Question

Plant growth is most likely to be limited by the available supply of usable: a. nitrogen b. carbon c. oxygen d. phosphorus

Short answer

Nitrogen

Step-by-step solution

Identify Essential Nutrients for Plant Growth

Plants require several essential nutrients to grow which include nitrogen, phosphorus, potassium, and other microelements. Among these, both nitrogen and phosphorus are critical.

Evaluate Carbon and Oxygen

Carbon and oxygen are also important for plants; carbon is a key component of photosynthesis, and oxygen is needed for respiration. However, these elements are generally abundant in the atmosphere.

Determine Limiting Nutrients

Among the nutrients listed, phosphorus and nitrogen are typically more likely to be limiting because they are often less available in the soil compared to their plant uptake.

Conclude the Limiting Nutrient

Out of the options provided, nitrogen is commonly the most limiting nutrient in plant growth as it is crucial for the formation of proteins and nucleic acids and is typically present in lower concentrations in the soil.

Key concepts

essential nutrients for plants

Plants need various essential nutrients to grow and thrive. There are macronutrients like nitrogen (N), phosphorus (P), and potassium (K), often referred to as NPK, which are needed in larger quantities. Micronutrients like iron (Fe), manganese (Mn), and zinc (Zn) are also essential but required in smaller amounts.

Each nutrient has a specific role. Nitrogen is vital for the formation of amino acids and proteins, phosphorus is key in energy transfer within the plant, and potassium regulates various metabolic processes. A deficiency in any of these nutrients can limit plant growth and development.

• Macronutrients: Needed in large amounts.
• Micronutrients: Needed in smaller amounts but equally important.

nitrogen limitation

Nitrogen limitation is a common issue affecting plant growth. While nitrogen is abundant in the atmosphere, plants can only absorb it in certain forms, like nitrate \((NO_3^-)\) or ammonium \((NH_4^+)\). Soil often lacks sufficient available nitrogen, which constrains plant growth.

Nitrogen does more than just help plants grow; it also assists in the production of chlorophyll, which is essential for photosynthesis. This limitation leads to reduced chlorophyll, resulting in yellow leaves (chlorosis) and stunted growth.

• Absorbable forms: nitrate \((NO_3^-)\) and ammonium \((NH_4^+)\).
• Signs of deficiency: Yellowing leaves and stunted growth.

plant growth factors

Plant growth is influenced by several factors, including light, water, temperature, and soil quality. Properly balanced nutrients in the soil are crucial for optimal plant health.

Light drives the process of photosynthesis, while water is necessary for transporting nutrients and photosynthesis. Temperature affects metabolic rates, and soil quality provides a medium for roots and a source of nutrients.

• Essential factors: Light, water, temperature, soil quality.
• Balance: All factors must be in proper balance for healthy plant growth.

photosynthesis

Photosynthesis is the process by which plants convert light energy into chemical energy stored in sugars. This process occurs in the chloroplasts within plant cells and uses carbon dioxide (CO2) and water (H2O).

The overall equation for photosynthesis is:
\[6CO_2 + 6H_2O + light energy \rightarrow C_6H_{12}O_6 + 6O_2\]

This process not only produces glucose (a sugar used for energy) but also releases oxygen into the atmosphere. Without photosynthesis, plants would not be able to grow and provide oxygen and food for other organisms.

• Reactants: Carbon dioxide and water.
• Products: Glucose and oxygen.

soil nutrients

Soil nutrients are crucial for plants to grow healthy and strong. The primary nutrients found in soil are nitrogen (N), phosphorus (P), and potassium (K). In addition, the soil contains other essential mineral nutrients including calcium (Ca), magnesium (Mg), and sulfur (S).

Soil quality depends on various factors like pH, organic matter, and microbial activity, which affect nutrient availability and uptake by plants. Fertilizers are often used to supplement soil nutrients, helping to ensure plants receive the necessary elements.

• Primary nutrients: Nitrogen, phosphorus, and potassium.
• Supplementing: Fertilizers can help provide additional nutrients.