Introduction to Horticulture PLANT PROPAGATION Introduction to Horticulture

INTRODUCTION Propagation or Reproduction is simply the process of increasing the numbers of a species. Two types of propagation are sexual and asexual.

INTRODUCTION Sexual Reproduction is the union of an egg (ovule) and sperm (pollen), resulting in a seed. Asexual Reproduction uses a vegetative part of only one parent plant.

ADVANTAGES OF SEXUAL PROPAGATION Less expensive cost of seed Requires little skill For some plants, it is the only way to propagate them Avoids passing on some diseases Hybrid Vigor is when offspring inherits the good traits of both parents

ADVANTAGES OF ASEXUAL PROPAGATION Produces a plant quicker Plants are identical to parent plants Guaranteed product In some species, it is the only way to propagate them

SEXUAL PROPAGATION Seed production is done in dry climates to reduce plant disease problems Harvesting and collecting seeds must be done gently to reduce seed damage Cleaning seeds is important to seed quality Dry fruit seeds are easily threshed from pods or capsules Fleshy fruit seeds are more difficult as seeds are washed and dried once removed Storing of seeds requires cool temperatures to prevent germination Some require moist storage, others dry, some don’t store

SEXUAL PROPAGATION Testing and labeling of seeds are bound by federal and state laws Seeds are tested for: Certification or trueness of name, based on parent traits Origin or place grown Germination percentage or amount of viable seeds Pure seed percentage Percentage of other ingredients

SEXUAL PROPAGATION Typical Certified Seed Label Origin Germination % Purity % Other Ingredients Must be present for sale and shipment of seed

SEXUAL PROPAGATION Parts of a Seed

SEED GERMINATION Germinate means to grow or sprout Germination is dependent upon: Moisture Temperature Air Light Medium

SEED GERMINATION Moisture Temperature Air Seeds must imbibe or absorb moisture to soften the seed coat and stimulate growth Temperature Different seeds require different temperatures to trigger the growing process Air When viable seeds begin to grow, the cells of the seed start the process of respiration which requires oxygen

SEED GERMINATION Light Medium Some seeds require light to grow and some seeds are inhibited by light Medium A suitable growing medium can be soil, peat moss, or other organics The most important trait is good seed to soil contact Should be firm and moist

SEED GERMINATION Dormancy is when little or no activity is happening in plants or seeds Some seeds need help overcoming this dormancy Scarification overcomes seed coat dormancy Mechanical scraping, sanding, gouging of seed coat Sometimes done chemically by digestion of animals Stratification overcomes embryo dormancy Chilling period in cool moist environment Many trees seeds require this winter simulation

SEED GERMINATION Indirect Seeding is planting in a greenhouse where conditions are easily controlled Plants are transplanted later to where they will complete their life cycle Damping-off is common among seedlings where fungal disease causes the plant to rot at the soil line Harden-off is the process of helping plants adjust to the outdoors by reducing the temperature gradually for weeks before transplanting

SEED GERMINATION Direct Seeding is seeding where the plant will complete its life cycle considering: Site Selection Seedbed Preparation Planting Date Planting Depth and Spacing Moisture

SEED GERMINATION Site Selection Seedbed Preparation Planting Date Sunlight and soil drainage are two important factors Seedbed Preparation Soil should be firm, yet particles small enough to provide seed-to-soil contact Soil too loose or fine will erode or compact to reduce plant growth Planting Date Check local average last frost dates and plant after that About May 20th for our area (USU Extension)

SEED GERMINATION Planting Depth and Spacing Moisture Depth rule of thumb is about twice the width of seed Ex: Corn seed 3/8” wide-plant 3/4” deep Spacing is dependent on mature plant size Close spacing means more plants that compete resulting in lower production Distance wastes space and allows weeds to grow Moisture Soil should be moist but not wet Wet soil lacks oxygen and suffocates seed Soil ball test

ASEXUAL PROPAGATION The production of plants using the vegetative parts of other stock or parent plants The resulting plant is an exact clone with the same DNA Used to ensure the same product as previous generations with no chance for crossing Can give growers a shorter growing period resulting in more profit Also used in species that require exacting conditions to germinate seeds

ASEXUAL PROPAGATION Cutting is the most common and simplest method of asexual propagation The cutting, or part of the plant that is removed, is placed in growing media Roots form and individual plant develops with roots, stem, leaves and flowers. Four main types: stem cuttings, leaf cuttings, leaf-bud cuttings, and root cuttings.

ASEXUAL PROPAGATION Stem Cuttings Herbaceous cuttings come from plants without wood like geraniums Softwood cuttings are taken from new spring growth and require care Hardwood cuttings are taken during dormancy from 1-year old growth

ASEXUAL PROPAGATION Leaf Cuttings Leaf blade and petiole placed in medium Usually used on houseplants Some varieties require vein cuts to stimulate root growth

ASEXUAL PROPAGATION Leaf-Bud Cuttings Leaf blade, petiole, and short piece of stem with a bud are cut and put in medium New bud provides growth and roots form on stem

ASEXUAL PROPAGATION Root Cuttings Root pieces are planted in medium Must be cleaned and treated with fungicide Plant horizontally or vertically If planting vertically, avoid planting upside-down Cut top of root or closest to crown of plant with straight cut, bottom of root with a slant cut Commonly used on raspberries or plants that produce suckers

ASEXUAL PROPAGATION Caring for Cuttings Timing and Collecting at the proper time of year is critical to success Preparation of cuttings varies with species but many times wounding or scraping plant stimulates root growth Providing a root-inducing environment is important Use good media that is moist but not too moist Indirect sun prevents drying out of cuttings High humidity reduces transpiration rates

ASEXUAL PROPAGATION Grafting is the process of connecting two plant parts together so they will unite and grow as one plant Usually only used on woody plants Scion is the part of the new plant, usually the top portion containing the desired genetics Rootstock is the bottom that provides the root system for nutrient and water absorption Usually done during the dormancy period of trees Three main types: Whip-and-Tongue, Cleft, and Bark

ASEXUAL PROPAGATION Whip-and-Tongue Grafts Both scion and rootstock are the same diameter Usually done when under 1-inch in diameter Many fruit trees are done this way

ASEXUAL PROPAGATION Cleft Grafts Small scions are grafted to larger rootstocks Must be careful to match up the cambium layers Used when rootstock is more mature such as damaged trees

ASEXUAL PROPAGATION Bark Grafts Similar to a cleft graft where rootstock is larger Done in early spring when bark separates easily

ASEXUAL PROPAGATION Budding is similar to grafting except that the scion is only a single bud Budding accomplishes the same purpose as grafting All growth from that point will be genetically the same as the bud Done in the early spring or late fall when bark separates easily Must be cared for the same as a graft Should cover with tape or wax to prevent drying out

ASEXUAL PROPAGATION T-Budding A bud is placed underneath the bark of the rootstock Named because of the cut made in the rootstock Bud is secured and covered with rubber bands or tape

ASEXUAL PROPAGATION Patch Budding Scion is a bud cut with a small section of bark Similar piece of bark is cut from rootstock Used when bark is thicker such as on nut trees

ASEXUAL PROPAGATION Layering is a simple method where roots are formed on a stem while the plant is still attached Easy to do because no cutting is required and plant can transpire normally Larger new plants can be produced but limited amounts can be made Four basic types: Simple, Trench, Mound and Air

ASEXUAL PROPAGATION Simple and Trench layering are very similar While still attached to main plant, a piece of the stem is buried in a trench or hole 3-6 inches deep Buried section produces roots and can then be removed from the plant as a duplicate Mound layering is done in early spring on vegetative perennials or suckers of trees New growth or shoots are cut back to 2-4 inches tall Soil is mounded to bury shoots which will then form new roots and new shoots and separated

ASEXUAL PROPAGATION Air Layering A portion of the bark is removed Moist medium like peat moss is applied to the bare stem and wrapped with plastic Roots form and the branch can be removed

ASEXUAL PROPAGATION Separation and Division multiplies plant numbers naturally Separation is when natural structures of the plant are separated to grow on their own Many bulbs and corms are separated Division requires cutting of the plant material into separate sections Rhizomes, Tubers and Crowns are divided becoming separate plants Grasses, potatoes and perennial plants are divided

ASEXUAL PROPAGATION Tissue Culture or Micropropagation is the most demanding of the asexual propagation methods Small pieces or masses of cells are taken from a growing plant and placed in agar Agar is a nutrient rich, Jell-O-like growing medium A few cells contain enough DNA to grow into a new plant identical to the donor plant Requires sterile conditions such as a laboratory Most strawberries are produced this way

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