Traits and selection strategies to improve root systems and water uptake in water-limited wheat crops.

By A. Wasson, R. Richards, Ravish Chatrath, S. Misra, S. Prasad, G. Rebetzke, J. Kirkegaard, Jack Christopher, M. Watt. Journal of Experimental Botany, 2012

816 citations recorded by the source corpus.

Wheat yields globally will depend increasingly on good management to conserve rainfall and new varieties that use water efficiently for grain production. Here we propose an approach for developing new varieties to make better use of deep stored water. We focus on water-limited wheat production in the summer-dominant rainfall regions of India and Australia, but the approach is generally applicable to other environments and root-based constraints. Use of stored deep water is valuable because it is more predictable than variable in-season rainfall and can be measured prior to sowing. Further, this moisture is converted into grain with twice the efficiently of in-season rainfall since it is taken up later in crop growth during the grain-filling period when the roots reach deeper layers. We propose that wheat varieties with a deeper root system, a redistribution of branch root density from the surface to depth, and with greater radial hydraulic conductivity at depth would have higher yields in rainfed systems where crops rely on deep water for grain fill. Developing selection systems for mature root system traits is challenging as there are limited high-throughput phenotyping methods for roots in the field, and there is a risk that traits selected in the lab on young plants will not translate into mature root system traits in the field. We give an example of a breeding programme that combines laboratory and field phenotyping with proof of concept evaluation of the trait at the beginning of the selection programme. This would greatly enhance confidence in a high-throughput laboratory or field screen, and avoid investment in screens without yield value. This approach requires careful selection of field sites and years that allow expression of deep roots and increased yield. It also requires careful selection and crossing of germplasm to allow comparison of root expression among genotypes that are similar for other traits, especially flowering time and disease and toxicity resistances. Such a programme with field and laboratory evaluation at the outset will speed up delivery of varieties with improved root systems for higher yield.

Subfields: Plant Science, Soil Science

View Paper: https://www.semanticscholar.org/paper/cc62eeba7120ffd63df75134f0752bf15f5c1f21

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Citations in the corpus

Global synthesis of drought effects on cereal, legume, tuber and root crops production: A review (2017, background): “Apart from being more reliable than rainfall, farmer could pre-condition the amount of soil moisture via management (Wasson et al., 2012).”
Root traits contributing to plant productivity under drought (2013, background): “In cases where deep water availability could promote crop productivity directly or via hydraulic redistribution, larger diameter xylem vessels may be advantageous to increase axial hydraulic conductivity of roots growing in deeper soil layers (Wasson et al., 2012).”
Root System Architecture and Its Association with Yield under Different Water Regimes in Durum Wheat (2018, methodology): “The significance of root traits contributing to yield under water-limited environments has long been recognized (Richards, 1991), and roots have likely been subjected to indirect selection in breeding programs as a result of selection for high yield in the target environment (Wasson et al., 2012).”
Comparison of drought tolerance of maize, sweet sorghum and sorghum-Sudangrass hybrids (2014, background): “However, even on shallow soils, the higher RLD of sorghum may be an advantage over maize, because a high RLD can improve water uptake and drought resistance (Henry et al. 2011, Wasson et al. 2012).”
Plant drought survival under climate change and strategies to improve perennial grasses. A review (2016, background): “Although research to develop roots of annual cereals better able to optimise yield in water-limited environments continues apace with examples already in wheat (Palta et al. 2011; Wasson et al. 2012), this work remains to be commenced in perennial forage grasses.”
Bacterial-mediated drought tolerance: Current and future prospects (2016, background): “…drought resistance has been established in several crops including soybeans (Sadok and Sinclair, 2011), chickpea (Cicer arietinum L.) (Varshney et al., 2011), maize (Tuberosa et al., 2003, 2007, 2011; Landi et al., 2010; Hund et al., 2011), and wheat (Triticum aestivum L.) (Wasson et al., 2012).”
Designing resilient and sustainable grasslands for a drier future: Adaptive strategies, functional traits and biotic interactions (2013, background): “A deep root system with a high density of roots at depth is a major trait to sustain higher yield in water- limited environments (Carrow 1996; Wasson et al. 2012; White and Snow 2012).”