Seed Germination PDF

Direct Germination: Occurs immediately after seed formation while still on the mother...

Direct Germination: Occurs immediately after seed formation while still on the mother as seen in viviparous plants like Phizophora. plant, Types of Seed Germination Delayed Germination: Seeds germinate after maturity when suitable conditions are avail- able. Definition: Dormancy is a rest period seeds where do not germinate despite favorable conditions. Dormancy in Seeds Duration: Dormancy can last from weeks to a hundred years. over Hard seed coats prevent water penetration Canna (e.g., indica, Amaranthus sp.). Seed Dormancy: Treatment methods include removing or puncturing the coat and chemical treatmen- ts. Prevents gas exchange, affecting oxygen in- and take CO2 release (common in Asteraceae family). Impermeable… Germination may occur over time due to decomposition or environmental expo- Internal Factors Affecting Germina… sure. Some plants, like Ranunculus, require com- Incomplete Embryo Forma… embryo plete development before germination. Develops from the plumule and epicotyl of the Seed Germination embryo. Some seeds, like Rosa sp. and Pyrus malus, Characteristics of Stems Post-Ripening Changes: a period after ripening for chemical changes. need Supports leaves, flowers, and fruits, and is generally aerial and ascending. Presence of substances in seeds (e.g., sunflower, Iris sp.) that prevent germination un- Support: Bears leaves, flowers, and… conditions change. Inhibitory Sub… til Transport: Conducts water and minerals roots from to other parts of the plant. Definition: The period seeds can remain vi- varies able by plant type. Storage: Some stems store food and water. Functions of Stems Seed Viability Oxalis sp. seeds are damaged by dry air. Stem Morphology Vegetative Propagation: Stems can reproduce asexually through structures like runners and Examples of Seed Longevity: Willow (Salix sp.) retains vitality for several days. tubers. Cassia seeds can remain viable for about 160 Tendrils: Help weak-stemmed plants climb years. grapevine). (e.g., Plant Vigour: Overall health and strength of the Thorns: Provide defense against herbi… plant. Phylloclades and Cladodes: Reduce Environmental Conditions: Conditions dur- transpiration and perform photosynthe- Modifications of Stems seed ing formation impact vitality. sis. This outline captures the key concepts and Germination Timing: Early germination can detailed explanations from the provided text on Factors Affecting Seed Vitality to weak plants. lead plant morphology and anatomy. Storage Conditions: Temperature, humidity, ventilation and during seed storage. Anchorage: Fixes the plant in the soil. Fundamentals of Seed Age: Older seeds may have reduced viability. Absorption: Takes in water and minerals the Plant Morphology and fromsoil. Primary Functions Anatomy Synthesis of Growth Regulators: Produces Non-green, cylindrical, and descending parts of hormones for plant growth. the plant. Characteristics of Roots Prevention of Soil Erosion: Holds soil particles Develop from the radicle of the seed and are together. positively geotropic and hydrotropic. Storage of Food: Some roots store nutrients Protects the root meristem and secretes (e.g., carrot, sweet potato). mucilage for soil penetration. Root Cap: Additional Support: Roots like prop roots Contains starch grains for gravity percep… provide stability. Functions of Roots Actively dividing cells that add new cells to the Climbing: Clinging roots assist in… Meristematic Region: root. Nitrogen Fixation: Roots of legumes enrich Newly formed cells elongate, increasing root with soil nitrogen. Regions of the Root Region of Elongation: length and absorbing water. Breathing: Pneumatophores facilitate exchange. Contains root hairs for increased surface area gas Region of Root Hairs: for absorption. Moisture Absorption: Hygroscopic roots ab- moisture sorb from the air. Secondary Functions Permanent zone of the root where lateral roots Region of Maturation: emerge. Morphology of Roots Absorption of Food: Parasitic roots extract nutrients from host plants. Main Tap Root: Develops from the radicle, with secondary and tertiary branches. Assimilation: Green roots per- photosynthesis. Root System Types form Adventitious Roots: Develop from parts of the plant other than the radicle. Floating: Roots of aquatic plants help them stay afloat. Fleshy Taproot: Swollen roots for food storage (e.g., carrot, radish). Balancing: Roots in floating plants help maintain stability. Pneumatophores: Aerial roots in man- Modifications of Taproot plants grove for gas exchange. Reproduction: Adventitious buds on roots can grow into new plants. Nodulated Taproots: Contain nitrogen-fix- bacteria ing (e.g., legumes). Tuberous Roots: Swollen roots that store food (e.g., sweet potato). Prop Roots: Provide additional support Modifications of Adventitious Roots banyan (e.g., tree). Clinging Roots: Help climbing plants attach to supports (e.g., ivy).