scholarly journals Separating water‐potential induced swelling and shrinking from measured radial stem variations reveals a cambial growth and osmotic concentration signal

2015 ◽  
Vol 39 (2) ◽  
pp. 233-244 ◽  
Author(s):  
Tommy Chan ◽  
Teemu Hölttä ◽  
Frank Berninger ◽  
Harri Mäkinen ◽  
Pekka Nöjd ◽  
...  
Keyword(s):  
Water Potential ◽  
Osmotic Concentration ◽  
Cambial Growth ◽  
Swelling And Shrinking ◽  
Concentration Signal

August Krogh Lecture. The renal concentrating mechanism in insects and mammals: a new hypothesis involving hydrostatic pressures

1995 ◽  
Vol 268 (5) ◽  
pp. R1087-R1100 ◽  
Author(s):  
B. Schmidt-Nielsen
Keyword(s):  
Hydrostatic Pressure ◽  
Water Potential ◽  
Plasma Membranes ◽  
Water Molecules ◽  
Osmotic Concentration ◽  
Pelvic Wall ◽  
Collecting Ducts ◽  
Renal Concentrating Mechanism ◽  
Peristaltic Contractions ◽  
New Hypothesis

Water moves from compartments of higher to compartments of lower water potential. Osmotically active solutes and negative hydrostatic pressure both lower water potential by stretching the hydrogen bonds between water molecules (Hammel-Scholander hypothesis). In trees the negative hydrostatic pressure in the sap is balanced by the osmotic pressure of the leaves. In response to differences in water potential, water flows across biological membranes through water-filled pores. Protein molecules, aquaporins, forming hourglass-shaped pores have been identified, cloned, and located in plasma membranes in mammalian as well as other tissues. Water molecules flow single file through aquaporins. Insects concentrate the urine in the rectum. Mammals concentrate the urine in the collecting ducts in the inner medulla. In both, a compartment with a high osmotic concentration is created through ion transport. Both have a muscular coat surrounding the tissue, which shows peristaltic contractions. In insects it is the muscular layer around the rectum; in mammals it is the renal pelvic wall that surrounds the papilla. Mechanisms are proposed whereby these peristaltic contractions, through the creation of positive and negative hydrostatic pressures in the tissues, can lead to hyperosmotic excreta.

The study of important agronomic traits by multivariate analysis in winter rapeseed cultivars

2014 ◽  
Vol 1 (1) ◽  
pp. 20-24
Author(s):  
Gader Ghaffari ◽  
Farhad Baghbani ◽  
Behnam Tahmasebpour
Keyword(s):  
Water Potential ◽  
Water Deficit ◽  
Leaf Water Potential ◽  
Seed Weight ◽  
Dry Weight ◽  
Total Variance ◽  
Water Deficit Stress ◽  
The Third ◽  
High Eigenvalue ◽  
Winter Rapeseed

In order to group winter rapeseed cultivars according to evaluated traits, an experiment was conducted in the Research Greenhouse of Agriculture Faculty, University of Tabriz - IRAN. In the experiment were included 12 cultivars of winter rapeseed and 3 levels of water deficit stress. Gypsum blocks were used to monitor soil moisture. Water deficit stress was imposed from stem elongation to physiological maturity. According to the principal component analysis, five principal components were chosen with greater eigenvalue (more than 0.7) that are including 81.34% of the primeval variance of variables. The first component that explained the 48.02% of total variance had the high eigenvalue. The second component could justify about 13.64% of total variance and had positive association with leaf water potential and proline content and had negative relationship with leaf stomatal conductivity. The third, fourth and fifth components expressed around, 10.18, 4.83 and 4.68% of the total variance respectively. The third component had the high eigenvalue for plant dry weight. The fourth component put 1000-seed weight, seed yield, Silique per Plant and root dry weight against plant dry weight, chlorophyll fluorescence and leaf water potential. The fifth component had the high eigenvalue for root dry weight, root volume and 1000-seed weight.

Micro-variation in peach stem diameter and its relationship withsoil water potential and meteorological factors

2009 ◽  
Vol 17 (3) ◽  
pp. 489-494
Author(s):  
Jing-Wu ZHAN ◽  
You-Ke WANG ◽  
Lu-Jun ZHANG ◽  
Ping ZHANG ◽  
Jun-Qi HE
Keyword(s):  
Water Potential ◽  
Meteorological Factors ◽  
Stem Diameter

The Effect of Water Shortage on Potted Peach Trees in Relation to Ecophysiological Parameters and Infra-red Thermometry

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 541b-541
Author(s):  
Rita Giuliani ◽  
James A. Flore
Keyword(s):  
Chlorophyll Fluorescence ◽  
Gas Exchange ◽  
Early Detection ◽  
Water Potential ◽  
Canopy Temperature ◽  
Water Shortage ◽  
Development Rate ◽  
Plant Water ◽  
Infra Red ◽  
Peach Trees

Potted peach trees grown outdoors during the 1997 season were subjected to drought and subsequent rewatering to evaluate their dynamic response to soil water content. The investigation was primarily focused on the early detection of plant water stress to prevent negative effects on the growth. Leaf chlorophyll fluorescence and canopy temperature estimates (by infra-red thermometry) were conducted. Drought effect on physiological processes were detected through by estimates of canopy development rate, leaf gas-exchange measurements; while leaf water potential was measured to characterize plant water status. A decrease in the canopy's development rate was found 1 week after irrigation was stopped, which also coincided with a more-negative leaf water potential, whereas a decrease of the gas-exchange activities occurred several days later. No significant differences between the stressed and control plants were recorded by the chlorophyll fluorescence parameters (Fo, Fm, Fv and the ratio Fv/Fm), whereas the infra-red estimates of canopy temperature detected a slight increase of the canopy surface temperature (connected to the change of leaf energy balance and in relation to partial stomatal closure) on the non-irrigated plants 1 week after the beginning of the trial. The use of infra-red thermometry for early detection of water shortage is discussed.

Irrigation of Geraniums with an Automatic Controlled Water Table System

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 522d-522 ◽  
Author(s):  
J.W. Buxton ◽  
D.L. Ingram ◽  
Wenwei Jia
Keyword(s):  
Water Potential ◽  
Leaf Area ◽  
Water Table ◽  
Nutrient Solution ◽  
Irrigation System ◽  
Central Area ◽  
Dry Weight ◽  
Trickle Irrigation ◽  
Run Off ◽  
Optimum Water

Geraniums in 15-cm pots were irrigated automatically for 8 weeks with a Controlled Water Table (CWT) irrigation system. Plants were irrigated with a nutrient solution supplied by a capillary mat with one end of the mat suspended in a trough below the bottom of the pot. The nutrient solution remained at a constant level in the trough. Nutrient solution removed from the trough was immediately replaced from a larger reservoir. The vertical distance from the surface of the nutrient solution and the bottom of the pot determined the water/air ratio and water potential in the growing media. Treatments consisted of placing pots at 0, 2, 4, and 6 cm above the nutrient solution. Control plants were irrigated as needed with a trickle irrigation system. Geraniums grown at 0,2 and 4 CWT were ≈25% larger than the control plants and those grown at 6 CWT as measured by dry weight and leaf area. Roots of plants grown at 0 CWT were concentrated in the central area of the root ball; whereas roots of plants in other treatments were located more near the bottom of the pot. Advantages of the CWT system include: Plant controlled automatic irrigation; no run off; optimum water/air ratio.

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