The effect of arsenic (32 -96 μM) on the phosphorus content and Chl fluorescence was studied in soybean (Glycine max Merril) grown in the nutrient solution with and without phosphorus. The increased concentration of As led to the decrease in P content in plant organs. Parameters of Chl fluorescence of soybean leaves in the presence of these As concentrations did not show significant changes.Additional key words: Glycine max, photosystem 2, quantum yield. ⎯⎯⎯⎯Pollution of the soil and atmosphere by arsenic (As) is conditioned by the industry development. Copper smelters and thermal plants are great pollutants of the atmosphere. According to Smirnov and Muravin (1977) natural As content in the soil is 5 mg(As) kg -1 (soil). As, an analogue to phosphorus, is absorbed from the soil by P transporters. As inhibits P uptake in barley (Asher and Reay 1979) and Arabidopsis (Dunlop et al. 1997). In many of plant species, arsenates and arsenites have an affinity for thiols, such as glutathione. Furthermore, phytochelatins are formed as a response to As (Schmöger et al. 2000). Hartley-Whitaker et al. (2000a, 2000b confirmed that As-tolerant Holcus lanatus L. had higher phytochelatins concentrations than As-intolerant species. Hence, similar to heavy metals, As also mobilises the socalled nonenzymic antioxidants, such as glutathione, ascorbates, and phytochelatins. In order to investigate As effects on the uptake and distribution of phosphorus (P) in plant organs and chlorophyll (Chl) fluorescence in the soybean leaves, different As concentrations were used: 2.4, 4.8, 6.0, and 7.2 g(As) m -3 , corresponding to 32, 64, 80 and 96 μM As.After the 5-d germination in the dark, plants of soybean (Glycine max Merril. cv. ZP S015) were transferred into pots with the nutrient medium of pH 7.0 (Hoagland and Arnon 1950). Plants were grown in growth chambers at a 12-h photoperiod, irradiance of 300 μmol m -2 s -1 (Sylvania cool white lamp P9GT12-CEW-VHO, Danvers, USA) and day/night temperature of 24/20 °C. Plants grown on the complete medium were the control ones. The P content in the other three variants was half or double of that in the control or zero. Plants grown with and without P were exposed to 32, 64, 80 and 96 μM Na 2 HAsO 4 for 5 d.

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Maize (Zea mays L. hybrid ZP‐704) and black pine (Pinus nigra Arn.) were grown for five days at low fluence rate (0.4–4.0, μmol m–2 s−1) in blue or red light. Compared to red light of the same fluence rate, blue light effects in maize were repressive for the accumulation of Chita, b, carotenoids and light‐harvesting complex‐2 (LHC‐2) proteins. The maximal reduction of proteins bound to the light‐harvesting complex of photosystem 2 and pigments was attained at different fluence rate levels. In black pine, blue light compared to the red of the same fluence rate level either activated or reduced accumulation of pigments and LHC proteins, the effect being dependent on its fluence rate level. At fluence less than 3.0 μmol m−2 s−1 blue light was more efficient for the synthesis of Chi a, b and carotenoids, hut for LHC‐2 complexes, fluence rates between 0.4 and 1.5 [μmol m−2 s−1 were more effective. In pine the effects of the two lights on the accumulation of pigments and LHC proteins were demonstrated separately and were dependent on fluence rate level. This suggests irradianoe‐controlled activation/deactivation of the photoreceptor at the level of the cell.

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