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Root traits contributing to plant productivity under drought.

Comas LH, Becker SR, Cruz VM, Byrne PF, Dierig DA - Front Plant Sci (2013)

Bottom Line: Root traits associated with maintaining plant productivity under drought include small fine root diameters, long specific root length, and considerable root length density, especially at depths in soil with available water.Rapid resumption of root growth following soil rewetting may improve plant productivity under episodic drought.Examples in lesquerella (Physaria) and rice (Oryza) show approaches to phenotyping of root traits and current understanding of root trait genetics for breeding.

View Article: PubMed Central - PubMed

Affiliation: Water Management Research, United States Department of Agriculture-Agricultural Research Service Fort Collins, CO, USA.

ABSTRACT
Geneticists and breeders are positioned to breed plants with root traits that improve productivity under drought. However, a better understanding of root functional traits and how traits are related to whole plant strategies to increase crop productivity under different drought conditions is needed. Root traits associated with maintaining plant productivity under drought include small fine root diameters, long specific root length, and considerable root length density, especially at depths in soil with available water. In environments with late season water deficits, small xylem diameters in targeted seminal roots save soil water deep in the soil profile for use during crop maturation and result in improved yields. Capacity for deep root growth and large xylem diameters in deep roots may also improve root acquisition of water when ample water at depth is available. Xylem pit anatomy that makes xylem less "leaky" and prone to cavitation warrants further exploration holding promise that such traits may improve plant productivity in water-limited environments without negatively impacting yield under adequate water conditions. Rapid resumption of root growth following soil rewetting may improve plant productivity under episodic drought. Genetic control of many of these traits through breeding appears feasible. Several recent reviews have covered methods for screening root traits but an appreciation for the complexity of root systems (e.g., functional differences between fine and coarse roots) needs to be paired with these methods to successfully identify relevant traits for crop improvement. Screening of root traits at early stages in plant development can proxy traits at mature stages but verification is needed on a case by case basis that traits are linked to increased crop productivity under drought. Examples in lesquerella (Physaria) and rice (Oryza) show approaches to phenotyping of root traits and current understanding of root trait genetics for breeding.

No MeSH data available.


Related in: MedlinePlus

Areas of focus of plant studies seeking to understand root traits related to plant productivity under water shortages and genetic screening of traits to identify their coding. Organism level refers to whole plant traits, organ system to the entire root system (fine and coarse roots, as the shoot system would refer to leaves and stems), organ to single root types (e.g., fine roots), and tissue or cell to single cell types (e.g., xylem or cortical cells). Root traits in black text are traits that have been shown to be related to drought tolerance, and gray italic those that may be associated with drought tolerance but either require more research or have been equivocal.
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Figure 1: Areas of focus of plant studies seeking to understand root traits related to plant productivity under water shortages and genetic screening of traits to identify their coding. Organism level refers to whole plant traits, organ system to the entire root system (fine and coarse roots, as the shoot system would refer to leaves and stems), organ to single root types (e.g., fine roots), and tissue or cell to single cell types (e.g., xylem or cortical cells). Root traits in black text are traits that have been shown to be related to drought tolerance, and gray italic those that may be associated with drought tolerance but either require more research or have been equivocal.

Mentions: Past efforts in improvement of germplasm for water-limited environments have been accomplished by focusing on specific traits for particular crops and drought conditions, which appear more clearly when viewed through a framework that dissects the benchmark of water-limited yield potential into independent components (Passioura and Angus, 2010). An appreciation of the growth strategies of individual crops and specifics of particular drought conditions crops face will need to continue to be at the forefront of successful breeding programs. In agricultural systems without irrigation (dryland systems), drought may be episodic in varying degrees or extend through the majority of the growing season. These different scenarios of drought will have different impacts on crop growth and development above and below ground (Passioura, 2012). In irrigated agriculture, water may be applied in varying degrees of deficit irrigation throughout the season, as full irrigation during strategic periods of the season, or applied in different combinations of deficit and full irrigation during different periods of the growing season. Breeding efforts will also be more successful if coupled to advances being made in management (Kirkegaard and Hunt, 2010). It is widely recognized that breeding efforts need to account for the genotype by environment by management (G × E × M) interaction because improving crop productivity will require breeding for different plant traits and growth strategies in different environments and under different management (Sinclair et al., 2010; Passioura, 2012; Reynolds et al., 2012). Nevertheless, a few generalizations in root traits associated with crop productivity under drought are beginning to emerge (Wasson et al., 2012). Discussion of these root traits and others resulting from advances in the plant ecophysiological arena are the subject of this review and will be discussed at the organism, organ system, organ, and tissue and cellular level (Figure 1).


Root traits contributing to plant productivity under drought.

Comas LH, Becker SR, Cruz VM, Byrne PF, Dierig DA - Front Plant Sci (2013)

Areas of focus of plant studies seeking to understand root traits related to plant productivity under water shortages and genetic screening of traits to identify their coding. Organism level refers to whole plant traits, organ system to the entire root system (fine and coarse roots, as the shoot system would refer to leaves and stems), organ to single root types (e.g., fine roots), and tissue or cell to single cell types (e.g., xylem or cortical cells). Root traits in black text are traits that have been shown to be related to drought tolerance, and gray italic those that may be associated with drought tolerance but either require more research or have been equivocal.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3817922&req=5

Figure 1: Areas of focus of plant studies seeking to understand root traits related to plant productivity under water shortages and genetic screening of traits to identify their coding. Organism level refers to whole plant traits, organ system to the entire root system (fine and coarse roots, as the shoot system would refer to leaves and stems), organ to single root types (e.g., fine roots), and tissue or cell to single cell types (e.g., xylem or cortical cells). Root traits in black text are traits that have been shown to be related to drought tolerance, and gray italic those that may be associated with drought tolerance but either require more research or have been equivocal.
Mentions: Past efforts in improvement of germplasm for water-limited environments have been accomplished by focusing on specific traits for particular crops and drought conditions, which appear more clearly when viewed through a framework that dissects the benchmark of water-limited yield potential into independent components (Passioura and Angus, 2010). An appreciation of the growth strategies of individual crops and specifics of particular drought conditions crops face will need to continue to be at the forefront of successful breeding programs. In agricultural systems without irrigation (dryland systems), drought may be episodic in varying degrees or extend through the majority of the growing season. These different scenarios of drought will have different impacts on crop growth and development above and below ground (Passioura, 2012). In irrigated agriculture, water may be applied in varying degrees of deficit irrigation throughout the season, as full irrigation during strategic periods of the season, or applied in different combinations of deficit and full irrigation during different periods of the growing season. Breeding efforts will also be more successful if coupled to advances being made in management (Kirkegaard and Hunt, 2010). It is widely recognized that breeding efforts need to account for the genotype by environment by management (G × E × M) interaction because improving crop productivity will require breeding for different plant traits and growth strategies in different environments and under different management (Sinclair et al., 2010; Passioura, 2012; Reynolds et al., 2012). Nevertheless, a few generalizations in root traits associated with crop productivity under drought are beginning to emerge (Wasson et al., 2012). Discussion of these root traits and others resulting from advances in the plant ecophysiological arena are the subject of this review and will be discussed at the organism, organ system, organ, and tissue and cellular level (Figure 1).

Bottom Line: Root traits associated with maintaining plant productivity under drought include small fine root diameters, long specific root length, and considerable root length density, especially at depths in soil with available water.Rapid resumption of root growth following soil rewetting may improve plant productivity under episodic drought.Examples in lesquerella (Physaria) and rice (Oryza) show approaches to phenotyping of root traits and current understanding of root trait genetics for breeding.

View Article: PubMed Central - PubMed

Affiliation: Water Management Research, United States Department of Agriculture-Agricultural Research Service Fort Collins, CO, USA.

ABSTRACT
Geneticists and breeders are positioned to breed plants with root traits that improve productivity under drought. However, a better understanding of root functional traits and how traits are related to whole plant strategies to increase crop productivity under different drought conditions is needed. Root traits associated with maintaining plant productivity under drought include small fine root diameters, long specific root length, and considerable root length density, especially at depths in soil with available water. In environments with late season water deficits, small xylem diameters in targeted seminal roots save soil water deep in the soil profile for use during crop maturation and result in improved yields. Capacity for deep root growth and large xylem diameters in deep roots may also improve root acquisition of water when ample water at depth is available. Xylem pit anatomy that makes xylem less "leaky" and prone to cavitation warrants further exploration holding promise that such traits may improve plant productivity in water-limited environments without negatively impacting yield under adequate water conditions. Rapid resumption of root growth following soil rewetting may improve plant productivity under episodic drought. Genetic control of many of these traits through breeding appears feasible. Several recent reviews have covered methods for screening root traits but an appreciation for the complexity of root systems (e.g., functional differences between fine and coarse roots) needs to be paired with these methods to successfully identify relevant traits for crop improvement. Screening of root traits at early stages in plant development can proxy traits at mature stages but verification is needed on a case by case basis that traits are linked to increased crop productivity under drought. Examples in lesquerella (Physaria) and rice (Oryza) show approaches to phenotyping of root traits and current understanding of root trait genetics for breeding.

No MeSH data available.


Related in: MedlinePlus