Onni Pohjakallio

Abstract

Professor Onni Pohjakallio, an eminent Finnish agricultural scientist, was born in Viborg in 1903. In 1929 he obtained his Master’s degree in Agriculture and Forestry and in 1934 his Doctor’s degree in this same field. In the years 1931—34 he was inspector for the state local plant husbandry trials, in 1934—45 he served as chief assistant in the Department of Plant Breeding of the Agricultural Experimental Institute, and in 1945 he was appointed professor of plant biology and pathology at the University of Helsinki. In his position as professor, Pohjakallio had a profound influence in developing the instructional and experimental programme of the Department of Plant Pathology. One of his most important accomplishments was the acquisition of the Muddusniemi Experimental Farm in Lapland (69° 05' N), where long-term field trials threw new light on the behaviour of crops in the northern regions of Finland. Another of his notable achievements was the publication of a comprehensive two-volume text-book on plant pathology. Pohjakallio’s scientific activity was extremely wide and diversifield, and he published a great number of papers dealing with fertilisation, plant husbandry, breeding, physiology, ecology and pathology. The subject of his doctoral dissertation published in 1932 was the significance of sugar as a food source of certain rust fungi. During his years as inspector of local trials he published a series of papers on fertilisation. At the Department of Plant Breeding his main subjects were clover, oats and herbage crops. In his breeding of oats he succeeded in improving the resistance of this crop to Ustilago smut. Many of Pohjakallio’s studies cleared up problems dealing with the overwintering of crops. In these studies he drew attention to the important antibiotic effect of fungi, bacteria and other microorganisms on plant pathogens, particularly on Sclerotinia trifoliorum. He also conducted extensive investigations on total whiteheads of grasses, which he believed to be due to acute starvation in the meristematic tissues of the stems. Numerous papers on the lack of energy in plant tissues and their death by starvation were published by Pohjakallio. One of the most noteworthy of Pohjakallio’s research fields pertained to the effect of phoroperiodism and day-length on plant growth in northern and southern Finland. He showed that the earlier view about the exceedingly rapid plant growth under the constant summer illumination in Lapland were too optimistic, erroneously based on the results from certain especially favourable years and on the fact that in Lapland only the most early-maturing varieties are cultivated. Pohjakallio also was an active participant in international agricultural conferences where he often delivered papers. Professor Pohjakallio had a profound influence on agricultural research in this country. Not only did he accomplish much in his own studies, but he also opened new vistas and provided stimulus for further work in many fields of agricultural science.