Investigating Heat Tolerant Traits in Pea Cultivars.

Field pea is a major grain legume crop in western Canada.  However, pea cultivars are heat sensitive and readily abort flowers and young pods in air temperatures above 30 °C, resulting in reduced and unstable yield from year to year.   Our goal is to improve pea heat tolerance through a combination of phenology, pollen viability and canopy traits.  In 2010 to 2012, 12 cultivars were grown in the field in two soil zones at a normal and late seeding date to investigate yield formation in current cultivars.  Daily maximum temperatures >29 °C caused abortion of flowers and young pods.  Yield losses were greater in the later seeded plots where flowering was displaced into warmer temperatures.  In 2012 we mapped the pod yield in more detail to specific nodes, dates of flowering and corresponding weather conditions.  We also measured pollen viability on a subset of five cultivars at one site (2012), noting abnormal pollen tube germination in vitro at temperatures > 30 °C and an overall sensitivity of all five to heat.  The more heat tolerant cultivars achieved greater pod retention through early flowering, and a longer flowering duration via indeterminate growth.  An overview of our findings to date and future research strategies will be presented.