Parameterizing macroscopic root water uptake under salt stress and non-uniform salt distribution: II. Field-scale experiments

Autor: Chaali N., Dragonetti G., Lamaddalena N., Todorovic M., Albrizio R, Comegna V., Coppola A.
Jazyk: angličtina
Rok vydání: 2013
Zdroj: 1st CIGR Inter-Regional Conference on Land and Water Challenges, pp. 157–158, Bari, 10-14 settembre
info:cnr-pdr/source/autori:Chaali N., Dragonetti G., Lamaddalena N., Todorovic M., Albrizio R,. Comegna V., Coppola A./congresso_nome:1st CIGR Inter-Regional Conference on Land and Water Challenges/congresso_luogo:Bari/congresso_data:10-14 settembre/anno:2013/pagina_da:157/pagina_a:158/intervallo_pagine:157–158
Popis: Much of the crop response under saline irrigation depends on the root distribution over the root zone. In turn, this largely depends on whether the root system preliminary developed into a saline or non-saline profile. The salt distribution in the root zone depends, besides management practices and other environmental factors, on the complex non-linear processes of water flow and solute transport in soil determining variable distributions and storage of solutes and water along the whole root-zone, as well as their upward and downward fluxes. The effect of all these processes on the response of a crop to irrigation with saline water cannot be assessed without a detailed spatio-temporal monitoring of water contents and solute concentrations in soils during irrigation with saline water. An answer may be a methodology coupling adequate soil monitoring to numerical models simulating the transfer of water and solutes in the soil-plant-atmosphere continuum. A detailed monitoring allows following continuously the evolution of the local processes of water and salt storage and transport which mainly influence root uptake. By integrating such a database in numerical models, insights may be gained on the effects of the main physicochemical interacting processes affecting root-zone salinity and root uptake response to increasing osmotic potentials. Nevertheless, proper modeling and parameterization of the root water uptake as a function of water and salinity stresses remain one of the main challenges. The main reason for this is that the required data cannot be obtained easily and with the necessary detailed spatial and temporal resolution. Additionally, an accurate transpiration rate is required when validating the prediction capacity of the sink term functions in the numerical models. With such premises, this study has investigated the possibility for monitoring simultaneously and continuously the relationship between the macroscopic crop (tomato) response and the evolution of water content, electrical conductivity and root density along the soil profile during the whole growing season of a tomato crop under different salinity treatments. Water storages measured by TDR sensors were used for calculating directly the actual water uptake by the root system along the whole soil profile under the different salinity levels imposed during the experiments. It was observed that during irrigation with saline water the salt content increased along the whole profile but that it tended to accumulate quite uniformly below the 20 cm in the case of the 4 dSm-1 treatment and at depth between 15 and 25 cm in the case of the 8dSm-1 salinity treatment. Compared to the reference freshwater treatment, the evapotranspiration under salinity treatments started to decrease at a threshold value of the time-depth average electrical conductivity (EC) of soil water of about 3dSm-1. Based on the results of soil and plant monitoring, the root uptake process was simulated by using a model for water and solute flow in the soil-plant-atmosphere continuum. This way, the root activity reduction at each depth-node was calculated as a function of the salinity (and eventually water) stress. This enabled relating the distribution of higher/lower activity of root uptake along the soil profile in response to the actual distribution of salts.
Databáze: OpenAIRE
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