engleski

Antioxidative responses induced by temperature stress in soybean (Glycine max (L.) Merr.) leaf at flowering

Grain crops such as soybean are very sensitive to unfavourable climatic conditions at flowering stage. Drought and/or temperature deviations at this developmental stage result with low fertilization, diminished grain number per plant and consequently significant yield loss. In such stress conditions various antioxidative mechanisms at physiological levels can be detected. This research shows some of the responses to unfavourable temperature in flowering stage of two soybean cultivars, after three day exposure to heat (30oC) and chilling stress (10oC) in growth chamber. As the water supply was not restricted, leaf tissue analysis showed different responses to temperature treatments in particular cultivar. In general, lipid peroxidation intensity was higher at low temperature, however, hydrogen peroxide level, free proline and total phenols content were higher at 30oC. This temperature resulted with higher antioxidative enzymes activities (ascorbate peroxidase, catalase, guaiacol peroxidase) as compared to low temperature conditions. On the contrary, the highest glutathione reductase activity was established at low temperature but not statistically different from 20oC (control) and 30oC. Tested cultivars showed significant differences only at high temperature, with lower lipid peroxidation level in cultivar Zora, which had the higher ascorbate- and guaiacol peroxidase activity as well, in comparison with cultivar Tena. As a low temperature is rare during the soybean flowering stage in a continental climate, and above optimal temperatures are expected to occur more frequently due to global climate changes, it is obvious that high temperature stress tolerance is an important trait in soybean.

soybean ; temperature stress ; antioxidative response ; enzyme activity

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