Leaf Carbon Isotope Discrimination as an Accurate Indicator of Water‐Use Efficiency in Sunflower Genotypes Subjected to Five Stable Soil Water Contents

A L Adiredjo,T Lamaze,P Grieu,O Navaud

doi:10.1111/jac.12079

Abstract

AbstractLeaf carbon isotope discrimination (CID) has been suggested as an indirect tool for breeding for water‐use efficiency (WUE) in various crops. This work focused on assessing phenotypic correlations between WUE and leaf CID and analysing genotypic variability in four sunflower genotypes grown in a greenhouse in pots with five different stable levels of soil water content (SWC). We measured WUE at whole plant and leaf (intrinsic) level. At whole plant level, WUE was derived from the ratio of total dry aerial biomass (BM) to cumulative water transpired (CWT). At leaf level, intrinsic WUE was calculated as the ratio of light‐saturated CO2 assimilation to stomatal conductance (A/gs) in younger expanded leaves. Significant differences among the four genotypes and the five SWCs were observed for whole plant and leaf WUE and CID. Strong negative correlations were observed between whole plant WUE and CID as well as between intrinsic WUE and CID with decreasing water availability. No relationships appeared between BM production and WUE or CID. Our results can help agronomists and breeders to evaluate sunflower lines with high WUE for adaptation to drought conditions and for reducing water consumption and crop water needs. Leaf CID appears to be a pertinent and valuable trait to select sunflower genotypes with high WUE.

Highlights

Sunflower (Helianthus annuus L.), the fourth important sources of vegetable oil in the world (List 2014), is mainly produced in Ukraine, Russia, European countries and Argentina (USDA 2014)
In this study, exploring the possibility of using carbon isotope discrimination (CID) as an indicator to select sunflower genotypes with high water-use efficiency (WUE), we studied the relationship between CID and WUE in four recombinant inbred lines (RILs) of juvenile sunflowers
A highly significant negative correlation was observed between WUE and CID (Table 1, rp = À0.66, P < 0.001, n = 20 in Exp. 1, and rp = À0.67, P < 0.001, n = 20 in Exp. 2), while there were no significant correlations between BM and CID or WUE

Summary

Introduction

Sunflower (Helianthus annuus L.), the fourth important sources of vegetable oil in the world (List 2014), is mainly produced in Ukraine, Russia, European countries and Argentina (USDA 2014). Sunflower planted area has increased (Labalette et al 2012) and expanded in the arid region of the Mediterranean and North Africa (Blamey et al 1997, Kane et al 2013). According to Food and Agriculture Organization of the United Nations (FAO) publication reported by Garcia-Via et al (2012), sunflower yields vary between 5 ton haÀ1 under ample water supply. Sunflower is considered well adapted to drought, but genotypes are not homogeneously efficient in the use of water. Systematic analyses of the physiological basis of drought tolerance in sunflower and purposeful attempts to breed for greater drought resistance are still limited (Grieu et al 2008)

Methods

Results

Conclusion