Carbon Isotope Composition and the NDVI as Phenotyping Approaches for Drought Adaptation in Durum Wheat: Beyond Trait Selection

Rut Sanchez-Bragado,Fadia Chairi,Roberto Tuberosa,Jeffrey W White,Jose Luis Araus,Giuseppe Emanuele Condorelli,Richard W Ward,Marco Maccaferri,Maria Dolors Serret Molins,Maria Newcomb

doi:10.3390/agronomy10111679

Abstract

High-throughput phenotyping platforms provide valuable opportunities to investigate biomass and drought-adaptive traits. We explored the capacity of traits associated with drought adaptation such as aerial measurements of the Normalized Difference Vegetation Index (NDVI) and carbon isotope composition (δ13C) determined at the leaf level to predict genetic variation in biomass. A panel of 248 elite durum wheat accessions was grown at the Maricopa Phenotyping platform (US) under well-watered conditions until anthesis, and then irrigation was stopped and plot biomass was harvested about three weeks later. Globally, the δ13C values increased from the first to the second sampling date, in keeping with the imposition of progressive water stress. Additionally, δ13C was negatively correlated with final biomass, and the correlation increased at the second sampling, suggesting that accessions with lower water-use efficiency maintained better water status and, thus, performed better. Flowering time affected NDVI predictions of biomass, revealing the importance of developmental stage when measuring the NDVI and the effect that phenology has on its accuracy when monitoring genotypic adaptation to specific environments. The results indicate that in addition to choosing the optimal phenotypic traits, the time at which they are assessed, and avoiding a wide genotypic range in phenology is crucial.

Highlights

Global warming makes agricultural productivity more unpredictable, especially in the semiarid regions of the world
The plant material included 248 accessions of durum wheat (Triticum turgidum L. subsp. durum (Desf.) Husn.) from the association mapping population assembled by Maccaferri and co-workers at the University of Bologna (UNIBO), namely the UNIBO-Durum Panel representing an Elite Durum Panel (EDP) that comprises a large portion of the genetic diversity present in the most important improved durum wheat gene pools
The unmanned aerial vehicles (UAVs)-based Normalized Difference Vegetation Index (NDVI) measured at different time points in the crop cycle reflected the increase in biomass during crop development until anthesis and the degree of staygreen during grain filling in response to progressive drought (Table 1)

Summary

Introduction

Global warming makes agricultural productivity more unpredictable, especially in the semiarid regions of the world. Agronomy 2020, 10, 1679 area, the number of grains per spike, grain weight, harvest index, or plant height [3,4] In this context there is an urgent need to increase genetic yield potential and drought resilience in new cultivars [5]. Crop phenology has been one of the most successful proxies used by breeders in Mediterranean environments, where the frequency and intensity of drought episodes occurring during grain filling have increased in the past decades. In these conditions, genotypes with earlier anthesis have demonstrated their value [6,7,8]. It is expected that it will have an important impact on future genetic gain in yield [12,13]

Objectives

Methods

Results

Discussion

Conclusion