Monitoring wheat root development in a rainfed vertisol: Tillage effect

Good root system development is essential for optimum wheat (Triticum aestivum L.) grain yield, especially under water-limiting conditions. Published information about the influence of tillage system on root dynamic and their effect on grain yield in Mediterranean rainfed Vertisols is scarce. A three-year field study was conducted on a typical Mediterranean rainfed Vertisol to determine, using a minirhizotron system, the effects of tillage system on root growth and grain yield in wheat. Tillage treatments were no-tillage (NT) and conventional tillage (CT). The parameters measured were root length (RL) and root diameter (RD) for 6 depths. Minirhizotron measurements were performed at 5 wheat growth stages. The RL was greater under NT than under CT for most growth stages and depths, this being the key to its greater grain yield (3.2 vs 3.0 Mg ha−1, respectively). The RD was not significantly affected by the tillage treatments, but was lower from stem elongation onward and during the dry years. The key to the development of a good wheat root system is the rainfall received during the tillering stage, regardless of soil water content at planting and rainfall before or after this growth stage. Under the rainfed Mediterranean Vertisol studied, wheat productivity is greater under NT due to better root system development.