Seed Testing With the Use of X-Rays

1992

S. 69-93

24 Lit. Ang.

Unselbständiges Werk

200048874

A comparison of results of seed testing by various roentgenological methods with results of germination tests shows that the X-ray examination can be used only as an orientation method for quick evaluation of the seed or as a complementary method to germination test, rendering, possible to determine the causes of bad germination. It is, however, then very useful in seed testing when the tested seed will be still sowed, as well as in investigations on the influence of environement on the development and dying of the germs (biological monitoring). On the basis of testing of many samples one determined the optimum parameters of X-ray radiation of seeds of 69 tree and shrub species most important for the forest economy. The quality (readability) of the X-rays depends on suitable choice of following values: voltage of X-ray lamp, product of voltage of this lamp and duration of X-ray action, sensivity of X-ray plate and distance of seeds from the source of X- rays. One elaborated formulae for calculation of the germination potential of freshly collected seeds of larch, birch and alder, giving more precise results than the universal Russian formulae. They are as follows: (Formel) N2, N3, N4 and N5 mean the numbers of seeds in individual classes of germ development, and N the number of seeds in the whole sample. One improved the criteria of seed testing on the basis of saturation of dead tissues with contrasting substances by the elaboration of a graphical scale of seed classification into able and unable to germination and by the application of uniform criteria and transparency of the picture of tissues saturated with the contrasting substance. Trials of testing stored pine and larch seeds on the basis of the degree of their swelling (water contrast method) show that this method is mote simple and safe in application than methods with chemical contrasting substance, and give satisfactory results without destroying the seeds.