Bigger is not always better: Reducing leaf area helps stay-green sorghum use soil water more slowly

George‐Jaeggli, Barbara; Mortlock, Miranda Y.; Borrell, Andrew

doi:10.1016/j.envexpbot.2017.03.002

Cited by 51 publications

(35 citation statements)

References 32 publications

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“…Delayed senescence under water deficit can be engineered via the metabolism of cytokinins (110), but in field conditions it often appears as a consequence of early events in the plant cycle ( Table 1). In sorghum, the stay-green phenotype is probably the consequence of low water consumption during the vegetative phase in plants presenting reduced tillering and lower leaf size (53). Low water consumption increases water availability during late stages of the plant cycle, thereby causing the stay-green phenotype (53) ( Table 1).…”

Section: Genomic Selectionmentioning

confidence: 99%

The Physiological Basis of Drought Tolerance in Crop Plants: A Scenario-Dependent Probabilistic Approach

Tardieu

Simonneau

Muller

2018

Annu. Rev. Plant Biol.

391

286

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Drought tolerance involves mechanisms operating at different spatial and temporal scales, from rapid stomatal closure to maintenance of crop yield. We review how short-term mechanisms are controlled for stabilizing shoot water potential and how long-term processes have been constrained by evolution or breeding to fit into acclimation strategies for specific drought scenarios. These short- or long-term feedback processes participate in trade-offs between carbon accumulation and the risk of deleterious soil water depletion. Corresponding traits and alleles may therefore have positive or negative effects on crop yield depending on drought scenarios. We propose an approach that analyzes the genetic architecture of traits in phenotyping platforms and of yield in tens of field experiments. A combination of modeling and genomic prediction is then used to estimate the comparative interests of combinations of alleles depending on drought scenarios. Hence, drought tolerance is understood probabilistically by estimating the benefit and risk of each combination of alleles.

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Section: Genomic Selectionmentioning

confidence: 99%

The Physiological Basis of Drought Tolerance in Crop Plants: A Scenario-Dependent Probabilistic Approach

Tardieu

Simonneau

Muller

2018

Annu. Rev. Plant Biol.

391

286

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“…However, this was not observed in this study ( Figure 2). This contrast may be because the stay-green trait can improve yield under drought conditions by reducing plant size at anthesis through a number of mechanisms other than reducing tillering, including reducing leaf number of the main stem, increasing sizes of upper leaves of the main stem [12,13], or accelerating age-related senescence of lower leaves [34].…”

Section: The Impacts Of Dtf and Ftn On Grain Yield Varied Across Envimentioning

confidence: 99%

The Impacts of Flowering Time and Tillering on Grain Yield of Sorghum Hybrids across Diverse Environments

Wang¹,

Hunt²,

Cruickshank³

et al. 2019

Preprint

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Sorghum in Australia is grown in water-limited environments of varying extent, generating substantial genotype × environment interaction (GEI). Much of the yield variation and GEI results from variations in flowering time and tillering through their effects on canopy development. The confounding effects of flowering and tillering complicate the interpretation of breeding trials. In this study, we evaluated the impacts of both flowering time (DTF) and tillering capacity (FTN) on yield of 1741 unique test hybrids derived from three common female testers in 21 yield testing trials (48 tester/trial combinations) across the major sorghum production regions in Australia in three seasons. Contributions of DTF and FTN to genetic variation in grain yield were significant in 14 and 12 tester/trial combinations, respectively. The proportion of genetic variance in grain yield explained by DTF and FTN ranged from 0.2% to 61.0% and from 1.4% to 56.9%, respectively, depending on trials and genetic background of female testers. The relationship of DTF or FTN with grain yield of hybrids was frequently positive, but varied across the genetic background of testers. Accounting for the effects of DTF and FTN using linear models did not substantially increase the between trial genetic correlations for grain yield. The results suggested that other factors affecting canopy development dynamics and grain yield might contribute GEI and/or the linear approach to account for DTF and FTN on grain yield did not capture the complex non-linear interactions.

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Section: Increasing Te By Manipulation Of Transpiration Ratesmentioning

confidence: 99%

“…Ultimately, this leads to a smaller canopy that reduces pre-anthesis transpiration and conserves soil water that can be used during grain filling (George-Jaeggli et al, 2017; van Oosterom et al, 2011). This has been found to be beneficial for improved yield under post-anthesis water limitation, as reported by Borrell et al…”

Section: Increasing Te By Manipulation Of Transpiration Ratesmentioning

confidence: 99%

“…Hence, the approach of leaf senescence is a final measure taken by plants to cope with severe water stress and can result in severe yield declines under drought. However, it has also been found that stay-green lines show increased senescence of older leaves lower in the canopy even under water non-limited conditions which reduces plant transpiration and leads to pre-anthesis water savings (George-Jaeggli et al, 2017).Plant transpiration responds to environmental factors such as vapour pressure deficit (VPD), which depends on the temperature and relative humidity of the air (Craufurd et al, 2013). The gradient between saturated water vapour inside leaves and the non-saturated water vapour in the atmosphere places a strong demand on plants to transpire, particularly when the VPD is high (Sadras and McDonald, 2012;Sinclair et al, 2005).…”

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confidence: 99%

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Role of leaf photosynthesis and stomatal conductance in determining the genotypic variation in whole-plant Transpiration Efficiency (TE) in Sorghum

Geetika¹

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Traits such as transpiration efficiency (TE) that are influenced by plant water use can be used to characterise the adaptability of crops to specific growth environments. TE is defined as the amount of biomass produced per unit of water used, and can ensure continued crop production in droughtprone regions. Where TE is associated with reduced use of soil water during the vegetative growth phase, water availability during grain filling may be greater, which can delay the onset of drought stress and increase grain yield under water-limited conditions. This may become even more pertinent with predicted increases in severity and frequency of droughts with climate change. The aims of this study were to firstly dissect TE into its leaf-level physiological components to better understand the effects of genetic variation in these components on TE in sorghum. Secondly, to examine whether TE responses observed under well-watered conditions were preserved under drought, and whether transpiration response was an adaptive response to drought. Twenty-seven genotypes were screened for TE under well-watered conditions using a fully automated lysimetry platform to obtain accurate plant water use data. To determine whether variation in TE among these genotypes was associated with differences in maximum photosynthesis (Amax) or leaf conductance (g) we measured the net carbon assimilation rate of the second last fully expanded leaf at high light intensity, using an infrared gas analyser, and leaf water flux was measured using a porometer, as a proxy for conductance. Genotypic variation in TE among the sorghum germplasm used was mainly associated with differences in the response of transpiration rates to vapour pressure deficit (VPD).Genotypes with low transpiration rates per unit green leaf area (T/GLA) tended to have high TE.Variation in Amax explained some of the differences in TE that could not be explained by T/GLA and may have been a result of mechanisms associated with differences in biochemical pathways that affect the efficiency of conversion of CO2 into photosynthate. While drought tended to increase TE, genotypic variation in TE was largely conserved. However, the response of transpiration rates to drought stress differed across genotypes, with some genotypes showing reduced T/GLA under drought when VPD was high, whereas others did not. These contrasting responses were associated with differences in stomatal responses to drought stress, such that some genotypes were better able to conserve water under drought stress than others. This adaptive response was not related to TE per se and may have important implications for adaptation to drought stress. Hence, the phenotyping of sorghum lines using the associated physiological traits underpinning TE differences is beneficial in identifying traits that may support growth in certain environments and can optimise grain yield production under water-limited conditions. III Declaration by AuthorThis thesis is composed of my original work, and contains no material previously ...

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Bigger is not always better: Reducing leaf area helps stay-green sorghum use soil water more slowly

Cited by 51 publications

References 32 publications

The Physiological Basis of Drought Tolerance in Crop Plants: A Scenario-Dependent Probabilistic Approach

The Physiological Basis of Drought Tolerance in Crop Plants: A Scenario-Dependent Probabilistic Approach

The Impacts of Flowering Time and Tillering on Grain Yield of Sorghum Hybrids across Diverse Environments

Role of leaf photosynthesis and stomatal conductance in determining the genotypic variation in whole-plant Transpiration Efficiency (TE) in Sorghum

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