Diversity of Root Traits in Great Plains Winter Wheat Under Drought Stress

Drought is considered the main cause for yield reduction in dry regions. The development of a deep and extensive root system is a drought adaptation mechanism to allow water and nutrient extraction from the soil profile. We conducted two studies to investigate the variation in root architecture and its related physiological and morphological traits in winter wheat (Triticum aestivum L.) under drought stress. The first study evaluated 30 genotypes from Colorado, and the second study included 30 entries from seven Great Plains states. Entries were evaluated in a Colorado State University greenhouse in Fort Collins, in 2012 and 2013 in 1 m x 10 cm plastic tubes filled with fritted clay. Drought stress was imposed by withholding water for three weeks after the emergence of the fourth leaf. Roots were separated, washed, scanned, and analyzed with WinRhizo software. Related traits such as water loss from the tubes and above ground biomass were measured. Entries differed significantly (P<0.05) for root traits (average root diameter and total root length overall and for bottom, middle, and top sections, as well as root length per diameter class). Total root length of Colorado entries ranged from 4850 to 7204 cm. Additionally, there were significant positive correlations between total root length and both water loss from the tubes and above ground biomass (P<0.05). The variation in root traits among Colorado and Great Plains winter wheat entries can be exploited in breeding programs to help design plants with the best adapted root traits to withstand drought stress.