© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Chapter 9 Plant Growth

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Importance of Seed Most ag crops begin as seeds Seeds compose ~70% of diets Used for varied purposes –Cereals, oils, snacks –Beverages –Oils and dryers –Cosmetics, ointments, pharmas

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Types of Seeds Dicot –Leaf has two distinct halves –Stores energy in cotyledons Monocot –One seed leaf –Stores energy in endosperm

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Seed Germination Water Oxygen Temperature Light

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Process of Germination Moisture enters seed, seed swells Coat ruptures, oxygen enters Respiration provides energy Cells multiply, growth bidirectional

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Growth after Germination Growth types –Increase in cell size –Increase in cell number –Cell differentiation Mitosis occurs in meristem –Tips of stems and branches –Tips of roots

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Plant Growth Hormones Chemical substances that control or influence activities Control growth in plants –Proper balance is essential –Stimulate or inhibit

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Major Hormone Groups Auxins Cytokinins Gibberellins

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Effects of Light on Plant Growth Phototropism (grow toward light) Photoperiodism (respond to amount of daylight and darkness) –Blooming –Leaf shedding –Dormancy Flowering intervals

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Effect of Gravity on Plant Growth Geotropism (grow toward gravity) Plant grows in opposite directions –Stem: Negatively geotropic –Root: Positively geotropic

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Plant Nutrition All systems need nutrients Nutrients provide energy Come from air and soil Proper balance is necessary –Macronutrients: In large amounts –Micronutrients: In small amounts

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Nonmineral Nutrients Carbon Hydrogen Oxygen

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Primary Nutrients Nitrogen Phosphorus Potassium

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Secondary Nutrients Calcium Magnesium Sulfur

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Micronutrients Iron Chlorine Copper Zinc Boron Manganese Molybdenum

© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Summary Plants grow more efficiently due to human techniques All use biology principles found in nature Research uses these principles to grow food and fiber more efficiently