Abstract
Soybeans are known to abscise 26 to 72% of their flowers and pods. High temperatures, long photoperiods, inadequate water, low nitrogen, carbohydrate availability, insects and disease have all been shown to affect abscission. The physiological understanding of how such effects induce changes in abortion of reproductive structure is not known. The development of the vascular connections in the flower peduncle, the level of ABA in the nodal region and the application of ABA and IAA to leaves of flowering soybeans that differ significantly in the abortion of reproductive structures were examined and their potential as effectors is discussed. The mediation of the carbohydrate contribution to premature abscission could reside in the vascular development of the flower pedicel in the area. The physiological understanding for how such effectors induce changes in reproductive abortion is not known. The development of the vascular connections in the flower pedicel. The concentration of ABA in the nodal regions and the application of ABA and IAA were examined in intermediate and determinate cultivars with different percentage abscission. Three soybean cultivars were planted at 3.8 and 15.1-cm plant spacings in the field as a randomized-complete-block design. The abscission of reproductive structures in the determinate cultiver, Fuji (58%), was significantly greater than that of the indeterminate cultivars, Williams (17.94%) and Amsoy '71 (18.40), for nodes 10-15. Nodal regions, peduncles, buds, and flowers were obtained from growth-chamber grown Amsoy '71 soybeans. Plant tissue was prepared in paraffin using standard techniques. Longitudinal and transverse sections 8 to 10 (mu) thick were examined. It was apparent that all flower primordia developed vascular connections with the central axis of the peduncle. No transfer cells were observed in regions where the peduncle merges with the stem. The absence of transfer cells limit the available assimilates to the flowers at that node. Concentrations of ABA were analyzed in nodes 5, 6, 8, 9, 11, and 12 of Fuji and Williams. Field-grown plants were randomly selected at initial flowering, one week, two weeks, and four weeks later. Tissue was extracted in methanol, dried in-vacuo, and the quantity of ABA (free and conjugated) determined by radioimmunoassay. ABA concentrations in the nodal tissue of Williams were higher than Fuji throughout the sampling period. Two patterns of changes in the concentration of ABA were found. Pattern 1 began at low concentration (15-25 ng ABA/GFW) before declining (3-20 ng ABA/GFW). Pattern 2 began high (up to 140 ng ABA/GFW) and then decreased 3-40 ng ABA/GFW). The Patterns were not statistically correlated with cultivar, node or abscission. Three concentrations of IAA and ABA (control, 10('-6)M, 10('-3)M or 10('-4)M, respectively) were applied to leaves of field grown Amsoy '71, Fuji and Williams at nodes 9, 10, 11 and 12 at anthesis. Applications were made every other day until flowering ceased at these nodes. Abscission of reproductive structures in the cultivars, Fuji, Williams and Amsoy '71, were statistically different (79%, 53%, and 29%, respectively). Abscission at node 11 in Fuji and Williams was statistically lower (48%) than the other three nodes (ranging between 53 and 57%). IAA at 10('-3)M increased abscission significantly (15%).
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Claims 11
Claim · model-written summary
Fuji had greater reproductive abscission than Williams and Amsoy 71 at nodes 10–15.
- Taxon
- soybeans
Glycine maxt0 - Material
- Fujie0
- Outcome
- abscission of reproductive structurese0
- Direction
- significantly greatere0
- Value
- 58%e0
- Qualifier
- nodes 10-15e0
- Comparator
- Williamse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The abscission of reproductive structures in the determinate cultiver, Fuji (58%), was significantly greater than that of the indeterminate cultivars, Williams (17.94%) and Amsoy '71 (18.40), for nodes 10-15.”
t0“SOYBEANS”
Claim · model-written summary
All flower primordia had vascular connections to the peduncle central axis.
- Taxon
- soybeansGlycine maxt0
- Organ / stage
- flower primordiae0
- Outcome
- flower primordia developed vascular connections with the central axis of the pedunclee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“all flower primordia developed vascular connections with the central axis of the peduncle”
t0“SOYBEANS”
Claim · model-written summary
Transfer cells were absent where the peduncle merges with the stem.
- Taxon
- soybeansGlycine maxt0
- Organ / stage
- pedunclee0
- Outcome
- No transfer cells were observede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No transfer cells were observed in regions where the peduncle merges with the stem”
t0“SOYBEANS”
Claim · model-written summary
The authors interpret absent transfer cells as limiting assimilates available to flowers.
- Taxon
- soybeansGlycine maxt0
- Outcome
- available assimilates to the flowerse0
- Qualifier
- absence of transfer cellse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The absence of transfer cells limit the available assimilates to the flowers at that node”
t0“SOYBEANS”
Claim · model-written summary
Williams nodal ABA concentrations were higher than Fuji throughout sampling.
- Taxon
- soybeansGlycine maxt0
- Material
- Williamse0
- Outcome
- ABA concentrations in the nodal tissuee0
- Direction
- highere0
- Comparator
- Fujie0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ABA concentrations in the nodal tissue of Williams were higher than Fuji throughout the sampling period”
t0“SOYBEANS”
Claim · model-written summary
One nodal ABA pattern decreased from 15–25 to 3–20 ng ABA/GFW.
- Taxon
- soybeansGlycine maxt0
- Outcome
- concentratione0
- Direction
- declininge0
- Value
- 15-25 ng ABA/GFWe0
- Qualifier
- 3-20 ng ABA/GFWe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pattern 1 began at low concentration (15-25 ng ABA/GFW) before declining (3-20 ng ABA/GFW)”
t0“SOYBEANS”
Claim · model-written summary
A second nodal ABA pattern decreased from up to 140 to 3–40 ng ABA/GFW.
- Taxon
- soybeansGlycine maxt0
- Outcome
- ABAe0
- Direction
- decreasede0
- Value
- 140 ng ABA/GFWe0
- Qualifier
- 3-40 ng ABA/GFWe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pattern 2 began high (up to 140 ng ABA/GFW) and then decreased 3-40 ng ABA/GFW)”
t0“SOYBEANS”
Claim · model-written summary
The ABA patterns were not statistically correlated with cultivar, node, or abscission.
- Taxon
- soybeansGlycine maxt0
- Material
- cultivare0
- Outcome
- abscissione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Patterns were not statistically correlated with cultivar, node or abscission”
t0“SOYBEANS”
Claim · model-written summary
Reproductive abscission differed among Fuji, Williams and Amsoy 71, at 79%, 53% and 29%.
- Taxon
- soybeansGlycine maxt0
- Material
- Fujie0
- Outcome
- Abscission of reproductive structurese0
- Direction
- statistically differente0
- Value
- 79%e0
- Qualifier
- 53%, and 29%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Abscission of reproductive structures in the cultivars, Fuji, Williams and Amsoy '71, were statistically different (79%, 53%, and 29%, respectively)”
t0“SOYBEANS”
Claim · model-written summary
At node 11, Fuji and Williams abscission was lower than at the other three nodes.
- Taxon
- soybeansGlycine maxt0
- Organ / stage
- node 11e0
- Outcome
- Abscissione0
- Direction
- statistically lowere0
- Value
- 48%e0
- Qualifier
- ranging between 53 and 57%e0
- Comparator
- other three nodese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Abscission at node 11 in Fuji and Williams was statistically lower (48%) than the other three nodes (ranging between 53 and 57%)”
t0“SOYBEANS”
Claim · model-written summary
IAA at 10⁻³ M significantly increased reproductive abscission by 15%.
- Taxon
- soybeansGlycine maxt0
- Treatment
- IAA at 10('-3)Me0
- Outcome
- abscissione0
- Direction
- increasede0
- Value
- 15%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“IAA at 10('-3)M increased abscission significantly (15%)”
t0“SOYBEANS”
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