Uptake of Nutrients by Roots

2012 ◽  
pp. 55-122
Keyword(s):  
Uptake Of Nutrients

Chloride Accumulation as a Homeostatic System: Negative Feedback Signals for Concentration and Turgor Maintenance Differ in a Glycophyte and a Halophyte

1980 ◽  
Vol 7 (3) ◽  
pp. 237 ◽  
Author(s):  
WJ Cram
Keyword(s):  
Negative Feedback ◽  
Turgor Maintenance ◽  
Non Linear ◽  
Steady Level ◽  
Homeostatic System ◽  
Chloride Accumulation ◽  
Relationship Of ◽  
The Relationship ◽  
Uptake Of Nutrients

Carrot tissue is taken as a representative glycophilic tissue. It accumulates K+, Cl- and total osmotica to a steady level after 10-15 days. This level of Cl- is nearly constant and is independent of external KCl concentration and of turgor. Cl- influx is also independent of turgor. It therefore appears that the Cl- accumulating system in carrot (and possibly in other glycophytes) can, under artificial conditions, act as a homeostat for intracellular C- concentration, and is not the basis of turgor maintenance. It is suggested that turgor might be maintained by controlled accumulation of K+ carboxylates in glycophytes. Beet tissue is taken as a representative halophilic tissue. It accumulates K+, Cl-, and total osmotica to a steady level after about 4 days. At this stage turgor is constant, due to differences in the levels of KCl accumulated. Cl- influx is stimulated by reducing turgor after a lag of 3-5 h. The relationship of Cl- influx to turgor is non-linear. It therefore appears that in beet (and possibly in other halophytes) turgor maintenance is based on the turgor-sensitive accumulation of Cl- salts. Cl- influx in beet is also affected by changes in intracellular Cl- concentration, as in carrot. It is suggested that this feedback relationship may primarily be part of a system for the controlled uptake of nutrients rather than of Cl- in both tissues.

Functions of Macrophytes in Constructed Wetlands

1994 ◽  
Vol 29 (4) ◽  
pp. 71-78 ◽  
Author(s):  
Hans Brix
Keyword(s):  
Constructed Wetlands ◽  
Microbial Growth ◽  
Surface Flow ◽  
Wetland Plant ◽  
Intrinsic Properties ◽  
Treatment Processes ◽  
Flow Systems ◽  
Physical Effects ◽  
Uptake Of Nutrients ◽  
Quantitative Importance

Macrophytes have several intrinsic properties that makes them an indispensable component of constructed wetlands. The most important functions of the macrophytes in relation to the treatment of wastewater are the physical effects brought about by the presence of the plants. The macrophytes stabilise the surface of the beds, provide good conditions for physical filtration, prevent vertical flow systems from clogging, insulate against frost during winter, and provide a huge surface area for attached microbial growth. Contrary to earlier belief, the growth of macrophytes does not increase the hydraulic conductivity of the substrate in soil-based subsurface flow constructed wetlands. The metabolism of the macrophytes affects the treatment processes to different extents depending on the design of the constructed wetland. Plant uptake of nutrients is only of quantitative importance in low-loaded systems (surface flow systems). Macrophyte-mediated transfer of oxygen to the rhizosphere by leakage from roots increases aerobic degradation of organic matter and nitrification. The macrophytes have additional site-specific values by providing habitat for wildlife and making wastewater treatment systems aesthetically pleasing.

scholarly journals Pteridium Aquilinum (L.) Kuhn (Bracken) As an Invasive Species in Permanent Grassland Ecosystems - Possibilities and Methods of Control

2011 ◽  
Vol 68 (1) ◽  
Author(s):  
Dorin PLESA ◽  
Gheorghe MIHAI ◽  
Nicuşor SIMA ◽  
Dan PAVEL ◽  
Mihaela MIHAI ◽  
...  
Keyword(s):  
Pteridium Aquilinum ◽  
Good Reduction ◽  
Grassland Ecosystems ◽  
Mechanical Methods ◽  
Wide Range ◽  
The World ◽  
Efficient Uptake ◽  
Uptake Of Nutrients ◽  
Spring Sowing ◽  
Methods Of Control

. Pteridium species around the world are aggressive, very productive, functionally closer to shrubs than ferns. Their rhizomes, buried deep and rich in starch, allow them to survive repeated fires and their efficient uptake of nutrients allow them to exploit a wide range of soils (McGlone et al., 2005). Mechanical methods. Tillage and cultivation. On lands that are not too steep or rocky, a good reduction in fern coverage can be achieved by plowing from late June to early August. The goal is to plow deep in order to expose the rhizomes, leaving them undisturbed throughout the winter and followed by the spring sowing

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