The Essential Nutrient Elements: Requirements and Interactions in Plants

CHAPTER T W O

The Essential Nutrient Elements: Requirements and Interactions in Plants E.

J.

HEWITT

I. Introduction II. Morphological, Anatomical, Chemical, and Physiological Effects of Mineral Disorders and Nutrient Interactions A. Macronutrient Elements 1. Nitrogen 2. Phosphorus 3. Sulfur 4. Calcium 5. Magnesium 6. Potassium 7. Interrelationships among Nitrogen, Phosphorus, Potassium, Calcium, and Sodium in Water Content, Dry Matter, Growth, Assimilation Rates, and Respiration B. Micronutrient or Trace Elements 1. Iron 2. Relationships between Iron and Other Elements 3. Manganese 4. Copper 5. Zinc . . 6. Boron 7. Molybdenum 8. Chlorine C. Effects of Nutrient Status on Free Amino Acids and Amides . . . . D. Beneficial and Other Elements 1. Alkali Metals 2. Strontium 3. Cobalt 4. Selenium 5. Aluminum 6. Silicon 7. Other Elements References

I.

137 139 140 140 143 149 155 172 176

183 192 192 198 212 222 229 240 270 292 299 318 318 322 322 326 326 328 329 329

Introduction

I n v e s t i g a t i o n s t h a t l e a d to t h e r e c o g n i t i o n of t h e essential m a c r o a n d m i c r o n u t r i e n t m i n e r a l e l e m e n t s for h i g h e r p l a n t s h a v e b e e n de137