Sensitivity Cycling and Mechanism of Physical Dormancy Break in Seeds of<i>Ipomoea hederacea</i>(Convolvulaceae)

Jayasuriya, K.M.G. Gehan; Baskin, Jerry M.; Geneve, Robert L.; Baskin, Carol C.

doi:10.1086/597270

Cited by 27 publications

(37 citation statements)

References 24 publications

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“…The requirement for wet-high temperatures to break PY in S . multijuga seeds and the relationship between seed traits of this species support the role of internal pressure in the PY-breaking mechanism in seeds proposed by Jayasuriya et al [ 25 , 29 ].…”

Section: Discussionsupporting

confidence: 82%

“…This relation is true in the case of physically dormant seeds that need moisture to break dormancy. The role of internal pressure in breaking PY was hypothesized by Jayasuriya et al [ 25 , 29 ], who observed a distinct response to wet and dry conditions for seeds of congeneric species of Convolvulaceae to become permeable. Similarities are shared by S .…”

Section: Discussionmentioning

confidence: 99%

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Why large seeds with physical dormancy become nondormant earlier than small ones

et al. 2018

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Under natural conditions, large seeds with physical dormancy (PY) may become water permeable earlier than small ones. However, the mechanism for this difference has not been elucidated. Thus, our aim was to evaluate the traits associated with PY in seeds of Senna multijuga (Fabaceae) and to propose a mechanism for earlier dormancy-break in large than in small seeds. Two seedlots were collected and each separated into large and small seeds. Seed dry mass, water content, thickness of palisade layer in the hilar and distal regions and the ratio between palisade layer thickness (P) in the lens fissure and seed mass (M) were evaluated. Further, the correlation between seed mass and seed dimensions was investigated. Large seeds had higher dry mass and water content than small seeds. The absolute thickness of the palisade layer in the different regions did not show any trend with seed size; however, large seeds had a lower P:M ratio than small seeds. Seed mass correlated positively with all seed dimensions, providing evidence for a substantially higher volume in large seeds. Since wet, but not dry, high temperatures break PY in sensitive seeds of S. multijuga, the data support our prediction that internal pressure potential in the seed and palisade layer thickness in the water gap (lens), which is related to seed mass (i.e. P:M ratio), act together to modulate the second step (dormancy break) of the two-stage sensitivity cycling model for PY break. In which case, large seeds are predetermined to become water-permeable earlier than small ones.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Why large seeds with physical dormancy become nondormant earlier than small ones

et al. 2018

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“…Jayasuriya et al . (,b, ,b) interpreted these two steps for breaking PY as changes between insensitive and sensitive stages (sensitivity cycling) and reported the effect of moisture on this process. Sensitivity cycling has been reported only in seeds of Fabaceae and Convolvulaceae and only in herbaceous species of these two families (see Jayasuriya et al .…”

Section: Introductionmentioning

confidence: 99%

Sensitivity cycling in physically dormant seeds of the Neotropical tree Senna multijuga (Fabaceae)

Rodrigues-Junior

Baskin

et al. 2018

Plant Biol J

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Cycling of sensitivity to physical dormancy (PY) break has been documented in herbaceous species. However, it has not been reported in tree seeds, nor has the effect of seed size on sensitivity to PY-breaking been evaluated in any species. Thus, the aims of this study were to investigate how PY is broken in seeds of the tropical legume tree Senna multijuga, if seeds exhibit sensitivity cycling and if seed size affects induction into sensitivity. Dormancy and germination were evaluated in intact and scarified seeds from two collections of S. multijuga. The effects of temperature, moisture and seed size on induction of sensitivity to dormancy-breaking were assessed, and seasonal changes in germination and persistence of buried seeds were determined. Reversal of sensitivity was also investigated. Fresh seeds were insensitive to dormancy break at wet-high temperatures, and an increase in sensitivity occurred in buried seeds after they experienced low temperatures during winter (dry season). Temperatures ≤20 °C increased sensitivity, whereas temperatures ≥30 °C decreased it regardless of moisture conditions. Dormancy was broken in sensitive seeds by incubating them at 35 °C. Sensitivity could be reversed, and large seeds were more sensitive than small seeds to sensitivity induction. Seeds of S. multijuga exhibit sensitivity cycling to PY-breaking. Seeds become sensitive during winter and can germinate with the onset of the spring-summer rainy season in Brazil. Small seeds are slower to become sensitive than large ones, and this may be a mechanism by which germination is spread over time. Sensitive seeds that fail to germinate become insensitive during exposure to drought during summer. This is the first report of sensitivity cycling in a tree species.

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“…In general, the ability to remain ungerminated can result from either an innate dormancy mechanism or the absence of conditions conducive to radicle protrusion (Thompson 2000). Burial conditions in this investigation were previously determined to be conducive to radicle protrusion for both velvetleaf and ivyleaf morningglory (Baloch et al 2001;Jayasuriya et al 2009). Thus, seeds categorized as persistent were also dormant.…”

Section: Methodsmentioning

confidence: 85%

Methods for Optimizing Seed Mortality Experiments

2010

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Experiments investigating mortality in the soil seedbank are aided by using only seeds that are initially viable and capable of remaining ungerminated (hereafter “persistent seeds”). However, seed mortality experiments often use heterogeneous populations containing persistent, nonviable, and germinable individuals. In this investigation we developed and compared nondestructive tests for isolating persistent seeds of two weed species characterized by physical seed dormancy (dormancy imposed by a water-impermeable seed coat): velvetleaf and ivyleaf morningglory. Individual seeds were weighed, steeped in water (hereafter “steepate”) for 48 h, and then assayed for imbibition. These seeds were then subjected to persistence assays conducted under controlled conditions (60 d in hydrated soil under 25/15 C day/night temperatures, 14-h photoperiod). Persistent seeds were less likely to imbibe and more likely to produce steepates with low electrical conductivity compared with germinable and nonviable seeds. For velvetleaf, persistent seeds were best segregated by comparing changes in steepate conductivity during 4 to 48 h of soaking, with the corresponding classification and regression tree (CART) model making few false discoveries (false discovery rate for persistence; FDRp= 8.6%,n= 93) and many true positive classifications (true positive rate for persistence; TPRp= 100%,n= 85). For ivyleaf morningglory, both a change in steepate conductivity from 4 to 48 h of soaking and imbibition status after soaking accurately separated persistent seeds (accuracy measures of corresponding CART models: FDRp= 5.6%,n= 150; TPRp= 100%,n= 142). Thus, for species with physical seed dormancy, we recommend use of steepate conductivity and imbibition status after soaking for isolation of persistent seeds. These seeds can then be used to optimize experiments on mortality in the soil seedbank. Nondestructive tests for isolating persistent seeds of species characterized by physiological seed dormancy require further research.

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Sensitivity Cycling and Mechanism of Physical Dormancy Break in Seeds ofIpomoea hederacea(Convolvulaceae)

Cited by 27 publications

References 24 publications

Why large seeds with physical dormancy become nondormant earlier than small ones

Why large seeds with physical dormancy become nondormant earlier than small ones

Sensitivity cycling in physically dormant seeds of the Neotropical tree Senna multijuga (Fabaceae)

Methods for Optimizing Seed Mortality Experiments

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