NCERT Exemplar class 11 Biology Solutions  Morphology of Flowering Plants

Multiple Choice Questions
1. Rearrange the following zones as seen in the root in vertical section and choose the correct option.
A. Root hair zone
B. Zone of meristems
C. Rootcapzone
D. Zone of maturation
E. Zone of elongation
(a) C, B, E, A, D (b) A,B,C,D,E
(c) D, E, A, C, B (d) E, D, C, B, A
Soln. (a): A typical root possesses five parts
or regions:
(i) Root cap covers the root meristem. The cells of the root cap secrete mucilage which lubricates the passage of root through the soil. Cells of root cap possess starch grains which are believed to take part in graviperception. Function cap is the protection of root meristem from soil particles.
(ii) Growing point or meristematic zone produces new cells for the root cap and basal region of the root. Therefore, it is essential for the growth of the root.
(iii) Cells of zone of elongation are newly formed cells which lose the power of division. They elongate rapidly which increases length of the root. The external cells possess the power of absorption of water and mineral salts from the soil.
(iv) Root hair zone also represents the zone of differentiation or maturation. Most of the water absorption occurs in this region. Some of the outer cells of this zone give rise tq lateral tubular outgrowths called root hairs. The root hairs increase the exposed surface of the root for absorption.
(v) Region or zone of mature cells forms the bulk of the root without undergoing any – further change. The outermost layer of this region cannot help the root in water absorption because they have thick walled or impermeable cells. Its only function is to anchor the plant firmly in the soil. Lateral roots also arise from the interior of this region.

2. In an inflorescence where flowers are borne laterally in an acropetal succession, the position of the youngest floral bud shall be
(a) proximal    (b) distal
(c) intercalary (d) anywhere.
Soln.(b): In acropetal succession, the youngest floral bud is towards growing point and oldest is towards the base.

3. The mature seeds of plants such as gram and peas, possess no endosperm, because
(a) these plants are not angiosperms
(b) there is no double fertilisation in them
(c) endosperm is not formed in them
(d) endosperm gets used up by the developing embryo during seed development.
Soln. (d): Majority of dicot seeds (e.g., pea, gram, bean, mustard, groundnut) and a few monocot seeds (e.g., orchids, Sagittaria), are . called nonendospermic or exalbuminous seeds because the endosperm gets consumed during seed development and the food is stored in cotyledons and other regions.

4. Roots developed from parts of the plant other than radicle are called
(a) taproots
(b) fibrous roots
(c) adventitious roots
(d) nodular roots.
Soln.(c): Adventitious roots are those which develop from any part of the plant other than radicle.

5. Venation is a term used to describe the pattern of arrangement of
(a) floral organs
(b) flower in inflorescence
(c) veins and veinlets in a lamina
(d) all of them.
Soln.(c): The arrangement of veins and veinlets on the lamina of a leaf is called venation. Venation is of three main types reticulate, parallel and furcate.
Reticulate venation : The veinlets form a reticulum or network. Reticulate venation is found in most dicots.
Parallel venation : Veinlets are inconspicuous. Reticulations are absent. The veins run parallel to one another. Parallel venation is characteristic of most monocots.
Furcate venation : The veins branch dichotomously. The finer branches do not form a reticulum. It is common in ferns (e.g., Adiantum). Among higher plants furcate venation is found in Circeaster.

6. Endosperm, a product of double fertilisation in angiosperms is absent in the seeds of
(a) coconut (b) orchids
(c) maize (d) castor.
Soln.(b): Refer answer 3.

7. Many pulses of daily use belong to one of the families below (tick the correct answer).
(a) Solanaceae (b) Fabaceae
(c) Liliaceae (d) Poceae
Soln.(b) : A number of legumes or pulses are obtained from Fabaceae- broad bean (Vicia faba), soyabean (Glycine max), kidney bean (Phaseolus vulgaris), cowpea (Vigna unguiculata = V. sinensis), pea (Pisum sativum), gram (Cicer arietinum), green gram (Vigna radiata = Phaseolus radiatus = P. aureus, mung), pigeon pea (Cajanus cajan, arhar), etc.

8. The placenta is attached to the developing seed near the
(a) testa (b) hilum
(c) micropyle (d) chalaza.
Soln.(d): Seed contains an embryo or miniature plant in suspended animation, adequate reserve food for future development of the embryo and a covering for protection against mechanical injury, loss of water, pathogens, etc. A seed may have one or two coverings called seed coats. The outer or the only seed coat (if one is present) is called testa while the inner one is named as tegmen. Surface of the seed possesses a fine pore at one end called micropyle. Hilum is a place where funiculus or stalk of seed is borne. Some seeds also show chalaza (place of origin of seed coats) and raphe (part of funiculus fused with seed wall).

9. Which of the following plants is used to extract the blue dye?
(a) Trifolium (b) Indigofera
(c) Lupin (d) Cassia
Soln.(b): Indigo (blue dye) is obtained from the leaves of Indigofera tinctoria and I.sujfruticosa. The leaves contain a colourless chemical which on exposure to air turns bluish.

10. Match the followings and choose correct option
Group A Group B
A. Aleurone layer           ( i)withoutfertilisation
B.Parthenocarpic fruit (ii)Nutrition
C.vule                                   (iii)Doublefertilisation
D.Endosperm                    (iv)Seed
(a) A-(i), B-(ii), C-(iii),D-(iv)
(b) A-(ii), B-(i), C-(lv), D-(iii)
(c) A-(iv), B-(ii), C-(i), D-(iii)
(d) A-(ii), B-(iv), C-(i), D-(iii)

Short Answer Type Questions
1. Roots obtain oxygen from air in the soil for respiration. In the absence or deficiency of 02, root growth is restricted or com pletely stopped. How do the plants growing in marshlands or swamps obtain their 02 required for root respiration?
Soln. Plants growing in marshlands or swamps obtain their 02 through modified negatively geotropic tap roots called pneumatophores. Pneumatophores or respiratory roots come out of water and pick up oxygen for root respiration.

2. Write floral formula for a flower which, is bisexual; actinomorphic; sepals five, twisted aestivation, petals five; valvate aestivation; stamens six; ovary tricarpellary, syncarpous, superior, trilocular with axile placentation.
Soln. Floral formula of a flower which, is bisexual; afctinomorphic; sepals five, twisted aestivation, petals five; valvate aestivation; stamens six; ovary tricarpellary, syncarpous, superior, trilocular with axile placentation is
ncrt-exemplar-class-11-biology-solutions-morphology-of-flowering-plants-1 (2)
3. In Opuntia the stem is modified into a flattened green structure to perform the function of leaves (/’.e., photosynthesis). Cite some other examples of modifications of plant parts for the purpose of photosynthesis.
Soln. In some plants, roots are become assimilatory or photosynthetic. Adventitious roots are modified into assimilatory or photosynthetic roots in Trapa, Tinospora. Cladode is an aerial modification of stem in Asparagus to perform photosynthesis.

4. In swampy areas like the Sunderbans in West Bengal, plants bear special kind of roots called _______
Soln. In swampy areas like the Sunderbans in West Bengal, plants bear special kind of roots called pneumatophores.

5. In aquatic plants like Pistia and Eichhornia, leaves and roots are found near_______
Soln. ln aquatic plants like Pistia and £ ichhorn ia, leaves and roots are found near surface of water

6. Reticulate and parallel venation are characteristic of_______and_______
Soln. respectively.
Reticulate and parallel venation are characteristic of dicots. and monocots respectively.

7. Which parts in ginger and onion are edible?
Soln. In ginger, edible part is rhizome which is modified shoot that stores food materials. The edible part of onion is fleshy scale leaves.

8. In epigynous flower, ovary is situated below the _______
Soln. In epigynous flower, ovary is situated below other floral organs viz sepals, petals and stamens.

9. Add the missing floral organs of the given floral formula of Fabaceae. ncrt-exemplar-class-11-biology-solutions-morphology-of-flowering-plants-2 (2)
Soln. Floral formula of Fabaceae is ncrt-exemplar-class-11-biology-solutions-morphology-of-flowering-plants-3 (2)

10. Namedhe body part modified for food storage in the following.
(a) Carrot________________
(b) Colocasia_______________
(c) Sweet potato_______________
(d) Asparagus_______________
(e) Radish_______________
(f) Potato_______________
(g) Dahlia_______________
(h) Turmeric_______________
(i) Gladiolus_______________
(j) Ginger________________
(k) Portulaca_______________
Soln. (a) Carrot – modified fleshy conical tap root
(b) Colocasia-highly condeused and specialised underground stem, corm
(c) Sweet potato – tuberous fleshy adventitious root
(d) Asparagus – fasciculated fleshy adventitious root
(e) Radish – fusiform fleshy tap root.
(f) Potato – modified underground stem, tuber
(g) Dahlia – fasciculated fleshy adventitious root
(h) Turmeric – modified underground stem, rhizome
(i) G/fld/o/iis-highly condensed and specialised underground stem, corm
(j) Ginger – modified underground stem, rhizome
(k) Portulaca – moniliform or beaded adventi ¬tious root.

Short Answer Type Questions
1. Give two examples of roots that develop from . different parts of the angiospermic plant other than the radicle.
Soln. Two examples of roots that develop from different parts of the angiospermic plant other than the radicle are as follows:
(i) Stilt roots develop from the basal node of the main stem, examples: maize and sugarcane.
(ii) Prop roots develop from the upper part of the stem, especially the horizontal branches. Example: Banyan.

2. The essential functions of roots are anchorage and absorption of water and minerals in the terrestrial plant. What functions are associated with the roots of aquatic plants. How are roots of aquatic plants and terrestrial plants different?
Soln. The root system in hydrophytes is feebly developed and root, root hairs and cap arq absent. In some floating plants such as Utricularia, Ceratophyllum, etc., no roots are developed, and in submerged plants such as Vallisneria, Hydrilla etc., water dissolved mineral salts and gases are absorbed by their whole surface. In plants like Pistia, Eichhornia, Lemna, etc., no root cap develops, but root pocket is formed instead. An aquatic plant is, in reality, submerged in or floating up on a nutrient solution. In hydrophytes the root system is functioning chiefly as holdfast or anchors, and a large part of the absorption takes place through the leaves and stems.

3. Draw diagrams of a typical monocot and dicot leaves to show their venation pattern.
Soln. Labelled diagrams of monocot leaves showing parallel venation are as follows:
Labelled diagrams of monocot leaves showing parallel venation are as follows

4. A typical angiosperm flower consists of four floral parts. Give the names of the floral parts . and their arrangements sequentially.
Soln. A typical angiosperm flower consists of following four parts:
(i) Calyx : This is the outermost whorl of the flower and first whorl of the non-essential organs. Calyx consists of sepals. Sepals are usually small, green and protect the other floral parts in the bud condition.
(ii) Corolla : Corolla is the next whorl of non ¬essential organs. It is composed of petals. Petals are usually brightly coloured to attract insects for pollination.
(iii) Androecium : Androecium forms the third whorl of the flower. Androecium consists of stamens which are the male reproductive organs. Stamen is morphologically equivalent to microsporophyll.
(iv) Gynoecium : The gynoecium or pistil is composed of one or more carpels. It is innermost whorl.

5. Given below are a few floral formulae of some well known plants. Draw floral diagrams from these formula.
Soln. (i) Floral diagram for floral formula,

(ii)Floral diagram for floral formula,
(iii)Floral diagram for floral formula,

6. Reticulate venation is found in dicot leaves while in monocot leaves venation is of parallel type. Biology being a ‘Science of exceptions’, find out any exception to this generalisation.
Soln. Exceptionally, reticulate venation is present in monocot leaves such as Smilax Dioscorea etc., and parallel venation is present in dicot leaves such as Calophyllum, Eryngium etc.

7. You have heard about several insectivorous plants that feed on insects. Nepenthes or the pitcher plant is one such example, which usually grows in shallow water or in marsh lands. What part of the plant is modified into a ‘pitcher’? How does this modification help the plant for food even though it can photosynthesise like any other green plant?
Soln. Insectivorous plants are those plants which grow in marsh lands or soils deficient in nitrogen. These plants contain chlorophyll and are capable of manufacturing carbohydrates by the process of photosynthesis but in order to fulfil their nitrogen requirement they capture and digest insects. In insectivorous plant Nepenthes, the leaf lamina gets modified into pitcher like structure and the apex of lamina changes into lid of pitcher. Pitcher contains digestive enzymes which digest the trapped insects. This type of modification supplements nitrogen nutrition in the nitrogen deficient substratum

8. Mango and coconut are ‘drupe’ type of fruits. In mango fleshy mesocarp is edible. What is the edible part of coconut? What does milk of tender coconut represent?
Soln. Mango and coconut are drupe type of fruits. In mango fleshy mesocarp is edible whereas in coconut, endosperm is edible part. Coconut meal represents cellular endoperm whereas milk of tender coconut represents the nuclear endosperm in liquid form.

9. How can you differentiate between free central and axile placentation?
Soln. Differences between free central and axile placentation are as follows:
(i) In axile placentation, ovary is partitioned into chambers whereas in free central placentation ovary is single chambered.
(ii)The ovule bearing column occurs in the central region where septa meet in axile placentation whereas in free central placentation ovule bearing column lies free in the centre of ovary and septa are absent.

10. Tendrils are found in the following plants. Identify whether they are stem tendrils or leaf tendrils.
(a) Cucumber
(b) Peas
(c) Pumpkins
(d) Grapevine
(e) Watermelons
(a) Cucumber: Stem tendril.
(b) Peas: Leaf tendril.
(c) Pumpkins: Stem tendril.
(d) Grapevine: Stem tendril.
(e) Watermelon: Stem tend i ii.

11 .Why is maize grain usually called as a fruit and not a seed?
Soln. Maize grain is caryopsis type of fruit which develops from monocarpellary pistil
with superior unilocular uniovuled ovary. The thin pericarp is inseparable and completely fused with the seed coat. It is most advanced kind of dry fruit.

12. Tendrils of grapevines are homologous to the tendril of pumpkins but are analogous to that of pea. Justify the above statement.
Soln. Tendrils of grapevine and tendrils of pumpkin have the same origin i.e., they are modification of stem, but different functions such as tendrils of grapevine help in climbing whereas tendrils of pumpkin help in creeping. So, tendrils of grapevine and tendrils of pumpkin are homologous because of same origin but different function. On the other hand, tendrils of pea are modification of leaves. Both tendrils of grapevine and tendrils of pea help in climbing. So, they are analogous because they have different origin but same function.

13. Rhizome of ginger is like the roots of other plants that grows underground. Despite this fact ginger is a stem and not a root. Justify.
Soln. Rhizome of ginger is like the roots of other plants that grows underground but rhizome of ginger is a modification of stem is not a root because it bears nodes, internodes, terminal buds, axillary buds and scale leaves, and it doesn’t bear root hair and root cap.

14 . Differentiate between:
(a) Bract and bracteole
(b) Pulvinus and petiole
(c) Pedicel and peduncle
(d) Spike and spadix
(e) Stamen and staminode
(f) Pollen and pollenium
(a) Differences between bract and bracteole are as follows:
(b) Differences between petiole and pulvinus are as follows:
(c) Differences between pedicel and peduncle are as follows:
(d) Differences between spike and spadix are as follows:
(e) Differences between stamen and stami-node are as follows:
(f) Differences between pollen and pollinium . are as follows:

Long Answer Type Questions
1. Distinguish between families Fabaceae, Solanaceae, Liliaceae on the basis of gynoecium characteristics (with figures). Also write economic importance of any one of the above families.
Soln. In the Family Fabaceae, gynoecium is monocarpellary, with unilocular superior ovary. Ovary has marginal placentation, and many ovules are arranged in two alternate rows. Style is bent, and stigma is simple or capitate.
In Family Solanaceae, gynoecium is bicarpellary, syncarpous, ovary is superior, carpels are placed obliquely, generally bilocular, placentation is axile. Ovules are many in each locule, placentae are swollen. A nectariferous disc or lobe may be present, stigma is capitate or lobed.
In Family Liliaceae gynoecium is tricarpellary, syncarpous. Ovary is superior, trilocular with two to many ovules in each locule. Placentation is axile, rarely parietal, styles are united or separate, stigma is free or fused and trilobed.
Economic importance of Family Fabaceae is as follows:
(i) Food : A number of legumes or pulses are obtained from Fabaceae. E.g., Pisum sativum (pea), Cicer arietinum (gram), Lens culinaris (Masur), Phaseolus mungo (urd),
Phaseolus aureus (mung) Cajanus cajan (arhar), Glycine max (soybean), etc.
(ii)Fodder : Medicago sativa (Alfalfa),
Medicago denticulata (toothed, bur clover), Trifolium alexandrium (Egyptian clover), etc’are common herbs used as fodder.
(iii)Oils : They are extracted from seeds of Arachis hypogaea (groundnut or peanut) and Glycine max (soybean).
(iv)Soil fertility: Nodule bearing papilionace ¬ous plants increase nitrogen content of the soil. E.g., Crotolaria, Sesbania, Cyamopsis.
(v) Fibres : Obtained from the stems of Crotolaria juncea (sunn hemp) and Sesbania species, used in making cordage, sacks, nets, tissue paper, etc.
(vi)Dyes : Indigo is obtained from the leaves of Indigofera tinctoria.
(vii)Gum : Cyamopsis tetragonoloba yields guar gum which is employed in pharmaceuticals, textiles, paper, plastics and photography.
(viii)Meditines : The roots of Glycyrrhiza glabra (malatthi) are used as demulcent, expectorant and in treating gastric ulcers. Fresh leaf juice of Abrus precatorius (Jeweller’s weights, ratti) is useful in treating leucoderma.
Juice of flowers of Sesbania grandiflora improves eye sight.
(ix)Timber : Dalbergia sissoo (Shisham) and Dalbergia latifolia (Indian rosewood) provide wood for making furniture.
(x)Ornamentals : Lathyrus odoratus, Clitoria ternatea, Lupinus. Erythrena indica are ornamental plants.

2. Describe various stem modifications associated with food storage, climbing and protection.
Soln. Stem modifications associated with food storage are as follows:
(i) Rhizome: Rhizome is a thickened,
underground, dorsiventral stem that grows horizontally at a particular depth within the soil. They store food materials and appear tuberous. E.g., Zingiber officinale (ginger), Curcuma longa (turmeric), Canna indica.
(ii) Corms: Corms is an underground, modified main stem. It grows vertically at a particular depth in the soil. It stores food materials. E.g., Colocasia.
(iii) Tubers: Tuber is the tuberous tip of an underground branch. The axillary branches (stolons) that are produced near the soil surface grow into the soil and their tips become swollen due to the accumulation of starch and proteins. E.g., Solanum tuberosum (potato).
Stem modifications associated with climbing are as follows:
(i) Tendrils: Tendrils are thin, wiry, leafless and spirally coiled branches. The terminal part of a tendril is sensitive. It holds the support by coiling around it. The tendrils help the weak stems to climb the support. In some weak stemmed plants, the axillary bud or terminal bud may be modified to form tendrils which are specially called stem tendrils, e.g., Passiflora, Cissus.
(ii) Hooks : Hook is hard, woody, persistent curved, climbing organs found in strangers. E.g., Hugonia, Artabotrys. The axillary buds in Hugonia are modified into hooks.
Stem modifications associated with protection are as follows:
Thoms: Thom is a hard, woody, pointed structure. Thom is formed by the modification of axillary bud or terminal bud which has lost the apical growth. Thoms are endogenous in origin and differ from spines and prickles. E.g., Bougainvillea, Carissa, Duranta. The terminal bud in Carissa and the axillary buds in Duranta and Bougainvillea are modified into thorns. Thoms protect the plant against attack by herbivorous animals.

3. Stolon, offset and rhizome are different forms of stem modifications. How can these modified forms of stem be distinguished from each other?
Soln. Stolon, offset and rhizome are different forms of stem modifications. Differences
between these modified stems are as follows: Stolon is modification of subaerial stem. It is a thin lateral stem branch which when comes in contact with the soil produces roots. Usually shrubs produce some weak thin branches (stolons) at ground level. If these branches happen to touch the soil, roots are produced at the point of contact. When these branches are separated from the mother plant, they grow into individual plants.
Offset: Offset is modification of subaerial stem. It is a weak, elongated, horizontal branch of one internode that arises in the axil of a leaf. At the trip, it produces cluster of leaves above and tuft of roots below. The offset may break off from the parent plant and act as an individual plant. Offset are found usually in aquatic plants and rarely in terrestrial plants. They are helpful for vegetative propagation e.g., Eichhornia, Agave, Pistia.
Rhizome: Rhizome is modification of
underground stem. It is a thickened, underground, dorsiventral stem that grows horizontally at a particular depth within the soil. It stores food materials and appears tuberous. E.g., Zingiber officinale (ginger), Curcuma longa (turmeric), Canna indica

4. The mode of arrangements of sepals or petals in a floral bud is known as aestivation. Draw the various types of aestivation possible for a typical pentamerous flower.
Soln. The various types of aestivation possible for a typical pentamerous flower are as follows:
(i) Valvate aestiva tion: In valvate aestivation, the margins of petals just touch each other without any overlapping, e.g., Brassica.
(ii) Twisted aestivation : In twisted or contorted type, one margin of each petal overlaps the margin of an adjacent petal and the other margin being overlapped by margin of another adjacent petal, e.g., china rose.
(iii) Imbricate aestivation : Imbricate is aestivation of five parts, where one is exterior, one is interior and rest three are having one margin exterior’ and other interior.
(iv) Quincuncial aestivation : Quincuncial is aestivation of five parts, where two are exterior, two interior and the fifth is having one margin exterior and the other interior.
(v) Vexillary aestivation: Vexillary aestivation when the standard petal is large and overlaps the two wing petals which in turn
overlap the keel petals. It is technically known as vexillary aestivation. E.g. pea,
bean, Irtdigofera, Tephrosia, etc.
overlap the keel petals. It is technically known as vexillary aestivation. E.g. pea,
bean, Irtdigofera, Tephrosia, etc.

5. The arrangements of ovules within the ovaryis known as placentation. What does the term placenta refer to? Name and draw varioustypes of placentations in the flower as seen inT.S.orV.S.
Soln. Placenta is a parenchymatous cushion present inside the ovary where ovules are borne. The arrangements of ovules within the ovary is known as placentation. __
(i) Marginal placentation : In marginal placentation the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, as in pea.
(ii) Axile placentation : When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentation is said to be axile, as in china rose, tomato and lemon.
(iii) Parietal placentation: In parietal placentation, the ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one-chambered but it becomes two chambered due to the formation of the false septum, e.g., mustard and Argemone. ‘
(iv) Free central placentation : When the ovules are borne on central axis and septa are absent, as in Dianthus and Primrose the placentation is called free central.
(v) Basal placentation : In basal placentation, the placenta develops at the base of ovary , an’d a single ovule is attached to it, as in sunflower, marigold.

6. Sunflower is not a flower. Explain.
Soln. Sunflower is not a single flower rather it represents a complete inflorescence, called capitulum or racemose head. Small sessile flowers called florets develop compactly over discoid peduncle. They open in centripetal order. They are surrounded and protected by an involucre of bracts. The florets are of two types namely, ray florets and disc florets. Ray florets are usually female and zygomorphic and disc florets are bisexual and actionomorphic.
In Helianthus, the ray florets are towards the periphery and disc florets are at the centre of the inflorescence.

7. How do you distinguish between hypogeal germination and epigeal germination? What is the role of cotyledon (s) and the endosperm in the germination of seeds?
Soln. In hypogeal germination, epicotyl grows first and only the plumule is pushed out of the soil, while cotyledons and all other parts remain under the soil. It is shown by some dicotyledons e.g., pea, gram, broad bean (Vicia faba), mango, etc. and by most of the monocotyledons, e.g., rice, maize, coconut, etc.
In epigeal germination, hypocotyl grows first and it pushes the cotyledons and other parts of the seed out of the soil. It takes place in cucurbits, mustard, Tatnarindus, French bean (Phaseolus vulgaris), Castor, Onion, Alusma plantago, etc.
Food is necessary for embryo during seed germinations which comes from cotyledons or endosperm. So, they have nutritive function.

8. Seeds of some plants germinate immediately after shedding from the plants while in other plants they require a period of rest before germination. The later phenomena is called as dormancy. Give the reasons for seed dormancy and some methods to break it.
Soln. The reasons for seed dormancy are as follows:
(i) Impermeability of seed coats to oxygen, E.g., Xanthium.
(ii)Impermeability of seed coats to water, e.g., many plants of Leguminosae.
(iii)Hard seed coat which does not allow proper growth of developing embryo, etg., mustard.
(iv)Some seeds contain an imperfectly developed immature embryo.
(v) Embryos require after-ripening in dry storage. These embryos although developed fully, do not germinate unless kept in storage in a dry place for sometime after harvest.
(vi) Some plants produce such chemical compounds (germination inhibitors) that inhibit the germination of their own seeds, e.g., tomato. The pulp of the fruit produces an inhibitor.
Various methods have been employed for breaking dormancy of seeds. Some of which are discussed as follows:
(i) Mechanical scarification : Weakening of hard seed coat with anything of sharp edge, e.g., pieces of glass.
(ii)Chemical scarification: Treating the seeds with dilute acids, fat solvents etc.
(iii)Chilling treatment : Low temperature treatment, alternating low and high temperature treatment.
(iv)High temperature treatment: Permeability of seed coat in Alfaalfa seed increases when they are kept in water at the temperature of 85-90 °C for sometime.
(v) Neutralising the effect of inhibitors: Effect of germination inhibitors in the seeds can be counteracted by giving low and high temperature treatment to seeds or by treating the seeds with KNO3, thiourea, gibberellin, ethylene chlorohydrin, etc.