scholarly journals Analysis of Seed Germinating Vigor, Germination Speed and Peak Time in 9 Fescues under Alternative and Natural Conditions at the Room Temperature

2017 ◽  
Vol 6 (3) ◽  
pp. 235-248
Author(s):  
Kyoung-Nam Kim
Keyword(s):  
Room Temperature ◽  
Peak Time ◽  
Natural Conditions ◽  
Germination Speed

scholarly journals DATA ON THE DEVELOPMENT OF HETERAKIS PAPILLOSA IN THE FOWL

1921 ◽  
Vol 34 (3) ◽  
pp. 259-270 ◽  
Author(s):  
H. W. Graybill
Keyword(s):  
Small Intestine ◽  
Salt Solution ◽  
Final Stage ◽  
Minimum Temperature ◽  
Growth And Development ◽  
Room Temperature ◽  
Freezing Temperature ◽  
Physiological Salt Solution ◽  
Natural Conditions ◽  
Short Intervals

In observations on the development of the ova of Heterakis papillosa in cultures, it was found that they failed to develop at a temperature ranging from 2.5–8°C., but developed slowly at a temperature of 11.5–13.5°C. The minimum temperature for development seems to lie between 8° and 11.5–13.5°C. At temperatures ranging in various cultures from 18–29°C. ova developed to their final stage in 7 to 12 days. Undeveloped ova subjected to a freezing temperature for a period of 4 days were viable at the end of that time. Fully developed ones remained alive when exposed out of doors for a period of 7 days at a temperature ranging from 5–62°F. Undeveloped ova survived desiccation at room temperature for a period of 16 days, but not for 41 days. Fully developed eggs were alive after desiccation for 18 days, but not after 49 days. In another instance they were no longer viable after 10 days. Embryos within ova kept in physiological salt solution at room temperature survived during a period of a little over 12 months. Fully developed ova kept in soil outdoors under circumstances approaching natural conditions contained living embryos after a period of 8 months. From a study of a series of artificially infested chickens killed at short intervals it appears that the ova of Heterakis hatch in the small intestine and the larvæ pass by way of the small and large intestines to the ceca where they undergo development to maturity. Larvæ found in the mucosa of the ceca were not in an encysted condition. Feeding of numerous artificially incubated ova may lead to a light infestation, the cause of which has not been definitely determined. A period of 57 days was required for larvæ to reach maturity in a host. The entire cycle from egg to adult requires a minimum time of about 64 days. A brief study of the growth and development of larvæ within the host has been made. No evidence was found of a migration through the tissues. A few penetrate into the mucosa of the ceca.

scholarly journals Germination of Croton urucurana L. seeds exposed to different storage temperatures and pre-germinative treatments

2012 ◽  
Vol 84 (1) ◽  
pp. 191-200 ◽  
Author(s):  
Silvana P.Q. Scalon ◽  
Rosilda M. Mussury ◽  
Andréa A. Lima
Keyword(s):  
Electrical Conductivity ◽  
Gibberellic Acid ◽  
Room Temperature ◽  
Germination Speed ◽  
Cold Chamber ◽  
Storage Temperatures

The present work evaluated the germinability and vigor of Croton urucurana seeds. 1) Seeds were sorted by color (caramel, gray and black) and were subjected to seven different pre-germination treatments followed by incubation at 20ºC, 25°C or 20/30°C. 2) Seeds were stored in cold chambers or at room temperature for up to 300 days and were subsequently incubated at 20/30ºC in a germination chamber or under greenhouse conditions. Only gray seeds showed significant germination rates. The highest first count percentages of total germination and the highest germination speed indices were observed in control seeds and in those which were treated with water or 200 mg. L-1 gibberellic acid for 12 hours. Seeds stored under refrigeration showed the highest values for all of the characteristics examined, as well as less electrical conductivity of the imbibing solution. Seedlings were more vigorous when seeds were stored for 300 days in a cold chamber. The seedlings production can be increased by incubating the seeds at alternating temperatures (20/30°C). The seeds do not need pre-germination treatments.

scholarly journals Ruptura de la latencia física y germinación de semillas de Chiranthodendron pentadactylon (Malvaceae)

2019 ◽  
Vol 97 (2) ◽  
pp. 211
Author(s):  
Maribel Apodaca-Martínez ◽  
Victor Manuel Cetina Alcalá ◽  
Jesús Jasso-Mata ◽  
Miguel Ángel López-López ◽  
Héctor González-Rosas ◽  
...  
Keyword(s):  
Moisture Content ◽  
Room Temperature ◽  
Block Design ◽  
Cold Stratification ◽  
Seedling Production ◽  
Juvenile Period ◽  
Tukey Test ◽  
Randomized Block Design ◽  
Germination Speed

<p><strong>Backgraund</strong>: The low availability, low percentage of germination, pests, and juvenile period higher than 25 years, are the problems to propagate C. pentadactylon by seed.</p><p><strong>Hypothesis</strong>: There is morphophysiological variation of the seeds between trees and the pregerminative treatments increase the percentage and speed of germination in seeds with six months of storage at room temperature.</p><p><strong>Species studied</strong>: Chiranthodendron pentadactylon Larreat.</p><p><strong>Study site and year of study</strong>: Postgrado en Ciencias Forestales, Campus Montecillo, Estado de  Mexico, Mex. June, 2016</p><p><strong>Methods</strong>: The moisture content, the viability and the effect of pregerminative treatments on the percentage and speed of germination of the seeds were determined. A randomized block design was used. The random blocks included the treatments: 1 (mechanical scarification + cold stratification at 5 ° C for 5 days), 2 (mechanical scarification + imbibition for 12 h), 3 (mechanical scarification + cut at the base of the seed) and 4 (control). The treatments were randomized within each block.</p><p><strong>Results</strong>: The moisture content was less than 10 % and the viability was 100 %. Significant differences between treatments were found for germination percent. The Tukey test (α = 0.05) showed differences between pregerminative treatments 1, 2 and 3 with respect to T4. Germination speed recorded the highest value in treatment 3.</p><p><strong>Conclusions</strong>: With treatments 1, 2 or 3, more than 77 % germination was obtained. Treatment 3 showed greater germination speed, which is important for seedling production.</p>

scholarly journals Internal Factors Controlling the Suboesophageal Ganglion Neurosecretory Cycle in Periplaneta Americana L

1960 ◽  
Vol 37 (1) ◽  
pp. 164-170
Author(s):  
JANET E. HARKER
Keyword(s):  
Locomotor Activity ◽  
Room Temperature ◽  
Periplaneta Americana ◽  
Activity Rhythm ◽  
The Body ◽  
Suboesophageal Ganglion ◽  
Natural Conditions ◽  
Internal Factors ◽  
Locomotor Rhythm ◽  
Locomotor Activity Rhythm

1. Two interacting factors, both following a 24 hr. rhythm, are found to be concerned in the control of the locomotor activity rhythm of Periplaneta americana. 2. When the suboesophageal ganglion is chilled to 30°C., the rest of the body being kept at room temperature, the phases of the neurosecretory cycle are delayed for a period equivalent to the period of chilling. 3. A second cycle, which follows a 24 hr. rhythm, can act as a stimulus to the neurosecretory cycle if the latter is at a stage which responds to a stimulus. If the second cycle affects the neurosecretory cycle the phases of the latter are reset by the stimulus. The phases of the second cycle can be reset by a change from light to darkness while the suboesophageal ganglion is in the chilled state. It appears that the second cycle is immediately reset by the onset of darkness, regardless of the time at which this occurs. 5. The value to the animal, in its natural conditions, of the control of the locomotor rhythm by two interacting cycles is discussed.

scholarly journals Short-period fluctuations in the numbers of bacterial cells in soil

1936 ◽  
Vol 119 (814) ◽  
pp. 269-295 ◽  
Keyword(s):  
Room Temperature ◽  
Short Interval ◽  
Bacterial Cells ◽  
Intensive Study ◽  
Natural Conditions ◽  
Short Period ◽  
Initial Decrease ◽  
Plate Counts ◽  
Micro Organisms ◽  
Different Parts

Seasonal changes in the numbers of micro-organisms in fresh soil were first reported at the beginning of the present century; their existence has since been confirmed by workers in many different parts of the world. (For references, see below .) More recently, short-period fluctuations in bacterial numbers were found to exist. Such fluctuations were found in plate counts from daily samples of field soil by Cutler, Crump, and Sandon (1922) and from 2-hourly samples by Thornton and Gray (1930). Periodic determinations of bacterial numbers in soils other than those taken from natural conditions have been few in number and have usually been made as checks on work of some other nature. In earlier work of Russell and Hutchinson (1909), soil incubated at room temperature showed fluctuations in microbial content over such a short interval as 8 hours and over as long a period as 60 days. In their later work, Russell and Hutchinson (1913) working with three soils of different moisture contents, dry, moist, and saturated, incubated at constant temperature, found changes in numbers between samples taken at from 5- to 8-day intervals. Such changes in numbers were not related to temperature, nor necessarily to moisture changes. A more intensive study was made by Allison (1917). He brought soil samples into the laboratory and made bacterial and fungal counts at short intervals of time. Samples taken during the winter showed a drop in numbers of as much as 40% during the first 1½ hours’ storage, followed by a large rise after some hours; in summer the initial decrease was less pronounced, this being attributed to the fact that at that season outdoor temperatures more nearly approached indoor temperatures. Cutler and Dixon (1927) found that, with soil stored at laboratory temperatures in deep narrow bottles, bacterial numbers decreased steadily over a period of 5 weeks. In soil stored in pots with a large surface area, fluctuations in bacterial numbers of as much as 100% were obtained from week to week, and the soil in general behaved as fresh soil.

COMPARATIVE SURVIVAL AND DECOMPOSING ABILITY OF FOUR FUNGI ISOLATED FROM LEAF LITTER AT LOW TEMPERATURES

1974 ◽  
Vol 54 (3) ◽  
pp. 245-253 ◽  
Author(s):  
K. C. IVARSON
Keyword(s):  
Leaf Litter ◽  
Low Temperatures ◽  
Room Temperature ◽  
Abundant Species ◽  
Decomposition Process ◽  
The Other ◽  
Natural Conditions ◽  
Cold Temperatures ◽  
Available Energy ◽  
Cold Tolerant

The survival and decomposing ability of the four dominant fungi found in low-temperature decomposing leaf litter was studied over a 46-mo period, at temperatures ranging from 1 C to room temperature. A Rhizoctonia sp. by itself and in association with the three other fungi disappeared. When alone it brought about no decomposition. Over the temperature range a Penicillium sp. that appeared to be a member of the Penicillium terrestre series showed strong survival properties in association with the other fungi, and by itself decomposed about the same amount of litter as the natural microbial flora of the unaltered litter, indicating that under natural conditions and at temperatures above 1 C this fungus is an important colonizer and decomposer of organic matter. Mucor spinescens alone and in association survived at room temperature and 10 C, but was absent at 4 and 1 C. By itself it decomposed a small amount of litter. The most abundant species, Chrysosporium pannorum (50% of all isolates at cold temperatures), a cellulolytic fungus, was not able to survive in litter in the absence of the other fungi. In their presence, it not only survived but increased in number as temperature decreased. The facts that pH changes and litter extract did not affect its growth suggest that C. pannorum does not possess the ability to be a pioneer colonist, and it is only after associated fungi begin the initial breakdown and perhaps supply easily available energy sources or growth factors that C. pannorum is able to take part in the decomposition process and survive. Thus, as temperature decreases, there is perhaps less competition for this cold-tolerant fungus, and its role in the decomposition process increases.

scholarly journals Storage of seeds of Cnidosculus phyllacanthus Pax & K. Hoffm.

2005 ◽  
Vol 9 (4) ◽  
pp. 591-595
Author(s):  
Lígia M. de M. Silva ◽  
Ivor B. de Aguiar ◽  
Déborah L. de Morais ◽  
Ricardo A. Viegas ◽  
Joaquim A. G. Silveira
Keyword(s):  
Moisture Content ◽  
Room Temperature ◽  
Storage Conditions ◽  
Seed Moisture Content ◽  
Seed Moisture ◽  
Room Condition ◽  
Germination Speed ◽  
Physiological Quality ◽  
Cold Chamber

This work aimed to determine the best environment for conservation of physiological quality of seeds of Cnidosculus phyllacanthus during storage. Seeds with 8.5% moisture content and 86% germinative capacity were filled in containers of different permeability, and storaged at different conditions during 360 days. Seeds packed in permeable container (paper bag) were stored at ordinary room temperature (18 to 25 ºC and 55 to 78% RH), and dry chamber (18 ºC and 60% RH) while those packed in semipermeable (polyethylene bag) and impermeable (glass) containers were stored in cold chamber (10 ºC and 75% RH). Seed moisture content, germinative capacity and germination speed were evaluated each 90 days interval. For all the tested storage conditions, seed germination speed was reduced at first evaluation and stabilized up to 360 days. Great deterioration in seeds stored at ordinary room condition was observed, while those stored in dry chamber maintained its germinative capacity for 270 days. The seed germinative capacity was better retained in cold storage, packaged either in semipemeable or impermeable containers. During storage, the seeds had a behavior classified as orthodox.

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