|Leakey, Andrew D B|
|Ainsworth, Elizabeth - Lisa|
Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/20/2011
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: With increases in mean global temperatures and associated climate change, extreme temperature events are predicted to increase in both intensity and frequency. Despite the clearly documented negative public health impacts of heat waves, the impact on physiology and yields of key agricultural species is less certain. Separate plots of soybean were subject to three day heat wave treatments at three progressive developmental stages: full bloom (R2), beginning pod development (R3) and beginning seed fill (R5). The experimental design was arranged in a randomized complete block design, n=3, in which three-m diameters plots were heated using an IR heating array with 24,000W maximum output. Temperatures of the canopy surface in the heat wave plots were maintained at a minimum 6 deg C above the 30-year mean temperatures for that day, with the daily maximum temperature threshold of 40 deg C. There was a strong effect of heating on photosynthesis measured on day three of the heat waves, particularly for the second and third heat waves of the season, with complete recovery within two days following the end of the heat wave. Soil respiration was stimulated during the first heat wave when the surface soil moisture was plentiful and before the canopy closed but no effects on soil respiration were seen in heat wave two and three after canopy closure. Total ascorbate levels decreased throughout the heat wave, consistent with increased ROS production induced by the heating. The impact of the reductions in photosynthetic carbon gain resulting from the heat wave treatments on end of season yield are being analyzed.