seed formation and maturation process.pptx

Thanks for your cooperation let continue a business

1. SEED FORMATION,DELELOPMENTAND MATURATION SEED FORMATION

2. SEED FORMATION,DELELOPMENTAND MATURATION SEED FORMATION

3. POLLINATION

4. POLLINATION,agents seen

5. POLLINATION,agents seen Biotic agents Ants Bats Beetle Moths Bees Butterflies Snails Birds Abiotic agents Wind water

6. POLLINATION,agents seen Importance of pollination It leads to the production of fruits Help in improving the immunity of offspring against environments stress and diseases Factors affecting pollination Loss of habitat or flower that provide pollen and nectar Pesticide exposure Parasite and pathogens

7. Cont….

8. Fertilization

9. cont

10. Fertilization

11. SEED QUALITY Analytical purity Species purity Free from weed and dieses

12. SEED GERMINATION AND DORMANCY

13. Seedling structures of maize Seedling structures Structure of a maize (monocotyledon )

14. Seedling structures of bean Seedling structures Structure of a bean (dicotyledonous)

15. Differences btn mono & dicot

16. Cont….

17. Cont….

18. Cont….

19. Cont,….

20. CALCULATION Seed germination % Plant population calc Seed rate calc

21. SEED GERMINATION AND DORMANCY

22. Germinaion germination , the sprouting of a  seed ,  spore , or other reproductive body, usually after a period of dormancy. The absorption of  water , the passage of time,  chilling , warming,  oxygen  availability, and light exposure may all operate in initiating the process.

23. Types of germination Types of Seed Germination There are  two main types of seed germination -- epigeal  and  hypogeal  germination--which indicate whether the  cotyledonary node  is above or below ground during germination. Epigeal Germination In epigeal germination,  cell division  in the hypocotyl is faster and more vigorous than cell division in the epicotyl . The hypocotyl's actively growing meristem induces  cell growth  and extension, pushing portions of the hypocotyl , the cotyledonary node, and epicotyl , above the ground.

24. Types of germination Hypogeal Germination In hypogeal germination,  cell division  in the apical meristem at the end of the epicotyl is faster and more vigorous than in the hypocotyl . The cotyledons and all the hypocotyl stay below the soil surface as a result of this cell division and elongation. The cotyledonary node, then, is found below ground.

25. Cont….. If you are having trouble distinguishing between epicotyl and hypocotyl as well as epigeal and hypogeal, it might help to remember that the prefix " epi " means above, while "hypo" means below. As such: Epi cotyl = embryonic region  above  the cotyledon attachment point. Hypo cotyl = embryonic region  below  the cotyledon attachment point. Epi geal = cotyledonary node is  above  ground. Hypo geal = cotyledonary node is  below  ground.

26. cont….

27. Cont….

28. Cont…. PATTERN OF SEED GERMINATION. The major events occurring during seed germination are water imbibitions Enzymes activation embryo growth , rupture of seed coat, emergence of seedling and finally seed establishment.

29. Pattren of germination IMBIBITIONS It is a process whereby water passés through natural openings in the seed coat, then diffusing into the seed tissues. The imbibed water performs several functions: Causes cells to become turgid and colloids to be hydrated causing the seed to swell Softens the seed coat rendering it more permeable to oxygen and carbondioxide The swelling cause rupture of the softened seed coat Stimulates enzymatic activity   ENZYME ACTIVATION When water is imbibed three type of enzymes activated; -Enzymes that aid transfer of nutrients from storage tissues to growing points -Enzymes that break down stored food in tissues -Enzymes that trigger chemical reactions for synthesis of new materials

30. Cont…. (iii) INITIATION OF EMBRYO GROWTH It is growth of the root – shoot axis that results into differentiation of the epicotyls hypocotyls and radicle . It occurs at the expense of storage tissues which are degenerated to release food reserves. Depending on the species embryo growth may be by cell division or elongation. In species like lettuce root protrusion is primarily the result of cell elongation. RUPTURE OF SEED COAT AND SEEDLING EMERGENCE The rupture is caused by internal pressure from enlarging root-shoot axis and partially by action imbibed water. Ordinarily the primary root is the first true structure to emerge. The imbibed water also causes softening of the seed coat. In some species for example coconuts seedling emergence is made possible after disintegration of the seed coast under action of decomposing microorganisms. SEEDLING ESTABLISHMENT. This starts when seedlings begin water uptake and photosynthesis. This is when the seedlings become firmly supported in the soil medium

31. Germination requirement REQUIREMENTS FOR SEED GERMINATION  Viability of the seed and absence of dormancy  Favorable environmental conditions: Water, temperature, oxygen, light, suitable medium

32. Cont…. Water . Is especially important for enzyme activation. The amount required for seed to start germination depends on species.  Optimum amount is that which completely saturates the seed.  Maize germination begins when seed absorbs 30.5% of its own weight of water. The seed is saturated at 43% m.c  Extreme moisture may inhibit germination as dwarf bean and sugar beet. Oxygen . It is necessary for respiration. Most species require the normal atmospheric oxygen concentration (21%). Few species geminate better at higher or lower concentrations.  Nitrogen has effect  Carbon dioxide concentration above 0.003% hinders germination while lower condemnation has no effect.

33. Cont…. Temperature. A specific continuous or alternating temperature range may be necessary for germination. Temperature influences the rate of water uptake and metabolism. Response depends on species and sometimes cultivar and time from harvest (thermo-dormancy). Optimum for most species is between 15- 30 c, 20- 30 c for tropical species. For most species the maximum range is 35-40 c. Minimum can be down to 0 c . Some species require diurnally fluctuating (during the day ) temperatures for optimum germination, for example many tree and grass species. The need for fluctuating temperature is associated with dormancy. Light It is a requirement for some species. The mechanism is similar to that controlling floral indication, stem elongation and formation of pigments in certain fruits and leaves, radical development in certain seedlings and unfolding of the epicotyls in bean seedlings . Both light quantity and quality are important. OTHER FACTORS INFLUENCING GERMINATION:  Chemicals example KNO 3 and H202  Osmotic pressure  pH  Pre- harvest and storage conditions  Radiation  Mechanical damage of the seed

34. Seed doemancy Seed dormancy can be defined as the state or a condition in which seeds are prevented from germinating even under the favourable environmental conditions for germination including, temperature, water, light, gas, seed coats, and other mechanical restriction

35. Cont….

36. Cont…. There are certain major causes for the seed dormancy. Listed below are the few reasons for the seed dormancy. Light Temperature Hard Seed Coat Period after ripening Germination inhibitors Immaturity of the seed embryo Impermeability of seed coat to water Impermeability of  seed coat to oxygen Mechanically resistant seed coat Presence of high concentrate solute

37. Cont…. Types of Seed Dormancy The seed dormancy is of following types: Innate dormancy It is the condition of seeds which is incapable of germination even if conditions suitable for seedling growth are supplied. This inability to germinate may be due in certain species to the embryo being immature at the time of dispersal. Enforced dormancy It is the condition of seeds which is incapable of germination due to an environmental restraint which includes, an adequate amount of moisture, oxygen, light and a suitable temperature. Induced dormancy This type of seed dormancy occurs when the seed has imbibed water, but has been placed under extremely unfavourable conditions for germination. Finally, seed fails to germinate even under more favourable conditions.

38. Cont…. Methods of Breaking Seed Dormancy The different methods of breaking dormancy are mentioned below: The natural breaking of Seed Dormancy Nature of dormancy stops when the embryo gets appropriate environment such as adaptive moisture and temperature. The seed coat that exists in many species becomes permeable due to the rupturing of smoothing action of natural agents like microorganism, temperature, and abrasion by the digestive tract of birds and animals that feed on these seeds. Other natural methods include: Completion of the over-ripening period. Leaching of inhibitors present in the seed coat. Inactivation of inhibitors by the supply of cold, heat, and light. Leaching of the excess and highly concentrated solutes from the seeds. Production of growth hormones which can neutralize the effect of inhibitors

39. Cont… Artificial Overcoming of Seed Dormancy Some of the artificial methods used for breaking seed dormancy are listed below: Action with hot water for termination of waxes, surface inhibitors, etc. Rupturing of seed coats by filing, chipping, or threshing through machines. Exposure to heat, cold or light, depending upon the type of seed dormancy. By applying Hydraulic pressure for 5 to 20 minutes in order to weaken the tough seed coats. Seed coats are treated with concentrated sulphuric acid for removing all traces of the mineral acid

40. Cont…. Treatment to break dormancy in seeds There are separate treatments to overcome dormancy, and they are further divided into the following groups: Seed coat treatment These treatments make a hard seed coat permeable to water or gases either by softening or cracking. This process is called scarification. The treatment can be either chemical or physical in nature. Embryo treatments Stratification:  The incubation of seeds at an appropriate low temperature over a moist layer before transferring to a temperature suitable for germination. High-temperature treatment:  Incubation at 40-50 °C for a few hours to a few days may have an effect in overcoming dormancy in some species. For instance, rice seeds treated with hot water at 40°C for at least 4 hours. Chemical treatments Plant growth regulators  or other chemicals can be used in induced germination growth regulators.

41. Cont… Importance of Seed Dormancy It follows the storage of seeds for later use by animals and man. It helps in the dispersal of the seeds through the unfavourable environment. Dormancy induced by the inhibitors present in the seed coats is highly useful to desert plants. Allows the seeds to continue to be in suspended animation without any harm during cold or high summer temperature and even under drought conditions. Dormancy helps seeds to remain alive in the soil for several years and provides a continuous source of new plants, even when all the mature plants of the area have died down due to natural disasters.

42. Cont…

43. Cont..

44. Cont…

45. Cont…

46. Cont…