Question

Give a brief account of plant nutrients.

Answer 1

Plant nutrition is the chemical elements and compounds necessary for plant growth, plant metabolism and their external supply. There are seventeen most important nutrients for plants. Plants must obtain the following mineral nutrients from their growing medium.

1. The macronutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), magnesium (Mg), carbon (C), oxygen(O), hydrogen (H).
2. The micronutrients (or trace minerals): iron (Fe), boron (B), chlorine (Cl), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni).

• Plants take up essential elements from the soil through their roots and from the air through their leaves. Nutrient uptake in the soil is achieved by cation exchange, wherein root hairs pump hydrogen ions ($H^{+}$) into the soil through proton pumps. In the leaves, stomata open to take in carbon dioxide and expel oxygen. The carbon dioxide molecules are used as the carbon source in photosynthesis.
  
• Xylem moves water and mineral ions within the plant and phloem accounts for organic molecule transportation. Water potential plays a key role in a plant's nutrient uptake. If the water potential is more negative within the plant than the surrounding soils, the nutrients will move from the region of higher solute concentration to a region of lower solute concentration in the plant.
  
• Nutrients are very important for plant growth as their deficiency causes stunting, deformity, discolouration, distress, and even death. For example, chlorosis of foliage is due to mineral nutrient deficiency.