This paper addresses the challenges to crop improvement in rainfed environments resulting from water deficit, either directly, or from the inability of plants to access soil water due to subsoil constraints or a combination of stresses. Special reference is made to two ecosystems where plants may be subjected to too much or too little water in the same season: rainfed lowland rice in South and Southeast Asia (flood-drought), and rainfed wheat in southern Australia (waterlogging-drought). In both cases, there are challenges to root access to soil water at depth, some concerns about the roles of root signals, and interest in the contribution from osmotic adjustment and its interaction with root function. Recent evidence is presented concerning the nature of root signals in rainfed lowland rice and their implications for adaptation and crop improvement. The use of fractal analysis for studying root systems is also illustrated with recent data from rice. In wheat, we have validated a method for examining the ability of roots to penetrate an artificial hardpan under drought in the growth room.Using this system, we have identified significant differences between Australian wheat cultivars in hardpan penetration ability, and we are now examining a DHL population. Associated field research has shown some consistency in rankings in the field, which are dependent upon the specific constraints that roots encounter at each field site. In addition, the role of osmotic adjustment in assisting plant response to water deficit is being examined, including any associated changes in access to soil water from deeper layers. Initial results indicate variation between cultivars in the solutes responsible for differing osmotic adjustment, but further work is needed here. These studies have now progressed to the stage that valuable information could be obtained from linkage with proteomic analysis of contrasting cultivars or genetic studies of DHL populations, using well-characterized materials in carefully-monitored environments, including the field.
|Title of host publication||IRRI Drought Frontier Project|
|Publication status||Published - 2007|
|Event||Root Biology and MAS Workshop - Bangalore, India, India|
Duration: 26 Sep 2007 → 29 Sep 2007
|Workshop||Root Biology and MAS Workshop|
|Period||26/09/07 → 29/09/07|