How do they quantify the water content of plants

Water is crucial for the survival and growth of plants. But how do scientists measure the water content of plants? There are several methods used to determine water content, each with its own advantages and limitations.

Gravimetric method

The gravimetric method is the most accurate and widely used method for measuring the water content of plants. This method involves weighing a plant sample before and after drying it in an oven at a specific temperature for a specific amount of time. The weight lost by the plant sample during drying is attributed to the water content. The water content is calculated as the weight lost divided by the initial weight of the sample multiplied by 100. The gravimetric method is highly precise and provides accurate values of water content but takes a long time to complete.

Hydrometer method

The hydrometer method is used to determine the water content of plant sap. This method involves extracting plant sap from the leaves or stems of the plant and measuring the specific gravity of the sap using a hydrometer. The specific gravity reading is then used to calculate the water content. The hydrometer method is quick and easy but is affected by temperature changes and variations in the concentration of solutes in the sap.

Relative water content method

The relative water content method is used to evaluate the water status of a plant. This method involves measuring the fresh weight, dry weight, and turgid weight of a plant tissue. The water content is then calculated using the formula: [(fresh weight - dry weight) / (turgid weight - dry weight)] x 100. The relative water content method is fast and useful for comparing the water status of different plants but only gives an estimate of water content and is affected by factors such as temperature and humidity.

Nuclear magnetic resonance method

The nuclear magnetic resonance method is a non-destructive and non-invasive method used to determine the water content of plants. This method involves subjecting plant tissues to a magnetic field and measuring the response of water molecules. The signal intensity is then used to calculate the water content. This method is highly accurate and does not require sample preparation, but it is expensive and requires specialized equipment.

Conclusion

Measuring the water content of plants is essential for understanding plant physiology and agronomic practices. The gravimetric method, hydrometer method, relative water content method, and nuclear magnetic resonance method are some of the methods used to quantify the water content of plants. Each method has its own advantages and limitations, and the choice of method depends on the specific research question and resource availability.