Water relations and growth of original barley plants and its ABA-deficient mutants at increased air temperature
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Data on the effects of air temperature increase by 4°C on leaf growth and water relation parameters in barley (Hordeum vulgare L.) plants in original cv. Steptoe and its ABA-deficient mutant (AZ24) are presented. An increase in temperature firstly resulted in the cessation of leaf elongation in both genotypes; however, later in cv. Steptoe plants, as distinct from mutants, the rate of leaf length increment was completely restored. Before air warming, transpiration was more intense in mutant plants; at increased temperature, transpiration was activated in both genotypes. After growth resumption, the water potential in cv. Steptoe plants somewhat increased as compared with initial level (before warming). In AZ34 leaves, in contrast, the water potential, which was initially below that in cv. Steptoe leaves, reduced after temperature increase. The calculation of total hydraulic conductivity of the plants and osmotic hydraulic conductivity in the roots showed that these parameters increased in cv. Steptoe and were not changed in AZ34 mutants. At temperature increase, the level of ABA was not changed in AZ34 mutants, whereas in Steptoe plants it increased in the roots and decreased in the shoots. It was concluded that a capability of ABA synthesis is required for the control of total hydraulic conductivity under changing environmental conditions.
KeywordsHordeum vulgare growth water relations ABA increased air temperature
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