Effects of differential drying rates on viability retention of recalcitrant seeds of Ekebergia capensis

1998 ◽  
Vol 8 (4) ◽  
pp. 463-471 ◽  
Author(s):  
N. W. Pammenter ◽  
Valerie Greggains ◽  
J. I. Kioko ◽  
J. Wesley-Smith ◽  
Patricia Berjak ◽  
...  
Keyword(s):  
Water Content ◽  
Exponential Function ◽  
Time Course ◽  
Drying Rate ◽  
Recalcitrant Seeds ◽  
Tissue Water ◽  
Initial Water ◽  
Viability Loss ◽  
Drying Rates ◽  
Water Contents

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.

scholarly journals Effects of different drying rates on the physiological quality of Coffea canephora Pierre seeds

2005 ◽  
Vol 17 (2) ◽  
pp. 199-205 ◽  
Author(s):  
Sttela Dellyzete Veiga Franco da Rosa ◽  
Delacyr da Silva Brandão Júnior ◽  
Édila Vilela de Resende Von Pinho ◽  
André Delly Veiga ◽  
Luiz Hildebrando de Castro e Silva
Keyword(s):  
Water Content ◽  
Storage Temperature ◽  
Removal Rate ◽  
Coffea Canephora ◽  
Development Stage ◽  
Seed Vigor ◽  
Drying Rate ◽  
Physiological Quality ◽  
Drying Rates

Desiccation tolerance in seeds depends on the species, development stage and drying conditions, especially the water removal rate. Coffea seeds are considered of intermediate performance, because they tolerate relative dehydration compared to orthodox seeds and are sensitive to low temperatures. The objective of this study was to verify the effect of different drying rates on the viability and storability of Coffea canephora seeds. A complete randomized experimental design was used, in a factorial 3 x 5 x 2 design, with three drying rates (fast, intermediate and slow), five final mean water contents after drying (51, 42, 33, 22 and 15 %) and two storage temperatures (10 and 20°C). The germination and seed vigor assessments, using radicle protrusion, cotyledon leaf opening, seedling emergence and emergence speed index, were performed shortly after drying and after two and four months storage. It was observed that with reduction in the water content there was reduction in the germination values and seed vigor, for all the drying rates. The greatest reductions in physiological quality occurred when the seeds were dried quickly and the best results were obtained at the intermediate drying rate. There was an effect of drying rate and storage temperature on the physiological quality of the seeds, and lower germination and vigor values were observed in seeds with lower water content stored at 20°C. C. canephora seeds were tolerant to desiccation down to 15 % water content and can be stored for four months at 10°C. A temperature of 20ºC can be used to store C. canephora seeds, as long as the water content is not reduced to values below 22 % water content.

scholarly journals Drying and storage of Eugenia involucrata DC. seeds

2003 ◽  
Vol 60 (3) ◽  
pp. 471-475 ◽  
Author(s):  
Angela Maria Maluf ◽  
Denise Augusta Camargo Bilia ◽  
Claudio José Barbedo
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Cold Storage ◽  
Native Species ◽  
Plastic Bags ◽  
Physiological Quality ◽  
Drying Rates ◽  
And Storage ◽  
Water Contents

The physiological quality of seeds of native species is important to produce healthy saplings and therefore guarantee the success of programs to recover disturbed vegetation. This reinforces the necessity for investigating the physiological quality of those seeds. To evaluate the effects of different drying rates on the germination, moisture content and storability of Eugenia involucrata diaspores, mature fruits collected at Mogi Guaçu, SP, Brazil had their epi- and mesocarps removed by washing and were dried at 30, 40 or 50ºC until their water content was reduced from 57% (fresh diaspores) to 13% (final drying), totaling six drying levels. In a second experiment, diaspores had their moisture content reduced from 57% to 49%, at 30ºC, totaling six drying levels (0h, 1h, 2h, 3h, 4h and 5h), and were kept for 180 days in plastic bags under cold storage. The drying rate had no effect on tolerance to desiccation by E. involucrata diaspores; water contents lower than 51% decreased both germinability and storability. Diaspores can be stored for up to 180 days as long as their water content is reduced to 53% and they are kept inside plastic bags under cold storage.

DRYING OF FROZEN SOILS

1988 ◽  
Vol 68 (4) ◽  
pp. 807-811 ◽  
Author(s):  
E. de JONG ◽  
R. G. KACHANOSKI
Keyword(s):  
Environmental Factors ◽  
Key Words ◽  
Water Content ◽  
Maximum Rate ◽  
Drying Rate ◽  
Frozen Soils ◽  
Drying Rates

Drying rates of frozen aggregates varied from 2 mg cm−2 h−1 to zero, mainly in response to decreasing water content. Temperature, windspeed and dryness of the air controlled the maximum rate of drying. The variation in drying rate with water content was explained by the balance between ice and water in the pores. Key words: Frozen soils, evaporation, environmental factors

The Influence of Dehumidifying Condition on Expansive Soil Engineering Properties

2012 ◽  
Vol 594-597 ◽  
pp. 487-492
Author(s):  
Xiong Wei Li ◽  
Ai Jun Wang ◽  
Guo Zhong Dai
Keyword(s):  
Shear Strength ◽  
Relative Humidity ◽  
Water Content ◽  
Expansive Soil ◽  
Expansion Ratio ◽  
Soil Samples ◽  
Engineering Properties ◽  
Drying Rate ◽  
Initial Water Content ◽  
Initial Water

The expansive soil behaviour of expansive deformation and shear strength is deeply influenced by humidity condition. Different soil drying rate was set with constant temperature and different relative humidity. When saturated soil samples was dried to the different predetermined water content, the expansion ratio test with the upper load was made. It is shown that in the condition of high relative humidity, the expansion ratio is high. The smaller initial water content and upper load may lead to a larger swelling deformation. When soil samples with different initial water content was fully expanded, the consolidated direct shear tests were made. It is shown that the smaller drying rate leads to the greater shear strength after full expansion. What’s more, the upper load may improve the soil shear strength.

Experimental Study on Dewatering Dredged Clay with Ventilating Vacuum Method

2011 ◽  
Vol 261-263 ◽  
pp. 1650-1654 ◽  
Author(s):  
Feng Ji ◽  
Jian Wen Ding ◽  
Zhen Shun Hong ◽  
Yue Gui
Keyword(s):  
Experimental Study ◽  
Spatial Distribution ◽  
Surface Water ◽  
Water Content ◽  
Liquid Limit ◽  
Initial Water Content ◽  
Distribution Law ◽  
Initial Water ◽  
Vacuum Method ◽  
Water Contents

A series of model tests were performed on dredged clay with high initial water contents for investigating the dewatering behavior by ventilating vacuum method (VVM). The results shows that the surface water separated from dredged clay can be quickly removed by VVM in which a new pattern PVD is used. In addition, the method also speeds up the deposition of dredged clay. The volume of dredged clay with an initial water content of 4.5 times liquid limit decreases by 50 percent within two months. This paper also investigated the spatial distribution law of water content by TDR method. It is found that the drainage distance of PVD is about 0.3-0.4m.

Prediction of evaporation with the CONSEVB simulation-model - an experimental evaluation

Soil Research ◽  
1994 ◽  
Vol 32 (1) ◽  
pp. 45
Author(s):  
HP Cresswell ◽  
DJ Painter ◽  
KC Cameron
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Simulation Model ◽  
Water Content ◽  
Soil Water ◽  
Cost Benefit ◽  
Initial Water ◽  
Input Parameters ◽  
Moisture Characteristic ◽  
Water Contents

The CONSERVB simulation model was evaluated by comparing predictions of evaporation, net radiation, and water and temperature profiles with measured values from a bare, tilled soil in New Zealand conditions. No model calibration was used whatsoever. The assessment included tests of the sensitivity of output to variations (uncertainty) in input parameters. On 18 of the 24 days simulated, evaporation was within 0.5 mm day-1 of the measured means, although that represented less than 20% error on only 6 days. The mean difference between measured and simulated surface soil temperature for the two drying cycles was 1.2 and 1.3�C; most of this error occurred in warm conditions around noon each day. Simulated soil temperature at 0.05 m exceeded measured values during the warmest parts of the day and fell below them at night. Soil temperature prediction was sensitive to the air temperature and solar radiation climatic inputs. Evaporation prediction was sensitive to initial profile water contents, to the soil moisture characteristic and to the unsaturated hydraulic conductivity inputs. An increase in the water content at each matric potential step in the soil moisture characteristic input by a factor of 1.10 resulted in an increase in simulated cumulative evaporation of over 40%. For the prediction of evaporation and soil water content, field effort in the measurement of the soil hydraulic properties and initial water contents (where simulations are short) for model parameterization is likely to give the highest cost-benefit. Very accurate determinations of these input parameters and functions are required for model evaluation. Given the sensitivities, and the uncertainties associated with measurement and prediction of model input parameters, the predictions from CONSERVB have large uncertainties associated with them. Field-measured values of cumulative evaporation were within the range of variation in predicted values that resulted from uncertainty in determination of initial soil water contents alone. CONSERVB is more applicable to an operations research modelling approach than to prediction of evaporation and surface water contents in specific conditions.

scholarly journals Syntrichia norvegica shoots exhibit a complex inducible response to desiccation: separating the effects of rate of drying and water content

Botany ◽  
2017 ◽  
Vol 95 (5) ◽  
pp. 481-491 ◽  
Author(s):  
Lloyd R. Stark ◽  
Joshua L. Greenwood ◽  
Mandy L. Slate ◽  
John C. Brinda
Keyword(s):  
Chlorophyll Fluorescence ◽  
Water Content ◽  
Desiccation Tolerance ◽  
Severe Damage ◽  
Regeneration Potential ◽  
Significant Damage ◽  
Drying Rates ◽  
Shoot Damage ◽  
Water Contents

Plants in the moss genus Syntrichia are considered to have constitutive desiccation tolerance (DT), as in, able to tolerate a rapid drying event without incurring significant damage upon rehydration. However, few researchers have considered the separate effects of rate of drying and water content, and incorporated fully dehardened (to DT) plants in the experiments. Plants of Syntrichia norvegica F.Weber were cultured under conditions of suprasaturation, and adult shoots were exposed to a range of drying rates and equilibrating relative humidities (RHs), rehydrated, and assessed for chlorophyll fluorescence and regeneration potential. Adult shoots exhibited severe damage across all drying rates when equilibrated at RHs <30%. However, an inducible response to desiccation was present across all water contents as the rate of drying was extended from 0 to 4 d. The least desiccation damage occurred at longer drying times and higher water contents (8 d at 75% RH). A constitutive phenotype for DT was not strictly evident in S. norvegica. Rather, we observed an incomplete pattern of environmentally inducible DT, coupled with heavy shoot damage at lower water contents. Rate of drying and equilibrating RH clearly interact in producing the pattern and strategy of DT for this species.

scholarly journals Penentuan Konstanta Laju Pengeringan Coconut Chips

2021 ◽  
Vol 7 (1) ◽  
pp. 39-49
Author(s):  
Hary Kurniawan ◽  
Sukmawaty Sukmawaty ◽  
Ansar Ansar ◽  
Kurniawan Yuniarto ◽  
Murad Murad ◽  
...  
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Rate Constant ◽  
Rate Constants ◽  
Arrhenius Equation ◽  
Drying Rate ◽  
Initial Water Content ◽  
Thermogravimetric Method ◽  
Initial Water

This study aims to determine the drying rate constant of coconut chips using an oven. Coconut chips drying is carried out at drying temperatures of 50 ° C, 60 ° C and 70 ° C. Drying coconut chips has been conducted at an initial water content of 40-50% wb until it reached ± 10% wb. The change of moisture content was measured every 15 minutes, and the measurement of the water content was determined by the thermogravimetric method. Newton's model was used in determining the observation drying rate constant. Furthermore, the observation drying rate constant was applied to predict the drying rate constant as a function of temperature using the Arrhenius equation. The results showed that the predicted drying rate constants ranged from 0.0090 - 0.0130 minute-1. 

scholarly journals Infiltration into Frozen Silty Clay Loam Soil with Different Soil Water Contents in the Red River of the North Basin in the USA

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 321 ◽  
Author(s):  
Debjit Roy ◽  
Xinhua Jia ◽  
Dean D. Steele ◽  
Xuefeng Chu ◽  
Zhulu Lin
Keyword(s):  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Frozen Soil ◽  
Silty Clay ◽  
Initial Water ◽  
Infiltration Rates ◽  
The North ◽  
Water Contents

Predicting surface runoff and flooding in seasonally frozen areas such as the Red River of the North Basin (RRB) in USA is a challenging task. It depends on the knowledge of the complex process of infiltration in frozen soil, such as phase changes of water, ice content and distribution in the infiltration zone (the top 0–30 cm of the soil profile), soil pore size distribution, soil temperature and freeze–thaw cycles. In this study, the infiltration rates into frozen soil (Colvin silty clay loam according to the United States Department of Agriculture (USDA) Classification, and Chernozem according to Food and Agriculture Organization of the United Nations (FAO) international soil Classification) were measured at three different initial water contents: permanent wilting point (PWP), θpwp; field capacity (FC), θfc; and between FC and PWP, θmid. Laboratory infiltration experiments were conducted using a Cornell sprinkle infiltrometer with three replications for each initial water content. Volumetric soil water content (θv) and soil temperature at three depths were also continuously monitored using sensors. The average infiltration rates were 0.66, 0.38, and 0.59 cm/min for three initial water contents (θpwp, θmid, and θfc, respectively). Initial infiltration into frozen soil occurred quickly in the soil with θpwp because the soil was dry. Melted ice water contributed to the total soil water content over time, so it made the initial infiltration comparatively slower in the soil with θmid. Initial infiltration was also slower in the soil with θfc because the wet soil had very small pore space, so the soil rapidly reached its saturation after the infiltration started. The Horton infiltration equation was fitted with the observed infiltration rates for the soils with three initial water contents, and the goodness of fit was evaluated by using the coefficient of determination (R2) and the root-mean-square error (RMSE). The final infiltration rates from the fitted Horton equations were 0.060, 0.010, and 0.027 cm/min for the initial water contents (θpwp, θmid, and θfc, respectively). The soil water content along the soil profile changed with the amount of infiltrating water over time. However, the initial soil water content and melt water from ice resulting from soil temperature rise regulated the change in soil water content. The amount of ice melt water contribution to soil water content change varied among the soils with different initial water contents (θpwp, θmid, and θfc, respectively). The θv changed gradually in the θpwp soil, rapidly at 0 °C in the θmid soil, and less in the θfc soil. The change in pore distribution due to freeze–thaw cycles and soil packing altered the soil hydraulic properties and the infiltration into the soil. This study can provide critical information for flood forecasting model and subsurface drainage design in the RRB.

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