engleski

Chlorophyll-a fluorescence OJIP transient as a tool to assess cold tolerance in wheat seedlings

Low temperature affects a broad spectrum of physiological processes, and photosynthesis is one of the essential processes, which is more inclined to cold stress. This study aimed to test the influence of cold stress on the photosynthetic machinery of wheat seedlings (<i>Triticum aestivum</i> L.). In two experiments, cold stress was investigated in the form of a sudden drop in temperature (from ~22°C/18°C day/night down to -2°C in the first hour of the night), and in the form of slow gradual decrease (also down to -2°C during the night). Chlorophyll <i>a</i> fluorescence induction was used as <i>in vivo</i> assessment of cold tolerance, and measurements were performed on two genotypes of winter wheat (L459-2012 and Osk 114/08), both non-acclimated (~22°C/18°C) and acclimated to low temperatures (~4°C, day/night). OJIP curves and JIP parameters revealed differences between the type of stress duration, acclimated and non- acclimated plants and between genotypes. Acclimated plants of L459-2012 genotype performed better (PI_ABS, PI_TOT) under both types of cold stress, whereas as performance indexes of Osk 114/08 genotype were increased only after the slow drop in temperature, while sudden drop caused a significant decrease of photosynthetic efficiency. On a subsequent day after the cold stress, acclimated plants of both genotypes increased their photosynthetic performance up to 21%. Detailed analysis of fluorescence data showed that OJIP transient contains useful information for the evaluation of cold stress tolerance of seedlings, that data is stress type and genotype-specific, and can complement the knowledge needed to address some fundamental issues, like the degree of plasticity.

performance index, photosynthesis, slow temperature decrease, sudden temperature drop, tolerance to stress

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