Genetic Analysis of Green Leaf Duration in Spring Wheat

ABSTRACT Genetic approaches to lengthening green leaf duration are becoming more important in spring wheat (Triticum aestivum L. em. Thell.) as increasing temperatures hasten leaf senescence. Green leaf duration after heading (GLDAH) has been reported to provide drought and heat tolerance in several crops. This study was conducted in Montana under a range of temperature and moisture conditions to evaluate the relationship of GLDAH to agronomic traits and to identify quantitative trait loci (QTL) for GLDAH using a recombinant inbred line (RIL) population derived from Reeder (longer GLDAH) and Conan (intermediate GLDAH). Correlation analysis showed a positive relationship between GLDAH and test weight, seed weight, and seed diameter under late‐season heat and drought stress conditions but not under cool, well‐watered conditions. Green leaf duration after heading was negatively correlated with grain yield under cool, well‐watered conditions. Earlier heading was consistently associated with longer GLDAH in a wide range of environments. The QTL QGfd.mst‐4A had an effect on GLDAH under stress conditions in the Conan/Reeder population and an RIL population derived from McNeal/Reeder. The Reeder allele of QGfd.mst‐4A resulted in longer GLDAH and also increased the amount of xylem exudate from de‐topped plants, indicating higher root mass and/or activity. Our results suggest that the impact of alleles at QGfd.mst‐4A may vary depending on the degree of heat and drought stress.