Seed Moisture Content Testing

The moisture content refers to the proportion of water a seed contains. Precise evaluation of the seeds' moisture content is essential for the determination of optimal harvest time, storage conditions, as well as for elongating the lifespan of seeds.

Lifeasible is one of the most innovating plant biotechnology companies in the world. With years of experience in seed testing, we offer a great variety of methods for seed moisture content testing, adjusting to characters of different plant species, and various research purposes.

First of all, as a direct testing approach, moisture content can be measured by quantifying water loss from dried seeds. Specifically, water can be removed from seeds via drying, distillation, or chemical solvent treatment. The most commonly used methods are:

• The air-oven method. Seeds of known wet-weight are dried in an oven at a certain temperature over a period of time, then cooled in a desiccator and re-weighed. Total loss of moisture is calculated based on wet- or dry-weights.
• Vacuum drying method (Figure 1A). For this method, seeds are dried at temperatures lower than 100°C in a partial vacuum until a stable weight is attained.
• Microwave oven method. Instead of a set temperature and time, the heating manner of this method is based on a pre-determined time period using microwave energy.
• Distillation method. The water within in the weighed seed sample is distilled in the flask with an organic solution (e.g., toluene), and is then collected in a glass tube for mass determination.
• Karl Fisher's method. It is based on titration of the methanol-water mixture with Karl Fischer reagents, which contain methanol, iodine, sulfur dioxide, and pyridine. The iodine will be reduced to colorless hydrogen iodide in the presence of water.

Secondly, the moisture content can be measured indirectly based on specific physical and/or chemical characteristics of seeds, or the interseed environment. Multiple approaches can be applied, including:

• Conductance meters (Figure 1B). The principle of conductance meters is based on the fact that the electric current within seeds increases as the seed moisture content increases. The conductance meters have the best accuracy for moisture contents between 7% and 23%.
• Capacitance meters (or dielectric meters). Also based on electric current changes, the capacitance meters function best for moisture contents between 6% and 25%.
• Hygrometric methods. Utilizing the hygroscopic nature of seeds, the moisture content is determined by the measurement of equilibrium relative humidity (eRH).
• Near-infrared spectroscopy. This method measures the reflectance of molecules in each seed components at specific near-infrared wavelengths.
• Nuclear magnetic resonance (NMR) spectroscopy (Figure 1C). It is a rapid, nondestructive, and accurate method adapting to a wide range of moisture contents.

Figure 1. Seed moisture content testing using a vacuum oven (A), an electronic moisture meter (B), and an NMR spectroscopy (C), respectively (Elias et al., 2012).

Being a team with excellent experts in plant genetics, biochemistry, biophysics, and seed development, we proudly provide our customers with efficient and reliable seed moisture content testing services. We also have established valuable national and international tie-ups with renowned companies to offer you the best solutions for your research projects.