Models of plant linear growth in conditions of oxidation stress induced by UV-B radiation

Decrease in the rate of growth under the impact of many unfavourable environmental factors, UV-B (280-320 nm) radiation in particular, is a defensive mechanism of plants that minimizes the negative action of the damage done and may be related to diminished number of mitoses. This mechanism is evidently at work also in case of UV-B radiation adaptation of crop plants with intercalary growth of a leaf whose meristem zone is protected by the axil. We compared growth dynamics of the first leaf of barley ( Hordeum vulgare L., cultivars Fukumugi and Belogorski) and wheat ( Triticum aestivum L., cultivar Leningradka). Plants were grown in phytotron as well as in field conditions with modelling enhanced UV-B radiation; parameters in various growth models under stress at early stages of ontogenesis were estimated experimentally. The results obtained allowed to substantiate the method of mathematical modelling in diurnal time scale of plant linear growth in conditions of oxidation stress caused by UV-B radiation. With the use of the models devised, the error of measuring linear growth slowdown was ±5-6 mm. The best results were obtained with dynamic models whose accuracy was 20-25 % higher than that of the static model. The models proposed make it possible to evaluate the slowdown of linear and/or mass-volume growth depending on the intensity and the dose of stressful radiation. The accuracy of identification and prediction suggest that the method elaborated may be used also for modelling plant linear growth under the impact of other abiotic factors causing oxidation stress as well as of their combinations.