Anatomical and Physiological Adaptation of Mangrove Wetlands in East Coast of Tamil Nadu

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WSN 129 (2019) 161-179 EISSN 2392-2192

Anatomical and physiological adaptation of mangrove wetlands in east coast of Tamil Nadu

R. Vinoth, S. Kumaravel and R. Ranganathan* Department of Botany, Annamalai University, Annamalai Nagar, Chidambaram, 608 002, Tamil Nadu, India *E-mail address: [email protected]

ABSTRACT The mangrove adaptations in the environment are the majority essential for the sustainable survival, development and intertidal zones due to special ability of salt tolerance. Mangroves possess a general characteristic to tolerating high salinity of seawater. Notably, they normalize ion homeostasis below brackish stress by salt secretion also ultrafiltration and ion appropriation. The plants have development of complex, physiological and anatomical adaptations allowing survival in their high stress habitat. The mangrove should restrain with aeration effect of sun, storm, osmotic disproportion, high salinity, brackish oxygen lacking and water- logged soils. Although, the reaction of adaptations the majority obvious attribute be succulent vegetation with increase mesophyll area, broad cuticle and wax deposition on the epidermis. The anatomical distinctiveness are the foundation designed for their physiological alteration to soaring salt condition.

Keywords: Mangroves, Adaptation, Anatomy, Ultrafiltration, Salinity

1. INTRODUCTION

Mangrove ecosystems are one of the major varieties of expected swamp alongside steamy and subtropical beaches, and collaborate a significant role in estuarine ecosystems. The Pichavaram mangrove wetlands is situated in the North extreme of the couvery delta, by the

( Received 03 May 2019; Accepted 21 May 2019; Date of Publication 22 May 2019 ) World Scientific News 129 (2019) 161-179

mouth of stream coleroon, Tamil Nadu, India. This mangrove is sandwiched among the important estuaries, the veller estuary in the north and south. The veller coleroon estuary multifaceted forms the killai backwater and pichavaram mangroves. Pichavaram denigration between 11º24’ N and 79º94’ E on the east coast of Tamil Nadu (Fig. 1).

Fig. 1. Pichavaram, the major block of mangrove forest of the world, showing its satilite position in couvery delta.

Mangrove forest are along with the largest part effectual and geographically significant ecosystems of the world, suitable to the fact they recommend a critical and precise environment that affects undoubtedly human society in using stabilizing seashores and decreasing the destructive impact of normal disorders, in adding to supplying meals, drugs, fuel and construction substances [18]. As individual of the coastal ecosystem, mangrove has a main role to human life. Mangrove ecosystems, specifically a high intensity of siltation, low oxygen levels, salinity (salt content) is high and the manipulate of the brandish cycle. Therefore that ecosystem is especially extreme by the identical time incredibly dynamic and is amongst the most hurriedly changing, particularly in the external part. Only various types of plants that can survive in the mangrove region and these types are regularly typical of mangroves having previously disappeared during the progression of adaptation and advancement of the older. The adaptive method followed by the salt lenient plants particularly grows on the riverine seashore where the inter-tidal environment is significantly variable. Some relationships into the coastal region are more than observable e.g. vegetation zonation in dune and salt swamp habitats, relative abundance of several geniuses in distinction to the virtual rarity of other species into the coastal district etc. The feature spatial division of plant kind or zonation in sea- affected habitats was first considered as preliminary stages of progression [13], [34]. Natural

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coastal habitat such as brackish marshes, mangroves aquatic grass beds, cushion coastlines from decomposition and stream, providing important defending services. Individual of the several advantages of nature-based protection is that similar habitat and provides other benefits, as well as nursery foundation for commercially with recreationally treasured genus, landing position for migrant plants, filtration of sediment, pollutants, carbon storage along with sequestration. Although, by occupying the coastline, which incorporates regions of high population density, mangroves are under consistent pressure from urban and horticultural extension, different modern exercises, hydrological changes of waterway bowls, spills of chemicals in spite of its awesome significance in managing the seaside zone. Mangrove has distinctive morphological qualities because of extraordinary natural conditions. These causes the underlying foundations of mangrove vegetation contain distinctive to survive the waves on the double grasping precarious substrate. Sedimentation is the part that happens progressively in nature. The deferral of sediment inflowing coastal conceded in streams, piling sludge and suspended substance back interested in the waves. The suspension of deposit in mangrove areas is produced in the progression of transportation of the substance in the tides. The stream of marine water entering silt particles that will caught aerial in the focus of the mangrove roots. The collection of residue that happens consistently will expand silt thickness. Pneumatophore is a portion of the underlying foundations of Avicennia engaged with the aeronautical crops. Though, residue cover the underlying driver harm, of which hinders the activity of lenticels that assume a part in the subsequent air circulation equipped for causing the passing of plants. Mangrove capacity to the distinctive sediment. Mangrove species, for example, Rhizophora and Avicennia had roots that are for the majority component shallow yet compelling holding mud. Rhizophora apiculata is individual of the predominant plant group in the mangrove regions generally utilized as a division of mangrove restoration program. Rhizophora apiculata had scattered the phase of time shorter than Rhizophora mucronata, Rhizophor apiculata then have a superior survival rate. As indicated the salt protection of vascular plants comprises of different parts, which might be isolated into two primary gatherings: systems of salt direction and salt resistance. Salt direction includes: i) shirking of admission; and ii) weakening; while salt resilience is characterized as a property of the cellular material to adapt to high salt fixation. Salt resistance incorporates particle compartmentation in the protoplast and resilience towards poisonous and osmotic impacts of high ion concentrations. It is the aspire of this document to decide the degree to which the diverse mechanism are vital for the adaptation of mangrove genus to their saline environments.

2. MATERIALS METHODS

Fresh leaf samples of seven identified mangrove taxa belonging to various genera and families were composed beginning unusual intertidal zones of Tamil Nadu. The species examined were Acanthus ilicifolius L, Aegiceras corniculatum (L.) Blanco., Avicennia marina (Forssk.) Vierh., Rhizophora mucronata Lam., Rhizophora apiculata Blume., Excoecaria agallocha L., Lumintzera recemosa Wild (Fig. 2). Individual of the solid plants were chosen and the developing leaves from fifth and 6th hub were taken for anatomical investigations. Segments were made at a position roughly somewhere between the base and summit of a segment from one region of the lamina, recoloured with toluidine blue and mounted in half glycerin.

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SG

Aegiceras coriculatum L. Acanthus ilicifolius L.

Excoecaria agallocha L. Lumintzera recemosa (Willd.)

Rhizophorra apiculata Blume. Avicennia marina (Forssk.)

Fig. 2. Morphology of different kinds of mangrove plants (S) salt glants.

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3. OBSERVATION

X Cuticle

P

ED

a) Avicennia officinalis Leaf T.S b) Avicennia marina Leaf T.S

c) Avicennia (Salt glands) d) Lumintzera recemosa Leaf T.S

VB

e) Rhizophora apiculata Leaf T.S f) Aegiceras coriculatum Leaf T.S

Fig. 3. Transfer section of mangrove leaves, xylem (X), phloem (P), vascular bundle (VB), epidermis (EP) and cuticle (Cu).

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S

EC E Rhizophora apiculata

EC

Excoecaria agallocha

EC

Aegiceras corniculatum

Cuticle is considerably broad in Aegiceras corniculatum leaves. In general dorsiventral and hypostomatic in the largest element of the genus except in Lumnitzera racemosa anywhere the leaves are isobilateral and amphistomatic. Regularly mangrove leaves are succulent and the cuticular surface is frequently flat except for Avicennia group wherever, it is intermittent by nonglandular and glandular trichomes. In a large quantity of the species adaxial epidermal cells are larger in range evaluate to those of abaxial cells. The epidermal cells are polygonal in summarize with additional or a lesser amount of instantly stockade in all species considered except. The epidermal cells are polygonal in diagram with pretty much straight dividers in all species considered aside from Excoecaria agallocha, the accumulation of epidermal cells were wavy. The mesophyll differentiated into palisade and spongy tissues excepting for Lumnitzera racemosa. The palisade tissue less than the superior epidermis is two layers in thickness in Acanthus illicifolius. Water storing tissues of varying proportions has been pragmatic in all

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species. In nearly every one of the species, the water storing tissue originate as a hypodermis except Lumnitzera racemosa. In Lumnitzera racemosa, the palisade tissue found in two layers on mutually sides of the epidermis. Idioblasts and stellate sclerieds are experimental in the mesophyll of Rhizophora apiculate (Fig. 3). Ranunculaceous sorts of stomata found in Aegiceras corniculatum, Excoecaria agallocha and Lumnitzera recemosa, cyclocytic in Rhizophora apiculata, Rhizophora mucronata and Acanthus cruciferous type were found. Equally glandular and non-glandular trichomes were seen in leaves of Avicennia species. Each glandular trichome or saline gland having originate on mutually adaxial and abaxial surfaces of leaves, The salt glands were seen in superficial pits on the higher surface, each salt gland consisted of 2-4 basal cells, a stalk cell and a terminal cell that are covered by a thin cuticle, where as non-glandular trichomes are multicellular with a stalk of 2 to 3 cells with an all shaped terminal cell experiential in abundance every more the lower epidermis (Fig. 4).

SEM section stomata (Lower epidermis)

Aegiceras corniculatum Rhizophora mucronata

Acanthus ilicifolius Excoecaria agallocha

Fig. 4. Epidermal peels of a leaves of mangroves showing stomata (S) and epidermal cells (EC).

3. 1. Adaptations of Mangroves The Mangrove leaves are evergreen since of the precipitation, tropical atmosphere and consistent temperatures throughout the year. Appropriate to high warmth present, the surfaces are thick and stringy and preventing in temperance water loss throughout transpiration. They also differ the direction of their leaves to circumvent the insensitive noon time sun and so

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condense departure from the leaves. A red mangrove in term just develops if its leaves are clouded with new water a few times each week, reenacting the continuous tropical rain storms. These leaves have dribble tips to enable abundance water to enclose the capacity to deplete or stream off rapidly, keeping destructive microscopic organisms from developing on it. The Avicennia sps. have fruits that are buoyant which can thus, be diverted by the water to another area where they will flourish. Mangrove seeds are additionally light and suitable to water diffusion. Once sprout, the seedling (Rhizophora seed) develops either inside the natural product or out through the organic product to shape a propagule (a prepared to-go seedling) which can create its own nourishment by way of photosynthesis, once developed, it will drop into the water. Propagules preserve survive drought and remain inactive for in excess of a instant prior to inward in an appropriate environment. Extended shape at the present floats vertically rather than parallel whereby it’s more possible to hunting lodge in the mud and root.The largest part typical adaptations of mangrove kind resulted in many types of specialized roots: flying buttress roots (Xylocarpus granatum), soaring buttresses (Rhizophora sps.), exterior roots (Excoecaria agallocha), piling roots (Rhizophora apiculata), stilt roots (R. stylosa), scattering roots (Rhizophora sps.), rope roots with pneumatophores, lap roots (Bruguiera gymnorrhiza), pencil roots (Sonneratia caseolaris) and cone-shaped tool roots (Avicennia sps.). Mangrove species contain roots with a higher extent of gas freedom while waterlogged and are fit for salt rejection, or are tolerant to high tissue salt concentrations (Fig. 5).

Avicennia officinalis Rhizophora mucronata

Rhizophora apiculata Avicennia marina

Fig. 5. Morphology of different kinds of mangrove root and pneumatophores.

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Different adjustments incorporate the capability to expulsion abundance salt from leaves, vivipary or the improvement of the developing life in seeds facing they are scattered, and seeds and propagules having distinctive [7]. Salt and Soaking adaptations of mangroves on the whole have a one of a kind blend of morphological and physiological traits for living in the tidal condition. Mangrove soils are routinely water-logged and stacked with salt. High tides transport marine oceanic and estuarine situation, though short tides uncover mud and roots to aridity, warmness and parching. Barely any other regular natural surroundings are liable to such emotional changes in abiotic factors - especially respects the consolidated impacts of tides, precipitation and spillover, waves, streams, impression and oceanic level change. All these elements have striking and significant special effects on the dispersion and attributes of Australia's mangroves. Adjustments required for survival in this condition are partaken partially by plants from no less than three other living space composes, to be specific deserts, rainforests and freshwater swamps. The salt adjustment for sodium and chloride are the two components that make up salt. Tragically, these two components can be toxic to plants. Since salt makes up around 90% of salt water, mangroves require a methodology to maintain a strategic distance from these components. Individual system that a few mangroves utilize is to strain salt through their underlying foundations. Along these appearances, they just retain the new water and utilize that to hydrate themselves. Another procedure is to ingest the salt in their bark, which they in the long run shed. Different mangroves utilize the salt discharge methodology, which is the point at which they utilize uncommon organs in their leaves to store the salt.

3. 2. Physiological adaptations of mangroves In their established work on East African mangroves Waiter and Steiner (1936) proposed that the xylem sap of mangroves ought to be liberated of sodium chloride. Examinations of the particle content and osmotic capability of mangrove roots and leaves of various ages, and in accumulation to transpiration rates, drove them to this theory. As a few different laborers in this field, they decided little contrast in the particle substance of leaves of various age and consequently inferred that there is no changeless admission of sodium chloride from the xylem sap. Preparatory examinations did without a doubt uncover low Sodium chloride fixations in xylem saps of mangroves [44]. The physiological procedures which enable mangroves to live in the always showing signs of change condition where the land meets the ocean are one of a kind among the plants. A mangrove must be contain drying impact of sun and wind, osmotic lopsidedness of the high saltiness of ocean water and development in salty oxygen insufficient and waterlogged soils. Mangroves should be likewise able to withstand the activity of the tides, introduction to new water, devastation impacts of tempest surges and the diurnal and regular variances of temperature [48]. There proposed two staged plant development reaction to saltiness development is first diminished by diminishing in soil water potential (water pressure impact) and a particular delayed consequence as salt increments in old clears out. These forget to kick the bucket as a consequence of quick increment of salt in cell divider or cytoplasm when vacuoles can never again sequester approaching salts. The defeat of more seasoned leaves diminishes the supply of sugars or development hormones to meristematic, in this way restraining development. It is hence critical for mangroves to organize cytosolic salt fixation when livelihood in intertidal zones with high saltiness. Mangroves create different components related with a few physiological and anatomical attributes to manage salt ingestion and

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rejection, for example, salt discharge, ultra filtration (Tomlinson 1986) and particle sequestration [30, 55-60]. Different technique of salt administration demonstrates that mangroves are versatile to high saltiness at the assorted histological and physiological levels. While considering the compelling stems and root frame works of mangroves it is entice to accept that a lot of salt are saved in the receiver divider of these plant parts, as known for some substantial metal safe plants. Sodium chloride maintenance inside roots and stems has been depicted for a few herbaceous halophytes, but this cannot be confirmed for mangroves on the basis of our results.

3. 3. Salt regulation Mangroves are physiologically tolerant of high salt levels and comprise systems to get crisp water despite of the solid osmotic capability of the residue. They dodge substantial salt loads through a mingle of salt prohibition, salt discharge and salt collection. For instance, Rhizophora, Bruguiera, and Ceriops all have ultra filters in their root frameworks. These channel prohibit salts while separating water from the dirt. Other species (e.g., Avicennia marina, Acanthus illicifolius, Aegiceras corniculatum) take several salt up, however discharge it through specific salt organs in the leaves [14], [17]. The salt discharging species permit additional salt into the xylem than do the non-secretors, however at the similar time reject around 90% of the salts [42]. The procedure is likely controlled by leaf hypodermal cells, which may amass up salt and also water [4]. The mangrove types of Lumnitzera recemosa and Excoecaria agallocha collect salts in leaf vacuoles and end up succulent. Salt concentrations in the incapacitate may well also be condensed in transferring the salts into senescent leaves or by storing them in the bark or the wood (Tomlinson, 1986). Since water salinity increases, various species basically turn into gradually more conventional in their water utilize, thus achieving better tolerance. In south Florida, Rhizophora sps. mangle decrease its salt stress by using features water as its sole water resource. In the soaking season, the superior root biomass increases in reaction to decreased salinity of the exterior waters, directly ornamental the uptake of low-salinity water [23]. The largest parts of mangrove species frankly regulate salts. However, they also gather or synthesize added solutes to standardize and sustain osmotic balance. For example, Aegiceras corniculatum, Aegialitis annulata and Laguncularia racemosa accumulate mannitol and proline (Polania, 1990) [37]. Avicennia marina accumulates glycine [3]. Sonneratia alba synthesizes purine nucleotides that facilitate it adapt to salt load of 100 mM NaCl [1]. Survive that as it may, thick, polymeric substance in as far as possible stream rate and abatement transpiration [54]. This is joined with high water-utilize productivity, moderates the rate of water take-up and keeps salts from gathering in the dirt encompassing the roots. This enables the mangroves to ration water and direct interior salt fixations [5], [6]. Low transpiration and moderate water take-up, be that as it may, are not normal for every mangrove genus. [9] estimated generally high transpiration charge in equally Avicennia marina and Rhizophora apiculata. Transpiration rates change with the season, living being superior in the dry season than in the soaked season in Bruguiera cylindrical [19], [20]. This compares to change in stomatal development. The oscillatory conduct of Avicennia germinans stomata is influenced by any factor that progressions water driven move through the plant. This incorporates increments in vapour weight deficiency and osmotic capability of the substrate [33].

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3. 4. Adaptations to Reproduction Mangroves are blossoming plants with male and female bloom parts arranged on either a similar tree or on independent trees as in Excoecaria agallocha L. A smooth mangrove flowers and organic products may illustrate up during the time as indicated by varieties in local atmosphere. In Rhizophora slylosa aeronautical roots for the mainly part create infant trees. The infant trees can drift for rather a while before it at long last locates a decent place and inhabit down. Avicinnia marina and Luminitzera racemosa are deliver seeds. Through viviparity incipient organism germination starts on the tree itself the tree later drops its created developing lives, called seedlings, which may have flourish in the dirt underneath. Viviparities have advanced as a versatile component to set up the seedlings for long-separate dispersal and survival and development inside a brutal saline condition. Amid this viviparous advancement, the propagules are supported on the parent tree, subsequently amassing the starches and different mixes required for later independent development. The basic many-sided quality accomplished by the seedlings at this beginning period of plant advancement adapts the seedlings to outrageous physical conditions which generally may block typical seed germination [46]. As for each the centralizations of chlorophyll, add up to sugars, starch and net photosynthetic rate expanded amid the viviparous germination of Rhizophora mucronata and Rhizophora apiculata hypocotyles. Another uncommon adjustment is the dispersal of certain mangrove propagules which swing from the branches of developing trees.

4. ANATOMICAL ADAPTATIONS OF MANGROVES 4. 1. Leaf anatomy Mangrove leaves are relatively weathered with shade leaf veins (present are rejection layer sheaths). This route of action lessens self-shading and creates branch frameworks that fill liberty in the mainly photosynthetically effective way (Tomlinson, 1986). Mangrove leaves include specific idioblast cells including tannin cells, mucous cells (Rhizophora, Sonneratia), crystalliferous cells, oil cells (Osbornia) and laticifers Excoecaria [55]. When all is said in done, the leaves need package sheath filaments and package sheath expansions, yet have extended tracheids ending in vein endings. Spread scleroids are copious and very much created in Aegiceras corniculatum, Rhizophora apiculata, and Sonneratia. The scleroids may give perfunctory help to leaves or demoralize herbivores. Both scleroids and tracheids may likewise be linked with water stockpiling [55]. Water is additionally put away in dismal, non- assimilatory water-stockpiling tissue that is hypodermal in dorsiventral leaves, yet is deep- seated in the broad mesophyll locale of isolateral clears out. In Rhizophora apiculata and several cases, chlorophyll was moved in the chloroplast response focus. The chlorophyll-restricting proteins (counting the useful cytochrome composite and the protein kinases) were originate in the thylakoid films in Bruguiera gymnorrhiza. Since leaf attributes are by and large considered as a consequence of condition, particular adjustments are required to empower plants to get by in saline dregs. Enormous vacuolar space for a capacity of salts is one of the fundamental components in saltiness resilience [32]. Stresses forced by saltiness impact leaf anatomical and stomatal highlights to a more noteworthy degree than phylogenetic connections [8]. The other tsunamis and a drought between tides cause residue salinities to be hoisted to an abnormal state. In this way, species that develop in such locales are required to have adjustment identified with high saltiness and in addition low to low water

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potential [2], [52]. Not withstanding water pressure the nearness of salts can likewise be harming a result of the presentation of destructive inorganic particles. Numerous halophytic species have consequently created salt discharging organs to lessen interior salt focus. Changed, bicellular miniaturized scale hairs differently called hydathodes, salt organs were seen in a few salt tolerant grass species. Then again salt organs in dicotyledonous mangrove species adjusted to comparative conditions typically have in excess of two cells [27], recommending an alternate developmental inception from salt organs. Most evident morphological adjustments of mangroves are their moderately littler leaves, less stomata per unit zone, expanded succulence, the thickness of leaf fingernail skin and the statement of wax that assume a critical part in preserving water for supported plant development under saline conditions.

4. 2. Wood and stem anatomy Tomlinson (1986) has abridged the special anatomical highlights of mangrove forest. Development rings are obviously odd as in Avicennia; (Ghose, 1998) or totally truant. Consequently and Pinzon (1992) propose that leaf wound nodal number is a superior method to estimate the time of Rhizophora seedlings. Mangrove wood has unique highlights that empower the vegetation to conquer the high osmotic capability of seawater and the transpiration caused by elevated temperatures. There are various thin vessels going through the wood. These assortment in thickness from 32 mm-2 in Excoecaria agallocha to 270 mm-2 in Aegiceras corniculatum [56]. The vessels help in making high pressures in the xylem since a slight decline in vessel breadth creates a disproportionally substantial increment in stream protection [42], [43]. The vessel components, which frame the vessels, regularly have basic puncturing plates (Tomlinson, 1986). In some case, mangroves in the family Rhizophoraceae (with the exception of Kandelia candel) have scalariform puncturing plates. Water conduction through wood is unequivocally affected by size and broadcasting of the vessels. Water moves most rapidly through ring-permeable woods in which the biggest vessels are in the furthest development layer (Fig. 6). Conduction is much slower in diffuse-permeable woods where vessels are additional standardized in size and appropriation. The wood of most mangroves is diffuse-permeable however Aegialitis rotundifolia has ring-permeable wood [56]. Mangrove trees developing at differentiating saltiness levels have appeared to contrast in xylem structure [16], [29], as well as both vessel and bury vessel qualities [39]. A cavitations safe xylem structure is individual of the system plants may have used to shield their water transport [49], [50]. Specifically, little course measurements are outstanding to cause an abatement in transport productivity yet the same may give more prominent pressure driven wellbeing [28]. In the mangrove Rhizophora mucronata (Rhizophoraceae) vessels delivered in the dry seasons are marginally littler than those created in the stormy season [40], [51]. Despite the vessel distance across, [11], [47]. The vessel measurement in Rhizophora mucronata changes just rather because of distinction in soil water saltiness [40]. Along these appearance, it is normal that variety in vessel structure and number has a practical centrality for the natural adjustment of these salt tolerant mangroves. A high vessel recurrence is well on the way to speak to a procedure for conductive security [39]. It is for the most division expected that mangroves need yearly development ring [55]. In any case, in an examination on Avicennia germinans reasoned that rings of included phloem are plainly obvious on sanded stem plates. This might be the importance of endogenous organize of cambium movement and consequently, don't show the age of the tree. Progressive

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cambia establish in the mangrove family Avicennia to be sure have biological essentialness which appears to be unequivocally identified with water constrained condition [38].

Aegiceras corniculatum stem T.S Excoecaria agallocha stem T.S

Rhizophora mucronata stem T.S

Fig. 6. Transfer section of mangrove stems.

4. 3. Root anatomy Mangroves are profoundly adjusted to the beachfront condition, with uncovered breathing roots, broad help roots and braces, salt-discharging leaves and viviparous water dispersed propagules. These adjustments change among taxa and with the physical-compound nature of the territory [15]. Possibly the most exceptional adjustments of the mangroves, however, are the still underlying foundations of Rhizophora apiculata the pneumatophores of Avicennia, Sonneratia and Lumnitzera, the root knees of Bruguiera and Ceriops the support underlying foundations of Xylocarpus. The underlying foundations of numerous mangroves don't infiltrate far into the anaerobic substrate. Rather, the trees deliver lavish parallel roots for help. The particular roots are vital locales of gas trade for mangroves livelihood in anaerobic substrate. The uncovered surfaces may encompass various lenticels (free, air breathing collections of cells; [55]. Avicennia has lenticel-prepared pneumatophores (upward coordinated roots)

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through which oxygen latently diffuses. The lenticels might be shut, incompletely opened or completely opened, contingent upon natural conditions [24]. Oxygen may likewise go through non-lenticellular segments of the pneumatophores. Level structures (subrisules) might be imperative in air trade, especially in quickly developing pneumatophores somewhere the recently framed tip needs lenticels [22]. Pneumatophores are typically unbranched (Fig. 7). The underlying foundations of saline-adjusted plants indicate decreased cortex to abbreviate the separation among epidermis and stele. The casparian stripe is significantly more extensive in the salt bog living space plants when contrasted with mesophytes. Frequently epidermis and exodermis (hypodermis with a casparian band) converse to hindrances of variable protection from the spiral stream of water and particles from cortex to the stele beneath winning situation [21], [53].

Aegiceras corniculatum root T.S Excoecaria agallocha root T.S

Fig. 7. Transfer section of mangrove roots.

Such an adjustment is worthwhile for the proficient working of epidermis. While, the protoplasts are appended to the higher parts of the outspread and transverse mass of epidermal cell. At times the dividers of root epidermal and root hair cells, create a bulge on the internal side because of high saltiness, alongside these position the epidermal cells move toward becoming exchange cells [25]. In several case, at nearly low saltiness, endodermis, pericycle and thick fingernail skin create and the enlistment of aerenchyma and emptiness of substance happen. The submerged foundations of mangroves indicate the exceptional limit of gas trade. A few specialists have broken down the gases in mangrove roots. These roots contain be observed to be circulated air through yet how it is done isn't sufficiently clear. The roots contain typically 16– 18 % oxygen despite the information that the medium may have zero oxygen [41].

5. CONCLUSION AND SUMMARY

The morphological, anatomical and physiological behavior of living plants are ordinarily connected with the specific blend of ecological conditions under which particular plants are built up and developed. Mangroves endure high saltiness by dismissing possibly destructive

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salts. A few types of mangroves effectively discharge those salts by methods for specific salt organs in their leaves salt in ultra-filtration at the root cell films of cortical cells. The flexibility of mangroves to unfavorable environment make them perfect natural models to contemplate adjustment of mangroves to various abiotic stresses. Mangroves likewise give a repository to a segment of the best recognized narrative qualities and proteins, associated with resistance to saltiness stress and water logging conditions that are probably going to be relevant in other yield plants. Morphological and physiological attributes for adjustment incorporate ethereal roots, viviparous incipient organisms, tidal dispersal of propagules, fast rates of covering generation, absence of development rings, wood with limit thickly disseminated vessels, profoundly effective supplement maintenance system and the capacity to adapt to salty and to keep up water and carbon adjust. Such differing interrelated qualities construct mangroves species poor contrasted with other tropical biological systems. In perspective of such a magnificent generation potential more basic investigations including the prevailing mangrove and different order in the locales like Sundarban, the largest mangrove environment, are required. Assessment about the endlessness of the territory, indifference in the greater component of the territories because of tiger inhabitation and ceaselessly fluctuating soil conditions, a similar record of the genus gathered from various zones of Pichavaram will be of incredible help in clarifying the species decent variety and their versatile ability. The many sided quality of the suite of attributes required for saltiness resistance might be connected to the wide variety in saltiness resilience developed among different mangrove taxa. The variety of adjustments in water directing pathways among mangrove taxa likely adds to the upkeep of abnormal amounts of profitability in heterogeneous saline conditions that happen in mangrove environments. In the grassland of plant protection science where each specific uncommon or jeopardized species speaks to gigantically high esteem, essential logical information is of extraordinary significance. Subsequently, new model species should be deposit that speaks to various adjustment systems of beachfront plants. In analysis of such an exceptional production prospective more significant studies involving the prevailing mangrove and other species in the regions like Pichavaram, the largest mangrove ecosystem, are necessary. Consider the immensity of the region, inaccessibility in most of the area due to tiger inhabitation and constantly fluctuating soil conditions, a virtual account of the genus composed from different zones of Pichavaram motivation of enormous facilitate in elucidating the genus diversity and their adaptive ability.

AKNOWLADGEMENT

The authors are thankful to Professor and Head Dr. V. Venkatesalu, Department of Botany, Annamalai University for having provided laboratory facilities and valuable suggestions during the investigation.

References

[1] Akatsu, M., Hosoi, Y., Sasamoto, H. and Ashihara, H. (1996). Purine metabolism in cells of a mangrove plant, Sonneratia alba, in tissue culture. Journal of Plant Physiology 149 (1-2), 133-137

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[2] Anderson VJ, Briske DD (1990). Stomatal distribution, density and conductance of three perennial grasses native to the southern true prairie of Texas. Am Midl Nat 123: 152-159 [3] Ashihara, H., Adachi, K., Otawa, M., Yasumoto, E., Fukushima, Y., Kato, M., Sano, H., Sasamoto, H., and Baba, S. (1997). Compatible solutes and inorganic ions in the mangrove plant Avicennia marina and their effects on the activities of enzymes. Zeitschrift fuer Naturforschung 52 (7-8), 433-440 [4] Balsamo, R.A. and Thomson, W.W. (1995). Salt effects on membranes of the hypodermis and mesophyll cells of Avicennia germinans (Avicenniaceae): a freeze- fracture study. American Journal of Botany 82 (4), 435-440 [5] Ball, M.C. (1996). Comparative ecophysiology of mangrove forest and tropical lowland moist forest. In “Tropical forest plant ecophysiology” (S.S. Mulkey, R.L. Chazdon and A.O. Smith, eds), pp.461-469. Chapman and Hall, New York. [6] Ball, M.C. and Passioura, J.B. (1993). Carbon gain in relation to water use: photosynthesis in mangroves. In “Ecophysiology of Photosynthesis” (E.D. Sehulze and N.M. Caldwell, eds), pp. 247-257. Springer, Kiedelberg, Berlin. [7] Baskin CC, Baskin JM (2001) Seeds: ecology, biogeography, and evolution of dormancy and germination. Academic Press, London. ISBN 0-12-080260-0. [8] Baumel A, Ainouche ML, Bayer RJ, Ainouche AK, Misset MT (2002) Molecular phylogeny of hybridizing species from the genus Spartina Schreb. (Poaceae). Mol Phylogenetic Evol 22: 303-314 [9] [9]Becker, P., Asmat, A., Mohamad, J., Moksin, M. and Tyree, M.T. (1997). Sap flow rates of mangrove trees are not usually low. Trees 11, 432-435 [10] Boeer, B. (1993). Anomalous pneumatophores and adventitious roots of Avicennia marina (Forssk.) Vierh. mangroves two years after the 1991 Gulf War oil spill in Saudi Arabia. Marine Pollution Bulletin 27, 207-211 [11] Choat B, Ball M, Luly J, Holtum J (2003) Pit membrane porosity and water stress- induced cavitation in four co-existing dry rainforest tree species. Plant Physiol 131: 41- 48 [12] Corcuera L, Camarero JJ, Gil-Pelegrin E (2004) Effects of a severe drought on Quercus ilex radial growth and xylem anatomy. Trees Struct Funct 18: 83-92 [13] Doing H. 1985. Coastal fore-dune zonation and succession in various parts of the world. Vegetatio 61: 65-75 [14] Dschida, W., Platt-Aloia, K. and Thomson, W. (1992). Epidermal peels of Avicennia germinans (L.) Stern: a useful system to study the function of salt glands. Annals of Botany 70 (6), 501-509 [15] Duke NC, Birch WR, Williams WT (1981) Growth rings and rainfall correlations in a mangrove tree of the genus Diospyros (Ebenaceae). Aust J Bot 29: 135-142 [16] Ewers FW, Lopez-Portillo J, Angeles G, Fisher JB (2004) Hydraulic conductivity and embolism in the mangrove tree Laguncularia racemosa. Tree Physiol 23: 1057-1062

-176- World Scientific News 129 (2019) 161-179

[17] Fitzgerald, M.A., Orlovich, D.A. and Allaway, W.G. (1992). Evidence that abaxial leaf glands are the sites of salt secretion in leaves of the mangrove Avicennia marina (Forsk.) Vierh. New Phytologist 120, 1-7 [18] Giri C, Ochieng E, Tieszen LL, Zhu Z, Singh A, Loveland T, Masek J, Duke N (2011) Status and distribution of mangrove forests of the world using earth observation satellite data. Global Ecol Biogeogr 20: 154-159 [19] Herppich, W.B. and Von Willert, D.J. (1995). Dynamic changes in leaf bulk water relations during stomatal oscillations in mangrove species. Continuous analysis using a dewpoint hygrometer. Physiologia Plantarum 94 (3), 479-485 [20] Hirano,T., Monji, N., Hamotani, K., Jintana, V. and Yabuki, K. (1996). Transpirational characteristics of mangrove species in southern Thailand. Environmental Control in Biology 34 (4), 285-293 [21] Hose E, Clarkson DT, Steudle E, Schreiber L, Hartung W (2001) The exodermis: a variable apoplastic barrier. J Exp Bot 52: 2245-2264 [22] Hovenden, M.J. and Allaway, W.G. (1994). Horizontal structures on pneumatophores of Avicennia marina (Forsk.) Vierh.: A new site of oxygen conductance. Annals of Botany 73 (4), 377-383 [23] Lin, G.H. and Sternberg, L.D.S.L. (1994). Utilization of surface water by red mangrove (Rhizophora mangle L.): An isotopic study. Bulletin of Marine Science 54 (1), 94-102 [24] Ish-Shalom-Gordon, N. and Dubinsky, Z. (1992). Ultrastructure of the pneumatophores of the mangrove Avicennia marina. South African Journal of Botany 58 (5), 358-362 [25] Karmer D, Anderson WP, Preston J (1978) Transfer cells in the root epidermis of Atriplex hastate L. as a response to salinity: a comparative cytological and X–ray microprobe investigation. Aust J Plant Physiol 5: 739-747 [26] Koizumi, M., Takahashi, K., Mineuchi, K., Nakamura, T. and Kano, H. (1998). Light gradients and the transverse distribution of chlorophyll fluorescence in mangrove and Camellia leaves. Annals of Botany 81 (4), 527-533 [27] Levering CA, Thomson WW (1971) The ultrastructure of the salt gland of Spartinia foliosa. Planta 97: 183-196 [28] Mauseth JD, Stevenson JF (2004) Theoretical considerations of vessel diameter and conductive safety in populations of vessels. Int J Plant Sci 165:359–368 [29] Melcher PJ, Goldstein G, Meinzer FC, Yount DE, Jones TJ, Holbrook NM (2001) Water relations of coastal and estuarine Rhizophora mangle: xylem pressurepotential and dynamics of embolism formation and repair. Oecologia 126: 182-192 [30] Menezes M, Berger U, Worbes M (2003) Annual growth rings and long-term growth patterns of mangrove trees from the Braganca peninsula, North Brazil. Wetl Ecol Manag 11: 233-242 [31] Mimura T, Kura-Hotta M, Tsujimura T, Ohnishi M, Miura M, Okazaki Y, Mimura M, Maeshima M, Washitani-Nemoto S (2003) Rapid increase of vacuolar volume in response to salt stress. Planta 216: 397-402

-177- World Scientific News 129 (2019) 161-179

[32] Munns R, Tester M (2008) Mechanisms of salinity tolerance. Ann Rev Plant Biol 59: 651-681 [33] Naidoo, G. and Von-Willert, D.J. (1994). Stomatal oscillations in the mangrove Avicennia germinans. Functional Ecology 8 (5), 651-657 [34] Odum E.P. 1969. T e strategy of ecosystem development. Science 164: 262-270 [35] Parida AK, Jha B (2010) Salt tolerance mechanisms in mangroves: a review. Trees 24: 199-217 [36] Peters EC, Gassman NJ, Firman JR, Richmond H, Power EA (1997). Ecotoxicology of tropical marine ecosystems. Environ Toxicol Chem 16: 12-40 [37] Polania, J. (1990). Physiological adaptations in some species of mangroves. Acta Biologica Columbiana 2 (6), 23-36 [38] Robert EMR, Schmitz N, Boeren I, Driessens T, Herremans K, Mey JD, Van de Casteele E, Beeckman H, Koedam N (2011). Successive Cambia: a developmental oddity or an adaptive structure? PLoS ONE 6: e16558 [39] Schmitz N, Jensen S, Verheyden A, Kairo JG, Beeckman H, Koedam N (2007) Comparative anatomy of intervessel pits in two mangrove species growing along a natural salinity gradient in Gazi Bay, Kenya. Ann Bot 100: 271-281 [40] Schmitz N, Verheyden A, Beeckman H, Kairo JG, Koedam N (2006) Influence of a salinity gradient on the vessel characters of the mangrove species Rhizophora mucronata Lam. Ann Bot 98: 1321-1330 [41] Scholander PF, van Dam L, Scholander SI (1955). Gas exchange in the roots of mangroves. Am J Bot 42: 92-98 [42] Scholander, P.F., Hammel, H.T., Bradstreet, E.D. and Hemmingsen, E.A. (1965). Sap pressure in vascular plants. Science 148, 339-346 [43] Scholander, P.F., Hammel, H.T., Hemmingsen, E.A. and Bradstreet, E.D. (1964). Hydrostatic pressure and osmotic potential in leaves of mangroves and some other plants. Proceedings of National Academy of Sciences, USA 52, 119-125 [44] Scholander, P.F., Hammel, H.T., Hemmingsen, E.A. and Cray, W. (1962). Salt balance in mangroves. Plant Physiology 37, 722-729 [45] Silvestri S., Defi na A., Marani M. 2005. Tidal regime, salinity and salt marsh plant zonation. Estuar. Coastal Shelf Sci. 62: 119-130 [46] Snedaker, S.C. (1993). Pantropical trends in mangrove above-ground biomass and annual litter fall. Oecologia 96, 293-299 [47] Sperry JS, Hacke UG (2004) Analysis of circular bordered pit function I. Angiosperm vessels with homogenous pit membranes. Am J Bot 91: 369-385 [48] Touchette BW, Smith GA, Rhodes KL, Poole M (2009) Tolerance and avoidance: two contrasting physiological responses to salt stress in mature marsh halophytes Juncus roemerianus Scheele and Spartina alterniflora Loisel. J Exp Mar Biol Ecol 380: 106-112

-178- World Scientific News 129 (2019) 161-179

[49] Tyree MT, Ewers FW (1991) The hydraulic architecture of trees and other woody plants. New Phytol 119: 345-360 [50] Tyree MT, Sperry JS (1989) Vulnerability of xylem to cavitation and embolism. Ann Rev Plant Physiol Plant Mol Biol 40: 19-38 [51] Verheyden A, Kairo JG, Beeckman H, Koedam N (2004) Growth rings, growth ring formation and age determination in the mangrove Rhizophora mucronata. Ann Bot 94: 59-66 [52] Zhu J (2001) Plant Salt Tolerance. Trends Plant Sci 6: 66-71 [53] Zeiger E (2002) Plant physiology, 3rd edn. Sinauer Associates, Massachusetts Takemura T, Hanagata N, Sugihara K, Baba S, Karube I, Dubinsky Z (2000) Physiological and biochemical responses to salt stress in the mangrove, Bruguiera gymnorrhiza. Aquat Bot 68: 15-28 [54] Zimmermann, U., Zhu, J.J., Meinzer, F.C., Goldstein, G., Schneider, H., Zimmermann, G., Benkert, R., Thuermer, F., Melcher, P., Webb, D. and Haase, A. 1994). High molecular weight organic compounds in the xylem sap of mangroves: Implications for long-distance water transport. Botanica Acta 107 (4), 218-229. [55] Tomlinson, P.B. (1986). The Botany of mangroves. Cambridge University Press, Cambridge, U.K. 413 pp. [56] Das, S. and Ghose, M. (1998). Anatomy of the woods of some mangroves of Sunderbans, West Bengal (India). In: International Symposium on Mangrove Ecology and Biology, April 25-27, 1998, Kuwait. 10p. Abstracts. [57] Siska Nurfitriani, Walim Lili, Herman Hamdani, Asep Sahidin, Density Effect of Mangrove Vegetation on Gastropods on Pandansari Mangrove Ecotourism Forest, Kaliwlingi Village, Brebes Central Java. Scientific News of Pacific Region 2 (2019) 51- 73 [58] Arun T. Ram, M. Shamina, Cyanobacterial diversity from seven mangrove environments of Kerala, India. World News of Natural Sciences 9 (2017) 91-97 [59] Achmad Rizal, Science and policy in the coastal zone management. World News of Natural Sciences 21 (2018) 1-8 [60] M. I. M. Kaleel, K. Nijamir, The environmental challenges of declining mangroves: an analytical survey in Puttalam District in Sri Lanka. World News of Natural Sciences 14 (2017) 106-115

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