ISSN:
1573-5036
Keywords:
compensation
;
growth
;
heterogeneity
;
inflow
;
nutrient
;
roots
;
soil
;
variability
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract In soil, the distributions of nutrients, water, pores, and microbes vary in time and space. These, in turn, contribute to the variations in root form and function that we see when we grow plants in soil and other non-uniform media. This paper addresses three questions about the consequences of non-uniform distributions of nutrients: how do roots respond to variations in nutrient distribution?; how specific are such responses?; to what extent can we predict them? Roots vary both physiologically and structurally in response to nutrient distributions. The first type of response is primarily a stimulation of nutrient uptake rate per unit of root; the second, a stimulation of root growth where and when the nutrient is most readily available. The first tends to be nutrient-specific and its magnitude related to the extent of the non-uniformity in nutrient availability. The second is less-specific in the sense that the magnitude of the response, when there is one, varies little from one nutrient to another. This leads to apparently exaggerated compensatory capacity, especially for ions that are relatively mobile in soil, such as NO3 -. Because the physiological and molecular mechanisms of these responses are largely unknown, we cannot say how they are co-ordinated within individual plants. Nor can we predict a plant's responses precisely. What we can do is generate statistical descriptions of them by comparing data collected in many experiments for many species. This produces general rules that summarise what happens, but which probably cannot be applied a priori to specific cases. H Lambers Section editor
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00011657
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