A Study of the State of Photosynthetic Pigments of Hybrid Maize Seeds Exposed to Ultraviolet and Radiation

Resumo

Abstract—We investigated the state of the pigments of inbred (zpp1225) and hybrid (zp341) maize (Zea mays L.) seeds exposed to ultraviolet radiation and α-irradiation using spectral methods. Exposure to different ultraviolet radiation doses from 5 to 13.39 kJ/m² and α-irradiation from 1.5 to 3 kGy stimulated plant growth and seed germination. Exposure of seeds to a high dose of α-irradiation (15 kGy) led to inhibition of plant growth and development. Irradiation of seeds can change the state and function of the pigments present in the leaves. Irradiation of seeds induced conformational changes of carotenoid modules (increase of the length of the polyene chain and amount of molecules in 15-cis-conformation); the effect depends on the type of irradiation (the effect was larger when seeds were exposed to α-irradiation). It was shown that the photosynthetic apparatus in hybrid (zp341) maize is characterized by a relatively increased I–P phase on the induction curve of fast fluorescence and a higher degree of oxidation of the P700 reaction center, indicating a higher acceptor pool on the acceptor side of the photosystem I in the hybrid maize. Seed exposure to ultraviolet radiation and α-irradiation caused inhibition of reactions in photosystem II in leaves, observed as a decrease in the quantum yield of electron transport (φ_Eo), an increase of non-photochemical quenching (DI₀/RC and φ_Do) and a decrease of the energy of thylakoid membranes (higher Δψ). The highest decease caused by radiation was determined for the generalized index of photosystem II performance (PI_ABS). The PI_ABS production index can be recommended for assessing the status of plants in selection studies.