Wednesday, November 15, 2006 - 9:15 AM

Net CO2 Uptake Rates for Wheat Under Saline Field Conditions: a Novel Method for Analyzing Temperature Effects on Irrigation Management.

Jiftah Ben-Asher, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion Univ of the Negev, Beer Sheva ,, 84993, Israel

Net CO2 uptake rates (PN) were measured under relatively moderate climatic conditions in Chukurove basin Turkey.The higher temperatures and lower relative humidity in the field led to a rapid response to drought. The upper envelopes of scatter diagrams for PN versus temperature which indicate the maximal rates at a particular temperature, were determined . As leaf temperature increased above 10 °C, for wheat under saline conditions ( near karakash on the easterm mediterranean ) the maximal PN increased exponentially, reaching maxima of 12 μmol m-2 s-1.near 21.5 °C. For wheat under more favourable conditions near Adana Turkey, as leaf temperature increased above 5 °C, the maximal PN increased exponentially, reaching maxima of 26 μmol m-2 s-1.near 24 °C μmol m-2 s-1,. Based on the Arrhenius equation, the apparent activation energies of enzymatic metabolism were 118 and 30 kJ mol-1, for wheat under favourable and saline conditions respectively. These values are within the range determined for a diverse group of species using different methodologies. Above the temperature of maximalP N it decreased by an average of 30 % per °C for the two cases. Such steep declines with temperature indicate that irrigation then may lead to only small enhancements in net CO2 uptake ability. The study was supported by the ICCAP project RIHN Kyoto Japan.