PHOTOSYNTHESIS AND RESPIRATION IN PLANTS GROWN UNDER RED AND WHITE-LIGHT

Tomato (Lycopersicon esculentum Mill), sunflower (Helianthus annuus L. ), and cucumber (Cucumis sativus L.) plants were grown under red or wh ite light at a radiance of 115 W/m(2) under controlled conditions. The red spectra were characterized by either two well-distinguished spect ral lines (RL1) or only one (RL2). Apparent photosynthesis (P-a), gros s photosynthesis (P-g), dark (R-d) and Light (R-l) respiration, the co ntent of pigments, and the biochemical composition of plants were esti mated. Enhancing the destructive red Light influence led to a rise in the P-a/R-l and P-a/P-g ratios and to a decrease in chlorophyll a, nit rate, and reduced nitrogen. RL1 was more inhibitory for plants than RL 2. It is concluded that declined energy efficiency of respiration cont ributes to the destructive effect of RL in sunflower and cucumber plan ts. The rearrangement of metabolic processes, at which energy efficien cy of respiration is maintained, is responsible for adaptation of toma to plants to red Light. The obtained results allow one to outline the ways to study the species-specific mechanisms of plant responses to pr olonged RL action.