POLLINATION and FERTILIZATION Review Pollen

POLLINATION Review Self pollination and Cross pollination

FERTILIZATION Review Fertilization Basics

FERTILIZATION Review Pollen grain with nuclei Pollen grain with pollen tube nucleus (1) and sperm nuclei (2)

ZYGOTE to EMBRYO

SEED- ANATOMY SEED COAT – tough outer layer PROTECTION of embryo PREVENTION of water loss PROTECTS from TOTALLY DRYING OUT and FREEZING temps HILUM SCAR left behind where OVULE (SEED) attached to OVARY wall Example: Like belly button is attachment point to placenta MICROPYLE Scar left behind where POLLEN TUBE entered OVULE

Draw the Bean Seed

SEED- ANATOMY EMBRYO MINIATURE PLANT surrounded by FOOD SOURCE EPICOTYL - develops into STEMS, LEAVES, and FLOWERS HYPOCOTYL - the STEM / ROOT transition area Example: in BEANS the rounded stem that breaks through the soil surface RADICLE - the EMBYONIC ROOT that forms PRIMARY ROOT

Draw the 2 pictures Corn Seed

SEED- FOOD SOURCE FOOD SOURCE (FATS, PROTEINS, STARCHES)- Cotyledons DICOTS – 2 COTYLEDONS for food storage Bean MONOCOTS – 1 small COTYLEDON, most food stored in ENDOSPERM Corn

STEPS TO SEED GERMINATION SEED takes in WATER SEED COAT BURSTS (more O 2 + H 2 O) EMBRYO produces HORMONES (Gibberellic Acid) which activate ENZYMES (alpha-amylase) converting STARCHES to SUGARS and transported to the EMBRYO RESPIRATION STARTS > ENERGY > produces new CELLS, TISSUES and GROWTH RADICLE emerges (germination) HYPOCOTYL and EPICOTYL emerge

SEED GERMINATION

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Assignment You need to label all the parts of the seed. You need to label all the parts of the seed germinating. Using the following sentence frames, answer the questions on a sheet of paper. 1. A bean seed is a ________ because ________, while a corn seeds is a _______ because ________. 2. During germinations ________________ sprouts first followed by __________________. 3. Bean and corn seeds have __________________ parts in common.

CONDITIONS for GERMINATION 1. VIABLE SEED 2. Favorable ENVIRONMENTAL conditions 3. Favorable INTERNAL conditions The seed is said to be DORMANT, if seed is VIABLE and one or more conditions is not met.

CONDITIONS for GERMINATION VIABLE SEED Dependent on SPECIES VIABILITY prolonged by: COOL temperatures Low HUMIDITY (low H 2 O) Low O 2

CONDITIONS for GERMINATION Favorable ENVIRONMENTAL conditions Water Saturated vs. not saturated Oxygen Dry, sandy vs. clay soils TEMPERATURE Cool vs. warm season crops LIGHT Light – celery, lettuce, weeds No light - peas

CONDITIONS for GERMINATION Favorable INTERNAL conditions If seed is VIABLE and it has FAVORABLE ENVIRONMENTAL CONDITIONS, but there is LACK of GERMINATION INTERNAL FACTORS causing DORMANCY 1. PHYSICAL BARRIERS 2. PHYSIOLOGICAL BARRIERS 3. CHEMICAL BARRIERS

PHYSICAL Barriers Seed coat IMPERMEABLE to H 2 O Seed coat RESISTS EXPANSION Fix- SCARIFICATION: BREAKING the SEED COAT using one of the following methods. MECHANICAL CHEMICAL TEMPERATURE- high

PHYSIOLOGICAL BARRIERS IMMATURE EMBRYO Fix- TIME AFTER RIPENING Fix– STRATIFICATION: Application of MOISTURE and LOW TEMPS or alternation to BREAK the SEED COAT Usually due to Abscissic Acid (ABS) and low temperatures

CHEMICAL Barriers INHIBITORS in SEED COAT Remedy – LEACH with WATER Desert seeds - Phenolic acid INHIBITORS in FRUIT Remedy – SOAK and REMOVE PULP and DRY seed Tomatoes and Strawberries

SURVIVAL SIGNIFICANCE of SEED DORMANCY Insures GERMINATION during times that maximize SURVIVAL of SEEDLINGS SOME SEEDS of the same SPECIES can VARY in LENGTH of DORMANCY ADVANTAGE to WILD, NATIVE seed and WEEDS Allows them to germinate over many seasons Example: Weeds – “ONE year’s seedin’ is SEVEN years weedin’.”

Assignment You will choose 5 from the list of seeds and tell me if the seed has a PHYSICAL BARRIERS, PHYSIOLOGICAL BARRIERS, and/or CHEMICAL BARRIERS. What needs to be done to the seed in order for it to germinate? Sunflower Tomato Peppers Cilantro Lettuce Peas Morning Glory Purple Hyacinth Bean Vine Egg plant Purple Coneflower