Unit 17 Agriscience Plant Reproduction The reason plants do such a good job of surviving all the problem That the environment throws at them is that they do such a good Job of reproducing. Reproduction using many methods have given Them the ability to adapt. The first ideas of cloning and genetic Manipulation came from the study of the vegetative reproduction Of plants. Propagation or reproduction – increasing the number of a Type of plant by Sexual or Asexual means. Sexual reproduction is The formation and union of gametes. Sexual reproduction allows us To crossbreed plants to increase vigor. Asexual reproduction, vegetative, is using parts or a part of a plant to produce another plant.

Sexual Reproduction A seed has stored food in it and remains dormant until germination. The following conditions are necessary for germination. Water – (imbibition) activates enzymes that starts the usage of the food Some seeds need to be scarified the nicking of the seed coat so they Can absorb water. All living (viable) seeds respire and need oxygen. Some seeds need light to aid the process of germination The correct temperature is needed for the germination process To take place each species requires a different temperature. If soil Conditions are too cold seeds may rot before they germinate.

Asexual Reproduction The processes of asexual reproduction is used extensively in the Greenhouse industry. Stem cuttings- can be made on herbaceous anytime while woody plants Need to be done in the fall. It requires the use of a rooting hormone And growth medium. Tip cuts – a long stem that has a terminal bud Section cut – taken from the middle of a stem with no terminal bud Cane cut – section of stem placed in a horizontal position Heel cut – a football shaped section cut out with a bud on it Single eye cut – one bud per cut Double eye cut – two buds per cut usually used on alternate leaf plants

Asexual Reproduction cont. Leaf cutting is another method of propagating plants. This can only Be used on herbaceous plants. Leaf – A leaf without a petiole is placed vertically in the growth medium Leaf petiole – petiole of the leaf is placed in the growth medium Leaf section – a leaf is cut into wedge shape each containing at least one Vein. Split vein – open a vein in a leaf turn leaf upside down and place it in the growth medium.

Asexual Reproduction cont. Root cuttings – can only be done when plants are dormant, the Roots are actually cut. Layering is done when the stem comes into contact with the growth Medium. Simple – The stem is made to contact the medium Tip – bend the stem and place the tip into a hole in the medium Air – splitting of bark, hormone applied and then covered Divisions – separating crowns like strawberries Grafting – the Scion is the top part that is grafted onto the root stock. The union is the place where the two parts meet. When grafting care Must be taken to make sure the cambium layers touch and that the Wound is protected from insects and disease.

Asexual Reproduction cont. Grafting continued Bud – a small piece of bark is cut with a bud on it to be placed On another stem T- bud – t cut in the root stock and a shield shaped bud is placed in

Tissue Culture This is the process of using a specialized part of a plant to create A new plant in sterile conditions so no diseased associated with The original plant. It may be called micro-propagation. Used exclusively in seed potato production. This process is very expensive and time consuming also the following Areas must be done. Everything must be clean and sterile Clean plant tissue must be collected Multiplication medium must be used usually agar. Transplant medium must be used Sterile glassware must be used Sterile tools must be used Scalpels must be used to make clean cuts.

Cloning This is the process of tissue culture where a single cell is used From a parent plant to create a genetically exact copy of that plant.