The liberty principle for this Freedom Friday is the simple fact that we cannot trust our government and many of the businesses in the world to provide good food for us and our families. The government has proven that it will do whatever is necessary to take control of Americans, and the bottom line is often more important to companies than doing what is right.
The best way to know what we are eating is to grow our own food. In an attempt to gain more knowledge about growing food, I enrolled in the Alaska Master Gardener course. Today’s post will be Basic Botany #2 and will be about seed germination, plant growth and development, and environmental factors that influence growth. I hope that my explaining the material to my readers will help me understand and retain the material better. The quotes will be from the class manual Sustainable Gardening – The Alaska Master Gardener Manual.
Seeds contain the entire DNA necessary to grow into an adult plant. Germination is a big word that describes “a complex process whereby a seed embryo goes from a dormant state to an active growing state. Seeds are usually covered by a hard coat that does not allow water to enter. Before some seeds can germinate, something must cause a change in the outer coat of the seed. This can be accomplished by “the heat of a forest fire, digestion of the seed by a bird or animal”, wearing away by fungi or insects, use of a file, or by chemical means. Other seeds must go through a cooling period. In all cases, the most important thing is to protect the embryo.
Germination of seeds can be affected by other factors such as (1) age of the seed – Older seeds are “less viable” and produce “less vigorous” seedlings. (2) The best seedbed is loose, fine-textured soil. (3) The seeds must receive a “continual supply of moisture” without getting too much water. (4) “Seeds must be planted at the proper depth and the right temperature” which is different for different species.
(5) As most gardeners already know, weeds seem to germinate and grow faster than flowers or vegetables.
In order for a plant to grow properly, there must be “three major physiological functions” present to “drive plant growth and development: photosynthesis, respiration and transpiration. “All three are essential to a plant’s survival. How well a plant is able to regulate these functions affects its ability to compete and reproduce.”
Plants manufacture their own food through a process “called photosynthesis, which literally means `to put together with light.’ To produce food, a plant requires energy from the sun, carbon dioxide from the air, and water transported from the soil through the xylem. During photosynthesis, it splits carbon dioxide into carbon and oxygen, adds water and forms carbohydrates (starches and sugars). Carbohydrates are used by the cells or transported through the phloem to other parts of the plant. Oxygen is a by-product that exits the plant through the stomata.”
If any of the ingredients – light, water and carbon dioxide – are missing, photosynthesis stops; if any of them is missing for a long period of time, the plant dies.
The second of the three major physiological functions is respiration. In order for the carbohydrates made during photosynthesis to be of value to the plant, they must be converted into energy. The plant uses energy “for cell growth and building new tissues.” “The chemical process by which sugars and starches are converted to energy is called oxidation. It is similar to the burning of wood or coal to produce heat. Controlled oxidation in a living cell is called respiration.” Respiration occurs at night and in all life forms and in all cells.
The third major physiological function is transpiration. This function takes place when water vapor is lost through an open stomata caused by the leaf’s guard cells shrinking. “Evaporating water causes a negative water pressure in the plant and more water is pulled up from the roots. Dissolved nutrients are pulled in with the water from the roots. The rate of transpiration is directly related to whether stomata are open or closed. Stomata account for only 1 percent of a leaf’s surface but 90 percent of the water transpired.”
Transpiration is important because it (1) transports “minerals from the soil throughout the plant,” (2) cools “the plant through evaporation,” (3) moves “sugars and plant chemicals,” and (4) maintains “cell firmness.” Different conditions cause different amounts and rates of water loss. “Transpiration is greatest in hot, dry (low relative humidity), windy weather.” Most plants are able to manage the intricate balancing of photosynthesis, respiration and transpiration.
Plants are affected greatly by their environment. For optimal growth, plants need to be in their ideal environment. We cannot expect desert plants to thrive in a rain forest and vice versa. “Either directly or indirectly, most plant problems are caused by environmental stress. In some cases, poor environmental conditions (e.g., too little water) damage a plant directly. In other cases, environmental stress weakens a plan and makes it more susceptible to disease or insect attack. I came to understand this fact last summer when I failed to have enough air moving throughout my greenhouse. My plants all developed powdery mildew about mid-summer and needed special help for the rest of the season.
Plants are affected by light, temperature, water, humidity, and nutrition. Problems arise with too little or too much of any of these factors. Quantity (how much), quality (what type) and duration (how long) of light affects plant growth. Quantity is the intensity of the light and varies with the seasons – with summer having the maximum amount of light. Quality refers to the color or wavelength of the light. “Sunlight supplies the complete range of wavelengths and can be broken up by a prism into bands of red, orange, green, blue, indigo and violet.” Duration is known as photoperiod and “refers to the amount of time a plant is exposed to light. Photoperiod controls flowering in many plants.” Plants are classified as short-day (long-night), long-day (short-night), or day-neutral depending on their needs. Flowering and other responses in plants are triggered by the “length of uninterrupted darkness,” a critical component of floral development.
Temperature is another very important factor in growing healthy plants. It “affects the rate of most biological and chemical reactions” and influences most plant processes, including photosynthesis, transpiration, respiration, germination and flowering…. High temperatures can damage fruit production …. Low temperatures reduce energy use and increase sugar storage…. Adverse temperatures can cause stunted growth and poor-quality vegetables.”
Other conditions affecting plants are their hardiness (ability to withstand cold temperatures), water and humidity, nutrition, fertilizers. My manual states that “Fertilizers are not plant food! Plants produce their own food from water, carbon dioxide and solar energy through photosynthesis. This food (sugars and carbohydrates) is combined with plant nutrients to produce proteins, enzymes, vitamins and other elements essential to growth.”