Plant Physiology

Plant Physiology Travis DeLozier

Plant Physiology • The study of how the many organs function and the complex chemical processes

Photosynthesis • Photosynthesis is the important process of manufacturing of food for a plant to carry on life processes of life, growth and reproduction • It is the conversion of carbon dioxide and water in the presence of light and chlorophyll into glucose, oxygen and water

Photosynthesis • Chlorophyll, or the green material inside the leaves and stems, are essential as a catalyst in the photosynthesis process • It is contained in small, membrane-bound bodies called chloroplasts which are located in the mesophyll of the leaf • Chloroplasts are the actual location of the conversion of solar energy (sunlight) into store energy or simple sugars called glucose

Respiration • A process in which energy and carbon dioxide are released due to digestion or the breakdown of plant tissues during periods of darkness • All living cells carry on the process of respiration • Occurs day and night • Uses the sugars and starches produced by photosynthesis, and convert them into energy for the plant

Photosynthesis Food is produced Energy is stored Occurs in cells that contain chloroplasts Oxygen is released Water is used Carbon dioxide is used Occurs in sunlight Respiration Food is used for plant energy Energy is released Occurs in all cells Oxygen is used Water is produced Carbon dioxide is produced Occurs in dark and light Photosynthesis/Transpiration

Transpiration • Transpiration is the process by which a plant gives up water vapor to the atmosphere • Most plants transpire about 90% of the water that enters through the roots • Transpiration takes place primarily through the stoma • As humidity transpiration , vice versa. • air movement the rate of transpiration • As temp. transpiration

Turgor

Water – Plant Growth • Cools the plant • Moves sugars and plant chemicals • Transporting minerals through the plant that it has dissolved in the soil making it possible to be transported • Maintaining turgor pressure

Air – Plant Growth • The atmosphere of air that surround the plant structure above ground must contain both carbon dioxide (photosynthesis) and oxygen (respiration) • Plants grown in a greenhouse may require a carbon dioxide generator

Soil – Plant Growth • Is a catalyst in the life processes of germination, growth, production, reproduction, and death of a plant. • Roots penetrate and absorb water and nutrients that are adhered to soil particles • Different soil textures will have different capacities for holding water and nutrients • During the growth of the root system in the soil, it also serves to anchor the part of the plant that is above ground • Root hairs must have space to move through the soil for growth and absorption of water and nutrients

Osmosis • A process whereby the flow of a fluid through a semipermeable membrane separating two solutions permits the passage of a solvent but not the dissolved substance • The semipermeable membrane is a structure that permits a solution to move through it in a direction controlled by the concentration of solutions • The epidermis of a root hair is semipermeable • Once water and nutrients are inside the root they can travel through the plant via the xylem

Plant Nutrition • Plant nutrition- availability and type of basic chemical elements in the plant • Plant fertilization- management practice of adding nutrients to the soil or leaves for increased availability to the plant

16 Essential Plant Nutrients • Nutrients obtained from the atmosphere- Carbon, Hydrogen, Oxygen • Macronutrients are used in relatively large amounts and obtained from the soil – Nitrogen (N), Phosphorous (P), Potassium (K), Calcium (Ca), Magnesium (Mg), Sulfur (S) • Micronutrients (trace elements) are used in small amounts and also obtained from the soil – Boron (B), Copper (Cu), Chlorine (Cl), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Zinc (Zn)

Remembering The 16 Plant Nutrients • Learn the chemical symbols • “C Hopkin’s café, mighty good.”

Plant Nutrition (Ions) • Plant nutrients are absorbed from the soil-water solution that surrounds the root hairs of the plant. 98% absorbed in solution – 2% extracted directly from soil particle • Most nutrients are absorbed as charged ions • Ion – Atom that has an electrical charge • Anion – Negatively charged ion • Cation- Positively charged ion • Electrical charges in the soil are paired so that the overall effect in the soil is not changed

Plant Nutrition (Ions) • Ions compete and interact with each other according to their relative charges • Opposite charges attract each other, but ions with similar charges compete for chemical reactions and interactions in the soil-water environment • Some ions are more active than others and might be able to compete better in the soil

Soil Acidity and Alkalinity • The chemistry of plant elements in the soil can be affected by pH • Soil pH- the measurement of acidity (sourness) and alkalinity (sweetness) • If soil pH is acid some micronutrients become too soluble and occur in concentrations high enough to harm the plant • If soil pH is very high in the alkaline range many of the nutrients can be precipitated out (when a solid is dropped out of solution) and not available to the plant

Soil Testing • Soil nutrient deficiencies can be determined by performing a soil test Not Recommended for Accurate Results

Soil Acidity and Alkalinity • Soil pH can be corrected by adding lime to raise it or gypsum or sulfur to lower it.

Nutrient Availability

Nutrient Deficiencies • A deficiency is when there is a shortage of a nutrient available for the plant to uptake. • These may be replaced by fertilizing

Nitrogen Deficiency • Because it exists in nature as a gas, it is easily leached . • Nitrogen is responsible fro the vegetative growth of the plant and its dark green color • Symptoms are reduced growth and yellowing of leaves (chlorosis)

Phosphorous Deficiency • It is present as a rock in nature and not easily leached out of the soil • Important in the growth of seedlings and young plants and helping develop good root systems • Symptoms include reduced growth, poor root system, and reduced flowering. Thins stems and browning or purpling of foilage

Potassium Deficiency • Mined as a rock and made into fertilizer, but it can be leached from the soil • If too much potassium is present, it can cause a N deficiency • Symptoms include reduced growth, brown leaf edges, dead spots in the leaf, and plants that wilt easily

Food Storage • When a plant makes it food through photosynthesis, it often manufactures more than it needs and stores the excess in roots, stems, seeds, or fruits. • This excess food is used during respiration or harvested for consumption by humans and animals

Food Storage • The common root that is used to store food is the taproot - (carrots,radishes,turnips, and sugar beets) • Specialized stems store food as well - (tuber – potato), Corms, Bulbs, and Rhizomes • As the ovule of a plant matures, it stores food for the young embryo to start its growth when it germinates. Both animals and humans utilize seeds as major food sources

Plant Physiology