SEED GERMINATION
SEED:
Fertilized and matured ovule containing an embryo in a dormant state.
Or
Seed is the germ of life.
A bridge between the old and new.
The fruit of yesterday s harvest,
Seed germination:
Resumption of active growth of embryo resulting the rupture of seed coat and emergence as well as establishment of young plant under favorable condition of water temperature O2 and some place of life.
Or
Germination is the emergence and development from the seed embryo of those essential structure which for the kind of the seed in question , are indicative of the ability to produce a normal plant under favorable condition (AOSA-2000)
A0SA-Association of Office Seed Analyst.
TYPE OF GERMINATION:
- Epigial germination. E.g. Gram
- Hypogial germination. E.g. Rice
- Viviparous germination .e.g. Jackfruit in some case.
Process of germination, pattern of germination, phases of germination or sequence of evince of germination:
- Water imbibitions.
- Enzyme activation and digestion.
- Initiation of embryo bulb.
- Ruptured of seed coat and seedling emergence.
- Seedling growth and establishment.
FACTOR AFFACTING SEED GERMINATION:
A. EXTERNAL FACTOR:
- Water
- Temperature
-Air
-Light in some case
B.INTERNAL FACTOR:
-Presence of oxine.
-Preserve food materials
-Computation of dormancy.
-viability of seed.
VIABLE:
POWER OF GERMINATION OF SEED.
Date: 09-07-o8
Lecture –o2
FACTOR AFFACTING SEED GERMINATION:
WATER IMBIBITION:
(1) The most medium seed absorb water from the environment.
(2) Some seed absorb water by its specific organs (seed coat, cotiaeton).
(3) Some seed absorb water by its all part (seed coat, epicotile, promeul,reticulum) and increase of hydration accelerate the internal activities.
(4) After imbibitions seed coat may rupture/ burst.
ENZYME ACTIVATION AND DIJESTION:
Each stage is characterize by the cellular activity with the appearance of some specific enzyme (hydrolytic enzyme or hydro less) and increase in chemical reaction digestion, transportation and assimilation of stored food material are express this stage. (Cellulose, lipase, maltase, proteinlase,)
INITIATION OF EMBRYO CROP:
Increases of root-shoot axis (Epicotile, Hypocotile) occur due to appearance of hydrolytic enzyme and these enzyme triggers chemical reaction within the seed. The wrought of root –shoot axis are caused by the expense of stored food material. The end of this stage some stored food materials are disabling or deleted.
RUPTURE OF SEED COAT AND SEEDLING EMERGENCE:
After imbibitions seedling may emerge due to some internal pressure created by an increase root-shoot axis. In dicotyledonous seed pressure may also create by its cotyledons.
SEEDLING GROWTH AND ESTABLISHMENT:
Seedling starts its usual growth following cell division and cell enlargement and cell differentiation. Establish of seedling follows epigeous and hypogenous germination. Epigeous germination hypocotyls increase quickly and raise the cotyledon above the ground. Research case is done for hypogenous germination (the germination starts at water imbibitions and end at self photosynthesis mechanism). When seedling produces it own fruit from soil than the germination process is completed.
FACTOR AFFECTING GERMINATION:
EXTERNAL FACTOR:
(1) WATER:
(a) Water help to soft the seed coat and sullen the internal structure.
(b) Water help to absorb the gas.
(c) Water help to transport the nutrient from endosperm (monocot) and cotyledon (dicot) to the growing point of embryo where it is necessary.
(d)ter lp to hydrate the food material and actives its various function.
(2)TEMPERATURE:
Every seeds have its maximum, minimum and optimum temperature for it germination is called cardinal temperature. The majority % of seeds are germinate at 15-30C. The maximum temperature at which the most of the seed are germinate 35-40C. Some seed germinate at freezing point.
(3) AIR:
Ordinarily air contains 0.3% CO2, 20%O2 and about 80%N2. In experiment it has been proved that O2 favor the germination process, CO2 > O.3% interred the germination process, N2 no influences the germination process.
SEED VIGOR
SEED VIABILITY:
Viability denotes the degree to which a seed is alive, metabolically active, and possesses enzymes capable of catalizing metabolic reaction needed for growth.
FACTOE AFFECTING SEED VIABILITY:
Environmental exposure during seed development.
Degree of maturation.
Storase condition.
SEED VIGOR:
It has defined as “the potential for rapid uniform germination and fast seedling growth under general field condition”