(37.2) Plants, Nutrients, Deficiencies, & Genetic Modification By Meg Swiatkowski

History ARISTOTLE hypothesized that plants “ate” soil because they arose from the ground. Jan Baptista van Helmont tested Aristotle’s theory and discovered it was not true. He hypothesize plants “drank” WATER to grow because it disappeared. Stephen Hales finally discovered plants are mostly nourished by AIR.

Today we know that Soil, Water, & Air all contribute to a plant’s growth. Water is 80-90% of a plant’s fresh mass Organic substances are 96% of a plant’s dry mass Most organic substances in the plant are made up of carbohydrates

Vocab Essential Element- a chemical element required for a plant to complete its life cycle and produce another generation. Macronutrients- essential elements required by plants in relatively large amounts. Hydroponic Culture- Helps determine which elements are essential by using mineral solutions. Micronutrients-essential elements needed by plants in tiny quantities.

MACROMOLECULES Carbon Oxygen Hydrogen Nitrogen Potassium Calcium Magnesium Phosphorous Sulfur Major components of of organic compounds forming plant’s structure. )

micromolecules Chlorine Iron Boron Zinc Copper Nickel Molybdenum Play catalytic roles that plants only need in tiny quantities.

Symptoms of Mineral Deficiency Symptoms of a deficiency depend on a nutrient’s function. They also depend on the mobility of the nutrient within the plant. –If a nutrient moves about freely, symptoms appear first in the older organs because the younger ones have more drawing power. Nutrient

On the opposite end, if the nutrient is immobile, it will most likely affect the younger organs first because the older ones may have adequate amounts from periods when the nutrient was in supply. Mineral requirements are subject to CHANGE with the time of year and age of the plant. Most common nutrient deficiencies are phosphorous, potassium, and NITROGEN! Micronutrient deficiencies are less common. –Mostly happen in geographic regions b/c soil composition.

To Correct a Deficiency… Analyze the mineral content of the plant/soil –Ex: Zinc deficiencies in fruit trees can be solved by hammering a few zinc nails into the trunk.

MODERATION =

Improving Plant Nutrition by Genetic Modification (examples) Resistance to Aluminum Toxicity- certain plants secret organic acids that bond to the aluminum and lower the levels. Flood Tolerance- too much water is not good. –Leads to oxygen deficiency and toxic product build-up –Gene called Submergence 1A-1 has flood resistance abilities SMART PLANTS- plants that signal a deficiency before it becomes a problem. By adding these genes/traits to a plant, it betters the chance of the plant’s survival.