Seedling emergence of Pinus sylvestris in characterized seedbed substrates under different moisture conditions

2000 ◽  
Vol 30 (11) ◽  
pp. 1766-1777 ◽  
Author(s):  
Gunilla Oleskog ◽  
Harald Grip ◽  
Urban Bergsten ◽  
Kenneth Sahlén
Keyword(s):  
Organic Matter ◽  
Pinus Sylvestris ◽  
Seedling Emergence ◽  
Air Humidity ◽  
Soil Water Tension ◽  
Relative Air Humidity ◽  
Negative Effect ◽  
Organic Admixture ◽  
Moisture Conditions ◽  
Water Tension

Establishment of Scots pine (Pinus sylvestris L.) stands from seed is often unsuccessful because of unsuitable environmental conditions, such as limited soil moisture or air humidity. Improved seedling emergence could be achieved by soil preparation if site-specific optimal seedbeds were specified. Therefore the effects of seedbed substrates (13 characterized mixtures of sand, silt, and organic matter) on seedling emergence were determined after 14-day emergence tests in small laboratory chambers with four moisture conditions (2 levels of relative air humidity (RH), 95 and 65%, in combination with 2 levels of substrate water tension, 3 and 10 kPa). Seeds were placed in (partially buried) and on noncompacted and compacted substrates. At 95% RH, seedling emergence was 80 to 95% (seed lot maximum 94%) regardless of the substrate, with the exception of seeds placed in silt substrates (30-70%). At 65% RH, seedling emergence was 90% on silt, but considerably lower on organic matter and sand substrates, where organic admixture improved emergence for sand, but had a neutral or negative effect for silt. At 65% RH, partial seed burial, i.e., with good seed-substrate contact, improved emergence for organic matter and sand substrates, but impaired emergence for pure silt in noncompacted substrates at 3 kPa soil water tension. The effect of compaction on emergence was small for most substrates and had an effect only at 65% RH and 10 kPa tension. Seedling emergence and soil hydraulic conductivity at 3 kPa water tension and 95% RH were negatively correlated for partially buried seeds, but regardless of seed position, they were positively correlated at 10 kPa tension and 65% RH. These results can be used as guiding principles for the creation of seedbed substrates and seeding techniques.

Emergence and survival of Populus tremula seedlings under varying moisture conditions

2003 ◽  
Vol 33 (11) ◽  
pp. 2081-2088 ◽  
Author(s):  
Tarja Latva-Karjanmaa ◽  
Leena Suvanto ◽  
Kari Leinonen ◽  
Hannu Rita
Keyword(s):  
Seedling Emergence ◽  
Populus Tremula ◽  
Sowing Time ◽  
Large Numbers ◽  
Seedling Emergence And Survival ◽  
Negative Effect ◽  
Sowing Experiment ◽  
Moisture Conditions ◽  
Root Suckers ◽  
Survival Of Seedlings

Aspen produces large numbers of seeds, even though it mainly reproduces asexually with root suckers. The aim of this study was to find out how different moisture conditions affect emergence and survival of Populus tremula L. seedlings. This was studied with a sowing experiment (totally randomized factorial design). There were altogether 10 blocks, each containing 16 microsites and three treatments (sowing time, watering, sowing shelter) replicated twice in each block. Seedlings emerged on 56% of microsites. Sowing time affected seedling emergence. Both the proportion of microsites with seedlings and the number of seedlings per microsite were lower after first than after second sowing, when the weather was rainier. Watering increased the number of seedlings per microsite, but the proportion of micro sites with at least one seedling was not affected. Sowing shelter had a negative effect on the seedling emergence, especially after second sowing. The survival of seedlings was low (10%) and strongly dependent on watering. The effect of block and its interactions with treatments indicated that seedling emergence and survival depended also on seedbed conditions. We conclude that sexual reproduction of aspen may occur in nature, but it is rare. The seeds also maintained their germinability longer than earlier observed.

scholarly journals Effect of environmental conditions and genotype on nectar secretion in sunflower (Helianthus annuus L.)

OCL ◽  
2020 ◽  
Vol 27 ◽  
pp. 51
Author(s):  
Stan Chabert ◽  
Christopher Sénéchal ◽  
André Fougeroux ◽  
Jérémy Pousse ◽  
Fabien Richard ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Strong Impact ◽  
Air Humidity ◽  
Nectar Secretion ◽  
Climate Conditions ◽  
Soil Water Tension ◽  
Potential Benefits ◽  
Similar Range ◽  
Nectar Sugar ◽  
Water Tension

The sunflower crop provides an important honey flow for beekeepers. In France, beekeepers observed a decrease in honey yield from this crop these past years compared to the 1980s–1990s. They suspect the new cultivars to be less productive in nectar compared to the older ones, but no data is available to support this, and it is known that climate conditions have a strong impact on nectar secretion. This study aimed to explore the effect of abiotic environmental conditions on nectar secretion in sunflower, as well the range of variation of this secretion in a sample of current cultivars. Thirty-four current sunflower hybrid cultivars were sampled in test plots for their nectar secretion under varying conditions of temperature, air humidity and soil moisture. Air humidity controlled the sugar concentration of nectar, and thus its volume. To study nectar secretion independently from this effect, analyses subsequently focused on nectar sugar mass per floret. The nectar sugar mass increased with temperature up to an optimum of 32 °C, while the variation range of soil water tension was not sufficient to detect an effect on nectar sugar mass. This varied by up to 100% among the 34 cultivars (from 101 to 216 μg sugar per staminate floret in average), with a similar range to those reported in the literature for older cultivars. Likewise, oleic cultivars, a new type introduced since the early 2000s, were found to secrete the same amounts of nectar as linoleic cultivars, an older conventional type. The more self-fertile cultivars also showed no reduction in nectar secretion. Finally, we tested the method that measures the nectar gross secretion rate in one hybrid, and we observed that this hybrid secreted in average 28 μg sugar per hour per staminate floret. The potential benefits of this method were discussed.

Visco-elastic changes of vocal fold mucosa related to high and low relative air humidity

2000 ◽  
Vol 25 (4) ◽  
pp. 329-330
Author(s):  
R.J.B. Hemler ◽  
G.H. Wieneke ◽  
P.H. Dejonckere
Keyword(s):  
Vocal Fold ◽  
Air Humidity ◽  
Relative Air Humidity

Clinical, epidemiological and climatic factors related to the occurrence of cutaneous leishmaniasis in an endemic area in northeastern Brazil

2020 ◽  
Author(s):  
R. S. Oliveira ◽  
K. B. A. Pimentel ◽  
M. L. Moura ◽  
C. F. Aragão ◽  
A. S. Guimarães-e-Silva ◽  
...  
Keyword(s):  
Cutaneous Leishmaniasis ◽  
Climatic Factors ◽  
Wide Distribution ◽  
Northeastern Brazil ◽  
Public Health Issue ◽  
Air Humidity ◽  
Disease Occurrence ◽  
Relative Air Humidity ◽  
Age Range ◽  
And Control

Abstract Cutaneous leishmaniasis (CL) is a neglected tropical disease with a wide distribution in the Americas. Brazil is an endemic country and present cases in all states. This study aimed to describe the occurrence, the underlying clinical and epidemiological factors, and the correlation of climatic variables with the frequency of reported CL cases in the municipality of Caxias, state of Maranhão, Brazil. This is a retrospective and descriptive epidemiological study based on data extracted from the Brazilian Information System of Diseases Notification, from 2007 to 2017. Maximum and minimum temperature, precipitation, and relative air humidity data were provided by the Brazilian National Institute of Meteorology. A total of 201 reported autochthonous CL cases were analyzed. The predominance of cases was observed in males (70.1%). The age range between 31 and 60 years old was the most affected, with 96 cases (47.9%). Of the total number of registered cases, 38.8% of the affected individuals were engaged in agriculture-related activities. The georeferenced distribution revealed the heterogeneity of disease occurrence, with cases concentrated in the Western and Southern regions of the municipality. An association was detected between relative air humidity (monthly mean) and the number of CL cases per month (p = 0.04). CL continues to be a concerning public health issue in Caxias. In this context, there is a pressing need to strengthen measures of prevention and control of the disease through the network of health services of the municipality, considering local and regional particularities.

Citrus Carbohydrate Levels were Related to Irrigation Frequency but Not Arbuscular Mycorrhizal Fungal (AMF) Inoculum

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 498a-498
Author(s):  
Matthew W. Fidelibus ◽  
Chris A. Martin
Keyword(s):  
Soil Water ◽  
Arbuscular Mycorrhizal ◽  
Irrigation Frequency ◽  
Soil Water Tension ◽  
Root Starch ◽  
Carbohydrate Levels ◽  
Amf Communities ◽  
Sugar Levels ◽  
Shoot Mass ◽  
Water Tension

Sugar and starch concentrations in leaves and roots of Citrus volkameriana Tan and Pasq were measured in response to irrigation frequency and AMF inoculum. Non-mycorrhizal seedlings were treated with a soil inoculum from one of five different communities of AMF; two AMF communities from Arizona citrus orchard soils, and three communities from undisturbed desert soils. Plants were assigned to frequent (soil water tension > –0.01 MPa) or infrequent (soil water tension > –0.06 MPa) irrigation cycles and were container-grown in a glasshouse for 4 months before tissues were analyzed. Fungal inoculum source did not affect shoot or root carbohydrate levels. Plants grown under high irrigation frequency had increased leaf and root starch levels and increased root sugar levels compared with those under low irrigation frequencies. High irrigation frequency also increased shoot mass.

scholarly journals Responses of Rice Growth to Day and Night Temperature and Relative Air Humidity—Leaf Elongation and Assimilation

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 134
Author(s):  
Sabine Stuerz ◽  
Folkard Asch
Keyword(s):  
Leaf Area ◽  
Leaf Growth ◽  
Crop Growth ◽  
Air Humidity ◽  
Leaf Elongation ◽  
Night Temperature ◽  
Relative Air Humidity ◽  
Leaf Area Expansion ◽  
Plant Level ◽  
Area Expansion

Predictions of future crop growth and yield under a changing climate require a precise knowledge of plant responses to their environment. Since leaf growth increases the photosynthesizing area of the plant, it occupies a central position during the vegetative phase. Rice is cultivated in diverse ecological zones largely differing in temperature and relative air humidity (RH). To investigate the effects of temperature and RH during day and night on leaf growth, one variety (IR64) was grown in a growth chamber using 9 day/night regimes around the same mean temperature and RH, which were combinations of 3 temperature treatments (30/20 °C, 25/25 °C, 20/30 °C day/night temperature) and 3 RH treatments (40/90%, 65/65%, 90/40% day/night RH). Day/night leaf elongation rates (LER) were measured and compared to leaf gas exchange measurements and leaf area expansion on the plant level. While daytime LER was mainly temperature-dependent, nighttime LER was equally affected by temperature and RH and closely correlated with leaf area expansion at the plant level. We hypothesize that the same parameters increasing LER during the night also enhance leaf area expansion via shifts in partitioning to larger and thinner leaves. Further, base temperatures estimated from LERs varied with RH, emphasizing the need to take RH into consideration when modeling crop growth in response to temperature.

scholarly journals Relationship between preterm birth and air pollution in Santos, Sao Paulo, Brazil

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
M E L Brandao ◽  
B A L F Braga ◽  
M L C Martins ◽  
P L A A Pereira
Keyword(s):  
Air Pollution ◽  
Preterm Birth ◽  
Air Pollutants ◽  
First Trimester ◽  
Sao Paulo ◽  
São Paulo ◽  
Air Humidity ◽  
Relative Air Humidity ◽  
The Impact ◽  
Fourth Quartile

Abstract Santos is a seaboard Brazilian city recognized by its port activity where the road and rail infrastructure along with the large transportation operation, displays an important factor to contribute with all kinds of toxic and air pollutants. Recent studies have suggested associations between air pollution and various birth outcomes. Pollutant gases such as NOx, O3 and particulate matter PM2,5, PM10 have been cited as factors involved in such outcomes. The present study aims to assess the relationship between atmospheric pollutants and perinatal outcomes in the city of Santos from Jan. 2012 to Dec. 2015. Cross-sectional study that analyzed 10.319 singleton births in an area set with 2 km radius of the monitoring stations. Birth weight and information on mother and pregnancy were obtained at the Brazilian “Born Alive National Information System”. Daily records of air pollutants (PM10, PM2.5, NO2 and O3), temperature and relative air humidity, for the study period, were obtained from São Paulo State Environmental Agency (CETESB). Associations between preterm birth and air pollutants mean levels at each gestational trimester were investigated using multiple logistic regression model controlled by the variables: infant sex, type of delivery, maternal education. prenatal care, and number of previous live births, temperature and relative air humidity. NO2 e PM2,5 was not associated with preterm birth. O3 was significantly associated in the first trimester in the fourth quartile (OR = 1,47 CI 95% 1,05; 2,07). PM10 was significantly associated in the first trimester for the fourth quartile (OR = 1,28 CI 95% 1,00; 1,64), second trimester for the second quartile (OR = 1,37 CI 95% 1,07; 1,77). Conclusions the results shows evidence that maternal exposure to air pollution especially during the first trimester of pregnancy may contribute to preterm birth. Further actions are needed towards controlling air pollution are strongly recommended for promoting early-life health. Key messages This is the first research of this kind that was made in Santos. It brings important evidence of the impact in the life of the population, especially those whose is not even born yet. It can be used as a resource to guide public policies in health, especially the guidelines that dictate the concentration of air pollutants and air quality.

Influence of Relative Air Humidity on Evaporation of Water–Ethanol Solution Droplets

2021 ◽  
Vol 83 (3) ◽  
pp. 277-283
Author(s):  
V. Yu. Borodulin ◽  
V. N. Letushko ◽  
M. I. Nizovtsev ◽  
A. N. Sterlyagov
Keyword(s):  
Ethanol Solution ◽  
Air Humidity ◽  
Relative Air Humidity

scholarly journals Drip irrigation in coffee crop under different planting densities: Growth and yield in southeastern Brazil

2014 ◽  
Vol 18 (11) ◽  
pp. 1116-1123 ◽  
Author(s):  
Gleice A. de Assis ◽  
Myriane S. Scalco ◽  
Rubens J. Guimarães ◽  
Alberto Colombo ◽  
Anderson W. Dominghetti ◽  
...  
Keyword(s):  
Plant Density ◽  
Block Design ◽  
Irrigation Management ◽  
Growth And Yield ◽  
Southeastern Brazil ◽  
Soil Water Tension ◽  
Randomized Block Design ◽  
Coffee Plants ◽  
Coffee Cultivation ◽  
Water Tension

Irrigation associated to reduction on planting spaces between rows and between coffee plants has been a featured practice in coffee cultivation. The objective of the present study was to assess, over a period of five consecutive years, influence of different irrigation management regimes and planting densities on growth and bean yield of Coffea arabica L.. The treatments consisted of four irrigation regimes: climatologic water balance, irrigation when the soil water tension reached values close to 20 and 60 kPa; and a control that was not irrigated. The treatments were distributed randomly in five planting densities: 2,500, 3,333, 5,000, 10,000 and 20,000 plants ha-1. A split-plot in randomized block design was used with four replications. Irrigation promoted better growth of coffee plants and increased yield that varied in function of the plant density per area. For densities from 10,000 to 20,000 plants ha-1, regardless of the used irrigation management, mean yield increases were over 49.6% compared to the non-irrigated crop.

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