Plant Applications

1. Plant Applications Plants can reproduce both sexually and asexually. Most organic crops are grown from sexually produced seed, though fruit and nursery crop reproduction often involves asexual methods of propagation.

2. Structure of a Seed

3. Factors in Seed Germination • Light • Moisture • Temperature

4. Light • Requirements of different seed differ. • Some need only a flash. • Example - weed seed • Some need continuous light. • Example – lettuce seed- don’t have to be on the surface, however

5. Moisture • Seed vary in amount of moisture needed. • Most agricultural crops need moist conditions, but not be surrounded by water. • Some require continuous moisture till germination which may take 10+ days – example- parsley and carrots.

6. Temperature • Plants vary in the optimum temperature they require for germination. • Most will germinate over a range of temperatures, with the optimum percentage of germination at some particular temperature. • Example optimum temperature for spinach is 72 degrees, optimum for peppers is 86.

7. Special techniques • Some seeds need special procedures to overcome their dormancy • Nicking or filing the seed coat – morning glory • Cold treatment – many perennial flowers such as echinacea • Varying hot and cold treatments

8. Humic acids • Recent research has shown that humic acids can stimulate germination. • Humic acids are found in compost. • Covering the seed with compost, especially vermicompost, can increase speed and percentage of germination.

9. Propagation by seed • Most agricultural crops are sown from seed. • Root crops, grains and legumes are sown in the field. • Root crops do best when sown in the field as their roots do not like to be disturbed. • Legumes and grains are sown thickly and germinate quickly.

10. Implements for seed sowing • Hand held broadcasters • Push seeders • Tractor mounted broadcasters • Hand seed sower • Large volume vacuum seeders • Pictures from Johnnys website

11. Transplants • Disadvantages of growing from transplants • More time and effort required • Greenhouse or other protected place necessary • More resources in soil mix and flats • Transplants must be watered in • Advantages of growing from transplants: • Accurate spacing • Ability to choose best plants • Ability to control conditions of germination • Earlier planting

12. Soil Mixes • Most commercially produced mixes contain chemical fertilizers and are not allowed in an organic operation. • Organic soil mixes are becoming more available. • Home made mixes allow you to tailor the mix to your crops.

13. Ingredients in soil mixes • Peat moss • Perlite • Vermiculite • Sand • Compost • Soil • Organic amendments to add fertility

14. Soil Blocks • Eliot Coleman method to avoid using plastic pots or plug trays. • Mix soil, add water to make very moist- like cake batter, use blocker to make block, place close together in tray. • Plant seed in indention on top. • Water gently to preserve the block.

15. Asexual Reproduction • Original by Linda Rist • Modified by Georgia Agricultural Education Curriculum Office July, 2002 • Modified by Georgia Organics 2009

16. Softwood & Semi-hardwood stem cuttings Take cuttings after current or present season’s growth has partially hardened. Stem should still be flexible. Parent plant that has made 2 to 6 inches new growth during current year. Early morning is the best time to take cuttings.

17. Stem Cuttings To remember which is the top of the cutting: cut bottom at an angle. cut top straight across. Place cuttings in water as they are cut. Include 2-3 buds on each cutting. Once all cuttings are made, insert in rooting media –use sand or perlite. Containers must have holes in the bottom for drainage. Auxin is the hormone which promotes rooting. Willow extract is organic source of auxin.

18. Stem Cuttings Keep relative humidity close to 100% by placing plastic or glass over flat. Keep temperature relatively low and out of direct sunlight. Check for roots by holding cutting and tugging gently, resistance - roots developing. Growth on the tips or sides is normal, but does not indicate root growth. Harden off when root ball is 2-3 inches. After hardening off, cuttings can be planted outside.

19. Root Cuttings Can be made from any plant that will sprout or sucker from the root. Cut roots 1/8 to 1/2 inch in diameter, in pieces 1-4 inches long. Place cuttings in a flat of sand, water and cover with glass or plastic. When new shoots sprout, move plants to nursery row. Example: raspberry

20. Asexual propagation methods • Root, stem or leaf cuttings • Root – raspberry • Stem – angel trumpet • Leaf – jade plant, Christmas cactus • Dividing a tuber • Potato • Layering • Hydrangea • Grafting • Heirloom tomatoes • Fruit trees

21. Transpiration stream application • Wilting when there is adequate water. • Caused when transpiration is more rapid than water uptake by roots. • Lettuce, other plants with large leaf areas. • Especially when drip irrigation used. • Overhead watering can lower temperature and transpiration.

22. Summary • 1. Describe the structure of a seed. • 2. List the three requirements for germination of most seeds. • 3. State the effect of humic acids on germination and where they can be found. • 4. List three benefits to starting seeds in flats in a greenhouse. • 5. Describe ways to get an acceptable organic soil mixture. • 6. Identify the hormone important in stimulating rooting of cuttings and where it can be found. • 7. List three other ways to asexually propagate plants.