Relationship between taproot morphological traits, carbon isotope composition and grain yield in safflower

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Mihoub, Imane | Badeck, Franz-W. | Aid, Fatiha | Lamothe-Sibold, Marlène | Ghashghaie, Jaleh

Edité par CCSD ; Taylor & Francis -

International audience. The purpose of this study was to determine to what extent root characteristics, other than the taproot length, contribute to high grain yield and/or high water use efficiency (WUE) in safflower. A greenhouse trial was conducted using four safflower accessions (USDA6, USDA23, USDA29 and VARTOUG) with contrasting yield and WUE. A randomised complete block design was chosen, which included a typical (control) and a drought stress (withholding watering at the pre-flowering stage) treatments. The carbon isotope composition (C-13) as an estimate of WUE, taproot diameter (D-TR), diameter and number of secondary roots (D-SR and N-SR, respectively), biomass of the upper section of the taproot (BMTR-up) as well as grain yield (GY) and its components were measured. Our results revealed that N-SR could be involved in drought adaptation of USDA23, with N-SR increasing significantly (p=0.045) by 27% under drought stress in this accession. BMTR-up was the only taproot trait correlated to GY and/or WUE, however the nature of the correlation was different for control and stressed plants. BMTR-up was significantly (p=0.01) and negatively correlated with C-13 (r=-0.63) but had no correlation with GY (r=0.23) in control plants. In contrast, BMTR-up was significantly (p=0.03) and positively correlated with GY (r=0.56) but not with C-13 (r=0.23) under drought stress conditions. This finding suggests that, in the absence of drought conditions selecting safflower for a lower biomass in the upper section of the taproot may lead to high WUE, without affecting the yield.

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