INVESTIGADORES
RUBIO Gerardo
artículos
Título:
The importance of root gravitropism for interroot competition and phosphorus acquisition efficiency: results from a geometric simulation model.
Autor/es:
GE Z., G. RUBIO, J. LYNCH
Revista:
PLANT AND SOIL
Editorial:
SPRINGER
Referencias:
Año: 2000 vol. 218 p. 159 - 171
ISSN:
0032-079X
Resumen:
We have observed that low soil phosphorus availability alters the gravitropic response of basal roots in commonbean (Phaseolus vulgaris L.), resulting in a shallower root system. In this study we use a geometricmodel to test thehypotheses that a shallower root system is a positive adaptive response to low soil P availability by (1) concentratingroot foraging in surface soil horizons, which generally have the highest P availability, and (2) reducing spatialcompetition for P among roots of the same plant. The growth of nine root systems contrasting in gravitropicresponse over 320 h was simulated in SimRoot, a dynamic three-dimensional geometric model of root growthand architecture. Phosphorus acquisition and inter-root competition were estimated with Depzone, a program thatdynamically models nutrient diffusion to roots. Shallower root systems had greater P acquisition per unit carboncost than deeper root systems, especially in older root systems. This was due to greater inter-root competition indeeper root systems, as measured by the volume of overlapping P depletion zones. Inter-root competition for P wasa significant fraction of total soil P depletion, and increased with increasing values of the P diffusion coefficient(De), with root age, and with increasing root gravitropism. In heterogenous soil having greater P availability insurface horizons, shallower root systems had greater P acquisition than deeper root systems, because of less inter-root competition as well as increased root foraging in the topsoil. Root P acquisition predicted by SimRoot wasvalidated against values for bean P uptake in the field, with an r2 between observed and predicted values of 0.75.Our results support the hypothesis that altered gravitropic sensitivity in P-stressed roots, resulting in a shallowerroot system, is a positive adaptive response to low P availability by reducing inter-root competition within the sameplant and by concentrating root activity in soil domains with the greatest P availability.