Wheat

Wheat (Triticum aestivum) is globally the most traded crop. The single, most important factor that jeopardizes wheat yield is drought. While some variation was found among genotypes in the threshold for partial stomatal closure with soil drying, the extent of variation in the threshold reported thus far is limited. Surprisingly, partial stomata closure in response to vapor pressure deficit was found for all tested genotypes of wheat in the range of 1.9 and 2.3 kPa. The universal expression of this trait may be the result from a hydraulic restriction in the roots of wheat. Evidence has been obtained indicating that aquaporins are directly involved in the hydraulic conductivity of wheat root cells. In a study of a RIL population from two wheat lines with extremes in their vapor pressure deficit sensitivity, six QTLs were identified that explained most of the variation in sensitivity.