Does root-sourced ABA play a role for regulation of stomata under drought in quinoa (Chenopodium quinoa Willd.) |
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Authors: | Sven-Erik Jacobsen Fulai LiuChristian Richardt Jensen |
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Institution: | Copenhagen University, Faculty of Life Sciences, Department of Agricultural Sciences, Højbakkegaard Allé 13, DK-2630 Taastrup, Denmark |
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Abstract: | The Andean seed crop quinoa (Chenopodium quinoa Willd.) is traditionally grown under drought and other adverse conditions that constrain crop production in the Andes, and it is regarded as having considerable tolerance to soil drying. The objective of this research was to study how chemical and hydraulic signalling from the root system controlled gas exchange in a drying soil in quinoa. It was observed that during soil drying, relative gs and photosynthesis Amax (drought stressed/fully watered plants) equalled 1, until the fraction of transpirable soil water (FTSW) decreased to 0.82 ± 0.152 and 0.33 ± 0.061, respectively, at bud formation, indicating that photosynthesis was maintained after stomata closure. The relationship between relative gs and relative Amax at bud formation was represented by a logarithmic function (r2 = 0.79), which resulted in a photosynthetic water use efficiency WUEAmax/gs of 1 when FTSW > 0.8, and increased by 50% with soil drying to FTSW 0.7–0.4. Mild soil drying slightly increased ABA in the xylem. It is concluded that during soil drying, quinoa plants have a sensitive stomatal closure, by which the plants are able to maintain leaf water potential (ψl) and Amax, resulting in an increase of WUE. Root originated ABA plays a role in stomata performance during soil drying. ABA regulation seems to be one of the mechanisms utilised by quinoa when facing drought inducing decrease of turgor of stomata guard cells. |
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Keywords: | ABA abscisic acid FTSW the fraction of transpirable soil water LER leaf expansion rate PAR photosynthetically active radiation ψr root water potential ψl leaf water potential Amax photosynthesis gs stomatal conductance WUEAmax/gs" target="_blank">gif" overflow="scroll">WUEAmax/gs photosynthetic water use efficiency |
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