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Tropentag, September 14 - 16, 2022, Prague

"Can agroecological farming feed the world? Farmers' and academia's views."


Impact of drought stress on leaf pigment concentration at different leaf positions in the canopy

Geckem Dambo1, Ilaria Parente1, Alejandro Pieters1, Folkard Asch1, Francisco Pinto2, Mathew Reynolds2, Carlos A Robles-Zazueta2

1University of Hohenheim, Inst. of Agric. Sci. in the Tropics (Hans-Ruthenberg-Institute), Germany
2CIMMYT Mexico, Physiology/Remote Sensing, Mexico


Abstract


Wheat productivity is being challenged by increasingly frequent water deficit periods. Under these conditions light induced damage is more likely. Thus, leaf pigments should adjust to mitigate the stress caused by water deficit on the photosynthetic machinery. The aim of this study is to evaluate the impact of water deficit on leaf pigment composition using hyperspectral reflectance and SPAD data. Measurements were taken at initiation of booting on the flag, the second and third leaves using a portable spectroradiometer and handheld SPAD-502 chlorophyll meter. Nine elite bread wheat genotypes from CIMMYT’s Best PT panel tolerant to heat and drought stresses were studied in the field at CIMMYT experiment station in NW Mexico during 2021/2022 growing season under drought (D) and yield potential (YP) conditions. The D treatment was irrigated at sowing, 50% emergency and before initiation of booting, whereas the YP treatment was irrigated at sowing, 50% emergency and every fourteen days until late grain filling. Spectral reflectance indices related to carotenoids, chlorophyll a and chlorophyll b were used for leaf pigment estimation. Results showed significant differences for treatment effect at flag and third leaves (p<0.001) for carotenoids (Car). Meanwhile chlorophyll a (chl a) showed differences in flag leaf (p<0.003) under YP and differences due to genotype by environment (GxE) (p<0.004), while for chlorophyll b (chl b) differences were found in flag leaf (p<0.01) among treatments and GxE interaction (p<0.003). Low levels of SRI for car, chl a and chl b were observed in D conditions compared to YP. SPAD showed significant differences among genotypes (p<0.05) in YP, and among position in the canopy (flag, second and third leaves (p<0.001). These results show that water deficit has significant effect on hyperspectral reflectance properties related to leaf pigment composition. Spectral indices genotypic variability highlights the potential of this phenotyping approach for identifying water stress tolerant wheat genotypes. Further confirmation will be established by analysis of leaf extracts using HPLC, which will demonstrate relationship between changes in pigment composition and grain yield.


Keywords: Leaf pigments, spectral reflectance indices, water deficit, wheat (Triticum aestivum L.)


Contact Address: Geckem Dambo, University of Hohenheim, Inst. of Agric. Sci. in the Tropics (Hans-Ruthenberg-Institute), Stuttgart, Germany, e-mail: geckem.dambo@uni-hohenheim.de


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