A MODEL DESCRIBING ROOT GROWTH AND WATER, N AND CL UPTAKE IN CLOSED LOOP IRRIGATION SYSTEMS

Root systems might restrict plant growth, particularly under conditions of limited substrate volume and salinity buildup.
The objective of this work was to develop a root growth-uptake model designed to evaluate the role of individual rhizospheric processes in plant development, particularly in closed loop irrigation systems.
The model accounts for dry matter (DM) partitioning, root growth, uptake of water, nutrients and Cl^–, and H⁺ excretion by roots in response to NH₄⁺ uptake and nitrification.
Calculated plant water deficit affects DM production and transpiration (TR), and leaf and root N affect N uptake and growth.
The model predicts temporal and spatial nutrients and Cl^– concentration distributions in closed loop irrigation systems and resulting growth restrictions.
Simulation results indicated that nitrate uptake inhibition in tomato plants and enhanced osmotic potential stemming from Cl^– accumulation in solution could explain observed reduction in tomato yield and DM production in closed loop irrigation systems.
The adverse Cl effects can be alleviated according to the model by increasing the plant root system or the NH₄⁺/NO₃^– ratio in solution.
The model predicted in a reasonable way root production and distribution in substrate by taking into account diffusive and convective carbohydrate flow.
It also provided realistic description of temporal N uptake and solution pH under different salinities and NH₄⁺/NO₃^– ratios.

III International Symposium on Models for Plant Growth, Environmental Control and Farm Management in Protected Cultivation (HortiModel 2006)

B. Bar-Yosef, S. Fishman, H.P. Klaering

Cl^–, competitive uptake, growth substrate, water stress, N stress

https://doi.org/10.17660/ActaHortic.2006.718.50