Enhancing Nitrogen-Use Efficiency in Winter Wheat to Combat Heat Stress Caused By Climate Change.

Enhancing Nitrogen Use Efficiency in Winter Wheat to Combat Heat Stress Caused by Climate Change

Nitrogen use efficient (NUE) genotypes may be more adapted to heat stress caused by climate change since they are able to pull from their stem reserves and continue grain filling when photosynthesis is compromised.  Breeding for regional adaptation of nitrogen use efficiency in a changing climate will be important to maximize yields in the future. The main objectives are to identify winter wheat genotypes that have sufficient NUE across environments, estimate the effect of warming on NUE among the genotypes, and determine whether NUE is associated with heat stress resistance.  In a 2012-2013 preliminary study eight winter wheat genotypes were grown as replicated hill plots at Spindletop Farm in Lexington, KY under 3 N environments. Planting dates were staggered to simulate climate change effects. The results showed that NUE had a significant correlation to temperature and planting date, p<.01.   In 2014, forty lines from an elite SRW mapping panel were planted in a randomized complete block design under warmed and controlled conditions at Spindletop Farm in Lexington, KY.   Buried heating cables were used to warm the rhizosphere 3-5 ° C above ambient temperature.  A Campbell weather station at the site monitored soil and air temperature in both control and warmed treatments.  The impact of warming on N uptake and partitioning was measured; grain yield and other agronomic traits were also assessed under control and warming conditions.   In an adjunct study, a larger set of lines that included the 40 was planted in a randomized block design under two N environments (0 and 100 lb/acre N) at Princeton and Lexington, KY to determine NUE stability among the genotypes.