THE EFFECTS OF CHRONIC UV-B IRRADIATION ON THE PRODUCTIVITY OF AGRICULTURAL CROPS AND THE SUSCEPTIBILITY OF PLANTS TO PHYTOPATHOGENS UNDER CONDITIONS OF THE NONCHERNOZEM ZONE

A field experiment was performed against two infection backgrounds to estimate the effects of UV-B radiation at doses corresponding to 25% d estruction of the ozone layer on the yield of barley, fodder beet, and potato and on the susceptibility of plants to diseases. A complex dep endence of the intensity and direction of radiation effects on the sen sitivity of crops, the resistance of pathogens, and the level of backg round infection was revealed. A suggestion is made concerning the poss ible significance of the higher levels of UV-B radiation for ecosystem s.