster regions with convolutional neural networks (R-CNN) and U-Net and image-processing techniques to count stomata and epidermal cells, and subsequently calculate the stomatal index. To improve the labeling speed, a semi-automatic strategy was employed for epidermal cell annotation in each micrograph. Benchmarking the pipeline on 1,000 microscopic images of leaf epidermis in the wheat dataset (Triticum aestivum L.), the average counting accuracies of 98.03 and 95.03% for stomata and epidermal cells, respectively, and the final measurement accuracy of the stomatal index of 95.35% was achieved. R2 values between automatic and manual measurement of stomata, epidermal cells, and stomatal index were 0.995, 0.983, and 0.895, respectively. The average running time (ART) for the entire pipeline could be as short as 0.32 s per microphotograph. The proposed pipeline also achieved a good transferability on the other families of the plant using transfer learning, with the mean counting accuracies of 94.36 and 91.13% for stomata and epidermal cells and the stomatal index accuracy of 89.38% in seven families of the plant. The pipeline is an automatic, rapid, and accurate tool for the stomatal index measurement, enabling high-throughput phenotyping, and facilitating further understanding of the stomatal and epidermal development for the plant physiology community. To the best of our knowledge, this is the first deep learning-based microphotograph analysis pipeline for stomatal index assessment.

Identification of drought resistance in winter wheat varieties in terms of xeromorphy and water-holding capacity

The effect of high temperatures on the xeromorphism of leaves and the water-holding capacity of various ecotypes tissues of winter wheat has been studied. In the weather conditions of 2013 in the forest-steppe zone, according to the xeromorphism of the flag leaf structure, a significant variation in the number of stomata in the studied wheat varieties was revealed. Significant differences were noted in winter wheat varieties in the number of stomata at the beginning of earing and flowering, with the exception of the Gordovita and Sonechko varieties. An increase in the number of stomata per leaf area unit corresponds to a smaller cell size, that is, an increase in xeromorphism. Varieties Natalka, Rozkishna, Sonechko, Bilitsya are characterized by the highest xeromorphism and by a high adaptive potential in the agro-climatic conditions of the forest-steppe zone. In the phase of the beginning of earing and flowering in the weather conditions of 2014, significant differences were defined between winter wheat varieties in the number of stomata on flag leaves. The exceptions for this indicator were Sonechko, Rozkishna, Gordovita, Pilipovka varieties. According to the parameter of the highest xeromorphism, the varieties Sonechko, Rozkishna, Gordovita were identified. This characterizes them as ecotypes with a high adaptive potential to arid conditions that arise when growing crops in a given zone. During the studies in 2013-2015 the varioust ability of winter wheat varieties to retain water, depending on their genetic characteristics and the duration of the action of the extreme environmental factor was identified. The varieties of winter wheat that have a higher water-holding capacity of tissues, after the impact on stress factor during 1.5 hours, include: Sonechko, Yuvilyar Mironivsky, Krasnodarskaya 99, in Memory of Craft.

Enhancing the Quality of Compost from Oil Palm Residue by Inoculating Nitrogen-Fixing Bacteria: Impact on Brassica rapa v. chinensis Growth

Oil palm empty fruit bunches (OPEFB) are by-products of the processing of oil palm mills. The addition of nitrogen-fixing microorganisms is carried out to improve nitrogen content in OPEFB compost and it can be used as a growing medium to increase the quality of vegetable crops. The aim of this study is to analyse the potential of empty fruit bunch composts enriched with Azotobacter for improving pak choi (Brassica rapa v. chinensis) growth. The process involved the conversion of OPEFB by fortifying it with Azotobacter into value-added composts. Temperature, pH, conductivity, and nutrient characteristics of composts were analyzed during the composting process. The Completely Randomized Design was conducted to observe the potential of Azotobacter-fortified composts on pak choi growth. The growing media made in seven combinations, namely: F0: 100% soil (control); T1P1: 30% OPEFB composts + 70% soil; T1P2: 50% OPEFB composts + 50% soil; T1P3: 70% OPEFB composts + 30% soil; T2P1: 28% OPEFB composts + 2% Azotobacter sp. + 70% soil; T2P2: 48% OPEFB composts + 2% Azotobacter sp. + 50% soil; T2P3: 68% OPEFB composts + 2% Azotobacter sp. + 30% soil. The research revealed that the highest pH and conductivity values are 8.46 and 1.16 mS.cm-1, which occurred in Azotobacter assisted OPEFB composting. In the application of the compost as the growing media for pak choi, the morphological parameter showed significant effects. The Azotobacer assisted compost promoted significant increase in plant height (23,7 cm), root dry weight (2,84 g), shoot dry weight (2,39 g), root length (28,56 cm), leaf area (73,37 cm2), and number of stomata (36,70 cm-1).

Potassium supply modulates Eucalyptus leaf water-status under PEG-induced osmotic stress: integrating leaf gas exchange, carbon and nitrogen isotopic composition and plant growth.

The objective of this study was to quantify the effect of potassium (K) supply on osmotic adjustment and drought avoidance mechanisms of Eucalyptus seedlings growing under short-term water stress. The effects of K supply on plant growth, nutritional status, leaf gas exchange parameters, leaf water potential (Ψw), leaf area (LA), stomatal density (SD), leaf carbon (C) and nitrogen (N) isotopic compositions (δ13C and δ15N ‰) and leaf C/N ratio under polyethylene glycol (PEG)-induced water deficit were measured. Under both control (non-PEG) and osmotic stress (+PEG) conditions, K supply increased plant growth, boosting dry matter yield with decreased C/N leaf ratio and δ15N ‰ values. The +PEG significantly reduced LA, plant growth, dry matter yield, Ψw, number of stomata per plant and leaf gas exchange, relative to non-PEG condition. Potassium supply alleviated osmotic-induced alterations in Eucalyptus seedlings by better regulating leaf development as well as SD, thus improving the rate of leaf gas exchange parameters, mesophyll conductance to CO2 (lower δ13C ‰ values) and water use efficiency (WUE). Consequently, K-supplied plants under drought better acclimated to osmotic stress than K-deficient plants, which in turn induced lower CO2 assimilation and dry matter yield, as well as higher leaf δ13C ‰ and δ15N ‰ values. In conclusion, management practices should seek to optimize K-nutrition to improve WUE, photosynthesis-related parameters and plant growth under water deficit conditions.