Chapter 15

Plant Nutrition of Greenhouse Crops

(draft book excerpts)

Although many different factors influence plant growth, the growth rate and quality of greenhouse plants is largely dependent on mineral nutrient availability. When nutrients are supplied in proper amounts, in the proper ratio, and at the proper time, plants can achieve growth rates many times faster than in nature. Thirteen mineral nutrients are considered essential to plant growth and development and are divided into macronutrients and micronutrients based on the amounts found in plant tissue. Mineral nutrients can have a structural function. For example, nitrogen is found in all proteins, and nitrogen and magnesium are structural components of chlorophyll molecules needed for photosynthesis. Having knowledge of these functions is practical because a deficiency of either nutrient causes plants to be chlorotic (that is, yellowish in color). Other mineral nutrients have no structural role, but potassium, for example, is critically important in the chemical reaction that causes stomata in leaves to open and close. Nitrogen is almost always limiting to plant growth in greenhouse production, which is the reason why nitrogen fertilizer is applied frequently in greenhouses. Nitrogen fertilization is one of the main reasons for the rapid growth and short production schedules of greenhouses, and a nitrogen deficiency often shows up as stunted growth. An important concept to understand in regard to fertilization is that plant growth is controlled by the mineral nutrient in shortest supply, even when sufficient quantities of other nutrients exist. Thus, a single nutrient element may be the only factor limiting to plant growth even if all other elements are supplied in sufficient quantity. Just as important as the absolute quantities of nutrients in the growing media is the balance of one nutrient to another in producing vigorous, efficient plants. In some cases when nutrients are out of balance severe deficiencies or toxicities may occur. The proper balance of nutrients to one another seems to be relatively consistent among plant species.

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Within This Chapter: Plant Nutrition of Greenhouse Crops

  • Introduction to Plant Nutrition of Greenhouse Crops
  • Fundamental Aspects of Plant Nutrition
  • Absorption of Plant Nutrients
  • Nutritional Interactions
  • Cation-Exchange Capacity
  • Anion-Exchange Capacity
  • Essential Plant Elements
  • Nutrient Mobility within the Plant
  • Nutrient Mobility in the Soil
  • Nitrogen (N)
  • Nitrogen Deficiency Symptoms
  • Excess Nitrogen
  • Phosphorous (P)
  • Phosphorous Deficiency Symptoms
  • Excess Phosphorous
  • Potassium (K)
  • Potassium Deficiency Symptoms
  • Excess Potassium
  • Calcium (Ca)
  • Calcium Deficiency Symptoms
  • Excess Calcium
  • Magnesium (Mg)
  • Magnesium Deficiency Symptoms
  • Excess Magnesium
  • Sulfur (S)
  • Sulfur Deficiency Symptoms
  • Excess Sulfur
  • Iron (Fe)
  • Iron Deficiency Symptoms
  • Excess Iron
  • Boron (B)
  • Boron Deficiency Symptoms
  • Excess Boron
  • Manganese (Mn)
  • Manganese Deficiency Symptoms
  • Excess Manganese
  • Copper (Cu)
  • Copper Deficiency Symptoms
  • Excess Copper
  • Zinc (Zn)
  • Zinc Deficiency Symptoms
  • Excess Zinc
  • Molybdenum (Mo)
  • Molybdenum Deficiency Symptoms
  • Excess Molybdenum
  • Chlorine (Cl)
  • Chlorine Deficiency Symptoms
  • Excess Chlorine
  • Growing Media pH
  • Factors Affecting Growing Media pH
  • Water Alkalinity
  • Media Components
  • Types of Fertilizers Applied
  • Managing Growing Media pH
  • Lowering Growing Media pH
  • Raising Growing Media pH
  • Monitoring and Managing Soluble Salts
  • Units of Measure
  • Action of Salt Injury
  • Sampling Techniques
  • Managing Soluble Salts
  • Leaching Fraction
  • Growing Media
  • Soil Amendments
  • Maintaining Adequate Media Moisture
  • Water Quality
  • Fertility Regime
  • Plant Tolerance
  • Diagnosing Plant Nutrient Deficiencies
  • Visual Diagnosis
  • Growing Media Testing
  • Sampling Procedures
  • Laboratory Reports
  • Understanding Laboratory Test Results
  • Tissue Analysis
  • Sampling Procedures
  • Greenhouse Fertilization Programs
  • Pre-Plant Fertilization
  • pH Adjustment
  • Nitrogen and Potassium
  • Phosphorus and Sulfur
  • Micronutrients
  • Controlled-Release Fertilizers
  • Post-Plant Fertilization
  • Fertilizers
  • Fertilization Rates
  • Fertilization Frequency
  • Methods of Fertilizer Application
  • References