Abstract
Zinc (Zn) deficiency is a major constraint to rice production and Zn is also often deficient in humans with rice-based diets. Efforts to breed more Zn-efficient rice are constrained by poor understanding of the mechanisms of tolerance to deficiency. Here we assess the contributions of root growth and root Zn uptake efficiency, and we seek to explain the results in terms of specific mechanisms. We made a field experiment in a highly Zn-deficient rice soil in the Philippines with deficiency-tolerant and -sensitive genotypes, and measured growth, Zn uptake and root development. We also measured the effect of planting density. Tolerant genotypes produced more crown roots per plant and had greater uptake rates per unit root surface area; the latter was at least as important as root number to overall tolerance. Tolerant and sensitive genotypes took up more Zn per plant at greater planting densities. The greater uptake per unit root surface area, and the planting density effect can only be explained by root-induced changes in the rhizosphere, either solubilizing Zn, or neutralizing a toxin that impedes Zn uptake (possibly [Formula: see text] or Fe(2+)), or both. Traits for these and crown root number are potential breeding targets.
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Claims 6
Claim · model-written summary
Tolerant rice genotypes produced more crown roots per plant.
- Taxon
- rice
Oryza sativat0 - Outcome
- crown roots per plante0
- Direction
- moree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tolerant genotypes produced more crown roots per plant”
t0“Rice”
Claim · model-written summary
Tolerant genotypes had greater zinc uptake per unit root surface area.
- Taxon
- riceOryza sativat0
- Outcome
- uptake rates per unit root surface areae0
- Direction
- greatere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“had greater uptake rates per unit root surface area”
t0“Rice”
Claim · model-written summary
Uptake rate per unit root area was at least as important as root number for zinc deficiency tolerance.
- Taxon
- riceOryza sativat0
- Organ / stage
- root numbere0
- Outcome
- overall tolerancee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the latter was at least as important as root number to overall tolerance”
t0“Rice”
Claim · model-written summary
Both tolerant and sensitive genotypes took up more zinc per plant at greater planting density.
- Taxon
- riceOryza sativat0
- Treatment
- greater planting densitiese0
- Outcome
- Zn per plante0
- Direction
- moree0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tolerant and sensitive genotypes took up more Zn per plant at greater planting densities”
t0“Rice”
Claim · model-written summary
The authors attributed greater root area uptake and density effects to root-induced rhizosphere changes.
- Taxon
- riceOryza sativat0
- Outcome
- greater uptake per unit root surface areae0
- Qualifier
- root-induced changes in the rhizospheree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The greater uptake per unit root surface area, and the planting density effect can only be explained by root-induced changes in the rhizosphere”
t0“Rice”
Claim · model-written summary
Rhizosphere change traits and crown root number were identified as potential breeding targets.
- Taxon
- riceOryza sativat0
- Outcome
- potential breeding targetse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Traits for these and crown root number are potential breeding targets”
t0“Rice”
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