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Accueil du site → Doctorat → Espagne → 2015 → ÚS D’ISÒTOPS ESTABLES D’O, H, C COM EINES DE SELECCIÓ DE RENDIMENT POTENCIAL I ADAPTACIÓ A LA SEQUERA I DEFICIÈNCIA DE NITROGEN EN CEREALS C3 I C4

Universidad BARCELONA (2015)

ÚS D’ISÒTOPS ESTABLES D’O, H, C COM EINES DE SELECCIÓ DE RENDIMENT POTENCIAL I ADAPTACIÓ A LA SEQUERA I DEFICIÈNCIA DE NITROGEN EN CEREALS C3 I C4

SÁNCHEZ BRAGADO, RUT

Titre : ÚS D’ISÒTOPS ESTABLES D’O, H, C COM EINES DE SELECCIÓ DE RENDIMENT POTENCIAL I ADAPTACIÓ A LA SEQUERA I DEFICIÈNCIA DE NITROGEN EN CEREALS C3 I C4

Auteur : SÁNCHEZ BRAGADO, RUT

Université de soutenance : Universidad BARCELONA

Grade : Tesis Doctoral 2015

Résumé
Water limitation, followed by low nitrogen availability, is the major constraints of yield in Mediterranean environments. Thus, it is necessary to search for novel phenotyping tools, which may help to accelerate breeding for yield potential and crop adaptation to limited conditions. This Thesis has studied the isotope composition on its natural abundance of carbon (¿13C), oxygen (¿18O) and hydrogen (¿2H) of different cereals. Regarding the ¿13C, only mature grains showed consistent phenotypic correlations (negative) against grain yield in durum wheat, especially under moderate stress conditions (Chapter 5). This Thesis also proposes the use of ¿13C (natural abundance) as an approach to quantify the relative contribution of different plant organs to grain filling (Chapters 1 and 2). The aim of this approach was to use the ¿13C in order to develop precise tools to select genotypes with enhanced ear photosynthesis. In durum wheat, the ¿13C approach assigned a higher role to the ear (both, whole body and awns) compared to the flag leaf and peduncle (which integrates the assimilates produced by photosynthetic organs below the ear), especially in the old landraces and regardless of growing conditions. Under good agronomic conditions, the contribution of awns of the ear to grain filling in bread wheat was also more important than the flag leaf. Finally, the ¿13C approach based on the different plant parts was compared with other conventional approaches (Chapter 3), such as shading or herbicide DCMU application. Shading treatment assigned a comparable contribution to the ear than the culm. On the contrary, DCMU approach assigned a greater role to the culm, but herbicide application to the culm affected the ear, thus biasing the final grain weight. This thesis also studied the oxygen isotope composition in both maize (Chapter 4) and durum wheat (Chapter 5). In maize, phenotypic correlations between ¿18O and grain yield were marginal, although the silks was the organ which showed the highest correlation against grain yield. In durum wheat, phenotypic correlations between ¿18O and grain yield were also marginal. Only when the two water regimes (supplementary irrigation and drought) were combined ¿18O of leaf water was strongly correlated with GY. The absence of such correlations will eventually help to discard plant tissues, which are more susceptible to post-photosynthetic fractionation processes, and may help to understand the use of ¿18O as a genotype selection tool for the adaptation of maize and other crops to drought. Finally the ¿13C and ¿18O were compared with ¿2H (Chapter 5) in durum wheat. ¿2H performed better than the other two isotopes predicting grain yield and nitrogen content under water stress but contrasting nitrogen regimes. Besides, genotypic correlations between ¿2H in the ear water-soluble fraction and grain yield were observed. In addition, ¿2H in the water soluble fraction of leaves was better correlated against ¿13C than with ¿18O, suggesting that ¿2H of leaf photo-assimilated is affected not only by transpiration and stomatal conductance but also by the photosynthetic reactions. In addition, the low values observed in the ¿2H of the ear compared to mature grains supported the photosynthetic role of the ear, which reinforced results obtained in Chapters 1, 2 and 3.

Descripteurs :FISIOLOGIA VEGETAL — CULTIVOS EXTENSIVOS

Présentation (TESEO)

Page publiée le 10 décembre 2015, mise à jour le 13 février 2019