Micronutrients refer to essential elements required by plants in relatively small quantities for their growth and development. Although they are required in smaller amounts compared to macronutrients, which include nitrogen, phosphorus, and potassium, micronutrients are equally important for healthy plant growth.

There are several micronutrients necessary for plants, including:

1. Iron (Fe): Iron is essential for chlorophyll synthesis and plays a crucial role in photosynthesis and energy production within the plant.
2. Manganese (Mn): Manganese is involved in enzyme activation, nitrogen metabolism, and photosynthesis. It also contributes to the metabolism of carbohydrates and the formation of chloroplasts.
3. Zinc (Zn): Zinc is essential for enzyme activity and plays a vital role in the synthesis of proteins and growth hormones. It also influences plant hormone balance and regulates the uptake and utilization of other nutrients.
4. Copper (Cu): Copper is important for several enzyme systems and is involved in various metabolic processes, including photosynthesis and the formation of lignin.
5. Boron (B): Boron is necessary for cell wall synthesis, sugar transport, and the metabolism of hormones. It is also involved in pollen development and seed production.
6. Molybdenum (Mo): Molybdenum is required for nitrogen fixation and nitrate reduction, as well as the synthesis of enzymes involved in these processes.
7. Chlorine (Cl): Chlorine is involved in the opening and closing of stomata, which regulate gas exchange in plants. It also helps maintain proper osmotic pressure within plant cells.
8. Nickel (Ni): Nickel is required for certain enzyme systems, such as urease, which plays a role in nitrogen metabolism.

Plants can obtain micronutrients from the soil or through foliar application. However, excessive or deficient levels of micronutrients can adversely affect plant growth and health. Soil pH and other factors can influence the availability and uptake of micronutrients by plants.

Micronutrient deficiencies can manifest in various ways, such as chlorosis (yellowing) of leaves, stunted growth, reduced yield, or abnormal development. Soil testing and plant tissue analysis can help identify nutrient deficiencies and guide appropriate fertilization practices.

In agriculture, micronutrient fertilizers are used to supplement the soil with deficient elements. These fertilizers are often applied in chelated forms to improve their availability and absorption by plants.