Dviejų vystymosi tarpsnių žirnių fotosintezės rodiklių atsakas į substrato rūgštumo ir UV-B spinduliuotės poveikį.

The aim of this work was to investigate the combined impact of substrate acidity (pH 4.8) and 1 and 3 kJ m-2 d-1 UV-B radiation on two growth stage pea (Pisum sativum L.) photosynthetic parameters. The investigated plants were sown in vegetative pots with prepared peat substrate. When the plants were at a leaf development stage (BBCH 14-16) and the stage of formation of lateral shoots (BBCH 21-23) the impact of substrate acidity and UV-B radiation was started. Photosynthetic parameters were measured with portable photosynthesis system LI-6400 and photosynthetic pigments were analyzed in acetone extract using a spectrophotometer on the last (5th) day of the experiments. UV-B radiation effect on the investigated indicators of BBCH 14-16 stage peas were stronger than on BBCH 21-23 stage, when the average decrease of all investigated indicators was 34.2% compared with the control plants. Meanwhile, the decrease of BBCH 21-23 stage was 21.8%, and the effect of the growth stage, as a factor, was statistically significant (p < 0.05). Substrate acidity had higher (38%) negative effect on BBCH stage 21-23 peas, but the effect of growth stage was statistically insignificant (p > 0.05). The combined UV-B radiation and substrate acidity affect the parameters of BBCH stage 14-16 peas decreased by 46.9%, and those of BBCH 21-23 peas slightly more - by 50.9%, but the growth stage, as a factor, was statistically insignificant (p > 0.05). The combined UV-B radiation and substrate acidity effect resulted in higher losses on peas than single ones, and higher losses (p > 0.05) were detected for BBCH 14-16 stage peas. [ABSTRACT FROM AUTHOR]