Diversity of Root Traits in Winter Wheat Under Drought Stress.

Drought is among most serious environmental challenges farmers face and is considered the major 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. The objective of this study was to investigate the variation in root architecture and its related physiological and morphological traits in winter wheat (Triticum aestivum L.) under drought stress. In this study, we evaluated 30 entries (cultivars and advanced lines) from Colorado. Entries were evaluated in a Colorado State University greenhouse, Fort Collins, CO in 2012 in 1 m x 10 cm plastic tubes filled with fritted clay. Drought stress was imposed for three weeks after the emergence of the fourth leaf. Roots were separated, washed, and scanned, and analyzed with WinRhizo software. Other physiological and morphological traits such as water loss from the tubes and above ground biomass were measured. Entries differed significantly (P<0.05) for water loss from the tubes, above ground biomass, and WinRhizo root traits (average root diameter, total root length, bottom, middle, and top sections root length, as well as root length per diameter class for all classes and sections). Total root length of entries ranged from 4850 to 7204 cm and average root diameter ranged from 0.338 to 0.402 mm. Additionally, there were significant positive correlations ((P<0.05) between total root length and both water loss from the tubes and above ground biomass (r= 0.56 and 0.50 respectively, n = 30). The variation in root traits among Colorado winter wheat entries can be exploited in breeding programs to help design plants with the best adapted root traits to withstand drought stress.