Investigating Combined Drought- and Heat Stress Effects in Wheat under Controlled Conditions by Dynamic Image-Based Phenotyping

Lamis Osama Anwar Abdelhakim,Bernd Wollenweber,Klára Panzarová,Ioannis Spyroglou,Carl-Otto Ottosen,Eva Rosenqvist

doi:10.3390/agronomy11020364

Abstract

As drought and heat stress are major challenges for crop productivity under future climate changes, tolerant cultivars are highly in demand. This study investigated the potential of existing Nordic wheat genotypes to resist unfavorable conditions. Four genotypes were selected based on their heat sensitivity (heat-sensitive: LM19, SF1; heat-tolerant: LM62, NS3). At the tillering stage, the plants were subjected to four treatments under controlled conditions: control, drought, heat and combined drought and heat stress. The morpho-physiological performance was quantified during the early and late phase of stress, as well as the recovery phase. We applied an integrative image-based phenotyping approach monitoring plant growth dynamics by structural Red Green Blue (RGB) imaging, photosynthetic performance by chlorophyll fluorescence imaging and transpiration efficiency by thermal infrared imaging. The results demonstrated that the selected genotypes were moderately affected in their photosynthetic efficiency and growth under drought stress, whereas heat and combined stress caused rapid reductions in photosynthesis and growth. Furthermore, drought stress had a major impact on canopy temperature. The NS3 genotype was the most robust genotype, as indicated by its improved response under all stress treatments due to its relatively small biomass. However, the genotypes showed different tolerance to individual and combined stress.

Highlights

The increase in climatic variability, such as heat waves together with prolonged drought episodes, is a threat to agricultural productivity [1,2]
The soil relative water content (SRWC) decreased significantly in LM19 and LM62 compared to SF1 and NS3 (Figure 2A2)
During heat and combined stress treatments, SRWC was the lowest in LM62 followed by LM19 and SF1, while NS3 showed significantly higher SRWC compared to the other genotypes (Figure 2A3,4)

Summary

Introduction

The increase in climatic variability, such as heat waves together with prolonged drought episodes, is a threat to agricultural productivity [1,2]. Sustaining the yield of economical crops such as wheat (Triticum aestivum) is crucial for the maintenance of food security [3]. Robust wheat varieties that can acclimate to adverse climate conditions are becoming a priority for crop breeding and production [6]. The effect of abiotic stress is dependent on its intensity, frequency and duration, as well as on the genotype used and the developmental stage of the crop [7]. As plants have developed several adaptive physiological and metabolic mechanisms, the sensitivity of genotypes to stress episodes varies [8]

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Discussion

Conclusion