Participation of Green Organs to Grain Filling in Triticum turgidum var durum Grown under Mediterranean Conditions.

Othmane Merah,Philippe Monneveux,Philippe Evon

doi:10.3390/ijms19010056

Abstract

In wheat, flag leaf, stem, chaff and awns contribute to grain filling through photosynthesis and/or re-mobilization. Environmental and genetic effects on the relative contribution of each organ were examined by analyzing the consequences of sink-source manipulations (shading and excision) and by comparing carbon isotope discrimination (Δ) values in dry matter (at maturity) and sap (two weeks after anthesis) in six durum wheat genotypes grown in two contrasting seasons. The contribution of flag leaf, stem, chaff and awns to grain filling, estimated by sink-source manipulations, highly varied with the season. The contribution of ear photosynthesis and re-mobilization from the stem increased with post-anthesis water stress. They showed a large genetic variation that was, however, not clearly associated to morphological characteristics of ear and stem. Isotopic imprints of chaff on grain Δ were identified as a possible surrogate of the destructive and cumbersome sink-source manipulations to evaluate the contribution of carbon assimilated in ears or re-mobilized from stem. This might facilitate screening of genetic resources and allow the combining of favourable drought tolerance mechanisms in wheat.

Highlights

Several researchers have attempted to estimate the respective participation of current assimilation and re-mobilization of pre-anthesis stored assimilates to winter cereal grain yield
thousand kernels weight (TKW) and Grain yield (GY) were lower in Season 1 as a consequence of the strong post-anthesis water stress experienced by the crop (Figure 1)
Carbon isotope discrimination in sap (∆s) was lower in chaff and awns than in leaves in both cultivars, and significant correlations were found between ∆s and dry matter ∆ (r = 0.903, p < 0.05 in Casablanca 7580 and r = 0.962, p < 0.01 in Caravaca Colorado). ∆Cs was correlated with TKW and GY. ∆As correlated with GY in Casablanca 7580 but not in Caravaca Colorado

Summary

Introduction

Several researchers have attempted to estimate the respective participation of current assimilation (resulting from photosynthesis productivity) and re-mobilization of pre-anthesis stored assimilates to winter cereal grain yield. There have been few attempts to quantify the impact of those factors on the relative contribution of different vegetative or reproductive organs to grain filling and final grain yield [5]. Labelling by radioactive carbon isotope can permit us to determine part of the translocation and photosynthesis and determine the source of carbon for grain filling. This methodology is very difficult and tiresome to achieve. Values of ∆ of different plant organs may reflect the variation of plant water status during the season, and the isotopic imprints of different organs on the final isotope composition of the grain could help advise their contribution to grain filling

Methods

Results

Discussion

Conclusion