A long-term response of chlorophyll fluorescence induction to one-shot application of cyanazine on barley plants and its relation to crop yield

Field-grown plants of spring barley (Hordeum vulgare L. cv. Akcent) in the growth phase 30 DC (beginning of stem extension) were exposed to a one-shot application of a commercial product containing cyanazine (Bladex 50 SC) in two doses, C-30 and C-60 (30 and 60 mg m(-2)). The reaction of the plant p hotosynthetic system was followed non-destructively using chlorophyll fluor escence induction (the O-J-I-P transient) within three weeks after the appl ication in the fifth developed leaf and thr ee further gradually appearing leaves, An immediate response of plants to the application of cyanazine and a regeneration of plants from cyanazine action were detected. The biologic al (plant dry mass) and crop yield production (the number and mass of grain s in a spike) were analyzed in time of full ripeness. The crop yield was lo wer-ed by the herbicide effect to the same level for the two doses used.