ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Influence of nitrate concentration at the root surface on yield and nitrate uptake of kohlrabi (Brassica oleracea gongyloides L.) and spinach (Spinacia oleracea L.) (1991)
    Springer
    Plant and soil 135 (1991), S. 205-211 
    Details
    ISSN: 1573-5036
    Keywords: kohlrabi ; nitrate ; spinach ; root ; root hairs ; uptake rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this study was to determine if plant roots have to take up nitrate at their maximum rate for achieving maximum yield. This was investigated in a flowing-solution system which kept nutrient concentrations at constant levels. Nitrate concentrations were maintained in the range 20 to 1000 μM. Maximum uptake rate for both species was obtained at 100 μM. Concentrations below 100 μM resulted in decreases in uptake rate per cm root (inflow) for both spinach and kohlrabi by 1/3 and 2/3, respectively. However, only with kohlrabi this caused a reduction in N uptake and yield. Thus indicating that this crop has to take up nitrate at the maximum inflow. Spinach, however, compensated for lower inflows by enhancing its root absorbing surface with more and longer roots hairs. Both species increased their root length by 1/3 at low nitrate concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010908
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Regulation of nitrogen uptake on the whole plant level (1996)
    Springer
    Plant and soil 181 (1996), S. 131-137 
    Details
    ISSN: 1573-5036
    Keywords: cucumber ; growth rate ; lettuce ; maximum inflow (Imax) ; model ; nitrate ; regulation ; uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The largest part of nitrogen requirements of crops is mostly covered by nitrate. The uptake of this ion is thermodynamically uphill and thus dependent on metabolism. This article considers regulation of N uptake in higher plants putting emphasis on NO3 - and the whole plant level. In field conditions the transport rate depends on the concentration at the root surface in Michaelis-Menten-Kinetics. Maximum net influx of NO3 - (Imax) was often reported at concentrations of 100 μM NO3 - and even lower. There are indications that for unrestricted growth the NO3 - concentration at root surface has to be in the order of magnitude allowing Imax if plants are not able to compensate for lower NO3 - concentrations by increasing root surface per unit of shoot. Imax is not a constant but depends for a given variety on N status of plants, the availability of NO3 - and plant age. The decrease of Imax with increasing plant age is closely related to relative growth rate as long as the relationship between N demand and new growth is linear and the root:shoot ratio keeps constant. It seems that Imax is a meaningful physiological characteristic of NO3 - uptake reflecting absolute N demand. There is evidence that shoot demand is linked to NO3 - uptake of the root through an amino acid transport pool cycling in the plant via phloem and xylem. The N demand of a crop depends on increase of dry mass and might not be linear if the “critical level” of nitrogen in plant dry matter changes during crop development or if retranslocation of nitrogen from older leaves to meristematic tissue occurs. Radiation and temperature drive plant growth and thus N demand of crops. These relationships can be described by mathematical models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011299
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Simulation of the maximum nitrate inflow (Imax) of lettuce (Lactuca sativa L.) grown under fluctuating climatic conditions in the greenhouse (1993)
    Springer
    Plant and soil 155-156 (1993), S. 163-166 
    Details
    ISSN: 1573-5036
    Keywords: lettuce ; maximum inflow (Imax) ; model ; nitrate ; relative growth rate ; root:shoot-ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Lettuce was grown in nutrient solution under fluctuating climatic conditions in the greenhouse. The maximum nitrate inflow (Imax) was measured twice a week to validate a model for calculating Imax, that was developed for constant conditions in a growth chamber. Growth and Imax were very similar between greenhouse and growth chamber plants, so that the model was able to predict Imax very precisely. The daily maximum nitrate inflow was calculated and its dependency on fluctuating temperature could be shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025009
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    A model relating the maximum nitrate inflow of lettuce (Lactuca satvia L.) to the growth of roots and shoots (1994)
    Springer
    Plant and soil 162 (1994), S. 249-257 
    Details
    ISSN: 1573-5036
    Keywords: lettuce ; maximum inflow (Imax) ; model ; nitrate ; relative growth rate ; root:shoot-ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The net inflow of nitrate can be calculated from the nitrate concentration at the root surface by means of the Michaelis-Menten equation. Because of maximum inflow (Imax) is not constant but varies with plant age and growing conditions, a model for calculating Imax during plant growth was derived. Lettuce was grown in nutrient solution. Variations in temperature, radiation and plant age were used to vary growth rates and N-demand of plants. There was a linear relationship between relative growth rates (RGR) and maximum nitrate inflow (Imax), that could be described by the following regression function: Imax = 0.24 + 6.57 RGR. A residual analysis showed a further influence on Imax from the root:shoot-ratio (RSR), the effects of which could be accounted for by including an e-function in the relationship: Imax = (0.27 + 10.63 RGR) e(−0.0017 RSR). This model for calculating Imax was validated in two further experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01347712
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...