engleski

Photosynthetic properties of maize hybrids under different environmental conditions probed by the chlorophyll a fluorescence

Temperatures and light intensities that deviate from optimum often affect maize (Zea mays L.) production in temperate regions. Objectives of the current study were (i) to investigate the effects of extreme temperatures and low light conditions on photosynthesis in maize hybrids, (ii) to test whether maize hybrids show distinctive reactions when subjected to different stresses, and (iii) to investigate informativeness of different fluorescence parameters in different stress conditions. Plants of five maize hybrids were subjected to: cold (Co), low light (LL), heat (H), and severe heat (SH) treatments and field (F) conditions along with control (C), and chlorophyll a fluo- rescence (ChlF) was measured. ChlF transients were shown to respond to different treatments by changing the appearance of OJIP band, mostly at steps J and I, while the appearance of the K step was confirmed as a good indicator of temperature stress. PC analysis revealed grouping of parameters with PCs according to their infor-mativeness. Parameter ψEo, was shown to be in most defined by the F treatment, probably due to higher light intensity compared to C. Variables regarding electron transport and dissipation showed specific reactions to H and SH treatments. Co and LL conditions caused specific changes in in parameters VJ and VI. Further research on usability of ChlF in maize breeding is needed, as it represents the data- rich, easy to measure method, providing the biological framework for explanation of reactions to different stresses.

stress assessment ; maize hybrids ; ChlF ; PIABS ; PC analysis

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