Low-Temperature Adaptation of Winter Wheat Seedlings under Excessive Zinc Content in the Root Medium

Resumo

Cold adaptation of winter wheat (Triticum aestivum L.) seedlings was investigated under excessive zinc content (1000 μM) in the root medium. The ability to adapt to chilling temperatures (4°C) in seedlings exposed over seven days to excessive Zn concentrations was lower than in seedlings exposed to optimal composition of mineral nutrients. The impaired adaptation capacity was evident from the lowered content of photosynthetic pigments in leaves, the decreased stomatal conductance, and the reduced water content in shoot tissues. The negative influence of low temperature on plant physiological parameters was enhanced with the prolongation of cold exposure under Zn excess in the root medium, unlike the alleviation of cold-induced disorders during prolonged chilling under optimal Zn concentration (2 μM). Based on this study, we propose that inhibition of photosynthesis and the disturbance of plant water balance are the main factors that impair the low-temperature adaptation of seedlings exposed to high zinc concentrations.