Background and Objective

In this project root growth will be studied in sorghum and maize grown under different water supply and with ambient and elevated CO2 concentration as expected at the end of this century. Experimental data will be used to develop models for root growth of the two plant species, which can be used to predict water uptake and water limited biomass production under changed climatic conditions in the future.

Approach

Sorghum and maize are cultivated on the FACE-field site of the Thünen-Institute under different CO2 and water supply. In addition both crops are grown at Kiel to assess the influence of temperature on root growth.

Data and Methods

Root growth will be determined by taken soil sample and by using Minirhizotrons. Data are used for the development of models for root growth, which can be used to estimate the water uptake under climate change.

Our Research Questions

Does the root system of maize and sorghum vary

• in temperature sensititivity of root growth
• in rooting depth
• in root/shoot ratio
• in the response of root growth to soil drought with ambient and elevated CO2 concentration

Results

The 'Sorghum cultivars used in this study had a more branched and deeper root system as compared the maize cultivar. This advantage of sorghum existed also under elevated CO2 and drought conditions. Moreover, CO2 enrichment decreased root length density in the top soil layer, and had a positive effect in deeper soil layers.