Vegetative Growth and Plant Propagation - Crop Production - Lecture Slides, Slides of Biology

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Unit 6: Vegetative Growth and Plant Propagation Docsity.com Unit 6: Vegetative Growth and Plant Propagation • Unit 6 Objectives – Understand how stems, leaves, and roots grow, and the coordinated efforts of the plant to make this happen – Stages of development, and factors affecting plant growth – Discuss seed germination – Understand sexual vs. asexual reproduction, and self-fertilization vs. cross-fertilization Docsity.com Unit 6: Vegetative Growth and Plant Propagation • Initiation of embryo growth • Anabolism and formation of new cell structures • Emergence – 4 environmental factors affecting germination • Water – Absorption of water is first step in germination – A sufficient amount of available water must be present at germination, and must continue to be present after growth begins – Medium for transport, activates enzymes that initiate metabolic function, Docsity.com Unit 6: Vegetative Growth and Plant Propagation • Light – Can stimulate or inhibit germination, depending on the species • Oxygen – Respiration is taking place in all viable seed – Medium where seed is placed should be loose enough for oxygen to permeate through the soil – Reduced oxygen supply can reduce or inhibit germination • Heat – Affects the rate and percentage of germination – Temperature needs for germination also vary w/ species – Usually 65-75º is optimal for most plants Docsity.com Unit 6: Vegetative Growth and Plant Propagation • Germination begins when: – Mature embryo in the seed – Large enough endosperm to sustain growth – Sufficient growth regulators to initiate the process • Seeds Lacking True Dormancy – Common vegetable seeds – Ready to sprout after planting – All they need is proper moisture and temperature • Seeds w/ True Dormant Embryos – Thick seed coat » Restricts water access to the seed » Scarification – allows thick coated seeds to germinate, usually occurs naturally (How?) Docsity.com Unit 6: Vegetative Growth and Plant Propagation • Radicle elongates and breaks through the seed coat – Grows in the direction the kernel is pointed (except up) • Coleoptile emerges from the seed • 2-5 seminal roots emerge • Can occur in 4-5d under optimal conditions • Crown area found 1-1.5” beneath soil surface – Permanent roots develop – If seed is planted deeper the mesocotyl is responsible for pushing coleoptile through the soil surface • First leaves emerge from the coleoptile after it emerges Docsity.com Unit 6: Vegetative Growth and Plant Propagation • Time from planting to emergence is most affected by temperature – 1 wk. under optimal conditions – May be 2-3 wks in cool conditions • What other factors can influence emergence? – The Seedling • 1st leaf blade has a rounded tip • Leaves begin photosynthesis and the plant no longer depends on the seed for survival • Crown root system begins to take control from the seed roots Docsity.com Unit 6: Vegetative Growth and Plant Propagation • Apical meristem initiates new leaf formation – Point is below ground until the internodes elongate – Aboveground leaves can be destroyed, and additional leaves can still form » Unless disease occurs • Hypogeal emergence – Growing point remains beneath soil surface for a period of time after emergence • Epigeal emergence – Growing point is above soil surface at the time of emergence Docsity.com Unit 6: Vegetative Growth and Plant Propagation – Growth Patterns • 3 classifications: – Annuals » Complete life cycle in less than 1 yr. » Shoot growth in continual until senescence » Flowering, fruit, and seed production occurs in the summer » Herbaceous – Biennials » Life cycle in two growing seasons, longer than 1 yr but not necessarily 2 yrs » Stored energy from 1st yr used in reproduction in 2nd yr Docsity.com Unit 6: Vegetative Growth and Plant Propagation » Ex. Celery, asparagus, sugar beets » Limited stem growth in first season » Dormant winter period » Flowering, fruit, and seed production during second season » Senescence and death follow soon after production » Herbaceous – Perennials » Continue growth for 2+ yrs » Vegetative growth during and after reproductive phase » Ex. Bermuda grass, shrubs, trees » Shoot growth resumes each spring » Herbaceous or woody Docsity.com Unit 6: Vegetative Growth and Plant Propagation • Phase Changes – Juvenility • Plant may have a different appearance • Inability to form flowers during this phase • Length varies from days to years – Most crops vary amount of days – Trees can have 30-40 yr juvenile stages – Maturity • Able to produce flowers, fruit, and seeds • May have different appearance • May last days to years Docsity.com Unit 6: Vegetative Growth and Plant Propagation • Sexual Reproduction – Requires formation of flowers in order to get pollination and fertilization – Flower Induction • Perfect flowers – both stamen & pistil • What do the parts of the flower do? • Houses gametes, attract pollinators Docsity.com Unit 6: Vegetative Growth and Plant Propagation – Pollination & Fertilization • Pollination – transfer of pollen from anther to stigma • What is self-pollination? – Ex. Soybean & tomato • What is cross pollination? – Ex. Corn & pine trees – How can this occur? • Fertilization occurs when a small tube from the pollen grain grows through an opening in the ovary (micropyle) Docsity.com Unit 6: Vegetative Growth and Plant Propagation – Results in: » Formation of the zygote or seed » Endosperm – Fruit Development & Maturation • Ovary begins to develop into a fruit after fertilization • Fruit aids in the dispersal of seeds – What are some adaptations to fruits that aid in dispersal? – Seeds • Three main parts of seeds: – Seed coat » Protects embryo Docsity.com Unit 6: Vegetative Growth and Plant Propagation • Layering • Division • Rhizomes • Stolons • Tillers/suckers • Plant Improvement – Deliberate attempt to change genetic architecture of a plant Docsity.com Unit 6: Vegetative Growth and Plant Propagation – Modern Practices • What is the most common criterion for selection? • Tends to affect all other functions of the plant • What are some other genetic selections? • Research has allowed farmers to produce more food from the same amount of land – Basic Genetics • Offspring tend to be very similar to the parent, but might not be identical – Ex. Soybeans will be almost identical, Apple trees may be very different Docsity.com Unit 6: Vegetative Growth and Plant Propagation – Related to the amount of genetic variation • New variations can suddenly appear (mutation) • Geneticists use these methods to create new/improved varieties • Phenotype vs. Genotype • Homozygous vs. Heterozygous • Dominant vs. Recessive & Incomplete Dominance – Self-pollination • Produces virtual clones of the parent Docsity.com