Influence of mineral fertilization of common bean (Phaseolus vulgaris L.) on yield and damage by Bean weevil (Acanthoscelides obtectus SAY) in a long-term stationary fertilizer experiment

The issue of storage and protection of yilded seeds from storage pests is fundamental to seed science, the nutrition of people and animals as well as the maintenance of state reserves. During 2019-2021, in the experimental field of IASS "Obraztsov chiflik" - Rousse, in a long-term stationary fertilizer experiment, seeds of common bean variety Obraztsov chiflik 12 were obtained utilizing the following fertilization options: 1 - individual nitrogen fertilization; 2 - individual phosphorus fertilization; 3 - individual potassium fertilization; 4 – combined NP application; 5 – combined NK application; 6 – combined PK application; 7 – triple combination of NPK. An unfertilized control variant was maintained for comparison purposes. The study aims to entomologically evaluate seeds regarding damage by bean weevils after crop harvesting. Measurements of yield, 1000-seed weight, damaged seeds percentage, Index of infestation, as well as weight loss were taken. The combined application of NP demonstrated the greatest positive effect on the yield qualities of beans, however it lead to an intermediate position of the yield in terms of damage by bean weevil. The variant treated with combined NK fertilization resulted in the lowest percentage of damaged seeds and Index of infestation; it was followed by the variant with full mineral fertilization and the control variant. The individual application of N resulted in highest damaged seeds percentage as well as highest Index of infestation; it also ensured the highest weight loss on average for the studied period.