1. Plant Reproduciton and Nutrient Needs
Basic Plant Science
AFNR-BAS-13: Explain and demonstrate basic plant science principles including plant health, growth and reproduction.

2. Asexual Reproduction
Asexual reproduction: producing new plants from parts of a plant (leaves, stems, etc.)
another name for plant reproduction is propagation
propagation: deliberately controlling and manipulating the reproduction of a plant
new plants created through asexual reproduction are identical to the parent plant
genetic duplicates of parents are often called clones

3. Asexual Reproduction Methods
Cuttings and Division/Separation
Grafting
Layering
Tissue Culture (a.k.a. Micropropagation)

4. Cuttings and Separation/Divsion
most common and simple methods of asexual reproduction
separation and division: splitting apart a root or root system into two or more pieces which each become a new plant
(ex. hostas, potatoes, daylillies, ornamental grasses)
cuttings: segments of leaves, stem, or roots are cut off and then placed in growing media to develop into new plants
(ex. begonias, ivy, pothos, African violet, wandering Jew)
usually plants that root easily are used and the cuttings are treated with rooting hormone before being planted

5. Grafting method commonly used on trees by orchards and nurseries
the upper part of one plant is joined to the lower part of another so they grow as one plant
(ex. apples, citrus, hibiscus)
scion: the part of the graft that will become the stem
rootstock: the lower portion of the graft that includes the roots
union: where the two grafts meet

6. Layering
part of a stem or tip that is still attached to the parent plant is covered in soil or media until adventitious roots form
most successful on woody plants
the parent plant provides water and nutrients to the new plant until roots are formed

7. Tissue Culture
entire new plants are grown from small pieces of plant tissue placed in in artificial media under sterile conditions
the media is a gel containing moisture, nutrients, and hormones for plant growth
used to make large populations of plants that are genetically identical
can be used to improve genetics quickly

8. Advantages of Asexual Reproduction
keep best characteristics pure
some plants are difficult to reproduce sexually
shorten the time to produce a mature plant versus starting from a seed
can create large numbers of identical plants
can reduce disease occurrence

9. Disadvantages of Asexual Reproduction
the main disadvantage is the potential for impact on biodiversity of a species
also if a particular plant clone is susceptible to certain diseases, there is potential to lose entire crops
can be more expensive and requires more skill

10. Sexual Reproduction in Plants
pollination: the transfer of pollen grains from the male part of the flower (the anther) to the female part (the stigma)
self-pollination: on plants with complete flowers the pollen falls from the anther onto its own stigma
cross-pollination: plants that have incomplete flowers (or have complete flowers but are not compatible for self-pollination) require pollinators to transfer the pollen to another plant
common pollinators: wind, birds, insects, bats

11. Flower Anatomy

12. Plant Parts
Flowers:
complete flowers: flowers that have all the parts (sepals, petals, stamen, and pistil)
incomplete flowers: flowers that lack one of the four main parts - petals, sepals, pistil, or stamen
male flowers will not have a pistil and female flowers will lack stamen
monoecious: plants that have male and female flowers on the same plant
dioecious: plants that have male and female flowers on separate plants

13. Sexual Reproduction in Plants
fertilization: when the male sex cell joins with the female sex cell (the ovule)
the pollen grain lands on the stigma and then grows a tube down the style to the ovary to make a gamete (a fertilized egg)
the ovule expands and develops into the seed while the petals and sepals fall off; most flowers have many ovules and therefore develop many seeds
in some plants, the ovary expands and develops into the fruit or pods

14. Sexual Reproduction in Plants
germination: the process of a seed developing into a plant
seeds will remain dormant until the proper conditions are met and these vary depending on the type of seed
common germination variables are planting depth, amount of moisture, and proper temperature
scarification: wearing away the seed coat to allow water in to the embryo
stratification: cold treatment of seeds to simulate natural winter conditions to promote germination

15. Sexual Reproduction Advantages
seeds are easily stored from year to year and over a long period of time
an inexpensive way to grow a large number of plants
easy to do and usually does not require special skills

16. Sexual Reproduction Disadvantages
offspring are genetically different from parents so desirable traits can be lost or depleted
germination rates can be low
length of time to a mature plant can be long

17. Nutrient Needs of Plants
Carbon (C), Hydrogen (H), and Oxygen (O) are the three elements plants obtain from the atmosphere
used by plants for metabolic processes to make food and break down stored sugars
nutrients in the soil must be dissolved in water before being absorbed through a plant's roots

18. Nutrient Needs of Plants
there are 16 or 17 essential nutrients needed by plants in different amounts
not always enough of these are in the soil for healthy plant growth so we use fertilizers or compost to add the nutrients to the soil
deficiency: a shortage of a given nutrient needed by a plant

19. Nutrient Needs of Plants
Macronutrients
needed in the greatest amount by plants for maximum growth
Nitrogen (N), Phosphorous (P), and Potassium (K) are the major nutrients usually lacking in the soil because plants use large amounts for growth
Calcium (Ca), Magnesium (Mg), and Sulfur (S) are also major nutrients but are not usually needed when fertilizing because there is enough in the soil

20. Nutrient Needs of Plants
Micronutrients
elements essential for plant growth which are needed in only very small quantities
also known as trace elements
Boron (B), Copper (Cu), Chlorine (Cl), Iron (Fe), Manganese (Mn), Molybdenum (Mo), and Zinc (Zn)

21. Nutrient Needs of Plants
Fertilizers
materials containing essential plant nutrients that are added to the environment around the plant
generally added to irrigation water or soil, but some can also be added to the air or sprayed on plant leaves
All fertilizers are labeled with three numbers giving the percentage of nitrogen, phosphorus, and potassium (N-P-K).

22. Nutrient Needs of Plants
Fertilizers
Filler is also included and is important to evenly spread the fertilizer and avoid burning plants with too much fertilizer.
The best fertilizer to use depends on many factors, such as the nutrients needed, soil structure, soil chemistry, and method of applying the fertilizer.
Soil pH is one of the most important soil properties that affects the availability of nutrients.

23. Nutrient Needs of Plants
Fertilizers
organic fertilizers: the nutrients contained in the product come from the remains or by-products of a once-living organism
examples: cottonseed meal, blood meal, bone meal, hoof and horn meal, and all manures

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