Acta Biochimica et Biophysica 10. (1975)
1975 / 1-2. szám - Horváth, I.-Szalay, L.: Photosynthetic Production and Wavelength-dependent Energy Migration
124 Horváth, Szalay: Photosynthetic Production and Energy Migration This phenomenon could be demonstrated in a mixed solution containing chlorophyll-й and chlorophyll-a (Bauer et ah, 1972) and also in solutions containing carotene, chlorophyll-a and chlorophyll-/; (Szabad, 1972; Szabad, Szalay, 1973). If the migration of the excitation energy depends on the wavelength of the exciting light, this can be expected to influence also photosynthetic production in monochromatic light. In the present investigations we started from this assumption. Materials and methods Tomato (Kecskeméti törpe variety) and paprika (Keszthelyi fehér variety) seedlings were used in the experiments. The practically monochromatic light was ensured with Zeiss metal interference filters. The filters were placed on doublewalled growing-boxes, in which the plants were grown in a sand culture. The growing-boxes’ double walls were perforated in an alternating manner (the facing surfaces were black), and thus the light could pass into the boxes via the interference filters only. The perforation was necessary because of the air exchange. A model experiment was also carried out in connection with the air exchange, in which the growing-boxes were additionally fitted with “aquarium aeraters”. A 10-per-cent difference was observed in the dry weights of plants grown in the boxes with perforated walls, and those with the additional aeration. The sand culture was adjusted with Knopp solution to a water capacity of 70 per cent, and the water content was maintained by daily irrigation with distilled water to weight. Taking into consideration the absorption spectra of chlorophyll-a and chlorophyll-/;, interference filters of the following transmissions were used in the examinations: 425, 450, 475, 650, and 675 nm. The two pigments absorb energy in strongly varying proportions from the light passed through these filters. A 1-kw halogen (iodine) lamp was used as light source, the infrared rays being filtered out with a 10 cm thick flowing water layer. The lamp caused practically no temperature increase below the water filter. The energy of the light under these filters was constant: 7.2 x 10~3 cal cm'2, cm-1. Illumination was maintained for 12 hours each day. By day the temperature was ca. 28°C, and by night ca. 20°C. Three examinations were made with tomato, and four with paprika. The seedlings were processed on the 17th and 14th day after sowing, on the average, in the case of tomato and paprika, respectively. In addition to the determination of the dry weight of each organ, the chlorophyll-a and chlorophyll-/; contents were measured. The pigments were extracted from 50 mg fresh mateiial with 1 ml acetone, which was then diluted to 5 ml with petroleum ether. The amounts of chlorophyll-a and chlorphyll-Z; were calculated from the extinctions measured at 647 and 664 nm, according to Ziegler and Egle (1965). Acta Biochimica et Biophysica Academiae Scientiarum Hungaricae 10, 1975