scholarly journals Growth responses to soil water potential indirectly shape local species distributions of tropical forest seedlings

2018 ◽  
Author(s):  
Stefan J. Kupers ◽  
Bettina M. J. Engelbrecht ◽  
Andrés Hernández ◽  
S. Joseph Wright ◽  
Christian Wirth ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Species Distributions ◽  
Growth Responses ◽  
Local Species

Modifying sexual expression of containerized jack pine by topping, altering soil nitrogen and water, and applying gibberellins

1994 ◽  
Vol 24 (5) ◽  
pp. 869-877 ◽  
Author(s):  
W.H. Fogal ◽  
S.J. Coleman ◽  
M.S. Wolynetz ◽  
H.O. Schooley ◽  
S.M. Lopushanski ◽  
...  
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Nitrogen ◽  
Soil Water Potential ◽  
Jack Pine ◽  
Sexual Expression ◽  
Growth Responses ◽  
Tree Crown ◽  
N Supply ◽  
Water Potentials

The numbers of seed strobili and pollen strobilus clusters and the extent of branch terminal growth were determined on 6-year-old containerized jack pine (Pinusbanksiana Lamb.) trees following modification of the soil nitrogen (N) supply (NH4NO3 at 3, 100, or 300 mg N/L; NO3− at 100 mg N/L; or NH4+ at 100 mg N/L in a nutrient solution), soil water supply (soil water potentials above −20 kPa compared with potentials near −70 kPa), and tree crown size (intact trees outside polythene shelters and lightly versus severely topped trees under polythene shelters). These factors were tested with or without biweekly foliar applications of spray solutions containing 400 mg/L of GA4/7. Intact trees outside polythene shelters did not display sexual or growth responses to N or GA4/7 treatments. Seed strobilus production on topped trees under shelters was not influenced by the level of topping or N supply, but it was depressed by low soil moisture potentials and stimulated by GA4/7 with high or low soil water potentials. Pollen strobilus production was depressed by severe topping and by low soil water potential; it was stimulated by GA4/7 on lightly topped trees but not on severely topped trees and by a low (3 mg N/L) N supply. In the year after treatment, terminal growth of a branch from the 2-year-old nodal whorl was not influenced by nitrogen supply or by light topping but it was increased by severe topping; it was increased by GA4/7 treatment if soil water potential was high but not with low water potential; it was depressed by low soil water potential.

scholarly journals Maize nodal root growth under water deficits

2016 ◽  
Author(s):  
◽  
Kara J. Riggs
Keyword(s):  
Root Growth ◽  
Water Potential ◽  
Root System ◽  
Soil Water ◽  
Soil Water Potential ◽  
Experimental System ◽  
Root Tip ◽  
Growth Responses ◽  
Water Potentials ◽  
Nodal Root

The nodal root system is critical for the development of the mature root system in maize (Zea mays L.) and other grasses. Under drought conditions, nodal root axes may need to grow through surface soil that is dry, hard, and hot. These roots are known to have a superior ability to continue elongation at low water potentials relative to other organs of the plant, but the physiology of this response has been little studied. The objective of this study was to develop an experimental system that models the field situation in which upper soil layers dry, to enable studies of nodal root growth regulation under water deficit conditions. A divided-chamber experimental system was developed to allow the growth of maize primary and seminal root systems in well-watered conditions while the nodal root system is exposed to precise conditions of low soil water potential. The divided-chamber system was used to characterize nodal root growth responses to a range of soil water potentials under steady-state and reproducible conditions. Two contrasting genotypes, selected for differences in root growth response to water stress based on a previous study of the primary root, displayed similarly sensitive growth responses to -0.3 MPa soil, but different capacities to maintain high root tip water potential corresponding with different growth responses at lower soil water potentials. Both genotypes maintained relatively high nodal root tip water potentials in -2.0 MPa soil, despite the decreased soil water potential, suggesting a stress-induced response that enhances water transport to the root tip. The difference in high tissue water potential maintenance was seen not only between the contrasting genotypes but also between the first two developmental nodes of roots. The divided-chamber system provides a powerful experimental approach to investigate the physiological mechanisms regulating nodal root growth responses to adverse soil conditions. Future studies may include measurements of hydraulic conductivity, anatomical characterization of vascular elements near the growth zone, aquaporin content and activity, and suberin deposition in response to low soil water potentials.

scholarly journals Dry season soil water potential maps of a 50 hectare tropical forest plot on Barro Colorado Island, Panama

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Stefan J. Kupers ◽  
Christian Wirth ◽  
Bettina M. J. Engelbrecht ◽  
Nadja Rüger
Keyword(s):  
Tropical Forest ◽  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Dry Season ◽  
Barro Colorado Island ◽  
Forest Plot

Vegetative Growth Distribution During Water Deficits in Vitis vinifera L

1988 ◽  
Vol 15 (5) ◽  
pp. 641 ◽  
Author(s):  
HR Schultz ◽  
MA Matthews
Keyword(s):  
Growth Inhibition ◽  
Vitis Vinifera ◽  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Vitis Vinifera L ◽  
Initial Growth ◽  
Growth Responses ◽  
Time Duration ◽  
Water Deficits

The expansion of plant organs is inhibited by water deficits but the effect of ontogeny on growth sensitivity is not known. Therefore, growth responses of shoot organs (internodes, leaves, tendrils) of Vitis vinifera L. cv. White Riesling to developing water deficit were investigated under controlled environmental conditions. Growth of organs at a node position was asynchronous, with internode growth being more restricted than leaf and tendril growth in time (duration of growth) and space (number of node positions at which growth occurred). The timing of initial growth inhibition and final growth cessation caused by soil water deficits was identical in internodes, leaves, and tendrils. The degree of growth inhibition at low water potential was similar among organs, whether linear or volume changes were considered and whether the most rapidly expanding organs or organs of similar developmental stage were compared. In addition, the relative partitioning of growth among internodes, leaves, and tendrils along single shoots was unaltered when growth was inhibited by water deficits. Growth of each organ was inhibited initially at soil water potential of -0.065 MPa and ceased completely at -0.54 MPa. Therefore, it was concluded that the sensitivity of growth to water deficits did not differ among shoot organs. The region along the shoot in which organs expanded was reduced during water deficits. Similarly, the regions within organs in which growth occurred diminished as water deficits developed. Although growth was inhibited in all tissues, inhibition was complete in older tissues when some growth was maintained in younger tissues. Therefore, it was concluded that sensitivity of growth to water deficits increased with ontogeny.

Effect of Soil Water Potential of Two Soils on Soybean Emergence 1

1979 ◽  
Vol 71 (6) ◽  
pp. 980-982 ◽  
Author(s):  
L. G. Heatherly ◽  
W. J. Russell
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential

scholarly journals A Data-Driven Method for the Temporal Estimation of Soil Water Potential and Its Application for Shallow Landslides Prediction

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1208
Author(s):  
Massimiliano Bordoni ◽  
Fabrizio Inzaghi ◽  
Valerio Vivaldi ◽  
Roberto Valentino ◽  
Marco Bittelli ◽  
...  
Keyword(s):  
Machine Learning ◽  
Water Potential ◽  
Soil Water ◽  
Temporal Trends ◽  
Soil Water Potential ◽  
Shallow Landslides ◽  
Water Dynamics ◽  
Data Driven ◽  
Machine Learning Techniques ◽  
Physically Based

Soil water potential is a key factor to study water dynamics in soil and for estimating the occurrence of natural hazards, as landslides. This parameter can be measured in field or estimated through physically-based models, limited by the availability of effective input soil properties and preliminary calibrations. Data-driven models, based on machine learning techniques, could overcome these gaps. The aim of this paper is then to develop an innovative machine learning methodology to assess soil water potential trends and to implement them in models to predict shallow landslides. Monitoring data since 2012 from test-sites slopes in Oltrepò Pavese (northern Italy) were used to build the models. Within the tested techniques, Random Forest models allowed an outstanding reconstruction of measured soil water potential temporal trends. Each model is sensitive to meteorological and hydrological characteristics according to soil depths and features. Reliability of the proposed models was confirmed by correct estimation of days when shallow landslides were triggered in the study areas in December 2020, after implementing the modeled trends on a slope stability model, and by the correct choice of physically-based rainfall thresholds. These results confirm the potential application of the developed methodology to estimate hydrological scenarios that could be used for decision-making purposes.

NITROGEN TRANSFORMATIONS NEAR UREA IN SOIL WITH DIFFERENT WATER POTENTIALS

1988 ◽  
Vol 68 (3) ◽  
pp. 569-576 ◽  
Author(s):  
YADVINDER SINGH ◽  
E. G. BEAUCHAMP
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Incubation Period ◽  
Relative Rate ◽  
Soil Water Potential ◽  
Nitrification Inhibitor ◽  
Silt Loam ◽  
Nitrogen Transformations ◽  
Water Potentials ◽  
Initial Soil

Two laboratory incubation experiments were conducted to determine the effect of initial soil water potential on the transformation of urea in large granules to nitrite and nitrate. In the first experiment two soils varying in initial soil water potentials (− 70 and − 140 kPa) were incubated with 2 g urea granules with and without a nitrification inhibitor (dicyandiamide) at 15 °C for 35 d. Only a trace of [Formula: see text] accumulated in a Brookston clay (pH 6.0) during the transformation of urea in 2 g granules. Accumulation of [Formula: see text] was also small (4–6 μg N g−1) in Conestogo silt loam (pH 7.6). Incorporation of dicyandiamide (DCD) into the urea granule at 50 g kg−1 urea significantly reduced the accumulation of [Formula: see text] in this soil. The relative rate of nitrification in the absence of DCD at −140 kPa water potential was 63.5% of that at −70 kPa (average of two soils). DCD reduced the nitrification of urea in 2 g granules by 85% during the 35-d period. In the second experiment a uniform layer of 2 g urea was placed in the center of 20-cm-long cores of Conestogo silt loam with three initial water potentials (−35, −60 and −120 kPa) and the soil was incubated at 15 °C for 45 d. The rate of urea hydrolysis was lowest at −120 kPa and greatest at −35 kPa. Soil pH in the vicinity of the urea layer increased from 7.6 to 9.1 and [Formula: see text] concentration was greater than 3000 μg g−1 soil. There were no significant differences in pH or [Formula: see text] concentration with the three soil water potential treatments at the 10th day of the incubation period. But, in the latter part of the incubation period, pH and [Formula: see text] concentration decreased with increasing soil water potential due to a higher rate of nitrification. Diffusion of various N species including [Formula: see text] was probably greater with the highest water potential treatment. Only small quantities of [Formula: see text] accumulated during nitrification of urea – N. Nitrification of urea increased with increasing water potential. After 35 d of incubation, 19.3, 15.4 and 8.9% of the applied urea had apparently nitrified at −35, −60 and −120 kPa, respectively. Nitrifier activity was completely inhibited in the 0- to 2-cm zone near the urea layer for 35 days. Nitrifier activity increased from an initial level of 8.5 to 73 μg [Formula: see text] in the 3- to 7-cm zone over the 35-d period. Nitrifier activity also increased with increasing soil water potential. Key words: Urea transformation, nitrification, water potential, large granules, nitrifier activity, [Formula: see text] production

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