Petro Kryzhevsky (1873–1923) is a scientist with a broad outlook, who has a prominent place in the development of biological, agricultural science and education, initiated new scientific directions in botany, herbology, and educational and pedagogical activities.

The purpose of the study is to highlight the life path and scientific and organizational activities of the scientist, to reproduce the main stages of his biography and professional career using historical, biographical and source analysis methods.

The main periods of activity of Petro Kryzhevsky are highlighted and characterized through the prism of agrarian science. The main activity of the scientist in the "Mykolaiv" period was focused on the study of the flora of the Kherson region, in particular Mykolaiv. He was one of the organizers and active members of the Mykolaiv Society of Nature Lovers. He carried out a wide range of floristic and faunal researches, spread natural knowledge and popularized biological science among the general population. Studying the flora of one or another region, Petro Kryzhevsky identified its physical, geographical and topographic features. He took part in congresses of naturalists and agricultural workers, educators and conducted active lecturing activities.

The next stage of scientific research is related to the flora of "Crimean Yaila" Unfortunately, the life of the scientist was not enough to finish the scientific work he started, which lasted for four years. Results of work Petro Kryzhevsky not only did not have time to print, but due to the difficult financial circumstances of recent years, he did not even have the opportunity to summarize.

"Uman" period – the scientist's talent as an organizer of science in the field of agricultural research was revealed. Here Petro Kryzhevskyi headed the Uman branch of the Agricultural Scientific Committee of Ukraine, where promising areas of scientific research in the region were formed in a short time, which eventually gave positive results; domestic scientific forces of the region are united; the Uman branch of the Agricultural Scientific Committee of Ukraine becomes the focus of agricultural research in the region and coordinates all branch research in the region. Subsequently, the scientist (1922) heads the seed control station, museum and library of the Uman Experimental Agricultural Station.

The results of long-term and systematic research by Petro Kryzhevskyi had an important value at the beginning of the 20th century, have a source value and relevance today. We must not only honor his memory, but also make fruitful use of his entire legacy. First of all, it is necessary to publish a collection of his most valuable unpublished works. After all, in-depth study and preservation of the scientist's scientific legacy will continue to contribute to the development of Ukrainian science.

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