1. Plant Nutrition & Soil Chapter 37

2. Macronutrients & Micronutrients  Essential nutrients – Nutrients that must be consumed, plants cannot make these nutrients  Macronutrients – Needed in large amounts  Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorous, Sulfur, Potassium, Calcium, & Magnesium  Micronutrients – Needed only in small amounts  Iron, Manganese, Zinc, & Copper

4. Nitrogen  80% of atmosphere  In the form of N 2  Unusable by plants  Most important macronutrient for plants  Important for plant growth and crop yield  Needed for proteins, nucleic acids, and chlorophyll  Nitrogen Fixation (N 2  NH 3 )  Converts atmospheric nitrogen into a biologically- usable form

5. -- Atmospheric N 2 is converted into NH 3 (Nitrogen fixing bacteria)  NH 4  NO 3 (nitrifying bacteria) which can be used by plants for incorporation into organic systems -- Ammonifying bacteria can also convert organic material into NH 4 as well

6. Rhizo -  Rhizosphere – soil layer bound to the plant’s roots  Rhizobacteria – soil bacteria  Some rhizobacteria are called plant-growth-promoting rhizobacteria (PGPR)  Wanna guess what they do? They promote plant growth by: Producing chemicals that stimulate growth Produce antibiotics to protect roots from infection Absorb toxic metals or make nutrients available for plants

7. Rhizobacteria (Page 2)  Plant benefits were discussed on prior slide  Bacterial benefits since 20% of photosynthetic products go to the bacteria  Hence, bacteria benefit from a healthy plant (roots) in the rhizosphere

8. Rhizobium Bacteria  Bacteria that fix atmospheric nitrogen + supply it as ammonium  Legumes have a ready source of nitrogen  Symbioses with Rhizobium (Root living) bacteria  Peas, soybeans, peanuts, and alfalfa  Nodules – swellings in the roots infected by rhizobium bacteria  Bacteroids – bacteria in vesicles in root cells in the nodules

10. Mutualistic Relationship?  Rhizobium bacteria provide nitrogen in a usable form Used to make amino acids for plant growth  Plant provides photosynthetic products to the nodules via the vascular system

12. Mycorrhizae  Mutualistic relationship between plant roots and fungus  Two types  Ectomycorrhizae Mycelium forms a dense sheath over the root surface Hyphae extend from the root to the soil = increase surface area for absorption of water & minerals Hyphae do NOT penetrate root cells

13. Mycorrhizae (Page 2)  Endomycorrizae Also called arbuscular mycorrhizae (That’s a mouthful!) Most common type (85% of associations) Look like regular roots No dense mantle covering root surface Hyphae penetrate the cortex (Which tissue type?)

15. Angiosperm Reproduction Chapter 38

16. Angiosperm Reproduction  Angiosperms have 3 unique features: Flowers, Fruits, & Double Fertilization  Microsporangia Pollen sacs in the anther Diploid cells = meiosis  male gametophyte (pollen) Pollen has 2 haploid nuclei Tube nucleus – 1 sperm develops into a pollen tube Generative nucleus – divides into 2 sperm cells which remain inside the pollen tube

18. Ovary  Ovules form with a diploid cell  Soon 4 haploid megapsores form  Eventually get 8 haploid nuclei, but only 3 are most important 1 haploid nucleus = egg Will combine with sperm nucleus to form the zygote 2 other nuclei are called polar nuclei Polar nuclei will fuse with sperm nucleus to make 3n endosperm

19. Watch Animation  38-01.swf

22. Pollination  Pollen lands on stigma  Pollen tube made from pollen grain Pollen tube grows down into the ovary  When pollen tube reaches ovule, double fertilization occurs

23. Double Fertilization  Double fertilization is the union of 2 sperm cells forming zygote & endosperm  Unique to angiosperms  1 sperm fertilizes the egg  zygote Zygote develops into the embryo  sporophyte  Other sperm combines with both polar nuclei = 3n nucleus This 3n tissue  endosperm Endosperm – food storing tissue in the seed

24. After double fertilization  Ovule develops into a seed  Ovary develops into fruit which encloses the seed Fruit protects the enclosed seed Fruit aids in dispersal by wind or animales  Seed coat – protects embryo & its food supply  Radicle – embryonic root  Epicotyl – shoot tip with pair of miniature leaves

26. Seed  As the seed matures, It goes dormant Low metabolic rate, growth and development are suspended  Seed resumes growth given suitable environmental conditions for germination

27. Asexual Reproduction in Plants  Asexual reproduction in plants is called vegetative reproduction  Fragmentation  Type of vegetative reproductive  When a part of the parent plant is separated and then generates into a new plant, genetically identical to parent plant  Self-fertilization is another means of asexual reproduction