Seed health testing is mainly to determine whether seeds carry pathogenic bacteria (such as fungi, bacteria and viruses), harmful animals (such as nematodes and pests) and other health conditions.
There are three main methods to determine the health of seeds: uncultivated test (which can not explain the viability of pathogens), post-culture test and other methods.
There is no cultural test. There are mainly direct examinations (suitable for diseases with obvious symptoms of larger pathogens or impurities, such as ergot, nematodes, galls, smut spores, mites, etc.). If necessary, the sample can be examined by binocular microscope, and the pathogenic bacteria or diseased particles can be taken out, and the number can be weighed or counted), and the imbibition seeds can be examined (in order to facilitate observation of fruiting bodies, diseases or pests or promote spore release, the test sample is immersed in water or other liquids,
After imbibition, check the surface or inside of seeds, preferably with binocular microscope), washing inspection (used to check the pathogenic nematodes attached to germ spores or glumes on the surface of seeds), and dyeing inspection (mainly potassium permanganate staining method: suitable for checking hidden rice weevil and millet weevil;
Iodine or potassium iodide staining method: suitable for the inspection of pea weevil), specific gravity inspection method (sampling and pouring into saturated salt solution, taking out seeds suspended in the upper layer, and combining with grain cutting inspection, calculating pest content), and soft X-ray inspection (used to check hidden pests in seeds, such as broad bean weevil, corn weevil, wheat moth, etc.). Through a photograph or direct observation from a fluorescent screen).
Post-cultural examination. It means to check whether there are pathogenic bacteria or their symptoms inside and outside the seeds and on the seedlings after the samples to be tested are cultured for a certain period of time.
Commonly used culture media include absorbent paper method (suitable for the inspection of seed-borne fungal diseases of various types of seeds, especially for various semi-fungi, which is beneficial to the formation of conidia and the development of symptoms of pathogenic fungi on seedlings), sand bed method (suitable for the inspection of some pathogenic fungi) and agar plate method (mainly used for the inspection of pathogenic fungi lurking in seeds and pathogens on the surface of seeds).