Effect of heat and precipitation on pea yield and reproductive performance in the field

Pea (Pisum sativum L.) is important globally as a cool season crop. Pea cultivars are heat-sensitive so our goal was to investigate how weather impacted growth and yield in recent cultivars in the Co-operative pea yield trials (2000 to 2009) for a dryland (Saskatoon) and an irrigated (Outlook) location. We explored relationships between days to maturity, days spent in reproductive growth (flowering to maturity), yield and various weather factors. Yield and the length of reproductive growth increased with seasonal precipitation. Pea was sensitive to heat but heat units did not satisfactorily describe growth and yield in all environments. Strong relationships were observed between crop growth and mean maximum daily temperature experienced during reproductive growth, and between crop growth and mean minimum temperature. The greater the mean maximum temperature (>25.5 degrees C), the fewer the number of days (<35) spent in reproductive growth at the dryland location. At Outlook, 35 to 40 d in reproductive growth occurred in a much wider temperature range from 24.5 to 27 degrees C, and irrigation mitigated some reduction in yield. For dryland pea, more than 20 d in the season above 28 degrees C were associated with less time in reproductive growth and less yield. The threshold maximum temperature for yield reduction in the field was closer to 28 degrees C than 32 degrees C from published studies, and above 17.5 degrees C mean seasonal daily temperature. Western Canadian cultivars currently have short lifecycles, which make them heat sensitive. Heat tolerance could be improved by earlier flowering and a longer duration of flowering via an indeterminate habit. Future research will investigate pea nodal development, flowering and abortion patterns in a range of pea cultivars in field conditions.