Sunday, November 12, 2006 - 4:00 PM
10-4

Identification of Wheat Genotypes with Large Root Volume to Potentially Increase Drought Tolerance.

Nicholas A. Crowley1, James Uphaus2, and Herbert Ohm1. (1) Purdue Univ, Agronomy Dept, West Lafayette, IN 47906, (2) AgReliant Genetics LLC, Lebanon, IN 46052

Water deficit is a common stress limiting productivity of wheat (Triticum aestivum L.) in large areas of the world.  The root system is important for water and nutrient uptake and anchoring the plant to the soil.  Crop improvements via plant breeding have largely focused on improving above-ground plant traits and grain yield as a ‘composite’ determinant of the plant’s ability to maximize growth under various environmental conditions; with limited research on root growth.  The objectives of this experiment are to identify genotypes with increased root volume for use in breeding as a way to increase drought tolerance of adapted wheat and to develop a more effective method of measuring root volume.
Four greenhouse experiments under controlled fertility, lighting, moisture, and temperature were used with replicated treatments of sand vs. top soil, and 10cm vs. 23cm diameter containers in the initial two experiments.  Washing roots efficiently and effectively was difficult.  Plexiglas root trays were designed to facilitate this process, and were used in the latter two experiments as the plant containers.  Plants were harvested 20d after flowering and roots washed in water.  Root volume was determined in aqueous solution using the WinRHIZO™ computer software.  We have identified Iran 14 as consistently developing less root volume than Iran 49 along with specific adapted genotypes, while the root trays provided excellent analysis and resulted in minimal loss of roots during washing as compared to previous experiments with cylindrical containers. In our two initial experiments, winter wheat line P99608C1, spring growth habit landraces Iran 14 and 49, and SN125 had root volumes of 6.05, 3.85, 10.3, and 3.17cm3/plant (LSD0.05=1.32), respectively, when grown in 23cm containers with sand.  The two latter experiments confirmed these results and identified two additional lines with large root volume.