The effect of drying rate on recalcitrant seeds: 'lethal water contents', causes of damage, and quantification of recalcitrance.

AbstractThe drying rate of whole seeds of Ekebergia capensis (Meliaceae) was shown to influence the response to desiccation, with rapidly dried seeds surviving to lower water contents. Short-term rapid drying (to water contents higher than those leading to viability loss) actually increased the rate of germination. The form of the time course of decline of axis water content varied with drying rate; slow drying could be described by an exponential function, whereas with rapid drying initial water loss was faster than predicted by an exponential function. These observations suggest that slow drying brought about homogeneous dehydration and that the rapid drying was uneven across the tissue. This raised the possibility that the different responses to dehydration were a function of different distributions of water in the axis tissue under the two drying regimes. However, ultrastructural observations indicated that different deleterious processes may be occurring under the different drying treatments. It was tentatively concluded that a major cause of viability loss in slowly dried material was likely to be a consequence of aqueous-based processes leading to considerable membrane degradation. Uneven distribution of tissue water could not be rejected as a contributory cause of the survival of rapidly dried seeds to low bulk water contents. The differential response to dehydration at different drying rates implies that it is not possible to determine a ‘critical water content’ for viability loss by recalcitrant seeds.

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Subcellular organization and metabolic activity during the development of seeds that attain different levels of desiccation tolerance

Seed Science Research ◽

10.1017/s0960258500003470 ◽

1997 ◽

Vol 7 (2) ◽

pp. 135-144 ◽

Cited By ~ 50

Author(s):

Jill M. Farrant ◽

N. W. Pammenter ◽

Patricia Berjak ◽

Christina Walters

Keyword(s):

Phaseolus Vulgaris ◽

Desiccation Tolerance ◽

Avicennia Marina ◽

Metabolic Rates ◽

Recalcitrant Seeds ◽

Concomitant Increase ◽

Orthodox Seeds ◽

Similar Development ◽

Different Levels ◽

Water Contents

AbstractWater contents, desiccation tolerance, respiratory rates and subcellular characteristics of three contrasting seed types were studied during development.Avicennia marina(a tropical wetland species) andAesculus hippocastanum(a temperate species) produce recalcitrant seeds andPhaseolus vulgarisproduces orthodox seeds. During development,A. hippocastanumandP. vulgarisseeds showed a decline in water content and respiration rate with a concomitant increase in desiccation tolerance. These parameters did not change during the development ofA. marinaseeds once they had become germinable. There was a decrease in the degree of vacuolation and an increase in the deposition of insoluble reserves inA. hippocastanumandP. vulgarisseeds, whileA. marinaseeds remained highly vacuolated and did not accumulate insoluble reserves. Mitochondria and endomembranes degenerated during the development ofA. hippocastanumandP. vulgarisseeds, but remained unchanged inA. marinaseeds. The data are consistent with the hypothesis that extensive vacuolation and high metabolic rates contribute to desiccation sensitivity. However, the development of recalcitrantA. hippocastanumseeds is similar to that of orthodoxP. vulgarisseeds. These data are in accord with the concept of seed recalcitrance being a consequence of truncated development. The results suggest that there may be three categories of seeds: orthodox seeds which develop desiccation tolerance, seeds which show similar development to orthodox seeds, but are shed before desiccation tolerance is well developed, and seeds which show no developmental trends giving rise to increased tolerance.

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The influence of the epidermis on the drying rate of red clover leaflets, leaf petioles and stems at low water contents

Grass and Forage Science ◽

10.1111/j.1365-2494.1982.tb01591.x ◽

1982 ◽

Vol 37 (2) ◽

pp. 151-157 ◽

Cited By ~ 12

Author(s):

C. E. HARRIS ◽

V. S. SHANMUGALINGAM

Keyword(s):

Red Clover ◽

Drying Rate ◽

Water Contents

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Seed mass variation potentially masks a single critical water content in recalcitrant seeds

Seed Science Research ◽

10.1079/ssr2004168 ◽

2004 ◽

Vol 14 (2) ◽

pp. 185-195 ◽

Cited By ~ 21

Author(s):

Matthew I. Daws ◽

Christiane S. Gaméné ◽

Sheila M. Glidewell ◽

Hugh W. Pritchard

Keyword(s):

Water Content ◽

Seed Mass ◽

Tropical Tree ◽

Recalcitrant Seeds ◽

Seed Population ◽

Wide Range ◽

Critical Water Content ◽

Whole Seed ◽

Water Contents ◽

Seed Water Content

For recalcitrant seeds, mortality curves of germination versus water content typically imply a wide range of desiccation sensitivities within a seed population. However, seed to seed differences in water content, during desiccation, may confound our interpretation of these mortality plots. Here, we illustrate this problem for two batches ofVitellaria paradoxa(Sapotaceae) seeds collected in 1996 and 2002. Whole seeds were desiccated to various target water contents (TWCs) using silica gel. During desiccation, smaller seeds in the population dried most rapidly. Consequently, there was a significant linear relationship between whole-seed water content and seed mass during the drying process. In addition, following desiccation to low TWCs, only the largest seeds in the population retained viability. Taken together, this suggests that the larger seeds survived, not as a consequence of great relative desiccation tolerance, but as a result of taking longer to desiccate. Subsequently, the critical water content (CWC) for viability loss was calculated, based on the assumptions that in the seed population whole-seed water content during desiccation was normally distributed and the smallest, and hence driest, seeds were killed first. Using this approach, the driest seeds in the population that were killed, at each TWC, were always below a single CWC (c. 20% and 26% in 1996 and 2002, respectively). In subsequent experiments the effect of seed size variation on the response to desiccation was confirmed by conducting desiccation screens on seeds sorted into two discrete size classes, i.e. the seed-lot heterogeneity in mass was reduced. Using this approach, the mortality curves had a steeper slope. Furthermore, data for 24 tropical tree species from the Database of Tropical Tree Seed Research (DABATTS) revealed that seed lots with less variability in mass had steeper mortality curves. Thus, taken together, the data suggest that, at least for whole seeds, the wide range of desiccation sensitivities typically inferred is an artefact of seed to seed variation in mass, and hence water contents, during drying.

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Water Content and Product Drying Rate as Well as the Amount of Propylene Glycol May Impact the Topical Bioavailability of Acyclovir from Cream Products

10.26226/morressier.57d6b2bad462b8028d88d970 ◽

2016 ◽

Author(s):

Yousuf Mohammed

Keyword(s):

Water Content ◽

Propylene Glycol ◽

Drying Rate ◽

Topical Bioavailability

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CATFISH DRYING (Clarias Batraclus) USING ‘TEKO BERSAYAP’ SOLAR DRYER

Jurnal Agroindustri ◽

10.31186/j.agroind.2.1.14-20 ◽

2012 ◽

Vol 2 (1) ◽

pp. 14-20

Author(s):

Yuwana Yuwana

Keyword(s):

Relative Humidity ◽

Moisture Content ◽

Ambient Temperature ◽

Drying Rate ◽

Drying Process ◽

Drying Time ◽

Ambient Relative Humidity ◽

Solar Dryer

Experiment on catfish drying employing ‘Teko Bersayap’ solar dryer was conducted. The result of the experiment indicated that the dryer was able to increase ambient temperature up to 44% and decrease ambient relative humidity up to 103%. Fish drying process followed equations : KAu = 74,94 e-0,03t for unsplitted fish and KAb = 79,25 e-0,09t for splitted fish, where KAu = moisture content of unsplitted fish (%), KAb = moisture content of splitted fish (%), t = drying time. Drying of unsplitted fish finished in 43.995 hours while drying of split fish completed in 15.29 hours. Splitting the fish increased 2,877 times drying rate.

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A review of the composition and evolution of hydrocarbon gases during solidification of the Ilímaussaq alkaline complex, South Greenland

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v190.5187 ◽

2001 ◽

pp. 159-166 ◽

Cited By ~ 6

Author(s):

Jens Konnerup-Madsen

Keyword(s):

Nepheline Syenite ◽

Subsequent Development ◽

High Water ◽

Vapour Phase ◽

Low Carbon ◽

Low Oxygen ◽

Alkaline Complex ◽

Hydrocarbon Gases ◽

Wide Range ◽

Water Contents

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Konnerup-Madsen, J. (2001). A review of the composition and evolution of hydrocarbon gases during solidification of the Ilímaussaq alkaline complex, South Greenland. Geology of Greenland Survey Bulletin, 190, 159-166. https://doi.org/10.34194/ggub.v190.5187 _______________ Fluid inclusions in minerals from agpaitic nepheline syenites and hydrothermal veins in the Ilímaussaq complex and in similar agpaitic complexes on the Kola Peninsula, Russia, are dominated by hydrocarbon gases (predominantly methane) and hydrogen. Such volatile compositions differ considerably from those of most other igneous rocks and their formation and entrapment in minerals reflects low oxygen fugacities and a wide range of crystallisation temperatures extending to a low-temperature solidus. Their composition reflects initial low carbon contents and high water contents of the magma resulting in the exsolution of a waterrich CO2–H2O dominated vapour phase. Fractionation of chlorides into the vapour phase results in high salinities and the subsequent development of a heterogeneous vapour phase with a highly saline aqueous-rich fraction and a methane-dominated fraction, with preferential entrapment of the latter, possibly due to different wetting characteristics. The light stable isotope compositions support an abiogenic origin for the hydrocarbons in agpaitic nepheline syenite complexes.

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Mitotic Activity Dynamics in Recalcitrant Seeds Acer sachharinum during Maturation and Germination

HortScience ◽

10.21273/hortsci.33.3.479c ◽

1998 ◽

Vol 33 (3) ◽

pp. 479c-479

Author(s):

L. Kozeko ◽

V. Troyan ◽

L. Musatenko

Keyword(s):

Cell Division ◽

Mitotic Activity ◽

Quiescent State ◽

Activity Levels ◽

Recalcitrant Seeds ◽

Mature Embryos ◽

Before And After ◽

Orthodox Seeds ◽

Mature Seeds ◽

Activity Dynamics

In orthodox seeds the cell division within the embryo meristems arrests during maturation at embryo moisture content (MC) 65% to 47%, and the maturation completion and transition of seeds to quiescent state occurs at MC about 10%. The arrest of cycling happens asynchronously in different meristematic tissues during desiccation: first in shoot and then in root. The aim of this work was to define a mitotic activity dynamics in recalcitrant seeds with the high MC at maturation end and the absence of quiescent state characteristic of it. The object was seeds of Acer saccharinum, using widely for planting of greenery in Kiev city. The mitotic activity was determined in 0.5 mm of the embryo root pole (RP) and 0.5 mm of the shoot pole with embryo leaves (SP). The A. sachharinum seeds completed them maturation at MC 53% (FW basis). During maturation the mitotic index (MI) in RP decreased from 3.2% in immature seeds (at embryos MC 80%) to 0 in mature seeds and in SP–from 5.4% to 3.3%, respectively. Cell division in SP arrested by dehydration of mature embryos to MC 46% by PEG 6000 (30%). The seeds lost viability by desiccation to MC 34%. The mature seeds were able to germinate immediately after abscission. During seed germination the cell division reactived in RP and increased in SP already before root protrusion. In plantlets 10–15 mm long the MI increased to 8% in RP and 12% in SP. Thus, the strategy of immediate germination of recalcitrant A. sachharinum seeds includes a preservation of cell division in SP of mature embryos, in contrast with orthodox seeds, and high mitotic activity levels in meristems of germinating embryos before and after root protrusion.

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