Environmental Requirements - Horticulture - Lecture Slides, Slides of Plant Biotechnology

Download Environmental Requirements - Horticulture - Lecture Slides and more Slides Plant Biotechnology in PDF only on Docsity! Environmental Requirements Docsity.com Soil • composed of sand, silt, and clay, organic matter, living organisms, and pore spaces Docsity.com Clay • particles hold moisture and plant food elements more effectively than larger particles. Docsity.com Soil Profile • consists of 3 basic layers • topsoil • subsoil • soil bedrock Docsity.com Topsoil * represents depth normally plowed Docsity.com Clayey Soil • must contain at least 30% clay • holds more moisture than is good for plants • poor drainage Docsity.com Loamy Soil • most desirable soil • equal parts sand, silt and clay Docsity.com Soil Improvement • Drainage – change soil structure –add organic matter to encourage earth worms Docsity.com Moisture retention • adding organic matter (o.m.) • sources of o.m. • animal manure • green manure - crop grown and plowed under to improve the soil Docsity.com Sources of O.M. • peat moss • sawdust • mulches - compost or wood chips Docsity.com Mulches • placed on the surface to help retain moisture • reduce runoff and evaporation • reduce weeds Docsity.com Diseases • plant resistant varieties • chemicals • soil pasteurization –heat to 180 degrees F for 30 minutes. Docsity.com Nutritional deficiencies • show on leaves of plants • Nitrogen - pale green leaves • Phosphorus - purple color on underside of leaves Docsity.com Planting Media Mixes • Soil less mixes • advantages include : uniformity - doesn’t vary in pH, fertility or texture Docsity.com Content of mixes • perlite • improve aeration • volcanic origin Docsity.com Vermiculite • exploded Mica • improves aeration Docsity.com Plant food and fertilizers • divided into two groups • Major elements (macro) • Nitrogen - N • Phosphorus - P • Potassium - K Docsity.com Plant requirements • large amounts of major elements • relatively small amounts of minor elements Docsity.com Commercial fertilizers • shows % or pounds per cwt. (100#) of the three major elements in large numbers on the container or bag. Docsity.com Commercial fertilizers • 5-10-5 • 5% N, 10% P, 5% K • remaining 80% is filler • NP&K are always listed in that order. Docsity.com Nitrogen * ammonium sulfate ¢ urea formaldehyde Docsity.com Nitrogen • has most noticeable effect on plants • encourages above ground vegetative growth • regulates use of other elements Docsity.com Too much N • lower disease resistance • weaken stem because of long soft growth • lower fruit quality Docsity.com N lost easily from soil • leaching - being filtered down through soil with water • not held by soil particles, dissolved in water • O.M. holds insoluble N for slow release Docsity.com Don’t use excess N • quickly lost through leaching • can damage plants Docsity.com Phosphorous • held tightly by soil particles • not easily leached Docsity.com Phosphorous • encourage root growth • makes K more available • increase disease resistance • improves quality of grain, roots and fruit crops Docsity.com Phosphorous • container plants can be damaged by excess P • increases soluble salt content of medium • causes dehydration of roots Docsity.com Phosphorous • Insufficient P • purple color on underside of leaf • reduced flower fruit and seed production Docsity.com Potassium • increase disease resistance • encourages healthy root systems • essential for starch formation Docsity.com Potassium • development of chlorophyll • efficient use of CO2 Docsity.com Insufficient K • leaves appear dry and scorched with irregular yellow areas on the surface Docsity.com pH • measure of acidity or alkalinity • pH scale - runs from 0 - 14 • most plants grow best from 5.6- 7.0 Docsity.com pH • 7.0 is neutral • pH of 7 or above is alkaline or basic • pH below 7 is acidic Docsity.com pH • as numbers decrease, solution becomes more acidic. • As numbers increase, solution becomes more basic or alkaline Docsity.com Temperature • there are temperatures above and below which plants stop growth • generally, plant growth rate increases as temps increase up to about 90 degrees Docsity.com Light • must be present before plants can manufacture food • plants vary in light requirement • effects flowering Docsity.com Photoperiodism • response to different periods of day and night in terms of growth and maturity Docsity.com Photoperiodism • day length indifferent • do not depend on length of light or darkness • African Violet and tomato Docsity.com Phototropism • plants appear to grow towards the sun or light source Docsity.com Humidity • moisture level of the air • most plants grow best in 40-80% relative humidity (R.H.) • Relative Humidity Docsity.com Gases and Air Particles • CO2 is vital to plants for Photosynthesis • Air pollutants can cause damage Docsity.com Air Pollutants • Sulfur Dioxide - SO2 - from burning coal • Carbon Monoxide - CO - exhaust from cars Docsity.com Carbon Monoxide e reduces plant growth ¢ can kill plants Docsity.com