AGR 3506 Plant Propagation - Sexual

AGR 3506 Ridzwan

AGR 3506

Prinsip Sains Tanaman

AGR 3506 Plant Propagation - Sexual

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Advantages

• Most inexpensive• Able to multiply planting material (seeds)

most rapidly• Easy to plant• Seeds can be stored over a long period• Greater variation in plants, provide

resistance to pests & diseases• Possible to select for new genotypes

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Disadvantages

• Crops are not uniform

• Cannot guarantee quality of the crops

• Some seeds are not viable

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What are seeds ?

• the term encompasses :- fruit- Vegetative parts- True seeds

• true seeds

- Seed coat - testa

- embryo- endosperm

AGR 3506 Plant Propagation - Sexual

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Development of Seeds

• Pollination

• Fertilization

- Self pollination

- Cross pollination

- zygote → embryo- endosperm

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Seed germination

• Requirements for germination- temperature- water- oxygen- light?

• Process from seeds to seedlings

- dependent on seed viability and environment

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Seed Germination

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Seed Germination

• Seeds without endosperm• Assisted germination

- orchids

• small seeds, no endosperm

• natural germination :

with help of symbiotic mycorrhiza

• artificial germination :

in vitro - use of media under sterile conditions in laboratory

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Seed Viability

- Percentage of seeds that germinate

- Measure of viability : % germination

- Seed Testing

germination in controlled conditions rate of germination is also considered

Tetrazolium Test (2,3,5- triphenyl tetrazolium chloride)

gross measure of germination

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Seed dormancy

- Inactive phase of seeds

- causes :

- Seeds will not germinate

• impermeable seed coat

• immature embryo

• chemical factors

• unsuitable environment

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Breaking dormancy

• Scarification to make seed coats permeable – physical or chemical methods

• vernalization – low temperature

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Seed Storage

- Seeds are living organs

- seeds are stored for later use

- storage requirements depend on species

- avoid excessive respiration and enzyme activity

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Seed Storage

- method – monitor temperature, humidity, oxygen level of storage conditions. Low temperature and humidity are ideal

- low temperature storageCold room CryopreservationLiquid nitrogen : - 1960 C

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Seed Certification

- To ensure that seeds are true to type- Seed Certification- Seeds are certified by special agencies

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- 4 classification of seeds :

• Breeder Seed : breeder• Foundation Seed : from Breeder Seed• Registered Seed :

to multiply Certified Seed

• Certified Seed :

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