Study of the relationship between fluorescence type and percentage content of good-quality cocoons of the silkworm Bombyx mori L. breeds and hybrids

Establishing relationship between fluorescence type and percentage content of good-quality cocoons from silkworm Bom-byx mori L. was the aim of this paper.The study was conducted during 2016-2020 at the training experimental station of the sub-department "Special branches (Sericulture)", department "Animal husbandry - Non-ruminant animals and special branches", Faculty of Agriculture, Trakia University - Stara Zagora. In fulfillment of the purpose and tasks, biological material from 8 breeds, 16 dihybrids and 10 tet-rahybrids reared with mulberry leaf was used. The type of fluorescence of the silk sheaths was established when exposed to ultraviolet (UV) rays with a wavelength in the range 254-365 nm.The analysis of the obtained data shows that the type of fluorescence of the silk sheath, as well as the breed (hybrid), have a highly reliable influence (p <= 0.001) on the variation of the percentage of good-quality cocoons (an-ras). Of the three fluores-cent groups, that of the yellow-fluorescent cocoons was characterized by the highest mean percentage of good-quality cocoons in both dihybrid (94.75%) and tetrahybrid (95.34%) forms of the mulberry silkworm.This gives reason to consider that the results obtained by us confirm the established in the scientific literature relationship between ultraviolet fluorescence and the technological qualities of cocoons. This relationship can be used to increase the qual-ity of the obtained production by applying the methods selection and breeding by type of the fluorescence.