Abstract
Abstract Plant water deficits affect many metabolic processes, and soybean ( Glycine max L. Merr.) is subject to water deficits during midday even when soil water is adequate under field conditions. Our objective was to determine if yield improvement by plant breeding has been associated with avoidance of these deficits in soybean. A 3‐ year experiment was conducted on highly productive soils in central Illinois with two soybean maturity groups each represented by four cultivars. The cultivars had been released between 1911 and 1968 in the USA. Soil water availability was high in all 3 years. However, leaf water potentials were frequently below −11 bars at midday, which we defined as a water deficit. Cultivars with low yields experienced larger water deficits than those with high yields. The largest water deficits were found in the oldest cultivars and were present in all the fully illuminated leaves of the canopy. The deficits were large enough to be potentially inhibitory to afternoon photosynthesis and other metabolic processes. Considerable yield improvement was apparent in the newer cultivars of both maturity groups when their yields were compared with those of older cultivars in the common environment represented by this experiment. Rooting densities of two cultivars showing extremes of midday water deficits indicated that the cultivar with the least water deficit (‘Wayne’) had a greater root density than the cultivar with the largest deficit (’Richland’). The data suggest that old cultivars experience yield inhibiting water deficits at midday in central Illinois in soil containing adequate water. Breeding soybean for high yield has, at the same time, selected for superior shoot water status in midday, perhaps as a result of increased root densities.
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Claims 7
Claim · model-written summary
Soybean leaf water potentials often fell below −11 bars at midday despite high soil water availability.
- Taxon
- soybean
Glycine maxt0 - Outcome
- leaf water potentialse0
- Value
- −11 barse0
- Qualifier
- at middaye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Soil water availability was high in all 3 years. However, leaf water potentials were frequently below −11 bars at midday, which we defined as a water deficit.”
t0“Soybean”
Claim · model-written summary
Lower yielding cultivars had larger water deficits than higher yielding ones.
- Taxon
- soybeanGlycine maxt0
- Outcome
- water deficitse0
- Direction
- largere0
- Comparator
- those with high yieldse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cultivars with low yields experienced larger water deficits than those with high yields.”
t0“Soybean”
Claim · model-written summary
The oldest cultivars showed the largest water deficits throughout fully lit canopy leaves.
- Taxon
- soybeanGlycine maxt0
- Material
- oldest cultivarse0
- Organ / stage
- fully illuminated leavese0
- Outcome
- water deficitse0
- Direction
- largeste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The largest water deficits were found in the oldest cultivars and were present in all the fully illuminated leaves of the canopy.”
t0“Soybean”
Claim · model-written summary
Newer cultivars had substantially improved yield in both maturity groups.
- Taxon
- soybeanGlycine maxt0
- Material
- newer cultivarse0
- Outcome
- yieldse0
- Direction
- improvemente0
- Comparator
- older cultivarse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Considerable yield improvement was apparent in the newer cultivars of both maturity groups when their yields were compared with those of older cultivars in the common environment represented by this experiment.”
t0“Soybean”
Claim · model-written summary
Wayne had greater root density and less midday water deficit than Richland.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rooting densities of two cultivars showing extremes of midday water deficits indicated that the cultivar with the least water deficit (‘Wayne’) had a greater root density than the cultivar with the largest deficit (’Richland’).”
t0“Soybean”
Claim · model-written summary
Old cultivars may experience yield inhibiting midday deficits despite adequate soil water.
- Taxon
- soybeanGlycine maxt0
- Material
- old cultivarse0
- Outcome
- yield inhibiting water deficitse0
- Qualifier
- soil containing adequate watere0
- Setting
- central Illinoise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The data suggest that old cultivars experience yield inhibiting water deficits at midday in central Illinois in soil containing adequate water.”
t0“Soybean”
Claim · model-written summary
The authors infer high yield breeding selected better midday shoot water status, perhaps through greater root density.
- Taxon
- soybeanGlycine maxe0
- Outcome
- superior shoot water statuse0
- Qualifier
- perhaps as a result of increased root densitiese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Breeding soybean for high yield has, at the same time, selected for superior shoot water status in midday, perhaps as a result of increased root densities.”