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Water culture experiments were undertaken for 14 days to examine the effect of increasing aluminum level (0,10, 20, 40 mg·dm⁻³ AlCl₃·6 H₂O) on growth of sunflower, red pepper and radish leaves. The early stage of Al toxicity was characterized by curling or rolling of young leaves, marginal and veinal chlorosis, dark green leaves as soon as purpling of margins and veins of leaves. Reduction of leaf size and increased stomata density were observed with increasing Al concentration. Additionally, length of stomata cells decreased after Al-treatment.
Malus fruits are covered with peel, which consists of the cuticle, epidermis and several layers of hypodermis. This peel, and especially the cuticle and epicuticular wax formed on the fruit surface, plays a crucial role in preserving the fruit life by preventing water evaporation and the penetration of pathogen, as well as maintaining fruit firmness. The protective function of these two layers is particularly important after harvest during storage. Using light and scanning electron microscopy, the present study examined the structure of the fruit peel in two apple cultivars, ‘Lobo’ and ‘Boskoop’; their fruits had been stored for 2 months in a controlled-atmosphere storehouse. The fruit epidermis in cv. ‘Lobo’, with a smooth and slick surface, was characterized by the occurrence of unidirectional microcracks that were less numerous and had a smaller depth than in cv. ‘Boskoop’. The fruit surface in ‘Boskoop’ was coarse and dry, its numerous microcracks ran in different directions along the walls of the epidermal cells. Mycelium hyphae were observed in these microcracks and inside the lenticels of the fruits of ‘Boskoop’, whereas no mycelium hyphae were found on the surface of the fruits in ‘Lobo’. The apple cultivars differed in the thickness of the cuticle layer, the height of the epidermal cells as well as in the thickness and number of hypodermis layers. Malus fruits are covered with peel, which consists of the cuticle, epidermis and several layers of hypodermis. This peel, and especially the cuticle and epicuticular wax formed on the fruit surface, plays a crucial role in preserving the fruit life by preventing water evaporation and the penetration of pathogen, as well as maintaining fruit firmness. The protective function of these two layers is particularly important after harvest during storage. Using light and scanning electron microscopy, the present study examined the structure of the fruit peel in two apple cultivars, ‘Lobo’ and ‘Boskoop’; their fruits had been stored for 2 months in a controlled-atmosphere storehouse. The fruit epidermis in cv. ‘Lobo’, with a smooth and slick surface, was characterized by the occurrence of unidirectional microcracks that were less numerous and had a smaller depth than in cv. ‘Boskoop’. The fruit surface in ‘Boskoop’ was coarse and dry, its numerous microcracks ran in different directions along the walls of the epidermal cells. Mycelium hyphae were observed in these microcracks and inside the lenticels of the fruits of ‘Boskoop’, whereas no mycelium hyphae were found on the surface of the fruits in ‘Lobo’. The apple cultivars differed in the thickness of the cuticle layer, the height of the epidermal cells as well as in the thickness and number of hypodermis layers.
The structure of floral nectaries of ivy (Hedera helix) was investigated under light, scanning, and transmission electron microscopes. The nectar of ivy is located on top of the inferior ovary forming a distinct undulating disc between the base of petals and the style. The ivy nectary represents open and persistent nectaries. During consecutive days of anthesis, nectaries change their colour from green to brown. The secretory epidermis is covered with a thick, deeply striated cuticle, and nectar is released by nectarostomata. Epidermal cells exhibited plastids with plastoglobules and a few starch grains as well as vacuoles containing anthocyanins, the content of which increased during the successive days of anthesis and nectar secretion. Multi-layered glandular parenchyma and, underneath, subglandular tissue are located under the epidermis. The nectary was supplied by vascular bundles with phloem and xylem. Numerous chloroplasts were visible in the cytoplasm of the external layers of glandular parenchyma; they were either typical with small starch grains or untypical with circular arrangement of thylakoids. Amyloplasts containing storage starch grains and numerous small vacuoles were present in the cells of deeper layers of the nectar-bearing tissue. Druses, flocculent residue, myelin figures and spherical deposits of unknown origin were visible in the gland parenchyma vacuoles.
Tilia cordata is a good source of food attractants for bees. These insects are the primary pollinators of flowers of this species. Nectar is produced in the floral trichomatous nectaries located on a projection of the adaxial, basal part of the sepals. There were two types of non-glandular hairs on the sepals; the first one to prevent the nectar from flowing out beyond the sepal and the other type to protect the nectary itself. The clavate secretory trichomes, forming dense clusters, are composed of a base, stalk, and multicellular head. The secretory cells of the trichome head contain a thick cytoplasm and a large nucleus; they are also characterized by a low degree of vacuolation. Nectar accumulates at the tip of the trichome in the space formed between the cell wall of the head cells and the cuticle. The several-layered subepidermal glandular parenchyma with densely packed cells is provided with vascular bundles containing xylem and phloem. Plastids containing small starch grains were noticed in many cells of the nectariferous tissue, whereas phenolic compounds were found in the adaxial epidermal cells of the sepals. No presence of starch, lipids, or phenolic compounds was found in the cells of the glandular hairs. However, numerous chloroplasts, calcium oxalate crystals and large mucilage cavities occurred in the subglandular tissue.
The biology of flowering and the micromorphology of Cornus alba flowers were studied using light and scanning electron microscopy. The flowering of white dogwood in 2008 lasted 35 days, and the lifespan of a single flower was 3 days. The number of flowers per inflorescence was variable (on the average, it was 89). The largest group of insects visiting the flowers of C. alba comprised Hymenoptera (mainly bees and andrenids), then ants, dipterans and beetles. They foraged the dogwood flowers most intensively between 11.00 and 15.00. The inconspicuous four-petalled flowers of C. alba were characterised by the occurrence of T-shaped, two-armed non-glandular trichomes covering the receptacle as well as observed on the petals of the corolla, the style of the pistil and the anthers in a smaller number. The trichomes were covered by a thick cuticle with characteristic outgrowths. They contained a living protoplast, and plastids were observed in the cytoplasm of the trichome cells. In addition, anomocytic stomata were found in the epidermis of the receptacle and in the epidermis of the corolla petals. The stigma of the pistil and the adaxial epidermis of the petals were composed of very numerous conical papillae.
Saxifrages are plants commonly found in all continents. Many of them are adapted to flowering and reproduction under mountainous and rocky conditions. They are pollinated by various groups of insects and have intrastaminal nectaries. The morpho- anatomy of the flowers and nectaries of Saxifraga stolonifera L. was examined using bright-field light and stereoscopic microscopy as well as scanning electron microscopy. The abaxial surface of the sepals has multicellular glandular trichomes containing anthocyanins in the base cells and polyphenols in the secretory cells of the head, whereas visual attractants in the form of color spots are found on the petals. The nectary gland is located at the apex of the ovary and forms a yellow-orange fleshy half-ring. Nectar is secreted through numerous modified stomata. The glandular parenchyma does not have vascular elements. Moreover, orange-brown polyphenols were observed in the nectary cells.
The structure of floral nectary of Malus sylvestris was examined using light and scanning electron microscopy. Nectaries in M. sylvestris flowers were situated on the adaxial surface of the receptacle, between the style and the base of filaments. The middle part of the nectary was covered epidermal cells with striated cuticle. The remaining part of the nectary was covered with smooth cuticle. Open and modified nectarostomata were situated at the same level as epidermal cells. The nectariferous tissue was formed by densely packed small parenchyma cells (secretory cells) with dark protoplasts.
Four-day-old seedlings of red pepper (Capsicum annuum L.) cv. ‘‘Trapez’’ were grown in nutrient solution containing 0, 10, 20 and 40 mg dm⁻³ of AlCl₃‧6H₂O for 14 days. Observations of leaves were carried out by light microscopy, as well as transmission and scanning electron microscopies. Exposure to aluminum resulted in reduction in the size and thickness of the leaf blades related to a decrease in the size of cells composing the leaves, as well as an increase in the number of stomata in the abaxial epidermis, with a simultaneous reduction of their size. The outer cell wall of the epidermis of the leaves was marked by a significant thickening in the presence of aluminum. The mesophyll cells contained enlarged chloroplasts having a disturbed structure of the lamellar system, filled with large starch grains. Rounded mitochondria were characterised by the electron lighter matrix and the destruction of the mitochondrial cristae. In the vacuoles of the parenchyma cells, as well as in the epidermis of the leaves, dark electron-dense bodies, presumably aluminum deposits, were observed.
‘Jonagold’ and ‘Szampion’ are winter apple cultivars, whose fruits are suitable for long-term storage. However, fruits of these cultivars differ markedly in the type of the surface and the rate and volume of water transpiration, which is manifested in fruit quality after storage and the length of apple shelf life. A majority of factors responsible for fruit quality and storability are genetically conditioned traits that are mainly developed before fruits reach harvest maturity or still develop during the storage period. The micromorphology, anatomy, and ultrastructure of 21-day-old fruit buds of the ‘Jonagold’ and ‘Szampion’ were examined using light microscopy as well as scanning and transmission electron microscopy. The analyses were particularly focused on the traits that determine fruit firmness and storability, which contribute to long-term storage capacity. It was found that the fruit buds in both cultivars differed significantly in the number of trichome scars and stomata on the fruit surface, the thickness of the hypodermis layer and the hypodermis cell walls, and in the content of phenolic compound deposits. At the fruit bud stage, the following features related to increased or decreased fruit firmness and storability were observed: platelet crystalline wax, cuticle microcracks, stomata and trichome scars, and presence of phenolic compounds.
The seedlings of the red pepper (Capsicum annuum L.) cv. Trapez grown in water culture for a period of 14 days with A1 (0, 10, 20 and 40 mg·dm⁻³ AlCl₃·6 H₂O). Some morphological and anatomical features of red pepper shoots were analyzed. Reduction in height and diameter of stems as well as decrease in fresh mass of shoots were observed after Al-treatment. In the hypocotyl the thickness of cortex parenchyma layer and the size of their cells were reduced. The aluminum treatment resulted in the increased in thickness of the epidermis outer cell wall. Under Al stress in the cotrex and the central cylinder parenchyma cells were present numerous enlarge plastids which contained large grains of starch and dark little bodies which were possible aluminum deposits. They weren't observed in control seedlings.
The structure of receptacular surfaces of floral nectaries at two flowering stages and the structure of the outer surface of the receptacle of Sorbus aucuparia were investigated using scanning electron microscopy. Changes in the development of the cuticular epithelium of the nectary epidermis and differences in the degree of aperture of stomata were observed. Increased undulation of the gland surface was found during flower development. Numerous stomata were situated slightly below the level of epidermal cells of the nectary. At the pollination stage, open pores or pores surrounded by the cuticular epithelium were observed, as well as covered by dried secretion. Dried nectar in the form of patches was also visible on the surface of the gland. Stomata of the outer surface of the receptacle were located on protrusions and surrounded by the cuticular epithelium.
Roots of radish (Raphanus sativus L. var. radicula Pers.) of Rowa cv. seedlings grown in water cultures (pH 4.3) have been tested. Aluminum as AlCl₃·6H₂O has been applied at 0, 10, 20 and 40 mg·dm⁻³ concentrations. Inhibition of the growth of root elongation and the following changes of root morphology have been observed after aluminum treatment: browning and thickening, root cap elongation or falling off, bending of the apex root and cracks on its surface. Roots have been characterized with the change of hair length and lateral zones. First lateral roots occurred closer to the basal root apex than first hair. Reduction of hair length was noticed too. Atrophy of outer root tissues has been accompanied by great enlargement of cortex cells size as a result of their hypertrophy.
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