Wheat Varietal Adaptation Needs for Predicted Abiotic Stresses in Dry Enviornments.

Wheat is grown annually on 220 million ha and is the most widely grown crop globally with 160 million ha of this being rainfed.  Despite decades of investment in plant biotechnology, when it comes to complex traits such as heat and drought adaptation, wheat breeding pipelines are still largely driven by empirical approaches, though, in cases where more deterministic approaches have been followed up, it is clear that they are effective in boosting genetic gains in the field and in genetic dissection of complex traits. But yield gains for rainfed wheat in developing countries have been mostly marginal, partly due to lack of access to improved varieties and lack of adoption of optimal agronomic practices. Though uncertainty surrounds projected rainfall change, many models suggest wheat producing regions in developing countries will face increased drought. There will be some crop growth compensation through the CO2 rise linked to warming, but the net effect of climate change on wheat yield in developing countries is likely to be negative. Synthetic wheats, derived from crosses between T. durum and T. tauschii, have shown an increased capacity to extract water from soil. A large scale evaluation of accessions in the CIMMYT and ICARDA gene banks, using high throughput technology, has identified significant variation for drought tolerance relevant traits among landraces and wild relatives, including biomass, canopy temperature, stay green and root biomass. The presentation shows the results from this evaluation and the impact the great impact the better characterization of parental lines has on performance of elite lines. A key to further enhance the drought tolerance of elite lines is to introgress genes for resistance to soil borne diseases. Priority soil borne diseases are cyst and root lesion nematodes and fungal diseases such as fusarium crown rot.