scholarly journals Quantifying the effect of nighttime interactions between roots and canopy physiology and their control of water and carbon cycling on feedbacks between soil moisture and terrestrial climatology under variable environmental conditions

2016 ◽  
Author(s):  
Jean-Christophe Domec ◽  
Sari Palmroth ◽  
Ram Oren ◽  
Jennifer Swenson ◽  
John S. King ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Carbon Cycling ◽  
Environmental Conditions ◽  
Canopy Physiology

scholarly journals Historical climate controls soil respiration responses to current soil moisture

2017 ◽  
Vol 114 (24) ◽  
pp. 6322-6327 ◽  
Author(s):  
Christine V. Hawkes ◽  
Bonnie G. Waring ◽  
Jennifer D. Rocca ◽  
Stephanie N. Kivlin
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
Soil Respiration ◽  
Carbon Cycling ◽  
Large Scale ◽  
Microbial Respiration ◽  
Rainfall Gradient ◽  
Soil Microbial ◽  
Historical Climate ◽  
Moisture Dependence

Ecosystem carbon losses from soil microbial respiration are a key component of global carbon cycling, resulting in the transfer of 40–70 Pg carbon from soil to the atmosphere each year. Because these microbial processes can feed back to climate change, understanding respiration responses to environmental factors is necessary for improved projections. We focus on respiration responses to soil moisture, which remain unresolved in ecosystem models. A common assumption of large-scale models is that soil microorganisms respond to moisture in the same way, regardless of location or climate. Here, we show that soil respiration is constrained by historical climate. We find that historical rainfall controls both the moisture dependence and sensitivity of respiration. Moisture sensitivity, defined as the slope of respiration vs. moisture, increased fourfold across a 480-mm rainfall gradient, resulting in twofold greater carbon loss on average in historically wetter soils compared with historically drier soils. The respiration–moisture relationship was resistant to environmental change in field common gardens and field rainfall manipulations, supporting a persistent effect of historical climate on microbial respiration. Based on these results, predicting future carbon cycling with climate change will require an understanding of the spatial variation and temporal lags in microbial responses created by historical rainfall.

scholarly journals Procedures for evaluating the tolerance of cassava genotypes to postharvest physiological deterioration

2015 ◽  
Vol 50 (7) ◽  
pp. 562-570 ◽  
Author(s):  
Marcela Tonini Venturini ◽  
Vanderlei da Silva Santos ◽  
Eder Jorge de Oliveira
Keyword(s):  
Soil Moisture ◽  
High Temperature ◽  
Low Temperature ◽  
Environmental Conditions ◽  
Fungicide Treatment ◽  
High Soil Moisture ◽  
Root Position ◽  
Postharvest Physiological Deterioration ◽  
Significant Interference ◽  
Diagrammatic Scale

Abstract: The objective of this work was to define procedures to assess the tolerance of cassava genotypes to postharvest physiological deterioration (PPD) and to microbial deterioration (MD). Roots of six cassava genotypes were evaluated in two experiments, during storage under different environmental conditions: high temperature and low soil moisture; or low temperature and high soil moisture. Roots were treated or not with fungicide (carbendazim) before storage. Genotype reactions to MD and PPD were evaluated at 0, 2, 5, 10, 15, 20, and 30 days after harvest (DAH), in the proximal, medial, and distal parts of the roots. A diagrammatic scale was proposed to evaluate nonperipheral symptoms of PPD. Fungicide treatment and root position did not influence PPD expression; however, all factors had significant effect on MD severity. Genotypes differed as to their tolerance to PPD and MD. Both deterioration types were more pronounced during periods of higher humidity and lower temperatures. The fungicide treatment increased root shelf life by reducing MD severity up to 10 DAH. Whole roots showed low MD severity and high PPD expression up to 10 DAH, which enabled the assessment of PPD without significant interference of MD symptoms during this period.

scholarly journals Soil water retention curves for the major soil types of the Kruger National Park

Koedoe ◽  
2014 ◽  
Vol 56 (1) ◽  
Author(s):  
Robert Buitenwerf ◽  
Andrew Kulmatiski ◽  
Steven I. Higgins
Keyword(s):  
Soil Moisture ◽  
Water Potential ◽  
Water Content ◽  
Carbon Cycling ◽  
Soil Water ◽  
National Park ◽  
Soil Water Potential ◽  
Kruger National Park ◽  
Soil Types ◽  
Soil Moisture Retention

Soil water potential is crucial to plant transpiration and thus to carbon cycling and biosphere–atmosphere interactions, yet it is difficult to measure in the field. Volumetric and gravimetric water contents are easy and cheap to measure in the field, but can be a poor proxy of plant-available water. Soil water content can be transformed to water potential using soil moisture retention curves. We provide empirically derived soil moisture retention curves for seven soil types in the Kruger National Park, South Africa. Site-specific curves produced excellent estimates of soil water potential from soil water content values. Curves from soils derived from the same geological substrate were similar, potentially allowing for the use of one curve for basalt soils and another for granite soils. It is anticipated that this dataset will help hydrologists and ecophysiologists understand water dynamics, carbon cycling and biosphere–atmosphere interactions under current and changing climatic conditions in the region.

Response of Gas Exchange in Jointed Goatgrass (Aegilops cylindrica) to Environmental Conditions

Weed Science ◽  
1989 ◽  
Vol 37 (4) ◽  
pp. 562-569 ◽  
Author(s):  
David R. Gealy
Keyword(s):  
Soil Moisture ◽  
Gas Exchange ◽  
Environmental Conditions ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Soil Matric Potential ◽  
Dark Respiration Rate ◽  
Matric Potential ◽  
Aegilops Cylindrica ◽  
Jointed Goatgrass

Gas exchange of jointed goatgrass leaves was affected by temperature, irradiance level, and soil matric potential. Net photosynthesis of leaves under saturating irradiance (PPFD3= 1850 (μE·m–2·s−1) was optimum at about 20 C. At 25 C, net photosynthesis was nearly 90% of maximum at a PPFD of 800 μE·m–2·−1. Transpiration, and presumably water use, increased steadily with temperature from 10 to 40 C. Dark respiration rate and compensation points for light and for CO2increased exponentially, or nearly so, from 10 to 40 C. Soil moisture deficits of −130 kPa reduced net photosynthesis and transpiration by about 30 and 55%, respectively, compared to well-watered plants.

Influence of Soil Temperature, Soil Moisture, and Seed Burial Depth on the Emergence of Round-Leaved Mallow (Malva pusilla)

Weed Science ◽  
1990 ◽  
Vol 38 (6) ◽  
pp. 518-521 ◽  
Author(s):  
Robert E. Blackshaw
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Water Content ◽  
Environmental Conditions ◽  
Control Strategies ◽  
Cultural Control ◽  
Burial Depth ◽  
Moisture Regime ◽  
Seed Burial ◽  
Rate Of Emergence

A study was conducted under controlled environmental conditions to determine the effect of soil temperature, soil moisture, and depth of seed burial on the emergence of round-leaved mallow. Emergence occurred from 5 to 30 C but was optimal at 15 to 20 C. Soil moisture had a greater effect than soil temperature on percentage emergence. Emergence progressively declined below a soil water content of −0.28 MPa, with less than 20% emergence attained at −1.03 to −1.53 MPa. In contrast, rate of emergence of round-leaved mallow was affected more by soil temperature than by moisture. A decrease in temperature from 30 to 5 C increased the time to reach 50% emergence by 10 to 12 days over the moisture regime of this study. Emergence was greatest at depths of 0.5 to 2 cm. No emergence occurred at 8 cm or below. The potential of using the findings of this study to develop cultural control strategies for round-leaved mallow is discussed.

scholarly journals Weed emergence in autumn under temperate conditions

2011 ◽  
Vol 29 (2) ◽  
pp. 343-349 ◽  
Author(s):  
J.M.G. Calado ◽  
G. Basch ◽  
M. Carvalho
Keyword(s):  
Soil Moisture ◽  
Seed Germination ◽  
Environmental Conditions ◽  
Growth Cycle ◽  
Annual Species ◽  
Weed Plants ◽  
Accumulated Rainfall ◽  
Winter Crops ◽  
Weed Emergence ◽  
Mediterranean Conditions

The emergence of weed plants depends on environmental conditions, especially temperature and soil moisture. The latter is extremely important in Mediterranean environments which are characterized by irregular amount and distribution of rain throughout the year, which influences the beginning of the growth cycle of the annual species (seed germination). This paper studies the influence of rainfall, in particular accumulated rainfall in autumn, on the emergence of weed plants. The experiment was carried out on Luvisols, and the appearance of flora under field conditions was observed. Through analysis of the results, it can be concluded that a high percentage of weed plants (> 85% related to the highest registered value) was obtained with more than 90 mm of accumulated rainfall from the beginning of September. Thus, in those years in which this amount of rainfall (90 mm) is registered until the end of October, the appearance of potential weed plants can be ensured, under Mediterranean conditions, in a period before sowing the autumn-winter crops.

Propanil Plus Methyl Parathion on Rice (Oryza sativa)

Weed Science ◽  
1988 ◽  
Vol 36 (3) ◽  
pp. 335-339 ◽  
Author(s):  
Gene D. Wills ◽  
Joe E. Street
Keyword(s):  
Oryza Sativa ◽  
Soil Moisture ◽  
Environmental Conditions ◽  
Methyl Parathion ◽  
Field Experiments ◽  
Controlled Environment ◽  
Planting Dates ◽  
Effects Of Temperature ◽  
Effect On Yield ◽  
Wilting Point

Effects of propanil [N-(3,4-dichlorophenyl)propanamide] applied to three- to four-leaf rice (Oryza sativaL.) 1 or 7 days before, after, or tank mixed with methyl parathion (O,O-dimethyl-O-4-nitrophenyl phosphorothioate) were determined under different environmental conditions. Field experiments determined the effect on yield of drill-seeded rice, ‘Labelle’ for two planting dates in 1982 and ‘Lemont’ for one planting date in 1986. Treatments were applied at sunrise and at noon. Growth chamber and greenhouse experiments determined the effects of temperature, relative humidity (RH), and soil moisture on response of Labelle rice. In all experiments, propanil, both alone and with methyl parathion, resulted in 20 to 30% leaf burn during the first week after treatment with rapid recovery to less than 10% injury after 3 to 4 weeks. In field experiments, yields were not reduced in the treated rice below that in the untreated controls. In controlled-environment experiments, rice was not injured by propanil plus methyl parathion more than by propanil alone after 2 to 4 weeks. Both treated and untreated rice were injured more by the environmental conditions of high (40 C) temperature, low (40%) RH, and low (near the wilting point) soil moisture than by low (30 C) temperature, high (100%) RH, and flooded soil.

Ecohydrological Behaviour of Mountain Beech Forest: Quantification of Stomatal Conductance Using Sap Flow Measurements

2020 ◽  
Author(s):  
Ye Su ◽  
Wei shao ◽  
Lukáš Vlček ◽  
Jakub Langhammer
Keyword(s):  
Soil Moisture ◽  
Stomatal Conductance ◽  
Bark Beetle ◽  
Environmental Conditions ◽  
Sap Flow ◽  
Beech Forest ◽  
Moisture Distribution ◽  
Rooting Depth ◽  
Accurate Estimation ◽  
Stomatal Response

<p>In forested regions, transpiration as the main component of evaporation fluxes is important for evaporation partitioning. Physiological behaviors among various vegetation species are quite different. Thus, an accurate estimation of the transpiration rate from a certain tree species needs specific parameterization of stomatal response to multiple environmental conditions. In this study, we chose a 300-m<sup>2 </sup>beech forest plot located in Vydra basin, the Czech Republic, to investigate the transpiration of beech (Fagus sylvatica) from the middle of the vegetative period to the beginning of the deciduous period, covering 100 days. The study area experienced bark beetle infestation, and the trees are newly formed, and mixed forest stands (spruce and beech) have transformed into beech stands. From the differences in the rooting depth of each kind of tree, an impact on the long-term water regime is expected. Furthermore, trees can change soil moisture distribution or water storage in aquifers by transpiration. Therefore, the sap flow equipment was installed in six trees with varying ages among 32 beech trees in the plot, and the measurements were used to infer the stomatal conductance for the beech forest. The diurnal pattern of stomatal conductance and the response of stomatal conductance under the multiple environmental conditions were analyzed. The results showed that the stomatal conductance inferred from sap flow reached the highest at midday but, on some days, there was a significant drop at midday, which might be attributed to the limits of the hydraulic potential of leaves (trees). The response of stomatal conductance showed no pattern with solar radiation and soil moisture, but it did show a clear correlation with the vapor deficit, in particular when explaining the midday drop. The relation to temperature was rather scattered as the measured period was in the moderate climate. The findings highlighted that the parametrization of stress functions based on the typical deciduous forest does not perfectly represent the measured stomatal response of beech. Therefore, measurements of sap flow can assist in better understanding transpiration in newly formed beech stands after bark beetle outbreaks in Central Europe.</p><p><strong>Keywords: </strong>Transpiration; beech forest; stomatal conductance; sap flow measurement</p>

Herbicide Control of Locoweeds: A Review

1988 ◽  
Vol 2 (4) ◽  
pp. 460-465 ◽  
Author(s):  
Michael H. Ralphs ◽  
Darrell N. Ueckert
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Plant Growth ◽  
Environmental Conditions ◽  
Plant Density ◽  
Historical Review ◽  
Western United States ◽  
Control Methods ◽  
Poisonous Plant ◽  
Phenoxy Herbicides

Locoweed poisoning of livestock is the most widespread poisonous plant problem in the western United States. This paper presents a historical review of control methods to reduce locoweed plant density. Hand grubbing, the most common method of control before phenoxy herbicides, was practical in small pastures considering the number of livestock saved. Trials in the 1950s indicated that 2,4-D and 2,4,5-T generally controlled locoweeds effectively if applied when plants were actively growing and soil moisture was not limiting plant growth. Picloram, dicamba, clopyralid, and triclopyr provide more consistent control than 2,4-D and 2,4,5-T when applied at less than optimum environmental conditions.

Endogenous jasmonates in dry and imbibed sunflower seeds from plants grown at different soil moisture contents

2007 ◽  
Vol 17 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Ana Vigliocco ◽  
Sergio Alemano ◽  
Otto Miersch ◽  
Daniel Alvarez ◽  
Guillermina Abdala
Keyword(s):  
Soil Moisture ◽  
Environmental Conditions ◽  
Differential Sensitivity ◽  
Sunflower Seeds ◽  
Seed Progeny ◽  
Hormonal Content ◽  
Tolerant Line ◽  
Sensitive Line ◽  
Moisture Conditions

AbstractIn this study, we characterized two sunflower (Helianthus annuus L.) lines with differential sensitivity to drought, the sensitive line B59 and the tolerant line B71. Using both lines, we compared the content of endogenous jasmonates (JAs) in dry and imbibed seeds from plants grown under irrigation and drought. Jasmonic acid (JA), 12-oxo-phytodienoic acid (OPDA), 11-hydroxyjasmonate (11-OH-JA) and 12-hydroxyjasmonate (12-OH-JA) were detected in dry and imbibed sunflower seeds. Seeds from plants grown under drought had a lower content of total JAs and exhibited higher germination percentages than seeds from irrigated plants, demonstrating that environmental conditions have a strong influence on the progeny. OPDA and 12-OH-JA were the main compounds found in dry seeds of both lines. Imbibed seeds showed an enhanced amount of total JAs with respect to dry seeds produced by plants grown in both soil moisture conditions. Imbibition triggered a dramatic OPDA increase in the embryo, suggesting a role of this compound in germination. We conclude that JAs patterns vary during sunflower germination and that the environmental conditions experienced by the mother plant modify the hormonal content of the seed progeny.

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