Original video: https://youtu.be/-l02lNP1pO4
Delivered on: 29 MARCH 2023
This video provides a comprehensive guide to seed viability testing using the tetrazolium test (TZ test), a rapid and reliable method for assessing seed quality. 🌿 We'll explore the science behind seed germination and demonstrate the step-by-step procedure for conducting the TZ test.
The food for the germinating seedling may be stored in part of the embryo itself, such as the fleshy cotyledons of a bean seed, or it may take other forms, including endosperm, which is a special starch-rich storage tissue that surrounds the embryo. A seed is officially considered to have germinated when the young root, called the radicle, emerges from the seed coat. To germinate, a seed requires three things – water, oxygen, and a suitable temperature. Water uptake, also called imbibition, is the first stage of seed germination. During this process the dry seed, which typically has a water content of less than 10%, absorbs water and swells. This process serves to hydrate the dry components of the seed and active the metabolic machinery necessary for germination. Among the early metabolic activities occurring in the seed is the breakdown of starches stored in the seed into simple sugars that can be used for energy and building blocks for necessary cellular structures. A seed that has not germinated because it is lacking one or more of the necessary requirements for germination is termed quiescent. These seeds are simply "resting", waiting for the appropriate conditions for germination. Given water, oxygen and/or a suitable temperature, a quiescent seed will germinate. However, even if given the proper conditions, a seed may not germinate. These seeds may fail to germinate because the seed is either dormant or "dead". Dormant seeds have the potential to germinate, but are prevented from doing so by some mechanism. Thus, even though all the proper growth conditions are present, they don't germinate unless they have been "primed" and their dormancy mechanism has been overcome. There are many dormancy mechanisms in seeds.
The purpose of laboratory testing of seed germination is to assess seed quality or viability and to predict performance of the seed and seedling in the field. Several different kinds of testing are available depending on the type of seed to be tested, the conditions of the test, and the potential uses of the seed.
Germination percentage is a good measurement of seed viability. One disadvantage of conventional germination tests is that they require a waiting period of two weeks or more. The tetrazolium test (TZ- test) is a quick chemical test that can be conducted in a short period of time with minimal equipment. In this test, a seed is incubated in a dilute (0.1%) solution of 2,3,5-triphenyltetrazolium chloride. Initially, the TZ solution is colorless, but changes to read (Triphenyl formazan) when it comes into contact with hydrogen (reduction) derived from enzymes in the respiration process.
Keywords: Seed viability, seed germination, tetrazolium test, TZ test, seed quality, dormancy, quiescence, respiration, 2,3,5-triphenyltetrazolium chloride, agriculture, horticulture, botany, science education, laboratory practical.
Location:
Faculty of Agriculture, Universiti Putra Malaysia
Fakulti Pertanian, Universiti Putra Malaysia, 43000 Seri Kembangan, Selangor
XPMM+9J Seri Kembangan, Selangor
2.9845517506267742, 101.73803356324866
Attribution 4.0 International — CC BY 4.0 - Creative Commons
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