Unit 5: Reproductive Biology

Unit-v SEED true seed is defined as a fertilized maturce ovule that passess and embryonic plant Cembry stored good materials & a protective seed coaf. A seed is a developed ovule and also represents. a reproductive unit. Structurce: The main structural units of seeds are ax Embryo by seed ccat C Endosperm cus Embryo It is composed of seed Leaves called cotyledons, which are attached to the tip of embicy- onic axis. It is developed on the zygote, which is divided into epicotyl, hipocotyl, radicle, plumwe & cotyledons. Epicotyl region is the embryonic axis above the point of the attachment of cotyledons Hypocotyl is the embryonic axis present below the point of the attachment of cotyledons. Radicle is the lower most tip of the hypocotyl, which give rise to primarey root upon germination. * The plumule is the tip of to shoot apex. epicotyl which give rise cotyledons are the embryonic Leaves, which arre two in dicots & one in monocots. by Seed coat The toteguments of the ovule develops into caocap, which is the cuterecovering of the ood. seed The inner integuments forma tegimen z, outere integuments, gorema testa. In some seeds like caster, theire is a ward like out growth) at the hilum region. -cie orn Arle... which is called coru It protects the embryo ondaeperem grcaro desicca tion, mechanical injury and attacks from micro-ot- ganismin seed coat helps to dispersal of seed due to presence of wings. Endosperm t' is the good reserve, which is the cheis H source of meutrcition. Endosperm when present the seed as is called albuminuts seed or endospermous goods. Ex: castern, maize, wheat etc. илалов 2010 when endosperem is not preesent it is called non- albuminuts or non-endosporrmous. Ex gream & bea2 2019 رودخ The endosperem lickin'oli, cacbohydrate & starich, protein beteranog ad * The resituas nucleus which is a thin paper layer in the seed is called percisperem. Ex: Found in amarcanthaceae, chenopodiaceae. * Importance of seed arce having geeds are very imporeteent fore plant which several functions. 10 seed protects the embryo from which mechanical inxjury, external injury due to it's seed coat 20 seeds helps in providing, nourishment as it conden- se endosperm, which arce Rich in carbohydrates, lipids 36 It helps in dispersal to diggn tions for reproduction & survival. geographically nota nole- y seed demostrates company dormancy Hil germinat -ion so that it can be preserve for congéictime 5% It is also economically benefits to moun terims 0f food reserves, minercars, alkaloids medicines, ete.. Bb seeds are the important where new plants can be generated nistong, Dispersal Mechanism of Seed toIt regers to the movement or transporet of seed away from the parcent plant. It involves the transfere of seeds from the main parent' to diggn. Locations by diggn, agencies... It is required for survival, reproduction & neutrei- tional purpose. seed dispersal mechanism is mainly two types go Autochorcy *It is the dispersal of seed through plants con mechanism. *It is found in caster, ruellia, night jusmin, etc. by Allochorcy ~ It is the dispersal of the seed through exterinol means (biotic & abiotic agents). commonly, by, wind Canemochorry) by water (hydrochory), by animals (roochory), by bireds (Arni- -thochorry). *This transports can be for long distance Callochary aru, for shoict distance (Autochorey) →Broadly all the above mechanism of seed dispersal is explained below. * Autochorry It is the dispersal of seed by own mechanism or can be explosive way It is gore shorect distance & limited dispersal met- -hod. * The drey foods due to hydroscopic nature burst of It is of diggn. types i Balochoreyant po * The turgore pressurce or the tension within the fruit Forcefully inject the seed. Outside upto 100 mt. 1 Ex: Mimosa, cassia 49% Barochory of It is due to the gravitational forcee Ex Apples, coconut. 747 Blastochory *Herre the stem, of the plant crawls along the ground. Contivy Herpochorry the seeds creoung. Due to trichomes & humidity * Allochory It is the dispersay seed for long distance to disan geographical location biotic is described bellow. & abiotic which *Dispersal by wind ~ It is called animochorry. minute, light weight which can be seeds are of blown away. →Winged seeds are present Ex: Moringa (drumstick) (Pinus) seeds possess parachute mechanism with minute hairs called pappus. Ex: Asteracya family. seeds posses sensore mechanism where porces are present within the capsules Ex: papaver or dog flower. perrcistance style, hairs, ballon like appendages are preesent în diggn, plants for easily careried away by. wind. *Dispersal by water It is called hydrochorcy. *It has floating devices & protective covering. It has spongy thovamus with airt spaces. arenchymatous tissue made up of parenchy- → It has a -matous cells Ex: found in seeds of coconut, arisma, sagittarcia & nymphia. *Dispersal by Animaus It is called biotic dispercscu ornby animals. The seeds possess hooked, stigg hair, bristles & spines * which becomes spine attached to the skin, que ol0001 of passing animals who carry them to Longere dista- -nce. Ex Pigers nali, arcistida It is of 2011owing types *Ornithoenory: Dispersal by birds * seurochorry Dispersal by reptiles