scholarly journals Factors limiting seed germination of terrestrial bromeliads in the sandy coastal plains (restinga) of Maricá, Rio de Janeiro, Brazil

Rodriguésia ◽  
2008 ◽  
Vol 59 (1) ◽  
pp. 135-150 ◽  
Author(s):  
André Mantovani ◽  
Ricardo Rios Iglesias
Keyword(s):  
Seed Germination ◽  
High Temperatures ◽  
Seedling Survival ◽  
Temporal Distribution ◽  
Limiting Factors ◽  
Limiting Factor ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Sand Burial ◽  
Water Potentials

ABSTRACT Vegetation islands surrounded by bare sand are one of the most characteristic features of the sandy plains (restinga) of the Brazilian coastline. Abiotic conditions outside the islands are too harsh for the establishment of plants. Bromeliads are frequent both inside and at the borders of islands, but infrequent outside the islands in the restinga of Maricá. We hypothesized that the rarity of bromeliad seedlings in the restinga is due to high mortality during the seed and/or seedling stages. In this study, we assessed the potential limiting factors for germination and seedling survival of three terrestrial bromeliads Neoregelia cruenta, Aechmea nudicaulis and Vriesea neoglutinosa. Seed viability, water balance during dry-wet cycles, germination under different water potentials and the susceptibility of seedlings to high temperatures, desiccation and sand burial were analyzed. The tested seeds were nondormant, and they germinated to >70% even after exposure to 60ºC and desiccation. At temperatures > 27ºC, seeds lost water faster than imbibited it, and drywet cycles and water potentials of -0.4 MPa decreased germination. Thus, low water availability is likely limiting factor for bromeliad seed germination in the restinga of Maricá. Seedlings were extremely sensitive to high temperatures and sand burial. Shoots failed to emerge if seed depth exceeded 10 mm. We suggest that unequal temporal distribution of rainfall, low water retention capacity of the soil, and high temperatures inhibit germination and seedling establishment through water stress. Consequently, bromeliads are not likely to act as pioneer plants in the barren regions that separate restinga islands.

scholarly journals Effects of hydrogel amendment on water storage of sandy loam and loam soils and seedling growth of barley, wheat and chickpea

2011 ◽  
Vol 50 (No. 10) ◽  
pp. 463-469 ◽  
Author(s):  
J. Akhter ◽  
K. Mahmood ◽  
K.A. Malik ◽  
A. Mardan ◽  
M. Ahmad ◽  
...  
Keyword(s):  
Seed Germination ◽  
Plant Species ◽  
Seedling Growth ◽  
Sandy Loam ◽  
Field Capacity ◽  
Water Retention Capacity ◽  
Arid Environments ◽  
Hordeum Vulgare L ◽  
Retention Capacity ◽  
Available Water

The hydrogel amendments may improve seedling growth and establishment by increasing water retention capacity of soils and regulating the plants available water supplies, particularly under arid environments. The effects of different levels of a locally prepared hydrogel were studied on the moisture properties of sandy loam and loam soils (fine-loamy, mixed, hyperthermic Typic Haplargids, USDA, Luvic Yermosol, FAO) and on growth response of three plant species, viz. barley (Hordeum vulgare L.), wheat (Triticum aestivum L.) and chickpea (Cicer arietinum L.). Water absorption by gel was rapid and highest in distilled water and was inhibited by an increase in water salinity. The addition of 0.1, 0.2 and 0.3% hydrogel increased the moisture retention (θr) at field capacity linearly (r = 0.988) and thus the amount of plant available water significantly in both sandy loam and loam soils compared to the untreated soils. Seed germination of wheat and barley was not affected but seedling growth of both species was improved by the gel amendment. In loam soil, seed germination of chickpea was higher with 0.2% gel and seedling growth increased with increase in gel level compared with control conditions. The hydrogel amendment caused a delay by 4–5 days in wilting of seedlings grown in both soils compared with control conditions. The hydrogel amendment was effective in improving soil moisture availability and thus increased plant establishment. However, the varied responses of plant species in sandy loam and loam soils warrant further studies on the behaviour of different soil types with gel amendments.

The effect of water supply on tree seed germination and seedling survival in a tropical seasonal forest in Veracruz, Mexico

1991 ◽  
Vol 7 (1) ◽  
pp. 69-83 ◽  
Author(s):  
Dominique Blain ◽  
Martin Kellman
Keyword(s):  
Water Supply ◽  
Tree Species ◽  
Seedling Survival ◽  
Light Level ◽  
Water Retention Capacity ◽  
Wet Season ◽  
Retention Capacity ◽  
Large Fluctuations ◽  
Rainfall Patterns ◽  
Tropical Seasonal Forest

ABSTRACTIn Iropical seasonal forests, mass seedling death may incidentally occur early in the rainy season following untimely germination provoked by an isolated heavy rainfall. We hypothesized that, in a soil with little moisture retention capacity, irregular rainfall patterns would result in large fluctuations of water supply and, in the early wet season, drought episodes could cause seedling death. This hypothesis was tested in a seasonal tropical forest in Mexico where seedling density is low and the soil consists of almost pure sand with a low water retention capacity. Various patterns of simulated rainfall were applied in the forest to seeds and seedlings of three common tree species. Overall very little difference in germination and seedling survival was observed between the various rainfall treatments. The results showed that rainfall patterns and the soil texture may interact in a much more complex way than was initially hypothesized, and that water availability to seeds and seedlings is not necessarily predictable. The absence of seedlings of the three tree species might be better explained by high seed predation and low light level in the understorey.

scholarly journals Enzymatic activity and gene expression related to drought stress tolerance in maize seeds and seedlings

2021 ◽  
Vol 37 ◽  
pp. e37079
Author(s):  
Milena Christy Santos ◽  
Édila Vilela de Resende Von Pinho ◽  
Heloisa Oliveira dos Santos ◽  
Danielle Rezende Vilela ◽  
Izabel Costa Silva Neta ◽  
...  
Keyword(s):  
Drought Stress ◽  
Water Deficit ◽  
Selection Process ◽  
Limiting Factor ◽  
Water Retention Capacity ◽  
Maize Seedlings ◽  
Retention Capacity ◽  
Maize Seeds ◽  
Expression Of Genes ◽  
Different Tissues

Drought stress is a major limiting factor for the development of maize, and the identification of the expression of genes related to this stress in seeds and seedlings can be an important tool to accelerate the selection process. The expression of genes related to tolerance to water deficit in seeds and in different tissues of maize seedlings were evaluated. Four tolerant genotypes (91-T, 32-T, 91x75-T, 32x75-T) and four non-tolerant genotypes (37-NT, 57-NT, 37x57-NT and 31x37-NT) were seeded in a substrate with 10% (stress) and 70% (control) water retention capacity. The expression of 4 enzymes were evaluated: catalase (CAT), peroxidase (PO), esterase (EST), and heat-resistant protein (HRP), as well as the relative expression of 6 genes: ZmLEA3, ZmPP2C, ZmCPK11, ZmDREB2A/2.1s, ZmDBP3 and ZmAN13 were evaluated in seed, shoots and roots of seedlings submitted or not to stress. There was variation in the expression of CAT, PO, SOD, EST and HRP enzymes among the evaluated genotypes and also in the different tissues evaluated. Higher expression of the CAT and PO was observed in the shoots. There was a greater expression of the EST in the genotypes non-tolerant to water deficit. HRP was expressed only in seeds. In the aerial part of maize seedlings, classified as tolerant, higher expression of genes ZmLEA3 and ZmCPK11 was observed. There was a higher expression of the ZmAN13 and ZmDREB2A/2.1S genes in roots developed under stress conditions and a higher expression of the ZmPP2C gene in seeds of line 91-T, which is classified as tolerant to drought stress.

scholarly journals Low-suction water retention capacity of bentonite at high temperature

2020 ◽  
Vol 195 ◽  
pp. 04010
Author(s):  
María Victoria Villar ◽  
Carlos Gutiérrez-Álvarez ◽  
Pedro Luis Martín
Keyword(s):  
High Temperatures ◽  
Water Retention ◽  
Water Retention Capacity ◽  
Dry Density ◽  
Retention Capacity ◽  
Compacted Bentonite ◽  
Buffer Material ◽  
Hydraulic Gradients ◽  
Radioactive Waste Repositories ◽  
Waste Repositories

The study of the hydro-mechanical properties of compacted bentonite is relevant in the context of deep geological radioactive waste repositories, where bentonite will be used as buffer material between the waste canisters and the host rock and will be subjected to high temperatures and hydraulic gradients. This research aimed at determining the water retention curves of bentonite compacted at a repository-significant dry density (1.6 g/cm3) and at high temperatures (up to 100°C). This had been previously undertaken, but below suctions around 10 MPa the accurateness of the curves obtained was very low because of the methods and instruments used to determine them. To overcome this uncertainty, thermocouple psychrometers, which work properly in the low-suction range (below ~6 MPa), were tested. However, calibration showed that their performance was compromised when temperature rose above 60°C. Nevertheless, the results obtained were consistent with previous ones and allowed to confirm the decrease of water retention capacity with temperature. Additionally, it was checked that this decrease was more important for the low suctions.

scholarly journals Herbivory and Competing Vegetation Interact as Site Limiting Factors in Maritime Forest Restoration

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 950 ◽  
Author(s):  
Emily C. Thyroff ◽  
Owen T. Burney ◽  
Douglass F. Jacobs
Keyword(s):  
Forest Restoration ◽  
Seedling Survival ◽  
Growing Season ◽  
Limiting Factors ◽  
Limiting Factor ◽  
Significant Treatment ◽  
Vegetation Control ◽  
Competing Vegetation ◽  
Live Oak ◽  
Maritime Forest

Herbivory and competition during the regeneration phase influence forest successional dynamics. We demonstrated the importance of using the Target Plant Concept to identify and overcome site limiting factors for subtropical maritime forest restoration associated with deer browsing and competition. Quercus virginiana Mill. (live oak) bareroot seedlings were planted into clearcuts along the US Southern Atlantic coast with different treatment combinations of herbivory control (fenced or non-fenced) against white-tailed deer (Odocoileus virginianus Zimm.) browsing and competing vegetation removal (none, one-year, or two-years). After three growing seasons, mean seedling survival was 61% with no significant treatment differences. Control of browse and vegetation interacted to facilitate growth of live oak; seedlings were significantly larger for all response parameters (diameter, height, crown width) when fenced and treated with vegetation control. Removal of vegetation improved seedling performance only in fenced plots, however, indicating a shift in pressure from herbivory to competition as the most limiting site factor when deer were excluded. After the second growing season, foliar nitrogen was greater in fenced plots than non-fenced plots and greater in two-year vegetation control subplots than non-vegetation control subplots. This result, however, was absent after the third growing season. Three years after clearcutting, there was no evidence of Q. virginiana natural regeneration in non-fenced plots. Even with artificial regeneration in non-fenced plots, Q. virginiana growth was slow, indicating that herbivory was a key limiting factor. Our findings illustrate the importance of accounting for site limiting factors and may aid in developing management prescriptions to promote semi-evergreen oak regeneration in ecosystems with high pressure from herbivory and competing vegetation.

Effect of high temperatures on seed germination and seedling survival in three pine species (Pinus pinaster, P. sylvestris and P. nigra)

2007 ◽  
Vol 16 (1) ◽  
pp. 63 ◽  
Author(s):  
R. Alvarez ◽  
L. Valbuena ◽  
L. Calvo
Keyword(s):  
Seed Germination ◽  
Root Growth ◽  
High Temperatures ◽  
Temperature Effects ◽  
Seedling Survival ◽  
Time Range ◽  
Percentage Germination ◽  
Negative Effects ◽  
Aerial Growth ◽  
Thermal Shocks

In the present study, we analyse the germination and seedling growth of three Pinus species (P. pinaster, P. sylvestris and P. nigra) under laboratory conditions after thermal shocks simulating the temperature effects of fire. Temperatures up to 150°C and 5 min exposure show negative effects on the percentage germination of P. pinaster seeds. P. sylvestris and P. nigra cannot stand temperatures greater than 110°C and 5 min exposure. In all three species, thermal shocks delay the start of germination. In addition, seeds from P. pinaster germinate over a longer time range. Seedling aerial growth after germination is influenced by high temperatures in P. sylvestris and P. nigra, but not in P. pinaster. Finally, thermal shocks produce a reduction in root growth in comparison with aerial growth in P. sylvestris.

Evaluation of Resistant Starch Quality from Different Types of Banana in Batter Coating Formulation to Reduce Oil Absorption in Fried Food

2019 ◽  
Vol 2 (2) ◽  
pp. 115-120
Author(s):  
Karissha Fritzi Della ◽  
Mutiara Pratiwi ◽  
Purwa Tri Cahyana ◽  
Maria DPT Gunawan-Puteri
Keyword(s):  
Resistant Starch ◽  
Extraction Process ◽  
Fat Content ◽  
Water Retention Capacity ◽  
Oil Absorption ◽  
Retention Capacity ◽  
Fried Food ◽  
Musa Paradisiaca ◽  
Different Types ◽  
Coating Formulation

Fried food is convenient for many people due to its pleasant texture and taste. On the other hand, it comes with the risk of high oil absorption which might lead to certain health problems. Resistant starch (RS) has been known to have a functionality of reducing oil absorption. Three different types of banana: Kepok (Musa paradisiaca formatypica), Raja Bulu (Musa paradisiaca L.) and Ambon (Musa paradisiaca L. var sapientum) were evaluated on its performance when utilized as source of resistant starch especially on their application in reducing oil absorption in fried food. Tempeh was used as the food model. Banana starch (RS2) was isolated through water alkaline extraction process, continued with modification process through three repeated cycles of autoclaving-cooling process to obtain the RS3. RS3 was added into the batter coating formulation at three substitution ratios (10%, 30% and 50%) and then used to coat tempeh before frying. Evaluation of resistant starch in batter and battered productwas conducted on the following parameters: fat content, water retention capacity (WRC), coating pick up and sensory analysis. The result of this study revealed that Raja Bulu showed the most effective result on reducing oil absorption in the food tested. In the three bananas used, the ratio of 50% performed best in coating pick up (highest), WRC (highest) and fat content(lowest) parameters, but not significantly different with the 30% ratio. In terms of sensory acceptance, using Raja Bulu as the selected banana type, 30% of substitution ratio was significantly more preferable by the panelists in crispness, oiliness, and overall acceptance attributes compared to control and other substitution ratios.

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