Oxygen isotope discrimination of wheat and its relationship with yield and stomatal conductance under irrigated conditions

Abstract

This study was carried out to determine the different irrigation regime effects on oxygen isotope discrimination of stem water (Δ 18 O s ) and its relationship with grain yield (GY), aboveground biomass (BM), and stomatal conductivity (g s ) of winter wheat. For this purpose a field experiment was conducted between 2009 and 2011 in a semiarid region of Turkey under rainfed (RF), deficit (DI), moderate (MI), and full irrigation (FI) conditions. The highest GY and BM (4.5 t ha -1 and 14.5 t ha -1 ) were measured from the FI treatment. However, the difference between the yield of DI and FI treatments was insignificant. It might be recommended that the DI treatment be used for wheat irrigation to increase water-use efficiency for semiarid climate conditions. Average Δ 18 O s values were obtained as 35.36‰, 34.56‰, 34.35‰, and 33.18‰ for RF, DI, MI, and FI treatments, respectively. Applied irrigation water and GY were found to be strongly negatively related to Δ 18 O s , so it may be a useful predictor of yield in irrigation programs. Effects of water regime on yield probably reflected the correlation with the isotopic composition of transpiration. A negative relationship was obtained between average Δ 18 O s and g s at a significant level for which the correlation coefficient was 0.68. However, the relationship was positive between GY and g s .

Crop phenotyping in a context of global change: What to measure and how to do it

“…Second, once the water enters the roots the δ 18 O and δ 2 H of the water does not change until water is exposed to the evaporation processes in the aerial parts of the plant, where isotopic fractionation occurs. The use of the stem water oxygen isotopic signature as an indicator of water status was highlighted in a recent study reporting that a reduced stomatal conductance, and thus reduced photosynthetic response, is triggered by limitations to root water uptake in wheat genotypes in water stressed environments (Kale Çelik et al, 2018).…”

“…Analysis of the stable isotope composition of oxygen and hydrogen (δ 18 O and δ 2 H) in the water of the plant stem base has been proposed as an approach to trace the provenance (e.g., irrigation versus precipitation) of the water captured by the plant or the soil depth from which the roots have extracted the water (Yepez et al, 2003; Williams et al, 2004; Kale Çelik et al, 2018; Sanchez‐Bragado et al, 2019; Liu et al, 2020; Rezzouk et al, 2022). The rationale of the approach is based on two considerations.…”

High-throughput root phenotyping of crop cultivars tolerant to low N in waterlogged soils

“…To understand root response, examination of the stable isotope composition of N in roots under WL can improve our understanding of the physiological basis of roots and NUE under WL. Having said that, isotopic signatures of oxygen in stem water were used as an indicator of water status in water-stressed roots ( Kale Celik et al., 2018 ). Thus, this approach should be used along with other HTRP techniques.…”