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Water Relations and Transpiration of Quinoa (Chenopodium quinoa Willd.) Under Salinity and Soil Drying

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  • Fatemeh Razzaghi, Denmark
  • Seyed Hamid Ahmadi, Irrigation Department, Shiraz University, Iran, Islamic Republic of
  • Verena Isabelle Adolf, Afgrødevidenskab, Denmark
  • Christian Richardt Jensen, Afgrødevidenskab, Denmark
  • S.-E. Jacobsen, University of Copenhagen, Denmark
  • Mathias Neumann Andersen
Drought and salinity are the two major factors limiting crop growth and production in arid and semi-arid regions. The separate and combined effects of
salinity and progressive drought in quinoa (Chenopodium quinoa Willd.) were
studied in a greenhouse experiment. Stomatal conductance (gs), leaf water
potential (Wl), shoot and root abscisic acid concentration ([ABA]) and transpiration
rate were measured in full irrigation (FI; around 95 % of water holding
capacity (WHC)) and progressive drought (PD) treatments using the irrigation
water with five salinity levels (0, 10, 20, 30 and 40 dS m)1); the treatments are
referred to as FI0, FI10, FI20, FI30, FI40; PD0, PD10, PD20, PD30, PD40, respectively.
The measurements were carried out over 9 days of continuous drought.
The results showed that increasing salinity levels decreased the total soil water
potential (WT) and consequently decreased gs and Wl values in both FI and
PD. During the drought period, the xylem [ABA] extracted from the shoots
increased faster than that extracted from the roots. A reduction in WT, caused
by salinity and soil drying, reduced transpiration and increased apparent root
resistance (R) to water uptake, especially in PD0 and PD40 during the last days
of the drought period. The reasons for the increase in apparent root resistance
are discussed. At the end of the drought period, the minimum value of relative
available soil water (RAW) was reached in PD0. Under non-saline conditions,
Wl decreased sharply when RAW reached 0.42 or lower, but under the saline
conditions of PD10 and PD20, the threshold values of RAW were 0.67 and 0.96,
respectively. In conclusion, due to the additive effect of osmotic and matric
potential during soil drying on soil water availability, quinoa should be
re-irrigated at higher RAW in salt-affected soils, i.e. before the soil water
content reaches the critical threshold level causing the drop in Wl resulting in
stomatal closure.
Original languageEnglish
JournalJournal of Agronomy and Crop Science
Pages (from-to)348-360
Number of pages13
Publication statusPublished - 2011

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