Аннотации:
© 2019, Dorma Journals. All rights reserved. The study of leaf gas exchange among medium and highly drought tolerant spring varieties of Tríticum aestívum during moderate osmotic stress modeling showed a significant difference in the dynamics of transpiration intensity (E) at the initial stage of the experiment. The monotonic dynamics of E decrease correlated with the change in stomatal conductance of water (gw) and CO2 assimilation rate decrease (A) in a highly drought tolerant variety, which is explained by stomata closure. The dynamics of E among the varieties resistant to drought had the form of a complex curve with an extremum during the first 12 minutes of the experiment, which is explained by the gas embolism of xylem vessels. Embolization of a part of xylem vessels has led to the imbalance in gas exchange rates. 75% decrease of E during the experiment did not coincide with the change of gw, which decreased only by 50%. In addition, under conditions of E decrease, a significant decrease of A was not observed. Transpiration decrease during osmotic stress due to stomata closure led to 28% drop of A, and comparable decrease in transpiration due to xylem vascular embolism reduced A by 6%. It has been shown that the tendency to xylem vascular embolization in the medium-drought-tolerant variety of spring wheat Tríticum aestívum under the conditions of moderate water deficiency makes it possible to maintain a high level of CO2 assimilation rate, which is comparable with a highly resistant variety that can ultimately lead to a higher yield.
